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Ontario Department of Mines Geological Branch

Open File Report 5001

Geology of the Black River Area

1967

ONTARIO DEPARTMENT OF MINES

GEOLOGICAL BRANCH

OPEN F I L E REPORT

No 5001

GEOLOGY OF THE

BLACK RIVER AREA

MARCH 1, 1©67

by V. G. M i l n e

v6',

O N T A R I O

DEPARTMENT OF MINES

GEOLOGICAL BRANCH PARLIAMENT BUILDINGS

TORONTO 2, ONTARIO

Open-file Reports

Open-file reports are made available to the public subject to certain conditions. Anyone using them shall be deemed to have agreed to these conditions which are as follows:

This report is unedited. Discrepancies may occur for which the Department does not assume liability.

Open-file copies may be read at the following places:

The Library (Room 1433, Whitney Block), Department of Mines, Parliament Buildings, Toronto.

The office of the Resident Geologist in whose district the area covered by this report is located.

A report cannot be taken out of these offices. Handwritten notes and sketches may be made from it. This particular report is on file in the Resident Geologist's office located at:

179 South Algoma St. , Port Arthur

pen-file reports cannot be handed out for office reading until a card, giving the name and address of the applicant, is filed with the Resident Geologist or Librarian.

A copy of this report is available for inter-l ibrary loan.

The Department cannot supply photocopies. Arrangements may be made for photocopying by an outside firm at the user ' s expense. The Librarian or Resident Geologist will supply information about these arrangements.

The right to reproduce this report is reserved by the Ontario Department of Mines. Pe rmi s sion for other reproduction must be obtained in writing from the Director, Geological Branch.

J. E. Thomson, Director, Geological Branch.

ONTARIO

DEPARTMENT OF MINES

GEOLOGY OF THE BLACK RIVER AREA

DISTRICT OF THUNDER BAY

by

V. G. Milne

Geological Report No. 5001

Project 64-7

Table of Contents

Abstract

Introduction

Prospecting and Mining Activity-

Present Geological Survey

Acknowledgments

Previous Geological Work

Topography

Natural Resources

General Geology

Table of Formations

Archean

Mafic to Intermediate Metavolcanic Rocks

Silicic to Intermediate Metavolcanic, Pyro and Metasedimentary Rocks

Metasedimentary Rocks

Mafic and Ultramafic Intrusive Rocks

Metagabbro

Serpentinized Peridotite

Anorthositic Gneiss

Mineralization

Early Silicic Plutonic Rocks

Late Silicic Plutonic Rocks

Fourbay Lake Pluton

Gowan Lake Pluton

Bullring Lake Pluton

Musher Lake Pluton

Dotted Lake Batholith

Silicic Dikes

-// -

Proterozoic

Diabase Dikes 84

Pleistocene and Recent 88

Structural Geology 93

Folding 93

Faulting 100

Major Faults 101

Bullring Lake Fault 101

Phil Lake Fault 102

Pinegrove Lake Fault 102

Jenny Creek Fault 103

White Lake Fault 104

Other Faults 104

Economic Geology 107

Introduction 107

Stratigraphic Considerations in Mineral Exploration 108

Descriptions of Mineral Showings 111

Fairservice Occurrence(1) 111

Kusins Occurrence(2) 113

von Klein Occurrences(3) 115

Occurrence No. 1 116




Other Mineral Occurrences 120

Considerations in Future Exploration 122

Selected ZefccHCts /IS

- / / / -

FIGURES

No. 1 - A hypothetical structural cross-section on a north-

south line through the Black River and bordering areas

to the north and south, (page 99)

No. 2 - Plan of the pit locations and geological sketch map of

the Kusins lead-zinc showing, (page 113)

No. 3 - Surface geology and location of drill holes and electro

magnetic anomalies on the von Klein property based on

assessment work filed in 1962 by Mclntyre Porcupine Mines

Ltd., O.D.M. File No. 63-1210. (page 116)

No. 4 - Geological plan in the location of electromagnetic

anomalous zone B (see Figure No. 3) with assay results

of trench samples. Based on assessment work filed in 1962

by Mclntyre Porcupine Mines Ltd., O.D.M. File No. 63-1210.

(page 118)

No. 5 - Geological plan in the location of electromagnetic

anomalous zone C (see Figure No. 3) with assay results

of trench samples. Based on assessment work filed in

1962 by Mclntyre Porcupine Mines Ltd., O.D.M. File No.

1210. (page 118)

"^ Illustrations are located at the rear of this report

ABSTRACT

The map-area covers approximately 600 square miles bounded

on the east by the Pic River Area (Ontario Department of Mines,

196 ), on the north by the Manitouwadge Area (Ontario Department

of Mines, 1957) and extending as far east as White Lake. The

report describes the geology, structure and mineral showings and

briefly discusses regional structure on the basis of information

from this area and from the adjoining areas noted above.

The consolidated rocks are all of Precambrian age but much

of the area is blanketed by thick deposits of glaciolacustrine

and glaciofluvial gravel, sand and clay of Pleistocene age. Within

the map-area a mafic metavolcanic formation, which includes

pillowed units, has been interpreted as the oldest formation.

The mafic metavolcanic rocks appear to form the lowermost horizon

of a gradational sequence, younging throughAa thin formation of s'l/iti't

mixed a-oi-4 to intermediate metavolcanic rocks, pyroclastic rocks

and minor metasediments,.into a thick succession of metasediments

consisting essentially of conglomerate and greywacke. These rocks

have been intruded by metagabbro, serpentinite and granodiorite

gneiss and folded about east-northeast and north-northwest

trending axes. The extrusive and sedimentary rocks have been

regionally metamorphosed to amphibolite facies and metamorphism

and folding are believed to have developed at catazonal level

cogenetically with the intrusion of the granodiorite gneiss which

forms a domical mass of batholithic dimensions. Subsequently

these rocks were intruded by large plutons, some of batholithic

size, composed of hornblende-biotite and biotite granodiorite and

- Vttt -

quartz monzonite. Finally all these formations were intruded by

swarms of diabase dikes.

Small showings of zinc and lead-zinc are present in the

mafic metavolcanic rocks but of greater economic interest are 51 lie i e

copper-nickel showings in the pyroclastic-acid- metavolcanic

formation adjacent to the mafic metavolcanic unit. In the

original copper-nickel showings in the area the mineralization

occurs in isolated blocks of amphibolite rafted in pyroclastic S///V/C

and areid extrusive rock units. Subsequent work has indicated

mineralization in fracture and shear zones along the boundary of

the mafic metavolcanic and pyroclastic formations and geophysical

prospecting has outlined a number of extensive electromagnetic

anomalies in the same zone. This area was under examination

in 1966.

-/y

(Project 64-7)

Geology, of the Black River Area

by

V. G. Milne 1

Introduction

There has been continued prospecting interest in the

Manitouwadge area since the discovery of the Geco ore body

in 1953 and more recently, much interest has been shown in

copper, and copper-nickel prospects, in the Marathon area

on the northeast shore of Lake Superior. A mapping project

was started in 1963>and in that year the/Pic River area

(Map Nos. 2098, 2099), north of Marathon, was completed. /v

The Black River area adjoins the Pic River area on the east

and extends north to the Manitouwadge Area (Map No. 1957-8). A.

The area covered in this report lies between latitudes

48°45T and 49°07T and longitudes 85°32» and 86°05» in the

District of Thunder Bay. This represents about 600 square

miles and includes parts of Grenville, Leslie, Gertrude and

Cecil townships. The eastern limit of the area follows the

west boundaries of Bryant, Atikameg and McGill townships and

the west limit is marked by the east boundary of township

75 and corresponds to the east boundary of the Pic River

Area Map Nos. 2098 and 2099- Ontario Highway No. 614 to

Manitouwadge extends north-south through the centre of the

area and the southern limit of the map is about 4 miles

Geologist, Ontario Department of Mines, Toronto. Manuscript received by the Director, Geological Branch, 20th October 1966.

north of the junction between this highway and Trans-Canada

Highway, Highway No. 17. The northern limit of the area

corresponds approximately to the southern limit of the

Manitouwadge AreaAMap No. 1957-8'.

Access to the area is very good. Much of the area is

accessible from Highways No. 17 and No. 614, Ontario Paper

Company roads, Marathon Corporation roads .and old lumbering

roads branching from Highway No. 614 to Theresa Lake, to

Dead Otter Lake, and to Amwri Lake and the Black River.

Log driving trails along the Black River and numerous over

grown logging trails also facilitate access. The Canadian

Pacific Railway spur line, extending from the main line at

Struthers to Manitouwadge, also passes through the centre of

the area. The least accessible parts of the area are in the

west and northeast but these can be reached quite easily by

float plane from White River about 40 miles east-southeast

of the map-area.

Prospecting and Mining Activity

Since discovery of the ore bodies in the Manitouwadge

area in 1953 the whole district generally has been regarded

with interest. Claims have been staked and restaked at

various times, mostly along a belt extending northeast from

Valley Lake to Dead Otter Lake. Extensive new staking was

done in the spring of 1965 in the area north, south and west

of Dotted and Dead Otter Lakes. In I965 most of the ground

between Dotted Lake, Theresa Lake and the Black River was

covered by staking,

In 1962 Mclntyre Porcupine Mines Ltd. surveyed and drilled

a 52 claim area enclosing the yon Klein (Location No. 3, see

map) copper-nickel showing just east of Summers Lake on

Highway No. 614 (Assessment File No. 63- ' P ) . I-u 196jj

auamo da illiii{j, waa dune by •M-i«4ag~^<M»f»og^^ LtTf.

in the area between Amwri, LflV nr>H +-h" BirxJi^iwEti %i:7;"l-

ir mila Lu 1 iiillu uaot of tho 'ifivei1 (TiltrWU'.' 6J- "—-) "awd

^ n late 1963 T. and W. Kusins uncovered a lead-zinc showing

(Location No. 2, see map) between the Black River and Valley

Lake, about 3/4 mile west of the river. The Kusins showing

was examined in 1965 by the Consolidated Mining and Smelting

Company of Canada Ltd. (M,M &»"''i£o ^ V .

(/LJj%(p)

At the time of writing Caravelle Mines Ltd. holds a large

block of more than 100 claims enclosing the Von Klein copper-

nickel showing and extending from Theresa Lake in the east

to Highway No. 614 on the west, south of Dead Otter Lake.

Irish Copper Mines Ltd. holds claims north of Dotted Lake

enclosing a zinc showing (Location No J^£, see map) staked

by B. Fair.service. Both companies flew geophysical surveys

during the summer of 1965 and follow up work is continuing.

A number of claims are held by M. Grey on the south and east

of the Caravelle Mines block of claims.

Present Geological Survey

The report area was mapped during the summer months of

1964 and 1965. About 150 square miles in the southwest

quarter of the area were mapped in I964 with the assistance

of M.E. Coates, senior assistant, and D. McBride, I. Ferguson,

and R.A.F. Grieve, junior assistants. The remainder of the

area was covered in I965 with about 150 square miles in the

southeast quarter being mapped in semi-detail and a further

300 square miles in the northern half of the area being

covered by reconnaissance mapping. Assistance in 1965 was

provided by R.A.F. Graham and W. McCrindle, senior assistants,

and I. Ferguson, R. Holland and J.P. Scholz, junior assistants.

Mapping was done on base maps of ^ mile to—1—inch -scale

supplied by the Cartography Unit of the Ontario Department

of Mines and traverses were spaced roughly at ~i to 2 mile

intervals. Outcrop locations and outlines were determined

from air photographs -of ~i m±3re~ ttr-l inch acalc, or from

pace-and-compass measurements tied into recognizable

features on base maps and air photographs. Information

from prospect plans and drill logs in the assessment work

files of the Ontario Department of Mines and information

derived from aeromagnetic maps (0.D.M.-G.S.C. Nos. 2157G,

2158G, 2168G and 2169G) has also been used in preparing

the map.

A preliminary uncoloured geological map of the south-

west quarter of the area, on the scale of jz-milo to 1- inch,

was released in April 1965 (Map No. P.294) and four uncoloured an

maps of- the same scale, together covering the whole report

area, were issued in February 1966 (Map Nos. P.332, P.333,

P.334 and P.335). The final coloured maps Nos. Oooo &»d 000Q. ///>c/> ?o

(back pocket) are reproduced on the scale of a-mile tt>

1 inohh.

Acknowledgment s

The author appreciates the cheerful and capable

co-operation of senior assistants M.E. Coates, R.A.F. Graham

and W. McCrindle all of whom conducted independent mapping

in the area. The accurate and willing work of junior

assistants I. Ferguson, R.A.F. Grieve, R. Holland, D.McBride

and J.P. Scholz is also greatly appreciated. Information

on trails in the Dotted Lake-Mobert Creek area provided by

B. Fairservice of Manitouwadge was of considerable help and

thanks are also due to E. Mitchell, Forest Ranger with the

Department of Lands and Forests in Manitouwadge.

Previous Geological Work

Geological examination of the area has been very

limited. The general geology of the area was described by

J.E. Thomson (1931) as part of the Hgrnlor-White Lake area ' -.;>Z-

report in 19>31'. More recently the south part of the area

was covered in an examination by M.W. Bartley and

T.W. Page for the Canadian Pacific Railway Company (1957)

in 1957. Otherwise the area has received little attention.

Topography

The northwest corner of the area is drained by north—

flowing creeks, originating from lakes such as Fourbay Lake

and Gaffhook Lake, which ultimately join the Pic River west

of the area via Nama Creek. In the remaining area drainage

flows south via the Black River and its tributary creeks

and, in the extreme southeast corner water^gathered in

#White Lake drains into White River south of the map-area.

The Black River meanders roughly south-southwest through

the centre of the area and occupies a low, wide valley

floored by a thick Pleistocene succession of varved clays

overlain by bedded silty sands with coarse sands and minor

gravels. These glaciovlacustrine deposits extend back up

the valleys of tributary creeks and at many places the

banks of the river and creeks consist of steep clay and sand

cliffs up to 50 feet above water level. Similar clays and

sands occupy the valleys of creeks which drain into Nama

Creek in the northwest of the area, and these deposits are

extensions of clays and sands flooring the Pic River valley

to the west of the map-area.

The rocks underlying the area west of the Black River

and north of Mobert Creek are predominantly granitic.

These granites are well exposed and high bare ridges are

common. The trend of th ese ridges is controlled by the

gneissosity and jointing, and northeast-southwest trending

7

valleys have been accentuated by glacial scouring. In the

area east of the Black River and south of Mobert Creek the

topography, where it is not influenced by drainage or glacial

scouring, is largely controlled by the underlying rock type.

The topography in areas underlain by paragneisses, acid

pyroclastic rocks and granitic rocks consists generally of

low rolling ridges interspersed with swamp and little rock

exposure whereas the mafic metavolcanic rocks commonly form

high bare ridges which conform to "the structural trends in

these rocks. (?fa&**»//$ w* I O^JMO) '/

In the main drainage valleys, as mentioned above, drift

cover is thick and rock exposures are few. Elevations in

the area, other than in the Black River valley, range

between 1000 and 1400 feet above sea level.

Natural Resources

Much of the area has been cut or burned over so that

thick tree cover now consists of older hardwood, mostly

trembling aspen and white birch, mixed with a dense younger

growth of softwoods, predominantly black spruce and balsam

with some jjackpine in granitic and in sandy areas to the

north. Scattered areas of cedar and tamarack occur around

lakeshores and in the swamps.

Two fires, one in 1923 and another in 1934> affected

large sections of the area extending as an almost continuous

swath about 6 miles wide, southwest from McGraw Lake to

Alberta Lake, a distance of about 26 miles. Other smaller

sections have been burned. In 1899 a section 2 miles wide

extending south from Twist Lake to Roger Lake was burned

and, in 1941 fire destroyed a I2 mile wide section paralleling

the west shore of Kaginu Lake in Gertrude township.

A large part of the map-area lies in the Black River

watershed and the timber resources of this section are held

by the Ontario Paper Company Ltd. The present highway to

Manitouwadge, Highway No. 6l4,in part follows old timber

cutting roads. Old roads in the south of the area are no

longer maintained but present cutting operations, which are

continuing northeast of the map-area, are serviced by a

private gravel road which branches off Highway No. 614

just north of No. 1 Lake and follows the Black River and

Macutagon River northeast. Between 1950 and 1957 a large

section was cut over between the Black River and the east

limit of its watershed extending from the south of the area

north to Dotted Lake, and in a 2-mile wide belt on the west

side of the Black and Macutagon Rivers from Barehead Creek

to the north of the area.

The northwest corner of the map-area lies within the

Nama Creek watershed and the southeast of the area lies in

the White River watershed. The timber resources of these

sections belong to the Marathon Corporation of Canada Ltd.

and the Abitibi Paper Company Ltd., respectively. Most of

the Abitibi section has been cut over and there are numerous

abandoned camps and overgrown trails in this region ,

The Marathon Corporation limits lie within Grenville and

Leslie townships. Cutting operations started in this region

in 1948 and are continuing. Access to Fourbay Creek is

possible via an old Marathon Corporation cutting road which

branches south at Nama Creek from the Industrial Highway

west of Manitouwadge.

The area is readily accessible from Trans-Canada Highway,

Ontario Highway No. 17> and large numbers of tourists use

the roads in the area. Lakes accessible by road are

extensively fished and fishermen and hunters are flown into

many of the less accessible lakes, in the west and northeast

of the area from White River airbase. Pike and pickerel

are relatively plentiful in most lakes but Dead Otter and

Dotted Lakes provide poor fishing although there are pike

in the small lakes just north of Dotted Lake. Speckled

trout have been caught in Mobert Creek, Dotted Creek and

in Amwri Creek.

Moose, bear, beaver and partridge were seen frequently

in the area and bobcat, deer»fox and otter were also seen.

There are a number of trap lines in the area operated by

trappers from Manitouwadge and Heron Bay.

There are no permanent residents in the area but the

gate operator on the Ontario Paper Company road lives

seasonally in the gatehouse at the junction with Highway

No. 614 and the Department of Lands and Forests maintain a

towerman at Dead Otter Lake during the fire season. The

tower is accessible by a rough road from Highway No. 614

to Dead Otter Lake and then by walking trail south from the

towerman's cabin on the lakeshore. In addition the

Ontario Department of Highways operates a road maintainance

camp on Highway No. 614 just north of Barehead Creek.

General Geology

The bedrock in the area is all of Precambrian age but

thick unconsolidated varved clays, silty sands and gravels

of Pleistocene and Recent age occur along the major

drainage valleys. The northern half and western parts of

the area are underlain essentially by granodiorite gneiss

which constitutes part of a large domical batholithic mass. parts

In the south and southeastôf the area the rocks consist of

an intensely folded series of metavolcanic, pyroclastic and

metasedimentary gneisses metamorphosed to almandine amphi-

bolite facies, and intruded by synorogenic serpentinite,

peridotite, and amphibolitic metagabbro sheets and lenses,

and granodiorite gneiss. These are all intruded by younger

plutons of massive augite and hornblende-biotite granodiorite, •^QA &L\î /QsT&s- \Cc£< c i l C'

quartz monzonite and^ggânite. These younger intrusive rocks have a relatively high magnetic response and the general

outline of the plutons can be determined from aeromagnetic

maps (Maps 2157G, 2158G, and 2168G). The serpentinite-r\

peridotite intrusives are also readily apparent on these maps.

11

Finally the whole area was dissected by swarms of diabase

dikes which intrude all the above mentioned formations.

Retrogressive metamorphism appears to be associated with

late faulting and shearing in the area and produces much

epidote in formations of basic composition and converts

biotite to chlorite in the pelitic and quartzo-feldspathic

formations.

None of the rocks in the map-area have-been dated but

ages have been determined in the adjoining Manitouwadge area

for biotites in the paragneisses (,1961), leads in the Wilroy

ore body Q965) and feldspars in granites and pegmatites I W M *i »/

cutting these f»1965). These determinations indicate that

the last maj'or metamorphism of the rocks occurred about

2600 million years ago, therefore the metasedimentary and

metavolcanic rocks would be considerably older than this.

The same granites and pegmatites that occur in the

Manitouwadge area are present in the Black River area and

the metasedimentary and metavolcanic rocks of the two areas

are believed by the writer to be equivalent. All the rocks

in the area therefore, other than the diabase dikes, can

reasonably be regarded as of Archean age. A Whole Rock

K-Ar age determination on a diabase dike outcrop about 4

miles south of the map-area (1965) gave an age for the rock

of 2320 million years. It is probable that there are a

number of different ages of diabase dike in the area.

TABLE OF GGfiTE-NT-S- fo£rf$T1 »/U$

CENOZOIC

Pleistocene - Varved clay, silty sand, sand and Recent and gravel.

;S£eat Unconformity

PRECAMBRIAN

PROTEROZOIC

Diabase 4±ksaB—

ARCHEAN

a / quartz diabase, porphyritic

diabase.

Late Silicic Plutonic Rocks H

•f hornblende-biotite granodiorite and quartz monzonite, biotite granodiorite, augite granodiorite, aplite, pegmatite, feldspar porphyry, hornblende-feldspar porphyry, muscovite granite, augite syenite and lamprophyre dikes.

Intrusive Contact

Early Silicic Plutonic Rocks H

f Mbrnblende-biotite granodiorite gneiss, biotite granodiorite gneiss, feldspar augen gneiss, migmatite.

Intrusive Contact

Mafic and Ultramafic Intrusive Rocks N

f irietagabbro, serpentinized peridotite,

anorthositic gneiss.

Intrusive Contact Metasedimentary Rocks

f- Conglomerate, greywacke, arkose, biotite-and muscovite-quartz-feldspar gneiss,

. sillimanite gneiss, garnet-biotite schist.

Acid to Intermediate Metavolcanic, Pyroclastic and Metasedimentary Rocks

f- acitic and rhyolitic flows, flow breccia, agglomerate, tuff, greywacke, iron formation, biotite gneiss, -wiymulitu.

Mafic to Intermediate Metavolcanic Rocks f amphibolite, hornblende gneiss, pillow ' l a v a , 4»igftittliLt3.

•Bacio- to Intermediate Metavolcanic Rocks

An irregularly shaped, highly folded mass of mafic

metavolcanic rocks occupies the south-central part of the

area. The original total thickness of these metavolcanic

rocks cannot be determined as the formation is in contact

with granitic intrusive rocks over much of its length. The

maximum unfolded thickness of the mafic metavolcanic formation

as it occurs in the area would probably be less than 4000

feet.

The rocks of this formation consist principally of

metamorphosed volcanic flows of basaltic to andesitic

composition, and pillowed flows make up a large part of the

sequence. The most common rock type is a fine-to medium-

grained mafic amphibolitic rock, dark green to dark grey

or black in colour, and usually foliated with planar or

fibrous orientation of hornblende grains. Quite frequently

the foliation is not strongly developed and is difficult

to detect. Schistose rock occurs only locally in shear

zones and occasionally, for example west of No. 2 Lake, very

fine-grained amphibolites develop a slaty structure. Medium— /

to coarse-grained flows are also present. These medium-/to

coarse-grained amphibolites may be equigranular or may

consist of poecilitic hornblende grains up to 2 inch in

diameter enclosing medium-yto fine-grained feldspathic or

saussuritic material, as in the area north of Pinegrove Lake.

Pillow lava is found throughout the area and is generally

fine-/to medium-grained but coarse-grained pillowed flows do

occur, for example northwest of Dead Otter Lake. Quite often

the centres of the pillows are lighter in colour than the

margins. Most commonly this is apparent as a slight difference

in the shade of green of the weathered surface between the

centres and the rims but in some outcrops, for example on

the Dead Otter Lake road opposite the south end of No. 3

Lake, the difference between the pillow core and rim is very

marked, the cores being light buff in colour and the rims

dark green. The pillows are invariably stretched and the

shearing may be severe enough to destroy the pillow structure

and convert the rock to a laminated hornblende gneiss with

dark green and light green or buff laminations an inch or

less in thickness liutu'-'S?)*. Lamination is also developed

in some non-pillowed flows. In coarse-grained lavas

lamination is generally poor or absent but in finer grained

flows it is often well developed with alternating light and

dark green bands. Grain orientation is also better developed

in the finer grained lavas. Good exposures of finely laminated

hornblende gneiss outcrop in the area west of No. 4 Lake .

between Roger and Olga Lakes.and along the northwest side

of Phil Lake. Epidote^sometimes develop^ as a major consti

tuent in the finely laminated gneisses.

Very occasionally porphyritic feldspar is present in the

fine—grained mafic lavas, for example in the pillowed lava in

the railway cut about 6000 feet north of Phil Lake, and

scattered exposures of vesicular and amygdular lavas were

found. Disseminated pyrite is found throughout the mafic

metavolcanic rocks and locally small concentrations of

pyrite occur in shear zones as for example south of Dead

Otter Lake, or on the shores of Theresa Lake.

The various types of amphibolite, coarse-grained, fine

grained, pillowed, non-pillowed etc. grade into each other

indicating that the variations in texture and structure are

related to variations in cooling rates, in the effects of

shearing etc. in individual flows and not to the existence

of separate flows with each of these different textures or

structures. The contacts of individual flows were rarely

seen, and intrusive metagabbroic amphibolite identical in

appearance to the coarse metavolcanic amphibolites intrude

the metavolcanic and metasedimentary rocks. It is possible,

that there is more intrusive amphibolitic material present

than is indicated on the map but it is not believed to be

quantitatively important. Since flow contacts are rarely

seen measurement of flow thicknesses is not possible.

The contact between the mafic metavolcanic rocks and

the,granodiorite gneiss is very poorly exposed being, for A A

the most part, buried beneath thick drift cover. The

granodiorite gneiss is intrusive into the metavolcanic

rocks with some interlayering of the two rock types over a

narrow zone of about 100 feet and the granodiorite is

16

hybridized slightly to a more mafic hornblendic granodiorite.

The contact between the metavolcanic amphibolites and the

massive biotite leucogranodiorite of the Dotted Lake Batholith is

better exposed. Good exposures of the contact can be found on the

southwest side of Dead Otter Lake. The leucogranodiorite is

intrusive into the metavolcanic rocks with sharp contacts and

generally in the contact area it is slightly finer grained and main

darker than in the interior of the/mass. The granodiorite in

contact with the metavolcanics is invariably sheared and this

shearing can be severe causing the formation of a granodiorite

gneiss. The shearing parallels the contact and the foliation of

the metavolcanic rocks.

Scattered granitic dikes are present throughout the area of

metavolcanic rocks but in the region between Garoche Lake and

Olga Lake the number of granitic dikes and sheets intruding the

metavolcanic rocks increases to the extent that the rocks are

essentially migmatites. Migmatite is also developed locally

around some of the smaller granitic bodies intruding the

metavolcanic rocks, for example in exposures in the railway cuts

north of Phil Lake (Photo No. 3).

The bulk of the mafic metavolcanic rock formation consists

of amphibolite and hornblende gneiss composed essentially of

dark green hornblende, and plagioclase feldspar ranging in

composition from oligoclase to andesine. The plagioclase

grains show simple and oscillatory zoning. Quartz is common

and most sections are cut by quartz stringers but large

quartz veins are not common. Garnet is rare but magnetite,

apatite, sphene, chlorite and epidote are common accessories.

Epidote minerals are developed in the amphibolites and

hornblende gneisses in varying degree. Epidote is absent

or an unimportant accessory in most of these rocks except

in the amygdular flows where epidote is an important

constituent concentrated in the original amygdular spots

with biotite and feldspar and surrounded by hornblende and

plagioclase of the ground mass. This retention of the

original compositional inhomogeneity of the rock indicates

the very limited range of diffusion during metamorphism of

these rocks. In general where epidote is an important

constituent of the no.-amygdular flows it appears to be of

secondary origin and related to fracturing and faulting of

the rocks. In slightly altered rocks jM4 epidote mineral

is largely confined to thin stringers with slight dusty

alteration of the plagioclase in the rock adjacent to the

stringers. In more intensely altered rocks which commonly

seem to occur near faults, for example in the railroad

cuts north of Phil Lake, the epidote pervades the whole

rock and is frequently accompanied by hematitic staining. z.

The granitic rocks in the fault zone are similarly epidotis'ed

and hematitized.

Most of the epidote is secondary in origin and the primary

metamorphism in the area appears to have converted the vol

canic flows to rocks composed of hornblende plus oligoclase-

andesine feldspar with scattered garnet and minor epidote.

These rocks would be ranked in the almandine amphibolite

metamorphic facies of Fyfe, Turner and Verhoogen (1959),

and are therefore comparable in metamorphic rank with the

mafic metavolcanic rocks of the Pic River and Manitouwadge

areas.

\

\

\.

\

Disseminated pyrite is present throughout much of the

mafic metavolcanic formation and small concentrations of

pyrite occur in a few scattered shear zones in the metavol

canic rocks. Pyritic shear zones outcrop on the shores of

Theresa Lake, north and south of the Dead Otter Lake fire-

tower, and on the Dead Otter Lake road. These zones appear

to contain only pyrite but there are a number of other

fracture and shear zones in the metavolcanic rocks which

carry more interesting types of mineralization. On the

yon Klein property the No. 4 showing (see p22&se ), about

800 feet west-northwest of the No. 1 showing on the Dead

Otter Lake road, consists, of pyrite mineralization with some

chalcopyrite in thin seams filling fractures in mafic meta

volcanic rocks. This is just north of the contact with the

pyroclastxc formation. The Kusins snowing.consists of a few

small silicified pyritic shear zones in metavolcanic horn

blende gneiss about 4000 feet southwest of the Black River.

Small pods of sphalerite and galena mineralization occur in

the pyritic zones. Finally, the Fairservice showing^ north

of Dotted Lake, consists of two very thin seams of massive

sphalerite in a shear zone with a maximum width of about 4

feet and length of about 50 feet, in mafic metavolcanic rock.

Thin quartz, and epidote and carbonate stringers are common

in the metavolcanic rocks but quartz veining is very rare.

The general outline of the mafic metavolcanic formation

is clearly outlined on aeromagnetic maps of the area (Map 2168G)

due to the higher magnetic response of these rocks in comparison

Sc

with the surrounding granodiorite gneiss andAb-iet*ke—gra-ni-fc-e.

The response is generally 100 to 200 gammas above the response

of the granitic rocks and is approximately the same as the

metavolcanic rocks of the Manitouwadge area.

A small area of mafic metavolcanic rocks is shown

along the northern boundary of the map-area. These rocks

lie on the southern side of the Manitouwadge metavolcanic

belt and have been described in detail by E.G. Pye (1957).

Most of the exposures examined in this region outcrop along

the, industrial road just west of Manitouwadge and they consist

of hornblende schists and laminated hornblende schists as

described by Pye. These rocks are similar to the laminated

hornblende gneisses in the southern part of the Black River

area except for the slightly more schistose character of the

rock in the Manitouwadge area.

£i licit Acid to Intermediate Metavolcanic, Pyroclastic and


Rocks included under this heading include salic and mafic

pyroclastic rocks, dacitic flows, rhyolite, greywacke, biotite

gneiss, migmatite and minor iron formation. Stratigraphically

this formation lies between, and is believed to be transitional

to, the older mafic metavolcanic rocks and subsequent metasedi

mentary rocks. Mafic metavolcanic flows are interleaved with

the pyroclastic and acid metavolcanic material and the pyro

clastic agglomerates and tuffs grade into the metasedimentary

conglomerates and greywackes.

* /

Rocks of this formation are found in a belt between

600 and 2,500 feet wide, extending from the south end of Theresa

Lake northwest to the Dead Otter Lake road and then southwest

through Phil Lake to the Black River, and in another mass

consisting largely of pillowed dacitic flows, extending from

just north of Phil Lake, northwards to about 5 mile beyond

Pinegrove Lake, on the west side of the Canadian Pacific

railway track.

In the area extending north from about Phil Lake, on

the west side of the railway track, the rocks are relatively

uniform in character. They are mainly dark blue grey, fine

grained, porphyritic, pillowed dacitic flows which weather a

light blue grey to pink colour. Pillows are abundant and

range in size up to 3 feet in diameter with darkgreen 12-inch

thick selvages. The pillows appear to have been balloon-

shaped originally but have been severely stretched, with the

most severe stretching in the general direction of dip,

essentially parallel to the hornblende lineation (Photo w*4- ).

The flows have a spotted appearance due to the presence of

white to pink weathering feldspar phenocrysts up to % inch

in size. The pillowed, scoriaceous and massive phases which

are,present are similar in composition^and grade into each

other. Particularly good exposures outcrop along the west

side of the railroad track, opposite Pinegrove Lake, and in

this region the rocks are cut by thin stringers of feldspathic

and epidotic material and by numerous dikes of feldspar

porphyry, hornblende-feldspar porphyry, augiteJK syenite,

amphibolite, biotite granite and diabase.

Microscopic examination indicates that these metadacites

now consist essentially of albitic plagioclase and hornblende

with some quartz and minor amounts of carbonate, epidote,

biotite, sericite and magnetite. Mafics" total between 25 and

30 percent. The plagioclase grains are generally sericitized

and many have a s|gpJve texture, being packed with small rounded

inclusions of quartz and needles of hornblende.

The second belt of rocks, extending from Theresa Lake

to the railroad tracks at Phil Lake, is extremely heterogeneous.

In the Theresa Lake region the rocks are interbedded agglomerates

and tuffs. The agglomerates are laminated and contain abundant,

len&ed>^ porphyry fragments in a hornblendic and epidotic

m atri$. The fragments are stretched to 1 foot or more in

length. The tuffs are thinly laminated and commonly have h

hornblende-rick garnetiferous bands up to 6 inches thick

alternating with grey-buff felsic layers of similar thickness.

Numerous intrusions of aplite, granite gneiss and amphibolite

cut these rocks and the aplitic and granitic dikes are commonly

stretched and boudinaged.

Further west, in the region of the Von Klein Property

(see map ), similar agglomerate and tuff are present but

in addition, thin, discontinuous beds of biotitic quartzite,

greywacke, garnetiferous siliceous tuff, iron formation,

metarhyolite and rhyolite breccia are also present, and thin,

pillowed, mafic to intermediate lava flows are interbedded with

these rocks.

I f,l, /Ji 3 „ In the area around the Von Klein No. 2 showing (Fl-4%e )

the predominant rock type is a strongly foliated garnet-biotite-

muscovite-quartz-oligoclase gneiss. The showing itself occurs

in a large block of amphibolite rafted in a rhyolite breccia,

whi-cit is only slightly foliated butA similar in composition

to the surrounding gneiss except for a lower biotite content

and an abundance of angular,inclusions ranging in composition

from amphibolite to rhyolite. It is believed by the writer

that the rhyolite breccia forms a plug in the surrounding

biotite-muscovite gneiss which may be metarhyolite or meta-

arkose material. No contacts between the breccia and the

gneiss were located and the general impression was of gradation

between the two rock types.

Iron formation was found in --©aly two outcrops about

250 feet south of the Von Klein No. 1 showing and consists

mainly of quartz with mafic hornblendic lenses, and streaks

and stringers of pyrite and pyrrhotite. The pyritic band

is about 8 feet wide and is bounded by agglomerate on the

north and a mafic volcanic flow to the south. The tuff units

are extremely heterogeneous in this region and in some outcrops,

for example on the south side of the Dead Otter Lake road

about 130 feet west of the Von Klein No. 1 showing, there

appears to be two distinct phases present. One of these

phases is light grey in colour and consists of quartz, andesine

and biotite with minor garnet and chlorite. It occurs as

<L4-

irregular blobs and streaks, containing rounded fragments up

to 8 inches long, mixed with a second dark green, mafic phase

of hornblende.plagioclase and garnet, also containing

scattered fragments. Compositionally these are not unlike

some of the pillowed flows in the region which have light cores

and wide dark selvages which when sheared resemble laminated

tuffs but the irregular blobs and streaks of the light

coloured phase are not derived from original pillow structures,

and fragments are present in the rock. It is possible that

this is a variety of welded tuff.

Further west again rocks of this formation are well

exposed on Highway 614 for about 2 mile north and south of

Summers Lake. On the highway opposite Summers Lake itself

there are excellent exposures of agglomerate. The fresh rock

is dark green grey in colour with light grey or yellow green /e^ncf/aP*

porphyritic leased fragments. The ground"~mass and fragments

weather dark green and buff respectively. The rock is well pa./~*e>-//e /

foliated with orientation of the fine-grained hornblende of

the matrix and 1-ensing-e-f the fragments. The fragments are

predominantly acid feldspar porphyry and range in size up to

about 4 inches. Feldspar phenocrysts or crystal fragments

are also scattered about in the matrix. The matrix is

essentially hornblende and oligoclase with some quartz,

biotite, chlorite and epidote, while the fragments are mainly

quartz and oligoclase with epidote and chlorite and minor

hornblende. The fragmental nature of the rocks is most

apparent on horizontal surfaces. Elongation of the fragments

seems to be more intense in the direction of dip so that in

vertical faces the rock has the appearance of a light and

dark green laminated hornblende gneiss (Photos & o~/>) . On

the east side of the highway, north of Summers Lake the

laminated tuff and agglomerate is invaded by irregular masses

of dacitic porphyry similar in appearance to "the dacitic flows

K west of the Canadian Pacific ^railway tracks.

South of Summers Lake a rock believed to be a metamor-.r /' lie 11

phosed acid* flow outcrops on the west side of the road just

north of a band of mafic hornblende gneiss. The rock is

fine-grained, thinly laminated and white to light grey in

colour with occasional 1 inch wide hornblende-rich laminae.

In part the rock is garnetiferous and in part irregular

porphyritic blebs are also present s^jgegmed with tine laminated

material. The lamination is essentially straight but minor

swirls are present. Similar rocks were encountered southwest

of the highway on the C.P.R. tracks and these are intruded

by numerous dikes of feldspar porphyry, hornblende-feldspar

porphyry, and biotite granite.

Rocks of this formation continue southwest of the C.P.R.

tracks and agglomerates are still present but metasedimentary

material in the form of biotite-quartz-feldspar gneisses

becomes important and sxithwest of the Amwri Lake road a strong

magnetic anomaly was noted in the vicinity of a small outcrop

of iron formation composed of thin laminations of quirtz

pyrrhotite.and magnetite.

ii/in c The pyroclastic-aeid- metavolcanic formation appears to

fade out east of Theresa Lake into mafic metavolcanic rocks

While in the southwest it appears to grade into metasedimen-

tary formations. The greatest thickness and heterogeneity

silicic of pyroclastic and a-eid- flow material occurs in the region

of the Von Klein property and Summers Lake. This fact and

the presence of a rhyolite breccia plug suggests that this

region was the locus of explosive acid vulcanism and that the

range of distribution of products from this vulcanism was

relatively limited;in the order of a 5-mile radius.

All the rocks of this formation have been metamorphosed

to the almandine amphibolite facies. The rocks present a

wide range of compositions from msa=idte amphibolite to s-aJ ic

metarhyolite and heterogeneous mixtures of any of these

compositions may occur in single rock units. In the more

salic rocks the common metamorphic mineral facies consists

of garnet-biotite-quartz-plagioclase with muscovite an

important constituent in the metarhyolitic rocks in the yon

Klein property. In the mafic phases of the agglomerates

and tuffs the common mineral association is hornblende-

biotite-quartz-plagioclase with garnet plentiful in some

outcrops and absent in others. The plagioclase in these rocks

ranges from sodic oligoclase to andesine with generally more

calcic plagioclase in the mafic rocks and more sodic plagio

clase in the salic rocks. Epidote is present in many of

the rocks but in general it is a minor constituent and of

secondary origin associated with chlorite and sericite

in veins and alteration patches replacing plagioclase and

hornblende. However, in some agglomerates some of the epidote

is of primary metamorphic origin. In the agglomerate outcrop

on Highway 614, opposite Summers Lake, the groundmass is quite

mafic and consists essentially of hornblende-biotite-quartz-

plagioclase while the fragments, which are much less mafic,

consist of epidote-quartz-plagioclase with minor hornblende.

This again illustrates the very limited range of diffusion

during metamorphism of these rocks.

There is little mineralization in the main mass of these

rocks but a number of mineralized showings are located in the

Von Klein property a short distance east and west of the Dead

Otter Lake road. In the two major showings in this area

copper-nickel mineralization is confined to large blocks of

amphibolite rafted in rhyolite breccia or silicic tuffs.

There are a number of large amphibolite fragments in the area

but not all of these are mineralized. Other small chalcopy-

rite showings in the region of the Von Klein property occur

in shear zones in the tuffs and in shear and fracture zones

in the mafic metavolcanic rocks on the north side of the

pyroclastic formation.


South of the pyroclastic and mafic metavolcanic formations

metasedimentary rocks occupy a large roughly triangular-shaped

area with the base in the south extending from White Lake west

to Gowan Creek and with the apex lying just south of the Von

Klein property. Large plutons of hornblende-biotite grano-

diorite intrude the metasediments so that part of the triangular

area is underlain by these acid intrusive rocks. The meta

sediments extend beyond the southern limit of the map-area

and the section mapped represents only part of a large belt

of metasedimentary rocks roughly centred on Highway 17 and

extending approximately from White Lake in the east to

beyond Rouse Lake in the west. Tight isoclinal folds have

formed in the metasediments due to shear folding and the

overall similarity in composition of the metasediments makes

it impossible to determine the absolute thickness of sediments

involved.

The dominant rock type in the sedimentary formation is

a biotite-quartz-feldspar paragneiss very similar lithologi-

cally to the biotite-quartz-feldspar gneisses of the

Manitouwadge area. However, over much oj- the area, especially

adjacent to the pyroclastic formation in the north, there is

much conglomerate interbedded with the biotite-quartz-feldspar

paragneiss, whereas there are no conglomerates in the

Manitouwadge area. In the map-area no contacts of the meta

sedimentary formation were found exposed; however the position

of the formation contact is relatively easily located in the

eastern part of the area as, in this region, the metasediments

are in contact with the mafic metavolcanic rocks and there is

an abrupt change in lithology. In the west part of the area,

on the other hand, the contact is more difficult to determine;

the metasediments are in contact with the pyroclastic formation

and there is a gradation between the pyroclastic tuffs and

agglomerates.and the sedimentary biotite paragneisses and

conglomerates. The distinction is made more difficult by the

fact that the rocks in this region are more strongly sheared

than those further east and all the fragments are stretched

out parallel to the foliation. In general the biotite

paragneisses and conglomerates are biotitic and noticeable

amounts of granite and quartz fragments are present whereas

the pyroclastic rocks are hornblendic, feldspar porphyry

fragments are most common, and no granite fragments were

noted.

Exposure of the metasedimentary rocks is very poor and

within the main mass of metasediments the gross composition

is relatively uniform with the exception that conglomerate

bands are present in the northern part of the sequence.

The principal rock type is a fine-grained, light and dark

grey banded, well foliated biotite-quartz-feldspar gneiss.

Small red garnets are present in many outcrops but these are

so sparsely distributed in-the rocks that they may be over

looked. The biotite content of the rocks is generally greater

than 5 per cent but less than 15 per cent, and the dark and

light banding in the rocks reflects differences in the biotite

content of the layers. The banding varies in thickness from

very thin to several feet and generally the thicker bands are

of the lighter coloured, less biotitic type.

A few outcrops of garnet-biotite schist were found in

the regions north of Amwri Lake and west of No. 2 Lake. These

rocks are more biotitic than the typical paragneiss and as a

result they are more schistose in character.

Conglomerates are abundant in the area between Etna Lake

and Musher Lake and in the area between the Amwri Lake road

and the Black River. The effects of folding are difficult to

assess therefore determination of the thickness of the

conglomeratic section of the metasedimentary formation is not

possible, but, the greater areal extent of the conglomerates

in the east part of the area as compared with the west suggests

that they may possibly thicken from west to east. The conglo

merate is interbedded/and occurs in graded beds,with biotite-

quartz-feldspar paragneiss which itself may contain small rock

fragments and is commonly in the high biotite range of 15 per

cent particularly in the Amwri Lake road. The paragneiss

would seem to have been greywacke originally. The conglomerate

beds range in thickness from 6 inches to 10 feet and are inter-

bedded with greywacke layers varying in width over the same

range. Most commonly the beds are between 6 inches and 1^

feet wide. Pebble density is extremely variable. Some beds

are densely packed while others contain only scattered pebbles

and in single beds pebble density varies. Pebbles of various

compositions are present including granite, quartz, feldspar

porphyry, arkose or quartzite and occasionally amphibolite.

No very large fragments were noted and the original pebbles

were probably never more than a few inches in diameter. The

pebbles are now mostly stretched, parallel to the foliation,

and the maximum observed length of these elongated pebbles, is

about 1 foot with the majority having stretched lengths of

between 3 to 6 inches. The pebble stretching appears to have

been more intense in the western part of the area. In the

Amwri Lake road region the metasediments grade into the pyro-

clastic rocks and in this area there are occasional thin

hornblende strata interbedded with the conglomerate and grey-

wacke. Graded bedding is not common and was generally

inconclusive as regards top directions.

The paragneisses consist essentially of quartz, oligo-

clase, and biotite with appreciable amounts of microcline and

minor garnet in some outcrops. Accessory minerals include

sphene, magnetite, apatite and zircon, and secondary chlorite,

muscovite, sericite3epidote and pyrite are developed to a

small extent. The biotite is brown and occurs predominantly

as elongated flakes in parallel to subparallel alignment in a

granoblastic matrix of quartz and feldspar. Pleochroic haloes

are common in the biotite and in some localities the biotite

is slightly altered to chlorite or muscovite. When garnet is

present it is generally as small anhedral to subhedral grains

up to 2 millimetres in diameter. These small grains rarely

contain inclusions and may be partly altered to biotite and

muscovite. The garnet grains are occasionally elongated

parallel to the foliation. Slight sericitization and saussuri-

tization of the feldspar is common.

A distinctive band of muscovitic quartz-feldspar gneiss

a. s

occurs along the northwest contact of the met^dedimentary forma

tion; the best exposures are in the small creek on the east

side of the Black River north of Amwri Creek, and on the Amwri

Lake road. The band varies in width from about 200 feet to

400 feet and was traced over a distance of about 2 miles. The

gneiss is generally fine-grained and thinly laminated with

light grey to white laminae between l/8 inch and "4 inch thick.

The rock is dominantly quartzo-feldspathic with minor muscovite

and a very low chlorite and biotite content. Fracture planes

parallel the lamination and these are coated with silvery

muscovite and minor chlorite. At some points along the belt

coarse quartz augen are developed in the gneiss and cause

bulging of the laminatbn. The rock commonly has a rusty

weathered surface due to presence of small streaks, lenses and

disseminations of pyrite. On the Amwri Lake road a very few,

small, scattered fragments ranging in size up to 1^ inches by

"5 inch were noted in the rusty weathering gneiss, and on the

north side of the creek bed about 500 feet northeast of the

Black River what appeared to be a 6 inch by 4 inch oval cobble

was observed. In general fragments were not observed in the

gneiss outcrops. Thin section examination revealed that some

of the laminae in the gneiss are graded indicating that the

lamination is a bedding feature of sedimentary origin. The

rusty muscovitic gneiss is intruded by irregular dikes and

sheets of granite and feldspar porphyry and shearing has

occurred parallel to the lamination in the gneiss as indicated

by offsetting of granitic dikes and granulation of quartz in

thin sections. Right-/and lefthanded strike separations of / A

between 4 inches and 6 feet occur on cross cutting fractures.

The right-handed faults vary in strike between N70W and

N60W and the left-hand faults between N10E and N25E.

The rusty gneiss consists essentially of quartz, plagioclase

and minor biotite with accessory magnetite, sphene, tourmaline

and zircon. The biotite is almost completely altered to

chlorite, and biotite and feldspar to sericite and muscovite.

Minor secondary epidote and carbonate are present and euhedral

to subhedral pyrite with some pyrrhotite is important locally.

It is probable that the rock was originally a greywacke meta

morphosed to a biotite gneiss and subsequently altered by

sericitization and chloritization and the introduction of

pyrite.

A small outcrop of intensely crenulated muscovite gneiss

outcrops about 100 feet east of Highway 614, on part of the

old road, about 7000 feet south of the junction with the Dead

Otter Lake road. The rock appears to be an intensely sheared

and altered paragneiss now consisting essentially of albitic

plagioclase and quartz with abundant muscovite^some chlorite.,

and scattered accessory pyrite. The muscovite is developed

at least in part, by alteration of the feldspar. The outcrop

is close to the south contact of a large granodiorite pluton

and it is possible that the alteration and shearing of the

paragneiss may be related to the intrusion of the grano

diorite. The yon Klein property lies on the north side of

this granodioritejand muscovite is an important constituent

in some of the pyroclastic and metarhyolite gneisses in that

area.

Only one outcrop of sLllimanite-bearing paragneiss was found

in the area and this is located on Highway 614, in the road cut

just north of the railroad crossing opposite East Barbara Lake.

The sillimanite occurs in garnetiferous layers 3 to 4 inches

wide in a band about 6 feet wide in typical biotite-quartz-

feldspar paragneiss. The sillimanite gneiss is dark grey in

colour, mediumyto fine-grained and has a crenulated foliation.

The rock appears to be slightly richer in biotite than the

typical paragneiss and contains appreciably more garnet. The

small euhedral red garnets range in size up to about 3 m/m.

The sillimanite grains range in size up to ^ inch long by l/8

inch wide and often have a bluish bladed appearance but the

bladed grains commonly have frayed fibrous terminations and the

sillimanite also occurs as groups of colourless needles which

may weather white on surface. Thin section examination indicates

that the rock consists essentially of sillimanite, garnet,

biotite, quartz and oligoclase with accessory magnetite, apatite,

and zircon and secondary muscovite and chlorite. Foliation in

the rock is imparted by orientation of the biotite grains. The

foliation is folded into small crenulations and also diverges

around garnet and sillimanite grains. The biotite occurs as

brown lath-like grains showing slight alteration to chlorite^,

and pleochroic haloes are common. The garnet grains are

subhedral to euhedral. They contain very few inclusions but

they are surrounded by haloes of fibrous mica and quartz and

some are partially pseudomorphed by biotite and muscovite.

The sillimanite porphyroblasts consist of bladed grains fraying

out at the ends to fibrous swarms and these grains appear to be

curved in association with the crenulation of the foliation.

Very fine-grained dusty biotitic stringers parallel the

crenulated foliation. These appear to be zones of incipient

alteration of the biotite to sillimanite and the larger

sillimanite porphyroblasts can be seen growing accross these

zones and replacing biotite. Muscovite also appears to replace

the biotite. The textures suggest that the paragneiss was

initially metamorphosed to a biotite gneiss and that subsequent

shearing produced crenulation of the foliation and that the

sillimanite developed during or in the waning stages of the

crenulation.

In the area south and west of Tri Lake two outcrops of

distinctively coloured and laminated meta-arkose were found

within the main body of the mafic metavolcanic formation. The

rock is a very fine—grained, pink weathering,thinly laminated

quartzo-feldspathic metasediment. The laminae range up to ~i

inch in thickness and may be pink, buff or light grey in colour.

The rock consists of about 35 per cent anhedral, rounded to

$7 irregular shaped, quartz grains mixed with about 57 • 5- Ver cent

similarly shaped grains of feldspar. The feldspar is albitic plagioclase very much clouded by a dusty sericitic alteration.

8 The rock contains about 7-*-5 per* cent muscovite which occurs

as poecilitic plates and small laths which have grown parallel

to, and across the lamination in the rock and may be related

to the sericitic alteration of the feldspar. Trace amounts

of epidote and chlorite occur together as scattered grains

associated with dusty patches of alteration and epidote also

occurs in thin veinlets cross-cutting the rock lamination.

Some dusty hematite is associated with these veinlets also.

In the outcrop about 3300 feet west of Tri Lake the meta-arkose

is tightly folded into small isoclinal shear-flow folds plunging

southwest. No contacts were found between the meta-arkose and

the mafic metavolcanic rocks.

Throughout the area the paragneisses are invariably

intruded by stringers of quartz-feldspar and granite and these

stringers are frequently ptygmatically folded. Sometimes

these rocks are also cut by later fractures and the fracture

planes are coated with epidote or hematite. The quantity of

intrusive material is generally low hut in some regions the

rocks are highly feldspathized and migmatized, as for example

in the region around Etna Lake, around the microwave tower

north of Jeanine Lake and in the vicinity of the Black River.

The distinction between the tuffaceous and sedimentary rocks

is extremely difficult because of this in the region around the

Black River. The rocks may be laminated with granitic material

parallel to the foliation or feldspar augen may develop throughout

the rock. In the vicinity of the Black River the feldspars

are commonly pink and this p-i-nk-ing appears to be related to

thin, cross-cutting carbonate-epidote veinlets. These migma-

titic gneisses consist essentially of quartz, albite or sodic

oligoclase, microcline, biotite andVor)hornblende with

accessory apatite, magnetite and pyrite.and secondary sericite^

chlorite, epidote and carbonate. Contacts between1 the metasedi-

mentary gneisses and the large granitic intrusive bodies are

not exposed but the numerous small granitic dikes and sheets

which intrude the metasediments have sharp contacts, with the

coarse grain of the minerals of the intrusive rocks contrasting

sharply with the fine-grained nature of the metasediments.

Examination of a small number of thin sections suggests

that the whole of the metasedimentary formation at one stage

was metamorphosed to a low rank subfacies of the almandine

amphibolite facies. The common mineral assemblage throughout

the metasediments is biotite-quartz-oligoclase commonly with

scattered garnets and sometimes with microcline. In the only

sillimanite-bearing metasediment recognized in the area the

sillimanite replaces earlier formed biotite and appears to be

rotated in association with a crenulation which distorts the

original foliation of the rock. Muscovite is present in the

sillimanite gneiss and it also replaces the biotite and

commonly has Jsrown across the original foliation . The silli

manite gneiss outcrops on Highway 614 just north of an intrusive

granodiorite contact. Likewise, about 5500 feet north of the

sillimanite gneiss outcrop a highly sheared, muscovite-rich

gneiss outcrops just south of an intrusive granodiorite contact

(see page §£T). In addition the metarhyolitic rocks on the

south of the Von Klein property are close to the granodiorite i

and are also rich in muscovite. It seems possible that a

certain amount of shearing was developed in the metasediments

at the contacts during the intrusion of the granodiorite

plutons and sillimanite and muscovite were developed in the

biotite paragneisses by contact metamorphism. Throughout the

area the metasediments have suffered late sericitization,

saussuritization and chloritization and in many outcrops this

is related to cross cutting epidote-,and carbonate-filled

fractures. This alteration reaches extreme proportions adja

cent to faults and is accompanied in faulted regions by

hematitization.

The conglomerates are restricted to the northern side

of the metasedimentary unit, adjacent to the pyroclastic and

mafic metavolcanic formations, and there appears to be a

simple gradation from the pyroclastic formation into the meta

sediments, The pyroclastic formation in turn contains mafic

metavolcanic horizons within it and appears to interleave

with the main mass of mafic metavolcanic rocks to the north.

There is no suggestion of a major break between any of these

formations. The general impression is of a continuous

depositional sequence beginning with the extrusion of pillowed

mafic volcanic flows, followed by the local extrusion and S / tie i'{_

explosive ejection of aj&id metavolcanic and pyroclastic

material contemporaneously with minor sedimentation and inter

mittent mafic volcanic extrusion and succeeded finally, by

extensive, coarse, followed by fine, clastic sedimentation.

Mafic and Ultramafic Intrusive Rocks

Rocks included in this group include amphibolitic

metagabbro, serpentinite.peridotite, talcose dikes and

saussuritized anorthositic gneiss. The amphibolitic meta-

gabbro intrudes the metavolcanic, pyroclastic and metasedi-

mentary formations and isolated blocks are found in the

granodiorite gneisses. The serpentinite and peridotite are

intruded into the mafic metavolcanic formation and the

anorthositic gneiss occurs as one small body within the

^?c/t./T _ granodiorite gneiss. ..

MeT^CJBMM^—^ Recognition of the amphibolitic metagabbro is

frequently difficult as it is similar in appearance to coarse

grained mafic metavolcanic rocks. Distinction is definite

only where contacts are visible and this is rare. The

amphibolitic metagabbro occurs as tji-i-n dikes and extensive

sheets intruding the mafic metavolcanic, pyroclastic and

metasedimentary formations. The metagabbro is itself intruded

by granodiorite gneiss and later massive granodiorite,quartz

monzonite and diabase. Metagabbro intrudes the metasediments

along the southwest shore of White Lake and is in turn agmatiti

by intrusion of diorite. A large sheet of metagabbro about

4 miles long and 2000 feet wide strikes southeasterly across

the south end of Theresa Lake and intrudes agglomerates and

mafic metavolcanic flows. Other small dikes of metagabbro were

noted in the railroad cuts east of Pinegrove Lake intruding

dacitic pillow lavas. These dikes have fine-grained margins,

are intruded by the feldspar porphyry dikes in the area and are

agmatitized by intrusion of granitic material (see photo K ).

A hybrid mixture of amphibolitic metagabbro, diorite and

granodiorite is poorly exposed southeast of Etna Lake and small

masses of metagabbro are scattered within the large northern

mass of granodiorite gneiss.

The amphibolitic metagabbro is typically a massive,

medium-.or coarse-grained, dark green rock composed essentially

of hornblende with variable amounts of plagioclase, biotite,

and epidote and occasionally quartz and garnet. Common

accessories are sphene, apatite and pyrite, and secondary epidote,

carbonate, chlorite, muscovite and sericite may be present.

The rock may vary in a single outcrop from a dense green rock

with little or no feldspar to a speckled white and green rock

containing 20 to 30 percent feldspar or saussuritized feldspar.

In areas where the metagabbro has been intruded by later

granodiorite or diorite the amphibolite is frequently hybridi

zed and foliated and a rock containing a high proportion of

feldspar results. The metagabbro is generally brecciated,

intruded and permeated from the contacts inwards by the

granodiorite or diorite. Although not within the map-area a

very good illustration of this feature is exposed in the road

cut on Trans-Canada Highway, Highway No. 17, about 2^ miles

east of White Lake, immediately west of the junction with the

Regan truck road of the Abitibi Paper Company Ltd. In this

location the amphibolitic metagabbro intrudes biotite-quartz-

feldspar paragneiss and is in turn intruded by hornblende

granodiorite along the contacts between the paragneiss and

metagabbro.

The hornblende in the metagabbro is often pale

coloured in thin section. Zoned grains are common with cores

of pale to moderately strong green colour and colourless to

pale green rims. The pale colour appears to be the result of

a secondary bleaching effect possibly related to the intrusion

of the metagabbro by the later granitic rocks. In one thin

section from a metagabbro block rafted in the granodiorite

gneiss numerous quartz stringers and lenses are present in

the amphibolite and bleaching of the hornblende in this section

is localized around the quartz masses.

Brown biotite is often present as laths and irregular/V

shaped grains replacing the hornblende and in the corase—

grained amphibolites the biotite is commonly concentrated in

the darker coloured cores of the hornblende grains. Biotite

content is usually between 5 and 10 percent and not readily

apparent in hand specimen but in one exposure on the Ontario

Paper Company road, about 2 mile northeast of Morley Lake,

the biotite content is about 15 percent and very evident

megascopically. This latter rock is also cut by mineralized

fractures.and occasional, small pods, containing pyrite,

chalcopyrite and pyrrhotite were found in loose blocks of this

material blasted from the outcrop for road fill.

Epidote is common in the metagabbros and appears to

be largely of secondary origin replacing feldspar and hornblende.

Carbonate and chlorite are sometimes associated with the epidote,

and sericite may also develop in the altered feldspar. Garnet

-2

was found in only one outcrop of metagabbro located on the

Ontario Paper Company road about I2 miles east of the south

end of Agonzon Lake. This metagabbro is intruded by grano-

diorite gneiss and foliated. The garnets occur as coarse

porphyroblasts up to 2 inch in diameter but more commonly

1 inch or less in a medium-grained, foliated, ground mass of

dark green hornblende and andesitic plagioclase. Sphene and

apatite are accessories. Quartz occurs as knots lenses and

stringers elongated parallel to the foliation and when

examined in thin section the hornblende adjacent to these

quartz masses is noticeably bleached. The garnet grains are

extensively pseudomorphed by a medium-grained intergrowth

of epidote and hornblende with some brown biotite. This

replacement occurs as coronas around garnet cores or may

completely replace the garnet grain. (Pho-fre &—*) . The

plagioclase in the rock is also slightly altered to saussurite

and sericite.

These metagabbros appear to have been metamorphosed

initially to rocks consisting of hornblende and plagioclase

with or without garnet and would therefore belong to the

almandine amphibolite facies. Subsequently, due to intrusion

by later granitic and granodioritic material, the hornblende

was partially altered to biotite, the hornblende pal©d- In/rr-'fi -<.&i cAM-y»

colour and garnet was pseudomorphed by intergrowths of epidote.

hornblende and biotite. In addition plagioclase in £he rock

may at this time have been partly saussuritized. These rocks

are similar to the metagabbros in the Manitouwadge area as

43

described by Pye (1957). ^ n >„„ .„ „. , O

Three roughly lens^-shaped bodies of serpentinized

peridotite outcrop in the area. The serpentinized peridotite

intrudes mafic metavolcanic rocks and is thought to be older

than the biotite granite of the Dotted Lake pluton. Therefore

it is grouped with the amphibolitic metagabbro intrusive

rocks. These ultrate^e&ie rocks have no equivalent in the

Manitouwadge area but are similar in appearance, and

occurrence to the serpentinite in the Pic River area (Milne,

196x).

All of the serpentinite bodies are very poorly

exposed and all of them outcrop on lakeshores, the best

exposures being on islands and small peninsulas on the lakes.

The largest body intrudes the metavolcanic rocks on the north

shore of Dotted Lake and is about 8000 feet long and 1000 feet

wide. Another lenticular mass intrudes the metavolcanic

rocks on the northwest shore of Theresa Lake and is about

3500 feet long by 700 feet wide. The third serpentinite mass

intrudes the metavolcanic rocks in the west arm of White Lake

and is 6500 feet long by 1000 feet wide. In all of these the

long dimension of the intrusive body trends parallel to the

foliation of the surrounding metavolcanic rocks. The location

and shape of these ultrab-a-s-ic intrusives is clearly indicated

by high magnetic contour ridges on aeromagnetic map 2168G

(O.D.M./G.S.C.). These indicate magnetic intensities

similar to the serpentinite intrusive in the Pic River area.

(Aeromagnetic map 2157G).

The serpentinized peridotite is predominantly massive

but a few narrow shears cut the various serpentinite bodies

and adjacent to the shears the serpentinite is schistose. The

fresh rock may be black, greenish black or dark grey in colour

but where the rock is sheared it may be yellow-green to grey-

green. The rock is quite soft on weathered surface and the

weathered colour is generally rusty brown to black. The

weathered surface may be smooth, knotted or pitted. The rough

weathering surfaces may have knots of 2 inch to the 1 inch

diameter standing out in relief on the surface or the surface

may be pock-marked by pits of similar dimensions. The

variation in the weathered surface may reflect in part the

extent of serpentinization of the peridotite. The rock is

o coarse-grained to very coarse-grained with gtphitic pyroxene

grains ranging up to more than 1 inch in diameter., The rock

in all three intrusive bodies is similar and texturally they

are relatively homogeneous. Where the rock is only slightly

serpentinized the black fresh surface glistens due to the

highly reflecting cleavage faces of the randomly oriented 2

inch to 1 inch diameter aphitic pyroxene grains. These

grains are studded with included olivine grains 1 to 2 milli

metres in diameter. Where the peridotite is extensively

serpentinized the fresh surface of the rock is a dull black

to dark green colour and has a?honeycomb* texture consisting

of 1 to 2 millimetre dark green to black polygonal grains in

a slightly lighter coloured interstitial mes+r. The polygonal

grains appear to be pseudomorphed olivine grains replaced by

serpentine. The interstitial material is serpentinized pyroxene.

This latter texture is identical to the texture of most of the

serpentinite in the Pic River area. Contacts between the

serpentinite and metavolcanic rocks were observed in only two

locations; on the north shore of Dotted Lake where a small mass

of metavolcanic rock has been included in the serpentinite and

on the northeast side of the serpentinite mass in the west arm

of White Lake. In the second locality the contact is between

a small apophysis of the main serpentinite body and the metavol

canic rock and is line sharp between two distinct rock types.

In the Dotted Lake locality the contact is sheared.

Most of the serpentinite exposures are massive and

relatively homogeneous with no suggestion of layering but at

the north end of the small peninsula on the northwest side

of Theresa Lake three magnetite rich layers strike N85°E

across the trend of the long axis of the main mass, which is

approximately N47°W. Each layer is about 1 foot wide and

separated from the next by about 3 feet of typical serpentinite.

The exposed length of the layers is short as they cross the

north point of the peninsula and strike into the lake. On this

same peninsula the serpentinite is intruded by two 2-fe;et wide

dikes composed of coarse pegmatitic hornblende and plagioclase.

The dikes have fine-grained contacts and appear to produce some

alteration of the serpentinite at the contacts. These are the

only dikes of this kind found in the area and the only

material found intruding the serpentinite.

In thin section the altered peridotite consists of

large ophitic clinopyroxene grains largely replaced by tremo-

litic amphibole and chlorite and containing relatively unal

tered anhedral grains of forsteritic olivine. Abundant

secondary magnetite is present with minor carbonate and

serpentinite. The olivine grains are commonly bounded by a

very thin corona of colourless, inclusion-free tremolite which

is optically continuous with tremolite rich in magnetite

inclusions, or having pale brownish pleochroism, which

replaces the ophitic clinopyroxene. The chlorite is colourless

to very pale green in colour and partly replaces the tremolite.

The chlorite appears to replace preferentially the inclusion-

rich or slightly coloured tremolite frequently leaving the

thin colourless tremolite coronas around the olivine grains.

The chlorite also occurs as vein filling with magnetite in

late cross cutting stringers. The tremolite-chlorite

association in the altered peridotite is similar to that found

in the metamorphosed serpentinite at the contacts of the Pic

0,1

River intrusive except for the presence of fresh olivine and

remnant pyroxene in the Black River altered peridotite. It

is possible that the ophitic textured, knotted weathering parts

of the serpentinite lenses represent nonserpentinized remnants

of an original peridotxte intrusive" and that later metamorphxsm

produced the tremolite-chlorite alteration. A small amount of

carbonate is associated with the tremolite and this tremolite-

carbonate-chlorite association indicates metamorphism of the

greenschist facies. This metamorphism may relate to the late

zoisitization or saussuritization in the amphibolitic rocks

and the chloritization in the pelitic rocks rather than to the

main regional metamorphism,

On the north sh ore of Dotted Lake a light green—grey

speckled, medium-/to fine-grained, massive altered gabbro is

associated with the serpentinite. The gabbro outcrops north

of the serpentinite on the .shore but the contact relationship

is not clear because of the poor outcrop and because of the

sheared nature of the rock in the vicinity of the contacts.

The gabbro consists of about half and half pale coloured

tremolitic amphibole and zoisite with albitic plagioclase,

the latter two probably representing a saussuritic replacement

of an original more basic plagioclase. This metagabbro is

quite unlike the amphibolitic metagabbro and was only found

in this one locality associated with the serpentinite.

One talcose intrusive dike was found in the area. The

dike occurs in a small outcrop about 300 feet west and 600

feet south of the Von Klein No. 1 showing which outcrops on

the Dead Otter Lake road. The dike is between 5 and 10 feet

wide, is of unknown length, and intrudes hornblende gneiss

derived from a mafic metavolcanic flow. The dike rock is

very soft and is greasy to the touch. It is fine-grained,

massive,and medium light grey colour on fresh surface,

weathering to light buff with a slight rusty stain. Thin

section examination indicates that the rock consists

essentially of talc, carbonate and very pale green chlorite

with about 3 percent magnetite and minor pyrite the latter

generally enclosed by rusty weathered rims. The ose dike

has produced some alteration in the hornblende gneiss in

contact with it. Near the contact inclusions of hornblende

gneiss have been incorporated in the dike and biotite rich

selvages have developed around these and in the hornblende

gneiss at the dike contact. The dike is probably related to

the serpentinite intrusives. ,i -, / , „.„„ „ „ . „ " \ Mf/0??/t(tSiTIC &/J&t-$J

SL^Z^S The last rock type included in this group is tentatively

named anorthositic gneiss. This rock was found only on the

east side of No. 5 lake and appears to be intimately mixed

with and possibly intrusive into amphibolitic gneiss and schist.

Information in this locality is limited but the amphibolitic

and anorthositic rocks seem to occur as a small mass about ~i

mile in diameter enclosed by feldspar augen gneiss which is a

sheared equivalent of the granodiorite gneiss further west in

the area. No contacts were seen between the anorthositic

material and the augen gneiss but aplitic dikes cut the

amphibolitic and anorthositic material. The anorthositic rock

may be massive, mediumyto coarse-grained, greenish-yellow to

grey in colour, weathering light buff to pink, or laminated

with 2—inch wide bands of white feldspar alternating with

dark green hornblendic bands. In thin section the anorthositic

gneiss is composed of coarse anhedral grains of andesine-

labradorite plagioclase largely altered to a medium-grained

saussuritic aggregate of epidote, pale green chlorite and

abundant sericite. Epidote also occurs as stringers cutting

the rock. Some euhedral sphene is associated with the epidote

and a very few small grains of pyrite were noted in hand

specimen. On aeromagnetic maps of the area (Map 2169G) the

??

location of the anorthositic body is indicated by a magnetic

anomaly rising between 400 and 500 gammas above the magnetic

intensity of the surrounding granodiorite gneiss. No

significant mineralization was noted in the anorthositic body,

and the anorthosite does not contain noticeable magnetite)

however, there is considerable amphibolitic material mixed with

the anorthosite and this may be the source of the high magnetic

response. v / . — - ^ y //•/£•£?} 4. tz t) T/& sJ

Except for the magnetite in the Theresa Lake serpentinite

body, no other mineralization was noted in the serpentinite,

the talcose dike, or the anorthositic gneiss. However, the

on Pic River serpentinite intrusive does not appear to contain

sulphides but sulphide mineralization occurs in the country

rock at several points along the intrusive contact. The

Black River serpentinite bodies are probably related to the

Pic River intrusive-, and, although much smaller, examination

of their contacts might still be worthwhile. The major

problem in such an examination is ,of course the very poor

exposure in the vicinity of the serpentinite bodies and the

related rarity of exposures of the contacts.

Disseminated pyrite is a common accessory in the

amphibolitic metagabbro and is of little importance but as

noted previously mineralized fractures and small pods contain

ing pyrite, chalcopyrite and pyrrhotite were found in a

biotitic amphibolite on the Ontario Paper Company road, about

"4 mile northeast of Morley Lake. It is interesting to note

also that the richest showings of chalcopyrite-pyrrhotite

JTD

mineralization on the Von Klein property occur in rafted

blocks of amphibolite, possibly metagabbro, in rhyolite

breccia and tuff. It is possible that some mineralization is

associated with the metagabbro or that in mineralized localities

the metagabbro represents a favourable host rock.

Early Silicic Plutonic Rocks

More than half the map-area, that is an area in excess

of 300 square miles, is underlain by granodiorite gneisses.

The gneiss underlie most of the northern half of the area and

much of the southwest quarter and extends westward into the

Pic River area as ?granitic gneiss * (Formation 4> maps 2098

and 2099, O.D.M. I966), northward into the Manitouwadge area

(Formation 7, map 1957-8, O.D.M 1957), and eastward beyond

the map limits. This formation therefore represents part of

a very large batholithic mass which is referred to here as the

Black-Pic Batholith since a large section of the mass lies

between the Black and the Pic Rivers.

The predominant rock type of the Black-Pic Batholith

is biotite granodiorite gneiss but subordinate amounts of

hornblende-biot£te granodiorite gneiss, feldspar augen gneiss,

xenolithic gneiss and migmatite are also present and throughout

the batholith the gneiss is permeated or intruded by small

irregular masses of massive leucocratic biotite granodiorite.

The biotite granodiorite gneiss is grey to bluish grey in

colour weathering light grey to white. The rock is essentially

medium-grained but may range from medium-to coarse-to medium-

to fine-grained. Biotite content is usually about 10 percent

4

but may range from about 5 to. 15 percent. A foliation due to

the alignment of biotite grains is generally well developed

and in many outcrops the granodiorite is laminated due to the

slight variation in grain size and biotite content of layers

and to the presence of thin laminae, generally between l/8

inch and 2 inch thick, of leucocratic granodiorite material

intruded or segregated parallel to the foliation. The rock

consists essentially of zoned oligoclase, quartz, microcline

and biotite with accessory sphene, magnetite, apatite and

zircon. Secondary minerals include epidote which may be

abundant, and minor chlorite, sericite and carbonate. Modal

analyses of two granodiorite samples are shown in Table S .

The quartz and feldspar grains are anhedral with the microcline

interstitial to the quartz and plagioclase. Some of the

plagioclase grains exhibit simple normal zoning, they sometimes

contain small rounded quartz inclusions and occasionally very

small irregular blebs of exsolved microcline. The quartz

invariably shows mottled strain extinction and the biotite

and accessory minerals occur as interstitial trains and

clusters.

Hornblendic layers are occasionally present in the

biotite granodiorite gneiss, for example in the railroad cut

on the southwest shore of No. 6 Lake the rock at the north end

of the exposure is wholly biotite granodiorite gneiss (sample

No. #»-, Table S) but towards the south end of the exposure

although the bulk of the rock is still biotite granodiorite,

a few laminae of hornblende-biotite granodiorite are interlayered.

In some areas the bulk of the material is hornblende-biotite

granodiorite, as, for example, north of No. 1 Lake and

between No. 1 Lake and Pan Lake. In the area north of No. 1

Lake the hornblendic and biotitic granodiorites are interlayered

but on Highway No. 614 about 4000 feet northwest of No. 1 Lake

there are indications that the biotite granodiorite may intrude

the hornblendic granodiorite.

The hornblende-biotite granodiorite gneiss is somewhat

similar in appearance to the biotite granodiorite gneiss and

in some outcrops the hornblende may be masked by the biotite

so that the two rock types may be difficult to differentiate.

However, in general the hornblendic gneiss is more mafic, up

to about 25 percent dark minerals as compared with 15 percent

in the biotitic gneiss, and the hornblende is evident in most

of the outcrops. The hornblendic gneiss is a slightly darker

grey colour than the biotitic gneiss, is medium—grained to

mediumyto coarse-grained and strongly foliated due to the

well developed alignment of the hornblende and biotite grains.

The rock may be equigranular but more commonly plagioclase

feldspar porphyroblasts and hornblende grains slightly coarser

than the average are scattered throughout the rock giving it

a spotted appearance, particularly on weathered surfaces.

The feldspar and hornblende porphyroblasts are usually

about 2 to 3 millimetres in size but some of the feldspar arc /" *'-J£

porphyroblasts ra-ng-e- up to about 1 centimetre. Plagioclase,

quartz, hornblende, biotite and small brown grains of sphene

are readily apparent in hand specimens and small grains of

epidote are sometimes visible. Thin section examination

reveals that a small percentage of microcline is present and

accessory apatite and magnetite.

Hornblende-biotite granodiorite similar to the rocks

in the locations mentioned above also outcrops in the north of

the area adjacent to the mafic metavolcanic rocks of the

Manitouwadge area. In the latter area the hornblendic grano-^

diorite forms a relatively homogeneous and persistent mass

paralleling the mafic metavolcanic contact and occurring

between the metavolcanic rocks and the biotite granodiorite.

This hornblendic granodiorite is the same rock as Formation

No. 6a- Hornblende-biotite-quartz-feldspar gneiss, map 1957-8,

mapped by Pye (1957). Pye believes, on the basis of gradational

contacts between the phases and examination of chemical analyses,

that "the fhornblende-biotitej gneiss was originally (mafic

metavolcanicLor an equivalent, less highly metamorphosed rock,

and that it represents an intermediate hybrid phase in the

transformation of the schist to biotite granodiorite gneiss."

In the Pic River area hornblendic gneisses occur at the contact

between the mafic metavolcanic rocks and the batholithic

gneisses and the writer interpreted these as hybrid rocks

(Milne, 196X). In the area east of Cirrus Lake particularly

the writer found that "Along the main contacts with the meta

volcanic rocks the (granitic) gneiss consists largely of a

mafic hybrid feldspar augen gneiss with much hornblende and

epidote. Partially feldspathized xenoliths of amphibolitic

metavolcanic rock are scattered in the hybrid gneiss. The

contact (of the Black-Pic Batholith) is not abrupt but

consists of a heterogeneous transitional zone several hundred

feet wide composed of various hybrid forms of amphibolitic

metavolcanic and granitic gneiss rock." L/'^''''e/ ' ^ //"' ./

Although the Pic River hornblendic feldspar augen

gneiss is interpreted as a hybrid rock it appears to have

intrusive characteristics as indicated by the presence of

angular xenoliths of metavolcanic rock and by sharp contacts

between the mafic metavolcanic rocks and the hybrid gneiss

exposed in the northeast corner of Cirrus Lake. Similarly,

in the Manitouwadge area it is the author*s experience,

limited mainly to the region between Manitouwadge and

Cadawaja Fault, that although the three phases, biotite grano-

diorite, hornblendic granodiorite and metavolcanic hornblende

schist are mixed and may be interlayered the contacts between

the phases are abrupt. On the Industrial Highway about 2.2

miles west of the junction with Highway No. 614 at Manitouwadge

a contact between hornblende-biotite granodiorite and meta

volcanic schist is exposed on the north side of the road. The

hornblende-biotite granodiorite gneiss is medium-grained with

numerous small feldspar and hornblende augen giving the rock

a spotted appearance on weathered surface which is quite distinct

ive relative to the biotite granodiorite gneiss. Approaching

the contact with the hornblende schist the hornblendic grano

diorite becomes fine-grained, has fewer feldspar and hornblende

augen and is a little more strongly foliated. At the contact

the layers of the hornblende-biotite granodiorite gneiss}a few

inches thick .are interleaved, lit-par-lit, with layers of

similar thickness of metavolcanic hornblende schist, over a

width of about 5 feet. The contacts between the layers are

non-gradational and would seem to be intrusive. In addition,

in the area around Highway No. 614 and the railway track just

south of Manitouwadge, the biotite granodiorite gneiss south

of the railway track contains many inclusions of hornblende-

biotite granodiorite gneiss and the contacts between the two

phases are not visibly gradational. Thus, although the

hornblende-biotite granodiorite gneiss may be a hybrid derived

by contamination of the biotite granodiorite gneiss with mafic

metavolcanic material, it appears to have been mobile and

intruded the mafic metavolcanic rocks and subsequently been

intruded itself by the biotite granodiorite gneiss.

In the northeast corner of the map-area, east of

Macutagon River and north of Twist Lake, outcrop examination

was limited to the lakeshores of McGraw, No. 5, No. 7 , No. 8

and No. 9 Lakes and in these locations the predominant rock

type is an augen feldspar gneiss. The augen gneiss is dark

grey in colour and weathers light grey to white with a mottled

appearance due to the abundant light coloured feldspar augen.

The rock is strongly foliated and has a typical flaser structure

/

with a fine-grained dark grey matrix and medium-yto coarse

grained light buff feldspar augen. Quartz, plagioclase, biotite

and epidote are evident in hand specimen. At first examination

the rock is quite unlike the granodiorite gneiss due to its

darker colour and sheared flaser structure but a modal analysis

(see Table rfaj ) of the augen gneiss indicates that minera-/A

logically the two rock types are almost identical and the

sheared character of the augen gneiss is very obvious in thin

section. The augen gneiss consists of quartz, microcline and

biotite with a trace of hornblende and accessory apatite

magnetite and sphene. Much of the biotite has been altered

to chlorite, and secondary epidote has been derived from

biotite and plagioclase. The plagioclase is also highly

sericitized. The augen gneiss thus appears to be a sheared

derivative of the granodiorite gneiss.

In some areas the granodiorite gneiss contains

abundant inclusions of amphibolite and in other areas the

granodiorite, and granodiorite with inclusions, is intruded

by great numbers of sheets and dikes of pegmatite, aplite, and

leucocratic biotite granodiorite so that the rock outcrops

are extremely heterogeneous and these areas have been desig

nated as migmatite.

The boundaries of the Black-Pic Batholith are not

completely known, particularly east of the Manitouwadge and

Black River map-areas, but within the mapped region the bath

olith shows a relatively consistant relationship to the adjoin

ing country rocks. In the south and southwest the batholith

is bounded by mafic metavolcanic rocks of the Black and Pic

River map-areas respectively, and in the north by mafic meta

volcanic rocks of the Manitouwadge area. On the basis of

aeromagnetic information (Map 2158G), and personal experience A

in the area, the writer believes the batholith to be bounded

on the northwest by a belt of metavolcanic or migmatitic

metasedimentary rocks, continuous with the metavolcanic rocks

of the Pic River area, and extending northeast from Huck Lake

to join migmatitic metasediments northwest of Manitouwadge.

The rocks of the batholith are well foliated through

out, and attitude determinations indicate that in the contact

areas, the granodiorite gneiss foliation is essentially

conformable in strike and dip with the foliation in the adjoin

ing country rock. Only in the Pic River area, south of

Runnalls Lake, does the granodiorite appear to cross-cut the

strike of the metavolcanic rocks. The granodiorite gneiss

invariably dips beneath the adjacent country rocks and all the

structures in the latter rocks dip and plunge away from the

batholith. In the contact areas the foliation of the

granodiorite gneiss dips between 35° and vertical, and many

dips are between 45° and 75°. In the central part of the

batholith, however, the foliation generally dips between 35°

and horizontal with most dips between 15° and horizontal. Thus,

within the area covered by mapping, the foliation of the

batholithic granodiorite gneiss dips outwards or near vertical

all around the contacts and is essentially flat with gentle

undulations in the centre. There is no information on the

open east end of the batholith but, within the known area it

gives every indication of being an elongated, syntectonic,

domical structure.

The country rocks adjacent to -the Black-Pic Batholith

appear to have undergone a moderately high rank metamorphism.

The metavolcanic and metasedimentary rocks of the Manitouwadge

(Pye, 1957), Flanders Lake (Milne, I964), Pic River (Milne,

1966) and Black River areas have been metamorphosed to at

least the almandine amphibolite facies (Fyffe ct al-7—L9-5-9-)

and the metasedimentary rocks to the east, northeast (Milne,

I964) and northwest (M.E. Coates, 196 ? ) of Manitouwadge

have been invaded by great quantities of granitic material

converting them to migmatites. These facts, plus the

domical, generally conformable, foliated character of the 00

batholith, suggest that it may be a deep level intrusive of

the catazone (Buddington, 1959). However, more information

is required on the metamorphic condition of country rocks

away from the batholith since the almandine amphibolite

metamorphic rank of the Manitouwadge, Pic River and Black River

rocks may reflect a high temperature aureole around the

margins of the batholith.

The Black-Pic Batholith is intruded by younger,

me^ozonal plutons of granodiorite and quartz monzonite, and

by dikes of pegmatite, aplite, biotite granite, augite syenite,

feldspar porphyry, l*mifpmwpiss$xy? and diabase. The batholith is

also cut by faults and adjacent to the faults the granodiorite

gneiss may be hematitized or silicified. Examples of this

may be seen northeast of Gowan Lake or, around and east of

Lineal Lake. In these locations the granodiorite near the

fault is altered from a light grey to a pink or brick-red colour

while,away from the fault the granodiorite is cut by very thin

fractures along which the adjacent granodiorite feldspar, which

xs normally white, is coloured pink. Yellowish green epidote

stringers also cut the granodiorite in these areas and in the

area northeast of Gowan Lake the red altered granodiorite is

cut by a stockwork of thin quartz veins. There was no

mineralization noted in the granodiorite gneiss.

Late Silicic Plutonic Rocks

At least five large plutons ranging in composition

between granodiorite and quartz monzonite outcrop wholly or

partly within the map-area. These plutrons have been named as A

follows:- the Fourbay Lake Pluton in the west-central part of

the area; the Gowan Lake Pluton, in the southwest corner; the

Bullring Lake Pluton, located near the middle of the south

boundary of the map—area; the Musher Lake Pluton lying on the

south side of the mafic and a=eid- metavolcanic formations; and

the Dotted Lake PI ui~.nq which outcrops in the southeast quarter

of the area.

There are variations in the composition of the rocks

in individual plutons and between different plutons (see Table/<6J).

In general the plutons become less mafic, and range from medium-

to coarse-grained, tending to porphyritic, in the order listed

above. Sampling was insufficient to determine whether any

systematic variation in composition occurred within individual

plutons. The megascopic distinction between the first three

plutons; the Fourbay, Gowan and Bullring, is much less apparent

than between these and the Dotted Lake P-lufooHr. The first three

are more mafic and characterized by the presence of hornblende

and biotite while the Dotted Lake g,lut<m is relatively leucocratic

£T>

and contains only biotite.

It seems probable that there is an intrusive

relationship between the leucocratic biotite granodiorite of

the Dotted Lake Pluton and the hornblende-biotite granodiorite

and hybrid diorite found on the west shore of White Lake. On

the other hand a gradational relationship between the mafic

hornblendic granodiorite and the leucocratic biotitic grano

diorite is suggested by the Musher Lake Pluton which consists,

on the west side, of hornblende-biotite granodiorite similar

to the Gowan Lake Pluton, and on the east side of biotite

granodiorite similar to the Dotted Lake Pluton. Since a

possible intrusive relationship existed and megascopic distinct

ion was relatively easy the mafic hornblende granodiorite and

the leucocratic biotite granodiorite were given separate

formational numbers on the map (Formations 6 and 7 respectively,

Map ). The three hornblendic granodiorite plutons also

differ from the Dotted Lake, and Musher Lake Pluton^/ in that

they have a relatively high magnetic response. The magnetic

response seems to vary directly with the mafic content. The

most mafic of the plutons (see Table^°7), the Fourbay Lake

Pluton, gives magnetic readings up to 1000 gammas above the

background of the surrounding granodiorite gneiss. The less

mafic Gowan Lake Pluton gives magnetic intensities up to about

450 gammas, and the least mafic Bullring Lake Pluton intensi

ties up to about 200 gammas above similar magnetic backgrounds.

As a result the general outlines of the Fourbay Lake and the

Gowan Lake Plutons are readily apparent on aeromagnetic maps

of the area (Maps 2156G, 2157G, 2158G, and 2168G). The

Bullring Lake Piuton is marked on the aeromagnetic maps by

an area of slightly higher magnetic response than the surround

ing rocks but this is insufficiently distinct to outline the

piuton. The Musher Lake and Dotted Lake Flu-Lang, have magnetic

responses similar to the adjacent granodiorite gneiss and

metasedimentary gneisses.

Fourbay Lake Piuton

This piuton covers an area of about 24 square miles

and is located on the west side of the area, mostly to the

east and northeast of Fourbay Lake. The piuton is roughly

oval in shape with its long dimension of about 8 miles oriented

north-south and its short dimension about 4 miles east-west.

The piuton consists of pyroxene-hornblende-biotite granodiorite

(see Table lUo,l ) and intrudes biotite granodiorite gneiss of

the Black-Pic Batholith. The piuton is poorly exposed over

much of its area and contacts exposures were not found. On

the north, east and southeast boundaries the contact of the

piuton is essentially parallel to the strike of the foliation

in the adjacent biotite granodiorite gneiss but on the south

the contact appears to cut across the general trend of the

gneiss foliation.

The most typical rock type of the piuton is usually

massive, medium-grained, equigranular with an overall light

grey to pink colour which in detail consists of about 80 to

85 percent light grey quartz and feldspar mixed homogeneously

a

with between 15 and 20 percent dark green to black mafic

minerals. Hornblende and biotite are easily recognized in hand

specimen and scattered grains of magnetite and epidote are

sometimes visible. Scattered pink spots, usually about 1

millimetre in size, and apparently the result of local

colouration of potassic feldspar grains are characteristic

of the rock. Two modal analyses of the typical rock of the

pluton are shown in Table Sample Nos. *r— and

The essential constituents are quartz, oligoclase, microcline,

hornblende, biotite and augite with accessory magnetite,

sphene, apatite and zircon and minor secondary epidote and

carbonate. The plagioclase, microcline and quartz grains are

anhedral with the microcline occasionally interstitial to the

plagioclase. The plagioclase is zoned and micrographic inter-

growths of quartz occur in the plagioclase. The microcline

is slightly perthitic with small amounts of plagioclase strings

and blebs confined largely to the cores of the microcline

grains. Augite is not abundant and generally occurs as kernels

enclosed by coronas of hornblende. The hornblende is dark

green in colour and the biotite dark brown and pleochroic

haloes are common in the biotite. The percentage of biotite

and hornblende in the rock generally totals about 15 percent

but the relative proportions of biotite and hornblende appears

to be quite variable. The accessories sphene, magnetite and

zircon are generally associated with the biotite in the rock

as is the secondary epidote. The apatite is scattered throughout.

In some parts of the pluton, particularly on the

east and north, the biotite in the granodiorite of the pluton

is much more obvious in hand specimen than in the typical rock

described above. The biotite is coarser grained and initially

it was thought that the biotite was more abundant but modal

analyses (Table w,/) of the two samples of *Biotitic augite

granodioriteT, formation 6d on Map ?, , Sample Nos. o

and, I , indicates that some of these Tbiotitic' rocks

have a biotite content similar to the typical rock (compare

samples No. J> and / ). The significant feature about

these TbiotiticT samples appears to be the coarser grain of

the biotite, a slightly higher mafic content and a significantly

higher content of clinopyroxene and magnetite. The *biotiticT

rock is similar in appearance to the typical rock except for

the presence of coarse-grained highly reflecting flakes of

biotite. It is interesting to note that on the aeromagnetic

maps (maps 2157G and 2158G) the highest magnetic response over

the area of the pluton occurs over the areas of tbiotitict rock

and this is presumably due to the higher magnetite content of

this rock.

The rocks of the pluton are usually foliated near

the contacts and in these areas contain numerous partly

digested xenoliths of hornblende gneiss or amphibolite. These

xenoliths are angular to subrounded and usually only a few

inches in size. Since there is little or no material equivalent

in composition to the xenoliths, in the surrounding granodio

rite gneiss of the Black-Pic Batholith, the xenolithic material

must have been brought from some other location during intrusion

of the pluton or stoped from the now eroded roof of the pluton.

Within the main mass the rocks are predominantly massive but

occasionally a faint banding due to variation in the mafic

content was noted. This feature can be seen in two outcrops

on the power line which crosses the pluton. The granodiorite

of the pluton is intruded by dikes of leucocratic pegmatite

and aplite and by diabase dikes. The pluton is also cut by

the &vr<5&& Lake Fault and the granodiorite near the fault is

commonly pinker in colour than the typical rock of the pluton.

A lineament, which is parallel to the .Swede Lake Fault, crosses

the pluton in the north and this may represent another fault

but no substantiating information is available.

Gowan Lake Pluton

Only part of this pluton outcrops in the Black River

map area. The entire pluton has not been mapped.but from the

aeromagnetic (Maps 2156G, 2157G, and 2168G) and geological A

information available (Milne/ I966).the pluton covers an area

in excess of 30 square miles and is roughly V-shaped in outline

with an oval apophysis on the inside of the eastern limb.

The apex of the V-shapet/lies southwest of the Black River area, A

apparently from the aeromagnetic map, about 1 mile northeast hUtZS

of the Pic River at Highway No. 17- The V-shape*is recumbent

to the east so that the west limb extends north-northeast from I

the apex through Sprucetop and Veronica Lakes in the Pic River

map-area, and the east limb trends east-northeast from the apex

through the south end of Gowan Lake and through Valley Lake,

in the southwest, corner of the Black River area. The oval

apophysis lies on the north side of the east limb, mainly

between Harriet and Gowan Lakes.

The pluton mainly consists of hornblende-biotite

granodiorite or quartz monzonite. The outer southeast and

northwest contacts of the V-shaped pluton cut mafic meta

volcanic and metasedimentary rocks while the inner contacts

of the V-shaped mass and the oval apophysis intrude biotite

granodiorite gneiss of the Black-Pic Batholith. The pluton

is well exposed in the Pic River map-area and in the

Harriet Lake-Gowan Lake region of the Black River area, but

exposures are poor between Gowan Lake and the Black River.

The contacts are rarely exposed and within the mapped areas

the contacts of the pluton are essentially parallel to the

foliation in the adjoining country rocks. However, on the

west shore near the south end of Gowan Lake a contact

between the pluton and biotite granodiorite gneiss is

exposed and at this location although the contact of the plut

is predominantly parallel to the foliation of the gneiss,

periodically the contact makes small, step-like jogs across

the foliation of the gneiss. In the Pic River area contacts

between the pluton and mafic metavolcanic rocks are exposed

and in this area 'TThe intrusive (pluton) interfingers with,

and a considerable number of quartz monzonite dikes intrude,

the metavolcanic rocks in the contact areas.*1 (Milne/ 1966).

The rocks of the Gowan Lake Pluton are generally

less mafic (see Table M>,I ) and slightly coarser grained than

the rocks of the Fourbay Lake Pluton. Modal analyses of

three samples, Sample Nos. ST , °i and 10 , Table /J&J ,

show a range in composition between granodiorite and quartz

monzonite and a wide range in the relative proportions of

biotite and hornblende present. The rocks of the Fourbay

and Gowan Lake Plutons are similar in colour; the small

percentage difference in the mafic content is not noticeable

in hand specimen, but the Gowan Lake rocks are medium-vto

coarse-grained and are commonly porphyritic. The porphyritic

character is not always readily apparent because the phenocrysts

of microcline in the rock are generally anhedral and peppered

with inclusions of biotite which reduces the contrast between

the phenocrysts and the ground mass. The minerals quartz,

plagioclase, potassic feldspar, hornblende, biotite, epidote

and sphene are usually visible in hand specimens of the Gowan

Lake rocks and in the porphyritic specimens pink or grey op 1

anhedral microcline phenocrysts, ranging- to about ^ inch xn t-rta- fir in

size, are set in a medium-to coarse-grained^of these minerals.

The plagioclase is zoned oligoclase or oligoclase-albite and

is generally anhedral but euhedral to subhedral laths are

sometimes enclosed in microcline grains. Lobes of myrmikite

are frequently present between grains of plagioclase and

microcline. The microcline is coarse, anhedral, commonly

porphyritic and usually slightly perthitic with a little

exsolved string and vein material in the cores of the grains.

Other major constituents are quartz, which is anhedral and

often interstitial, dark green hornblende and brown biotite.

A very amall quantity of clinopyroxene was present in one of

the samples examined (Sample No. % , Table /''Js< / ). Accessory

minerals include sphene, magnetite, apatite and zircon and

secondary epidote, chlorite and sericite is present as

alteration of the plagioclase and the epidote and chlorite

largely as alteration of the biotite. In sample No. iO ,

Table W*( , most of the biotite has been altered to chlorite.

The rocks of the pluton are generally massive but

they may show a poor foliation, especially near the contacts. on

In contact with the metavolcanic rocks the intrusive tends

to be equigranular, less quartzose and more mafic. In the

Pic River area it is common to find amphibolitic xenoliths

at the contact between the Gowan Lake Pluton and the biotite

granodiorite gneiss of the Black-Pic Batholith similar to those

in the Fourbay Lake Pluton. The Gowan Lake Pluton is also

intruded by leucocratic aplite dikes and diabase dikes and

is cut by a number of faults.


\

\ \

\


Only a small portion of this pluton, covering about

8 square miles, outcrops in the map-area. The mapped area

represents a very small part of a large mass, probably of

batholithic dimensions, which extends from the Black River,

just south of the map boundary, east-southeast across Highways

No.614 and No.17, through Cedar and Dune lakes and probably

beyond the south end of White Lake. The pluton appears to

intrude metasedimentary rocks over most of its known length.

There are no exposures of the contact within the map—area but

the contact is exposed on Highway No.17 about % mile west of

the junction with Highway N0.614. In this location the contact

is conformable with the foliation in the adjoining metasedimentary

rocks; the hornblende-biotite granodiorite of the pluton is

finer grained at the contact and granodiorite and metasedimen

tary bands of about 1-foot width are interlayered over about

10 feet from the main contact. Some contorted xenoliths of

metasediment are present in the granodiorite and occasional

layers of metasediment curve from the contact into the grano

diorite. The best exposures of the granodiorite intrusion

within the map-area are located at the south end of East Barbara

Lake, along Highway No.614 and on the Canadian Pacific Railway

spur line from Struthers.

The pluton consists essentailly of hornblende-biotite

granodiorite and modal analyses of two samples, Sample Nos. //

and / 2_ , are shown in Table /U». ) . The granodiorite is

massive, coarse-grained and porphyritic. The porphyritic

feldspar grains are up to ^ inch in size but, as in the Gowan

Lake Pluton, the porphyritic texture is not always apparent

immediately because the phenocrysts contain many inclusions of

biotite and the feldspar of the rock is uniform in colour.

The rock is normally light grey in colour with a mafic content

between 5 and 10 percent. The coarse grain size, porphyritic

texture and low mafic content render the rock distinctively

different from the granodiorite of the Fourbay Lake Pluton and

usually the mafic content is noticeably lower than in rocks of

the Gowan Lake Pluton. Scattered rounded mafic xenoliths are

present in many outcrops throughout the pluton and these are

usually less than 3 inches in size. A few irregularly shaped

xenoliths of metasedimentary material with dimensions of

several feet were noted near the contacts.

The granodiorite consists essentially of quartz,

oligoclase-albite, microcline, hornblende and biotite and these

are visible in most hand specimens. Accessory minerals include

sphene, magnetite, apatite and zircon and secondary chlorite;

sericite and epidote are usually present, the latter mineral

is commonly visible in hand specimens. The oligoclase-albite

exhibits oscillatory zoning and subhedral -§aa " phenocrysts of

the plagioclase usually contain inclusions of hornblende and

biot'ite which in some grains appear to be arranged in concentric

zones around the core. The microcline is frequently intersti

tial and a little string perthite is present. The hornblende

is dark green and the biotite dark brown with pleochroic haloes ,

and slight alteration to chlorite is common. Some purple

fluorite was noted coating fracture planes in the granodiorite

on Highway N0.614 but no fluorite has been observed in the main

mass of the rock.

The granodiorite is commonly pink to red in colour

adjacent to daijbase dikes and fault planes .and epidote and

hematite-carbonate veining is also common at these locations.

A particularly good exposure of the relationship of the reddening

of the granodiorite to faulting occurs in a road cut on Highway

No.614 about 1000 feet south of the map limit. The rock in

this locality is cut by at least three hematite-carbonate

gouge-filled shear planes which are up to 1 foot in width

(Photo 7 )• Immediately adjacent to the shear planes the

granodiorite is completely altered to a brick red colour and

small miarolitic cavities develop in the rock but the original

porphyritic massive texture is retained. The plagioclase is

albitic and clouded with sericite and dusty alteration products.

Dislocation of the grains is indicated by the plagioclase twinning.

The microcline is clouded with dusty inclusions along cleavages

and fractures but is clearer in comparison with the plagioclase.

The biotite is completely and the hornblende partly altered

to chlorite. Epidote and carbonate occur throughout the rock

and as fracture filling. A few feet away from the shears the

granodiorite is less strongly coloured. The rock is flesh pink

in colour but is cut by many thin fractures along which the

bordering feldspar of the granodiorite has been reddened .

(^h-oiSo^Sfc^b^ The feldspars are slightly less altered and the

chlorite alteration of the mafic minerals is less with much fresh

biotite remaining in the rock. The pjfrj&dtrtg and red fracture

veining persists with diminishing intensity up ^ mile to 1 mile

away from the fault zone. As mentioned above the same features

were noted in the vicinity of some diabase dikes but it is not

certain if this is due to the diabase dikes or that the diabase

dikes have been intruded along an earlier fault plane. The

granodiorite is intruded by diabase dikes and by dikes of

pegmatite and aplite.

Musher Lake Pluton

This pluton underlies an area of about 10 square miles

and is roughly tadpole-shaped with the head lying between Musher

Lake and Highway No.614 and the tail extending southeast from

Musher Lake to the trail between Theresa Lake and Etna Lake.

There are very few exposures of the pluton and location of the

contact is extremely speculative over much of its length. The

pluton is in contact with mafic and acid metavolcanic and pyro-

clastic rocks on the north side and metasediments on the south.

Outcrops on the west side of the pluton along Highway

No,614 consist of hornblende-biotite granodiorite similar to

that of the Bullring Lake Pluton. On the east however, the rocks

are less mafic, usually light pink-coloured, biotite granodiorite

similar to the rocks of the Dotted Lake Pirrfc-oi which is described

in the next chapter. Due to the very limited exposure it was

not possible to determine the relationship between the two phases

of the pluton. The principal differences between the two phases

are indicated by comparison of the modal analyses of the Bullring

Lake Pluton samples, Sample Nos.Jf and / 2. , and the Dotted

Lake P-i**fea*i sample, Sample No. Lj , Table Wo./. In hand

specimen the rocks of the eastern part of the pluton are light

coloured, generally pink, equigranular, coarse-grained and

massive with biotite the only apparent mafic mineral, while the

rocks of the western side are slightly darker, more mafic, grey

coloured, coarse-grained, porphyritic and massive with horn

blende and biotite both apparent.

Just south of the pluton on Highway No.614 the meta-

sedimentary gneiss has been intensely crenulated and almost

converted to a muscovite schist and on the north side of the

pluton the pyroclastic and aei-d metavolcanic rocks in the region

1 of the Von Klein Property also contain a great deal of muscovite.

It is possible that the development of the muscovite in these

rocks and the crenulation is related to the intrusion of the

pluton. Also on the north side of this pluton the pyroclastic

and metavolcanic rocks just east of Summers Lake have been

fractured into large blocks which are cemented together by

granitic material. It is uncertain whether this brecciation is

related to faulting or to the effects of intrusion of the Musher

Lake Pluton.

Dotted Lake Batholith

The full extent of this batholith is unknown but about

90 square miles of it outcrops in the southeastern part of the

map-area. The batholith intrudes rocks of the mafic metavolcanic

formation and biotite granodiorite gneiss of the Black-Pic

Batholith. Peninsulas of the mafic metavolcanic formation

project into the interior of the Dotted Lake Batholith and some

of these are almost separated from the main mass of metavolcanic

rock to become roof pendants. Dilation produced by intrusion of

the Dotted Lake Batholith is suggested by the presence of thin

layers of mafic, metavolcanic rock at the contact between this

batholith and the biotite granodiorite gneiss of the Black-Pic

Batholith, and these may be up to I2 miles from the main mafic

metavolcanic mass. Exposures of the contact are rare but good

exposures can be found on the southwest side of Dead Otter Lake

at the end of the access road and just south of the shore towards

the firetower trail.

No inhomogeneity was noted in the main mass of the

Dotted Lake Batholith which appears to consist throughout of f&uc o~~

1 rnnnnrntiin-hi ntitr granodiorite. The typical rock is light

pink to white in colour, massive, coarse-grained and inequigra-

nular with about 3 percent mafic minerals. Biotite is the only

mafic mineral visible in hand specimen with quartz and feldspar

and occasionally epidote. The granodiorite is intrusive into the

mafic metavolcanic rocks with sharp contacts and generally the

granodiorite in the contact area is slightly finer grained and

darker in colour than in the main mass of granodiorite. Between

Roger and Olga lakes the mafic metavolcanic rocks are almost

isolated as a roof pendant and are probably present as a very

thin veneer over the granodiorite. The rocks in this area are

essentially migmatites composed of mafic metavolcanic and aplitic

material.

>

In the contact areas the granodiorite is invariably

sheared and the shearing generally parallels the contact and the

foliation in the bordering country rock. The shearing produces a

foliation so that the rock around the Batholith contact is

essentially a granodiorite gneiss and in the area north of the

mafic metavolcanic rocks, north of Dotted Lake, this is sometimes

difficult to distinguish from the granodiorite gneiss of the

Black-Pic Batholith. However, the sheared gneiss of the Dotted

Lake Batholith is generally pink, tends to develop porphyroblas^"

tic feldspars and is less mafic than the grey, equigranular gneiss

of the Black-Pic Batholith. Foliation is also developed in the

main mass of the batholith adjacent to shear zones. An example

of this can be seen at the north end of Theresa Lake where a

steep, west-dipping foliation is developed in the granodiorite

adjacent to a 3-foot wide mylonitic zone in the granodiorite.

The foliation is marked by the orientationof biotite in the

granodiorite and by the squashing and elongation of quartz grains.

Another example occurs about 1 mile north of ThEresa Lake. In

this location the shear zone is not exposed but the granodiorite

is strongly foliated, trending roughly east-west and dipping at

a shallow angle to the north, suggesting that there may be some

low angle thrust faulting in the area.

On the west side of White Lake in the southeast corner

of the area, the metavolcanic and metasedimentary formations are

intruded by a great deal of amphibolitic metagabbro, hornblende-

biotite granodiorite similar to the Gowan Lake Pluton material,

and mafic hybrid granodiorites or diorites derived by contamination

of the granodiorite by mafic metavolcanic and metagabbroic

material. Agmatites composed of amphibolitic metagabbro frag

ments cemented by hornblendic granodiorite are very common in

the area from Etna Lake southeast to Highway No.17. Between

Tri Lake and White Lake a thin band of foliated hornblende-

biotite granodiorite lies between the mafic metavolcanic forma

tion and the leucogranodiorite of the Dotted Lake Batholith.

This band appears to be continuous with the hornblendic grano-

diorites and hybrid phases on the northwest and southwest shores

of White Lake. No contacts are exposed between the leucograno

diorite and the hornblendic granodiorite and its hybrid phases

so that the relationship between them is uncertain. Some mafic

hornblendic granodiorites or diorites also occur within the

Dotted Lake Batholith north of Roger Lake and the relationship

here is also unknown. Many of the hybrid granodiorites and

diorites are foliated and the mafic content is extremely

variable. Some of the less mafic phases resemble the hornblende-

biotite granodiorite gneiss of the Manitouwadge area (page i. — )

which is older than the biotite granodiorite gneiss of the

Black-Pic Batholith. However, the massive hornblendic grano

diorite phases in the White Lake area seem to be related to the

younger Gowan Lake granodiorite indicating a similar young age

for the hybrid rocks of the White Lake area. It seems probable

that any of the granodiorite intrusive phases in the area may

have been contaminated by mafic metavolcanic or metagabbroic

material thereby producing mafic hornblendic hybrid phases.

Since the compositions of these intrusiv-es are not vastly

1 Fragmental plutonic rock with more or less granitic cement. (AGI Glossary, Supplement, I960, p. 1 )

>c

different, separation of the respective hybrids on a lithological

basis would be very difficult.

The modal analysis of a typical leucogranodiorite from

the Dotted Lake Batholith is shown in Table "6,1, Sample No. 1^ .

The essential constituents are quartz.sodic oligoclase, microcline,

biotite and minor hornblende. Accessory sphene is present and

a little secondary epidote is associated with the biotite and

plagioclase. The grains are anhedral, inequigranular but

usually coarse except for the accessory sphene which is fine

grained and euhedral. The plagioclase is most commonly coarse

ns

grained, shows normal zoning and frequently exhibits myrm^kitic

lobes adjoining microcline grains. The microcline is generally

coarse and some grains appear to include some of the smaller

oligoclase grains, while others appear to be interstitial to

the plagioclase and quartz. The quartz grains are irregular in

shape, coarse, and usually slightly strained. The biotite is

dark brown, the hornblende dark green and the epidote is present

as a dusty alteration in the cores of some plagioclase grains

and associated with some of the biotite grains.

The Dotted Lake leucogranodiorite is cut by a few thin

scattered dikes of pegmatite and aplite and occasional quartz

veins. Quartz veins are rare in the main mass of the batholith

but in the area around Dead Otter Lake quartz veining is abundant.

A possible explanation of the quartz vein distribution is that

the leucogranodiorite in the Dead Otter Lake area is intruded

into an anticlinal fold in the mafic metavolcanic formation and

the quartz veins are concentrated in the crestal area of the

»

intrusi^ee. None of the veins examined contained visible

mineralization. A few dikes of fine-grained hornblende grano-

diorite intrude the leucogranodiorite in the Spider Lake area

and numerous diabase dikes also cut the batholith.

Silicic Dikes

There are a large number and variety of intrusive

silicic dikes and stocks in the area and for most of thsse it is

difficult to show a direct relationship to any of the large

plutons or batholiths. It is probable that early and late

intrusive dikes are associated with each of the granitic plutons

and batholiths in the area and many of these dikes from different

sources could have similar compositions. It is not possible

with the limited outcrop and the scale of mapping to separate

all these. The widest variety in type of dike intrusive occurs

in the mafic metavolcanic formation but quantitatively there

is more intrusive dike material in the metasedimentary formation.

The granodioritic plutons and batholiths are intruded by silicic

dikes but in the younger of these, the tLate Silicic Int-rusi-v-e

Rocks1, the dikes are few in number and almost entirely pegmatite

and aplite.

Dark grey feldspar (hornblende) porphyry dikes appear

to be among the oldest silicic dikes in the area. Most exposures

of this type of dike were found intruding the mafic and dacitic

pillow lavas and pyroclastic formations along the C.P.R. spur

line between Amwri Lake and Pinegrove Lake. On fresh surfaces

these rocks are dark grey in colour, medium-/to fine-grained with

?*r

white porphyritic feldspar grains wngimggup to 4 millimetres

in size. The rock may be massive or foliated. Small hornblende

phenocrysts are usually scattered among the feldspar phenocrysts

and in some dikes these predominate. Individual dikes may be

inhomogeneous having predominantly feldspar phenocrysts in one

part and dominantly hornblende phenocrysts in another and less

frequently parts of the dike are essentially non-porphyritic.

The rock consists of quartz, calcic oligoclase, hornblende and

biotite with accessory apatite and pyrite. The plagioclase and

biotite are usually altered and secondary minerals include epidote,

chlorite, carbonate and sericite. The plagioclase phenocrysts

are euhedral to anhedral and many are zoned, often with

oscillatory zoning. These dikes are intruded by light grey

feldspar porphyry dikes and fine-grained, dark green syenodiorite

dikes.

Light grey feldspar porphyry dikes are found throughout

C the mafic metavolcanic and pyrq^lastic formations in the area.

Good exposures of this type of dike are found along the C.P.R.

track in the same general area as the dark grey porphyry dikes.

The light grey porphyry dikes are light grey to pink in colour

massive to foliated, with a fine-grained quartzo-feldspathic

matrix containing short dark biotitic danhffls and densely packed

with light buff to white anhedral to euhedral feldspar pheno

crysts up to 5 millimetres in size. These dikes are readily

distinguishable from the dark grey porphyry dikes even when

direct comparison is not possible as on the C.P.R. railway track.

The light grey to pink colour is distinctive reflecting a lower

mafic content, the phenocrysts are generally more abundant and

exclusively feldspar, and hornblende is absent. The light grey

porphyries consist essentially of quartz, oligoclase-albite,

microcline, and biotite with accessory sphene, magnetite, pyrite

and apatite. Both the microcline and plagioclase form phenocrysts

and some of the plagioclase grains are slightly zoned. Altera

tion of the plagioclase and biotite is common and secondary

epidote, chlorite, and sericite are present. The coarser

phases of the light grey porphyry resemble some of the medium

to coarse-grained biotite granodiorite dikes, and the marginal

phases of the biotite granodiorite of the Dotted Lake Batholith

tend to be porphyritic and resemble the light grey porphyry.

It seems probably that the light grey porphyry dikes are

related to the biotite granodiorite of the batholith.

A great many biotite granodiorite or granite dikes

intrude the metavolcanic, pyroclastic and metasedimentary

formations and the biotite granodiorite gneiss of the Black-Pic

Batholith. These are generally white, light grey or pink in

colour, they may be foliated or massive and vary in grain size

from fine-grained to coarse-grained. These dikes are biotitic

with a mafic content usually less than 10 percent and are

probably related to the late silicxc plutonic intrusives xn

the area but it is not possible, as stated above, to relate

individual dikes to specific plutons.

A small number of very fine-grained, dark green, mafic

hornblendic dikes were found in the area. This type of dike

was found in the C.P.R. railway cuts in the vicinity of Jenny

Creek intruding metavolcanic rocks and dark grey feldspar

porphyry dikes and also on the west side of No.6 Lake intru

ding biotite granodiorite gneiss and biotite granodiorite dike

rocks. These dikes were mapped initially as lamprophyre but in

the No.6 Lake location they appeared to be associated with a

coarser grained dark to light grey porphyritic (hornblende )

syenodiorite. Thin section examination indicates that the fine

grained dark green dike rock consists of oligoclase-albite

plagioclase, microciine, and hornblende with accessory sphene

and pyrite and secondary biotite and chlorite alteration of

the hornblende. The mafics total between 20 and 30 percent.

The rock composition would thus appear to be syenodioritic.

The porphyritic syenodiorite is composed essentially of the

same zoned oligoclase, microciine and hornblende but has

appreciably more biotite. The hornblende occurs as coarse

grained phenocrysts in a fine-grained matrix of plagioclase and

microciine. The biotite is present as long thin laths replacing

the coarse hornblende grains and confined almost entirely to

the hornblnede grains. Accessory sphene, zircon and apatite

are plentiful and magnetite and secondary epidote are also

present. The mafic content of the porphyritic phase is about

20 percent but the rock is much lighter in colour than the fine

grained phase because of the porphyritic character of the mafics.

All the dikes described above are apparently older

than white to pink coloured, massive, fine-to medium-grained

leucogranitic dikes which, for example, intrude the granodiorite

gneisses around the junction of Highway No.614 and the C.P.R.

track just south of Manitouwadge, and intrude the gneisses and

other dike rocks exposed on the west side of No.6 Lake. These

leucogranitic dikes contain between 2 to 5 percent fine-grained

biotite peppered throughout the rock and quartz and plagioclase

are also visible in hand specimen.

Pegmatite and aplite dikes intrude the above leuco

granitic dikes, the granodiorite gneiss of the Black-Pic

Batholith and all the late silicic plutons and batholiths. It

is probably that pegmatitic and aplitic phases are associated

with several of the large intrusive plutonic masses in the area

and Pye (1957) indicates at least two ages of pegmatite-aplite

dikes. Relatively few pegmatite and aplite dikes occur in the

late silicic plutonic intrusive masses and they are not very

plentiful over much of the Black-Pic Batholith but in the northern

part of the batholith between Manitouwadge, Gaffhook Lake and

Twist Lake pegmatite and aplite dikes are abundant. The

pegmatite and aplite may be white or pink in colour and single

dikes may contain both white and pink rock. Pegmatites of

similar appearance cut each other and cut aplites, and, likewise,

aplites cut aplites and pegmatites, and single dikes were

observed composed of both aplite and pegmatite. In some dikes

the aplite and pegmatite material occur in layers parallel to

the contacts and in others pegmatitic grains of feldspar and

quartz are isolated in aplitic material. In some pegmatites

the co[r/a!se—grained pertitic microcline feldspars are oriented

perpendicular to the dike contacts and some of these are wedge-

shaped, enlarging inwards from the dike contacts. These feldspar

a.re grains range up to 9 inches in length. Good exposures of the

pegmatites are found on the Ontario Paper Company road south

of Morley Lake and along the Macutagon River just south of

Gertrude Township. Many of the pegmatites and aplites are

biotitic but the mafic content is usually less than 5 percent.

No economically interesting minerals were noted in these dikes.

A small number of other silicic intrusive bodies were

found in the area. Among these are hybridized granodiorite,

sheared muscovite dikes and augite syenite dikes. Two small

bodies of the granodiorite were mapped, one an irregular,

branching dike over 10 feet wide cutting mafic metavolcanic

material on the west side of Highway No.614? just south of

Summers Lake, and the other a small piug ©£ about 300 feet \n

diameter containing much mafic material and intruding the mafic

metavolcanic rocks about ^ mile east of Highway No.614 and

2000 feet north of Summers Lake. The rock contains about 30

percent mafic minerals and consists essentially of quartz,

zoned oligoclase-andesine, microcline, hornblende and biotite

with accessory sphene. Sericite, epidote and chlorite alteration

products of the plagioclase and biotite are also present.

The muscovite dikes were found only in the vicinity

of the Von Klein Property east of Summers Lake. These rocks may

be confused quite easily with the muscovitic metasedimentary

and metarhyolitic gneisses in this region but they are

distinguishable and chilled intrusive contacts were found on

these dikes. The rock is medium-to coarse-grained and light

grey to pearly white in colour. The rock may be massive but

more commonly it is sheared into a strongly foliated rock with

coarse Tquartz eyeT augen developed. Quartz,feldspar and

muscovite are the only minerals apparent in hand specimen.

In thin section the essential constituents were identified

as quartz, albite and muscovite but in some parts of the dikes

the albite seems to be completely replaced by muscovite, leaving

only quartz and muscovite. A little pyrite is disseminated in

the rock and minor chlorite is also present. Most of the

muscovite in these dikes appears to have developed by replace

ment and the original composition of these dikes is unknown.

The augite syenite dikes were found intruding the

porphyritic pillowed dacites on the east side of Pinegrove Lake

and intruding the granodiorite gneiss just north of the Swede

Lake Fault, west of Barehead Creek. The rock is often quite

distinctive on weathered surface being pink with coarse, dark

green hornblende spots. The fresh rock is grey to mauve in

colour, fine-grained with medium-to coarse-grained euhedral to

subhedral hornblende crystals densely, scattered throughout.

The mafic content is between 15 and 20 percent. In thin section

it was found that the phenocrysts consisted of augite clino-

pyroxene rimmed or completely altered to green hornblende.

These were set in a groundmass of highly altered, zoned albitic

plagioclase and microcline with secondary epidote and greenish

mica. Some dikes of similar appearjn/ajce but of finer grain

and containing only hornblende were found cutting the Dotted

Lake Batholith in the Spider Lake region and it is possible

that these are the same type of dikes with no remnant pyroxene.

These dikes are probably related to the Fourbay Lake Pluton but

it is also possible that they relate to the Port Coldwell

Alkalic Complex in the Marathon area.

Diabase BifeeH

There are many diabase dikes in the area and they

intrude all the formations previously discussed in this report.

The dikes are usually vertical to steeply dipping and although

the strike attitudes of the dikes vary locally there are he *H*rce

major strike trends. The dikes tend to strike approximately

northwest, north-south or N35°E. The northwest-trending dikes

seem to be the most consistent in attitude whereas there appears

to be a range of attitudes between north-south and N35°E and

examination of the dikes on the west side of White Lake suggests

the possibility that some of the north-south trending dikes

actually emanate from the N35°E dikes. Some of the larger

northwest-trending and N35°E-trending dikes are apparent on O.D.H. - &.$.C* fnapf i

aeromagnetic maps of the area (2156G, 2157G, 2158G, 2167G,

2168G and 2169G) as elongated magnetic ridges, particularly in

the areas of granitic rocks. Some of these^however^are not

apparent and there is usually little indication of the north-

south dikes. Dikes have been traced within the area for more

than 10 miles and aeromagnetic information suggests that they

may extend for hundreds of miles. Widths of the dikes vary

from a few inches to about 500 feet.

Most of the diabase dikes are very similar in appearance.

The typical rock is dark grey, medium-grained, equigranular, and

massive, with characteristic diabasic texture. At dike contacts

the diabase is invariably chilled to a black aphanitic rock

containing a few scattered fine-grained phenocrysts of plagio-

clase and clinopyroxene. In some of the wider dikes the interior

parts are coarse-grained and mottled light greenish-grey and

black in colour. In a few of the wider dikes, for example,

the dike intruding the north end of the Fourbay Lake Pluton,

irregular patches of red, granophyric, feldspar-rich diabase

are present in the interior of the dike. Disseminated pyrite

and pyrrhotite are very common accessories in the diabase and

the rock weathers a very distinctive rusty brown to buff colour

which makes it stand, out from the other rock types in the area.

A few of the dikes in the area contain coarse, rounded to

euhedral, yellowish phenocrysts of altered plagioclase up to

1 inch in size. These phenocrysts are not present throughout

the entire dike so that one dike may in ^art be porphyritic

and in part non-porphyritic. However, the few porphyritic dikes

encountered all seemed to belong to the northwesterly-trending

group so that in mapping a distinction was made between the

porphyritic and non-porphyritic types.

Essentially the diabase consists of felted mass of

zoned, labradorite feldspar laths with interstitial augite.

Quartz and granophyric material is present interstitially in

all the diabases, porphyritic and non-porphyritic, examined under

the microscope and is particularly evident in the coarse-grained

phases of the diles. Accessory minerals include magnetite,

ilmenite, pyrite and pyrrhotite. Secondary hornblende and

uralite are major alteration products of the pyroxene with

minor biotite and chlorite. The plagioclase is invariably

altered extensively to sericite. All the dikes in the area

would appear to be quartz diabase.

A porphyritic (plagioclase) diabase dike in the

vicinity of Cedar Lake,about 3 miles south of the map-area,

has been dated by a Whole Rock, K-Ar analysis as 2320 million

years old (Wanless et al, 1965). Another Whole Rock, K-Ar age

determination on a diabase dike on Highway No.17 just north of

Jackfish Bay, Lake Superior, and about 40 miles west of the

map area, indicated an age for the dike of 1810 million years

(Wanless et al, 1965). It is probable that among the many

diabase dikes in the area there are several ages of dikes,

However, since these are similar in appearance, are generally

quartz diabases, and since the porphyritic texture is not a

consistent feature in dikes showing this texture, it is unlikely

that different ages of dikes can be separated in the field.

It has been proposed (Fahrig et al, 1963) that in the

Canadian Shield dikes of a particular age occur in swarms

which conform generally to a particular strike direction and

this appears to be a reasonable generalization. However, there

are p(o/£bably sufficient exceptions to the generalization to

prevent the application of an age to a specific dike solely on

the basis of the dike attitude. In the Pic River area (Milne,

I966) there are at least two X-shaped dikes, one with limbs

trending north-south and northeast, and the other with limbs

trending north-northeast and northwest, and in the present map-

area there is a suggestion that some north-south dikes emanate

from the northeast-trending dike on the west side of White Lake.

Dikes in the Pic River and Black River map-areas generally

conform to joint directions in the country rocks. Some of the

dikes—;in-^hese—^o_.aneas_may„_coji£oxm^

country rocks. Some of the dikes in these two areas may conform

predominantly to one joint direction in a particular location

but the contact in fact zigyzags utilizing two joint directions

in the country rocks, and it is conceivable that at some point

along these dikes the emphasis may change from one joint

direction to the other. One further difficulty in determining

the age of a specific dike from its attitude is that although

dike attitudes seem to be fairly consistent in granitic areas,

in areas of metavolcanic rocks,for instance, where the structura

trend of the metavolcanic formations is in the quadrant between

northwest and northeast (see Pic River map-area, Milne, 1966),

the diabase dikes tend to conform to the structural trends

rather than to the jointing, and dikes may curve and vary from

northwest to northeast.

The diabase dikes are undoubtedly younger than all the fag C£t^7 6 S-/JZO

other conoolidatred rocks in the area and dikes were found

intruding all of the formations with the exception of the

serpentinized peridotite bodies. The same feature was found

in the Pic River area. The absence of dikes in the serpentinite

is probably due to the non-friable character of the rock.

Pleistocene and Recent

Most of the Black River area is covered by glacial

drift material and this seems to be of three principal types,

which are: (l) glaciolacustrine sediments (varved clays and

beach sands and gravels), (2) glaciofluvial sediments (sand

and gravel esker ridges, and (3) glacial moraine. Thick

deposits of the glaciolacustrine material appear to have the

greatest areal extent within the map—area, underlying the wide

Black and Macutagon River valleys and their tributary creeks

and underlying the drainage areas of the Nama and Fourbay

Creeks. The remainder of the area is generally higher with

good rock exposure and only thin drift cover, usually bouldery

clayey sand.

Varved clays are exposed in the lower parts of the

river banks along much of the Black and Macutagon Rivers and

in the banks of Mobert, Barehead, Fourbay and Nama Creeks,

around Agonzon Lake and occasionally along the C.P.R. railway

tracks. The varves generally range in thickness from less than

4 inch to 1 inch but in one exposure on the Black River the

total thickness of a light and dark layer was about 6 inches.

In most of the sections examined the varves were exposed in the

lower part of the river or creek bank and the total thickness

of clay exposed rarely exceeded 10 feet. In some locations

the varved clays have filled depressions between rock outcrops.

An example of this can be seen on the C.P.R. railway track just

north of the Ontario Department of Highways road maintainance

camp. The railroad cuts expose varved clays and granodiorite

gneiss in low ridges of about the same height.

Throughout most of the river and creek valley areas

the surface is sandy and in the river bank sections the varved

clays are always overlain by bedded sands. The exposed thick

nesses of the sands varies from 30 to 50 feet. The sands may

grade down through silty and clayey sands into the varved clays,

but in some sections the varved clay is overlain directly by

coarse sand beds, with interspersed 1-foot thick pebble bands,

and this in turn is overlain by well bedded fine-grained sands.

The pebble bands are densely packed with well rounded pebbles,

most of which are less than 1 inch in diameter. A few well

rounded pebbles, generally less than 1 inch -d-iamotor but in a Sam eft *"

ranging up to 22 inches, are usually scattered around on the A

sandy surface of the ground and these pebbles are often of /tntes/py? C varieties of

coralline or other limestone.-k ny-Wi*..

Gravel is generally of minor importance in the glacio-

lacustrine material but on Highway No.614, between the Ontario

Department of Highways camp and No.6 Lake, a beach spit or bar

containing a considerable amount of gravel, extends southwards

from a high outcrop area south of Barehead Lake. The deposit

is probably a bar rather than a spit as it is bounded on the

east and south by varved clays exposed along the C.P.R. tracks,

on the west and south by varved clays exposed in Barehead Creek,

and on the north, between the bar and the Barehead Lake outcrop

area, a depression just south of No.6 Lake is probably floored

by clays and silts. Highway No.614 follows the top of the bar

while the C.P.R. railway track follows the east base of the bar

and is over a hundred feet below the level of the road. In

the surfacd^ qaa-i rires along Highway No.614 no bedding is apparent

in the sedimentswhich consist of coarse sand and gravel and are

relatively unsorted except for the absence of very fine and

very coarse material. Pebbles and boulders are rounded to

subrounded with the largest being about 1 foot in diameter

and the majority about 1 inch in diameter. On the east side

of the highway an excellent vertical section through the bar is

exposed in a railway gravel quopry, serviced by a short spur

line, about 7000 feet south of No.6 Lake. The west face of

the quar-py xs over 100 feet high and is composed of well bedded

e coarse sands and gravels. Some of the beds are graded with

coarse sand at the base of the beds and pebbles up to 2 inch

diameter in the upper part of the beds. The coarsest gravel

beds occur near the top of the €fu-a-*»**y- face where there is 4 to

5 feet of gravels containing pebbles up to 6 inches in diameter.

The beds trend approximately N30°E, roughly parallel to the

elongation of the bar, and dip southeasterly towards the varved

clays on railway tracks at about 3®°•

A number of esker-like sand and gravel ridges occur

in the area, mostly on the east side of the Black and Macutagon

River valleys. Examples can be seen paralleling Twist Lake

and some of the lakes between Twist Lake and the Macutagon River.

Others occur paralleling the string of lakes just north of the

mafic metavolcanic formation in the Dotted Lake region and another

occurs about 1 mile west of Pinegrove Lake. These ridges tend

to border the glaciolacustrine deposits flooring the Black and

Macutagon River valleys and thereby parallel the borders of

high outcrop area which rise above these deposits. Thus in

Twist Lake aid Pinegrove Lake regions the ridges trend north-

south to northeast, while in the region north of Dotted Lake

the ridges trend nearly eastwest. Most of these ridges have A

the sinuous and acute form of eskers and trapped kettle lakes

are associated with them. They would therefore appear to be

of glaciofluvial origin, and—pjaesumafoi-y—would—fre—older—than

t e gXa-e-are3rarctxstT-±rre--"deposit-s. Some of the more rounded ridges might possibly be beach bars since they occur where

o. the lacustrine clays and sands shelve off the outcrpp areas.

The mafic metavolcanic formation in the south of the

map-area has resisted erosion to a greater extent than the

neighbouring rocks and as a result it forms high ridges

standing above the general level of its surroundings. These

mafic metavolcanic ridges are generally mantled by a thin

cover of glacial till material consisting of brown clayey

sand containing many large angular boulders. This type of

material is exposed in pits along the Dead Otter Lake road.

Similar material forms hummocky ridges in the area between

Kaginu and Morley Lakes. These ridges are composed of many

large angular boulders up to 5 feet in diameter in light

;ociEE2E§h brown sandy clay. The ridges do not appear to have

any particular form and probably represent till material

dumped from a melting ice sheet. A thin cover of the same

type of material covers much of the higher outcrop regions

in the map-area. Throughout the area glacial striations range

between S2QOw and S40°W indicating a general ice movement

southwards at about S30°W. This is similar to the predominant

direction of ice movement in the Pic River area (Milne, 196 ).

As stated previously varved clays and sands are

exposed in the Fourbay and Nama Creek valleys. The deposits

in these areas are an extension of glaciolacustrine deposits

filling the valley of the Pic River, and are similar to the

Black River deposits. It has been pointed out by W.R. Farrand

that "These quiet water sediments required high water levels

in the lake Superior basin so that the Pic-White Otter system

was drowned for a distance of more than 50 miles above its

present mouth. The northernmost exposure of varves in the Pic

area is 56 miles straingtline distance from the mouth of the A t-

Pic and occurs at 1040-1050 feet above sea level." Thus the

Pic and Black River varved clay deposits represent sedimentary

deposition in the ria shoreline area of a large glacial lake

which formerly occupied the Lake Superior basin.

Recent materials are accumulating in swamps and lakes

in the area. In addition the migratory nature of the Black

and Macutagon River channels is evident from the meandering

character of these rivers and the associated ox-bow lakes.

Examination of air photographs, particularly in the area

between Dotted Lake and Agonzon Lake, reveals the presence of

numerous gullies bounded by levees within the Black River valley

indicating that the surface sands and clays have been reworked

by the river wandering about the valley floor.

Structural Geology

Folding

The metavolcanic, pyroclastic and metasedimentary

rocks of the Black River area have been highly metamorphosed

and have undergone intense complex folding. Distinctive

marker horizons are absent in the main fold areas and the

number of reliable top determinations that could be made was

very small*However on the basis of the information available

it is possible to make a simple generalized interpretation.

Top determinations were obtained from pillow structures

and the few reliable observations recorded are restricted to

the mafic metavolcanic formation southwest of Dead Otter Lake

where south facings are indicated. There do not appear to be

•fro, .be any major breaks between the metavolcanic, pyroclastic

and metasedimentary formations. Southwards the mafic meta

volcanic flows appear to be interbedded with the pyroclastic

material which in turn grades southwards into the metasedimentary

formation. It seems reasonable to infer from these few top

determinations and the gradational relationships that these

formations ave- younging- southward-s and represent a relatively

uninterrupted depositional sequence beginning with mafic

vulcanism which terminated with less extensive extrusion of

acid and pyroclastic material succeeded finally by clastic

sedimentation.

The widening of the mafic metavolcanic formation

between Highway No. 614 and Ravine Lake is interpreted as being

Ik, <? v/. Li i f

due to folding. , A southwest—trending and-plunging anticline

is believed to bc "ggirfrpee e-n Dead Otter Lake and a parallel—

trending syncline lies /SJI the northwest -sfete of Dotted Lake.

The anticline appears to be assymmetrical with a steeply-

dipping north limb and a less steeply-dipping south limb. A

Tf -diagram •^d^^^^T was prepared by plotting the strike

and dip attitudes observed around the nose of the anticline

west of Dead Otter Lake and this indicates an average fold

axis plunge of 70° towards S60°W. (A TT'-diagram is constructed

by plotting on an equal area projection the poles of a large

number of bedding plane attitudes observed in the fold area.

These poles should fall on one great circle, the TT-circle,

and the normal to this circle is A , the fold axis). The

axial trace of the fold is difficult to locate accurately on

the map but, in fact, it seems to curve westwards from

west-southwest to southwest and lineation, and strike and dip

attitudes on the map indicate that the plunge of the fold

increases from about 50°SW, just west of Dead Otter Lake, to

near vertical near Highway No. 614.

The syncline northwest of Dotted Lake is less

readily apparent than the anticlinal fold. No distinct

lithological bands can be traced around the syncline and the

axial trace shown on the map is *®3*y approximate. The presence

of the fold is inferred from a change in dips from the north to

south, northwest of Dotted Lake, and from minor folds northeast

and northwest of Dotted Lake^ These minor folds are located

near the north boundary of the mafic metavolcanic formation

and indicate a syncline to the south. A //-diagram of the

strike and dip attitudes northwest of Dotted Lake, indicates a

possible fold axis trending S60°W and plunging between 40° and

60° southwest. Plunges measured directly from the minor folds

vary between 23° and 85° southwest.

The Dead Otter Lake anticline and Dotted Lake

syncline have similar axial trends and plunges. Similarly

trending folds on a slightly smaller scale are also indicated

in the metavolcanic rocks between Roger Lake and Olga Lake. A

west-plunging anticline and parallel syncline appear to be

combined in a S-shaped drag fold on the east side of Roger Lake

and#//-diagrams of these folds (*ii ir-SS5lf4- indicated axial trends

of about S75°W plunging between 15° and 20° west. These plunge

are much shallower than in the folds west of Dead Otter Lake.

Rocks of the metasedimentary formation are poorly

exposed. In most exposures the foliation due .to orientation f/a£e$

of biotite g¥»spjk%8- in the rocks is parallel to the original

bedding lamination but in at least two areas the bedding and

foliation are not parallel. In conglomerate exposures on the

trail between Theresa Lake and Etna Lake the foliation, marked

by elongation of pebbles and orientation of biotite gsjaaaas.,

cuts across the bedding at an acute angle and the attitudes

suggest that the exposures occur on the north side of a west-

plunging synclinal fold trending approximately S75°W and

plunging 40° west. Folding is also implied in the area south

of Solong Lake by an outcrop on the south shore of the lake

in which the pebble bands of conglomerate are cross cut at a

steep angle by the fLaliatJrGii, Within the map-area visible

folding of the metasedimentary beds was observed in only two

outcrops, one on Highway No. 614 just north of East Barbara

Lake and one on the west shore of East Barbara Lake at the

north end. In these outcrops the style of folding is

essentially similar and tightly isoclinal, slightly overturned

to the south. Cleavage is developed parallel to the axial

plane, paralleling the bedding on the fold limbs and cross-

cutting on the noses of the folds.

Excellent exposures of folds in the metasedimentary

formation occur on Highway No. 17 about 4 miles south of the

map^area, between the Highway No. 614 junction and Cigar Lake. A

These exposures indicate that the metasediments have been

subjected to intense shear folding which has produced tightly

isoclinal, symmetrical similar folds. Cleavage is well

developed in these folds and cuts across the metasedimentary

bedding in the noses of the folds but the noses represent a

very small part of the fold so that in most of the exposures

the cleavage is parallel to the bedding.

The mafic metavolcanic rocks are not strongly

foliated and in particular around the hinges of folds the

foliation is poorly developed. In most outcrops the foliation

can be termed a gneissosity but locally, where mica is present,

it becomes a schistosity. As far as can be determined the

foliation has developed parallel to the original banding on

the limbs of folds and this also seems to be true around the

crest of the fold just west of Dead Otter Lake. However, in

the area about 7000 feet north of No. 3 Lake the foliation

appears to have developed at an acute angle to the original

bedding. A few small scale folds were recognized in areas

Usujefcett" of mafic metavolcanic rocks and in most of these the

banding is folded into tight, similar folds with a cleavage

developed parallel to the axial plane indicating that these

are essentially shear slip folds, (r^'fc M>,//J

Stretching and shearing have been quite severe, as

witnessed by the stxi&aMp^rmit of pillows and agglomerate

fragmentSjbut in general this shearing does not appear to have

V/ est of been as intense around the crest of the major fold c^e^sad^n-

Dead Otter Lake as on the limbs. Lineation marked by

orientation of hornblende grains is developed in the mafic

metavolcanic rocks and small scale folds and crenulations are

sometimes exposed. A density plot of the plunge attitudes of

all the lineations and small scale folds observed in the mafic

metavolcanic and pyroclastic-acid metavolcanic formations was

made on an equal area Schmidt Net (^^p^?^^,) and this

indicates that there are two plunge maxima (1) S40°W, 47°SW.

and (2) S24°E, 70°SE.

Few plunge determinations could be made in the area

of metasediments. On the Etna Lake trail the foliation and

bedding attitudes indicate a westward plunge of about 40° but

in the middle of the metasedimentary area around Highway No. 6l4j

the plunges appear to be very gentle, ranging up to 10° east

and west

As noted above there are two major directions of

lineation and drag fold plunge in the area. One of these, S40°W,

47°SW, is essentially parallel to the plunge directions of the

folds described above. The presence of a second major plunge

direction trending S24°E, 70°SE, at a steep angle to the

plunge of the major folds, and the gently undulated east-west

plunge of minor folds in the metasediments on Highway No. 6li+3

north of East Barbara Lake, suggested that the area had been

affected by a second stage of folding. Examination of the

regional structure however, reveals the following:-

1. The country rocks around the mapped portion of the

Black-Pic Batholith all dip off the batholith,

2. Fold structures in the country rocks either plunge away

from or parallel to the adjacent batholith contact^

3. fioughly parallel fold trends occur in the Pic River

(Milne, 196 }, Black River, and Manitouwadge (Pye, 1957)

areas but the axial trend of the most intense folding is

not the same in all these areas. For example, in the

Black River area and the Manitouwadge area the axes of

the major, more intensely folded folds, trend between

east-west and southwest-northeast, approximately parallel

to the batholith contacts in these areas, while in the

Pic River area, where the batholith contact trends

northerly, the more tightly folded folds trend roughly

north-northeast, and the southwest-northeast trending

folds are much more open. Thus the axis of most intense

folding in the country rocks around the Black-Pic

Batholith roughly parallels the adjacent batholith contact

while the more gentle cross-folding plunges away from and

trends at a steep angle to the batholith contact.

4. The Black-Pic Batholith appears to have a domical form

(page S~f ) with essentially flat-dipping foliation near

the centre of the mass. The foliation in the centre is %? With

in fact gently undulated i-nt-o- flat-dipping open folds

trending southwest-northeast and southeast-northwest

(JSJg^fel)..

These facts indicate that a genetic relationship exists

between the folding of the country rocks and the form and

folding of the Black-Pic Batholith. The two fold trends in the

country rocks adjacent to the batholith must be contemporaneous

since in a specific area the most intense folding is parallel

to either one of the fold trends depending upon which one is

more nearly parallel to the batholith contact in that area.

The rocks of the Black River area are interpreted as

lying on the south flank of an anticlinorium with the rocks of

the.Manitouwadge area lying on the north flank, and the

granodiorite gneiss of the Black-Pic Batholith occupying the

core (See Fig7^*s&). Southwards from the Black River area it

is believed by the writer that the metasedimentary rocks form

a synclinorium, thus the mafic metavolcanic rocks which are

known to outcrop south of Highway No. 17 are probably

equivalent to the mafic metavolcanic rocks in the Black River

area. The ductile fold behaviour of the country rocks, their

high grade of metamorphism and the form of the Black-Pic

Batholith (page S"? ) indicates that the intrusion of the

granodiorite gneiss and the folding took place under deep

to o

seated catazonal conditions.

The younger granodiorite-quartz monzonite plutons of

Fourbay Lake, Gowan Lake, Bullring Lake, Musher Lake and

Dotted Lake have produced minor secondary modifications of

the folding. These later plutons have caused dilation of the

country rocks. For example the Musher Lake Pluton appears to

produce a sharp bend in the metasediments in the vicinity of

Highway No. 614, and north of Dotted Lake the granodiorite has

pried a thin band of mafic metavolcanic rocks away from the

main mass. Intrusion of the younger plutons has been controlled

to some extent by the earlier folding and by the contacts

between mafic metavolcanic and quartzo-feldspathic gneisses.

The V-shape of the Gowan Lake Pluton is essentially conformable

to the country rock structure and the Dotted Lake Batholith

conforms largely to the Dotted Lake anticlinal fold. Shearing

is common at the contacts of the younger intrusive masses and

is very apparent at the contacts of the Dotted Lake Batholith. A

Crenulation, minor drag folding, muscovitic alteration and

contact metamorphic effects may be present at the contacts of

the younger plutons. However, the dominant country rock

structures appear to have originated in association with the

syntectonic intrusion of the Black-Pic Batholith.

Faulting

Outcrop evidence of faulting is very limited, marker

horizons are rare, and the effects of folding are not always

clear due to the limited outcrop in many parts of the area but

a number of major faults have been interpreted and minor faulting

is undoubtedly present. Minor faulting is well displayed in

the band of muscovitic quartz-feldspar gneiss east of the

Black River where there are three sets of faults, a dextral

set trending N65°W, a sinWitral set trending N15°E and a set

of strike faults parallel to the gneiss foliation. These

faults show displacements varying between a few inches and a

few feet. Similar small shear faults were found at a few

locations in the mafic metavolcanic rocks, and examples can be

seen at the south end of Theresa Lake.

Major Faults

Bullring Lake Fault

Hematite-carbonate gouge filled shear planes of this

fault outcrop on Highway No. 614 about 1000 feet south of the

map boundary. In the outcrop the fault cuts granodiorite of

the Bullring Lake Pluton and red hematitic alteration of the

granodiorite extends outwards for up to half a mile on either

side of the fault. The fault strikes approximately N60°W,

cross-cutting the metasedimentary and metavolcanic formations

in the vicinity of the Black River and can be traced west-

northwestwards to a small lake about 6000 feet north of Gowan

Lake where the granodiorite of the Gowan Lake Pluton is stained

hematitic red and cut by a stockwork of small barren quartz

veins. A small right hand offset along the fault is suggested

by the mafic metavolcanic band west of the Black River and this

would conform with the small scale faulting noted in the

muscovitic quartz-feldspar gneiss just 1 mile northeast of the

fault. However outcrop is very poor in this area due to the

extensive Pleistocene deposits.

Phil Lake Fault

This fault strikes almost parallel to the Bullring Lake

Fault trending N65°W. The presence of the fault is inferred

from the presence of a lineament observed on aerial photographs

and indications of a right-hand offset in the mafic metavolcanic

band on the west side of Phil Lake. The fault seems to

terminate against the Jenny Creek Fault in the east and

disappears under thick drift cover to the west.

Pinegrove Lake Fault„

This fault is one of the most extensive in the area. It

trends N50°W and extends., at least3 from Pinegrove Lake in the

east•northwestwards through Swede Lake and the Fourbay Lake

Pluton to beyond the west limit of the map sheet. The fault

is apparent on aerial photographs as a strong lineament which

extends northwestwards well beyond the map-area. Indications

of the fault in outcrop are seen northeast of Fourbay Lake at

the north end of Lineal Lake and in the small lakes to the east.

In these areas the granodiorite gneiss of the Black-Pic

Batholith and the granodiorite of the Fourbay Lake Pluton are

extensively reddened and cut by red vein alteration. In

addition the mafic metavolcanic rocks at the north end of

Pinegrove Lake are fractured and sheared and in the vicinity of

the junction of Barehead Creek with the Black River a projection

of the mafic metavolcanic formation has undergone a right hand

strike separatidn of about 6000 feet. The Pinegrove Lake Fault

joz

appears to continue on the east side of the Jenny Creek Fault

producing right-handed offset of the pyroclastic-acid metavolcanic

formation just east of Summers Lake.

Jenny Creek Fault

This fault crosscuts the metavolcanica pyroclastic and

metasedimentary formations. Where the fault cuts the

metavolcanic formation it trends roughly north-south but the

trend swings to south-southwest where it cuts the metasediments.

The fault parallels Jenny Creek which lies in a well-defined

lineament. The lineament more or less forms a pass through the

area of high mafic metavolcanic ridges and has been utilized

in the contruction of Highway No. 614. The presence of the

fault is indicated by the juxtaposition of the acid metavolcanic

and mafic metavolcanic rocks on opposite sides of Highway No. 614

in the vicinity of Pinegrove Lake3 by the apparent offset of

the pyroclastic-acid metavolcanic formation in the vicinity of

Phil Lake' and by the fracturing and hematitic and epidotic

alteration of the mafic metavolcanic and granitic dikes in the

railroad cuts north of Phil Lake. To the north and south the

fault disappears beneath thick drift cover.

A south-southwest trending fault3 similar in trend to the

south part of the Jenny Creek Fault has been interpreted about

halfway between Pinegrove Lake and the Black River. The

presence of this fault is inferred from the presence of a

lineament observeable on aerial photographs and from the

interpretation of outcrop and aeromagnetic information (see O.D.M.-£.-;•<-.

aeromagnetic map 216BG).

10 +

White Lake Fault

This fault is apparent as a lineament on air photographs

and trends southwest across the northwest corner of White Lake.

Faulting is inferred from the abrupt termination of the mafic

metavolcanic formation at the lineament and a sharp swing in

the gneissic foliation. J r the southwest, between Etna Lake

and Buie Lake the fault plane appears to be occupied by a wide

diabase dike. This diabase may occupy the fault plane to the ca.

northwest also but there are no exposures.

In the south part of the area two other small faults have

been postulated, one just east of No. 3 Lake and one on the

/fk north side of Dotted Lake. East of No. 3 Lake a fault is

believed to lie in a north-northeast trending gully. The

pyroclastic-acid metavolcanic formation contacts swing sharply

or are offset in the vicinity of the gully and some mafic

metavolcanic flows interbedded with the pyroclastic rocks

appear to terminate at the gully. Geophysical investigations (p*P>M,

ile No. 63.169$) on the von Klein Property suggest that other

small faults may be' present in this region. On the north side o.p.rf. - GS>C*

of Dotted Lake aeromagnetic information (map 2168G) suggests

that the mafic metavolcanic rocks are faulted and outcrop

distribution in the region tends to support this. However

outcrop in the region is very poor and there are no apparent

lineaments so that location of the fault is very speculative.

There are a number of diabase dikes in the area and the attitude

of the inferred fault is based on the assumption that the

diabase dikes tend to follow a major fracture direction in the

A

region.

A number of lineaments are indicated in the map-area and

many of these are in the areas of granodiorite gneiss. It was

not possible to determine if these lineaments represented

faults, due to the reconnaissance nature of the mapping and

absence of marker horizons in these areas. One small fault

has been interpreted in the northeast corner of the map-area

paralleling No. 5 Lake. This fault is postulated on the basis

of the foliation attitude in the locality, the sheared and

fractured nature and widespread red hematitic alteration of the

granodiorite gneiss. Some shear zones are indicated in the

biotite granodiorite north^and east of Theresa Lake. In these

shear zones the normally massive granodiorite is strongly

foliated and occasionally mylonitic and it is possible that

some of these shears actually represent large faults -wMe-hr•&•*"f

wu.uld I'tiquix'c detailed mapping to/trace ttrgmr*

Examining the regional fault distribution it is apparent

that the Pinegrove Lake Fault is essentially parallel to the

major northwest-trending Runnalls Lake Fault in the Pic River

area (Milne, 196 ) and the Mose Lake Fault in the Manitouwadge

area (Pye, 1957) and in unmapped areas very extensive northwest-

trending lineaments are relatively common. The west-northwest

trend of the Bullring Lake and Phil Lake Faults is similar to

the trend of the Fallen Lake, Veronica Lake and Sprucetop Lake

Faults of the Pic River area and although this trend is close

to that of the northwest faults it seems to represent a different,

less extensive fault set. Extending the comparison of the

/o<S

Black River area faults with other faults in the region^ the

Jenny Creek Fault may relate to the north-south trending

Cadawaja, Clinger and Fox Creek Faults and the White Lake Fault

to the northeast-trending Nama Creek Fault of the Manitouwadge

area. Information in the Black River area is not sufficient

to determine the relative ages of these different fault sets

but information from the Manitouwadge area (Pye, 1957) and the

very persistent nature of the northwest-trending faults suggest

that these may be the youngest in the region. Diabase dikes

appear to haveAutilised many of the fault planes.

/*>

Economic Geology

Introduction

Until recently probQecting in the area has been

very limited but over the last few years the similarity of the

rock formations, and its proximity, to the Manitouwadge mining

camp and the potential mining area around Marathon, has brought

it increasing attention and at the present time much of the

southern part of the area is covered by staking. A certain

amount of assessment work, including geological and geophysical

reports and diamond drillhole logs, has been submitted to the

Ontario Department of Mines. Reports are on file at Toronto

in the Mining Lands Branch office, and reports and drill logs

are filed with the resident geologist in Port Arthur. The

company names,type of information, year reported and file

number are listed below.

Company Name Year Type of Information File No.

Mclntyre Porcupine Mines Ltd. 1963 Geological Survey 63-1210

Geophysical Survey 63-1210

Drilling Port Arthur

Carravelle Mines Ltd. 1965 Geological and 63.E6

Geophysical

Interpretation

1966 Geophysical Survey 63-I698

Irish Copper Mines Ltd. I966 Geophysical Survey 63-1716

^

T

108

Stratigraphic Considerations in Mineral Exploration

In the Pic River, Manitouwadge and Black River areas the

predominantly pillowed character of the metavolcanic rocks and

well bedded nature of the tuffs attest to their accumulation

under subaqueous conditions, and their association with

essentially metagreywacke-type sediments is characteristic of

a eugeosynclinal depositional environment. Mapping at the present

time is insufficiently complete to permit direct correlation

of the different formations but it is probable that there is

more than one period of mafic vulcanism represented in the

region and possibly there is repetition of a number of volcanic-

sedimentary depQsifcional cycles. i?or- exuuiple, i'Ax- rriafM.c

metavolcanic formation in the Pic River area appears to be underlain by

a pyroclastic-silicic metavolcanic formation (Milne 196 ) whereas

the mafic metavolcanic formations in the Manitouwadge (Pye 1957)

and Black River areas are overlain by metasedimentary and pyroclastic-

silicic metavolcanic formations-

On the basis of the presently known structure it is believed by

the writer that the Manitouwadge and Black River formations are

essentially equivalent in age and belong to a single volcanic-

sedimentary cycle. The biotite-quartz-feldspar paragneisses and

mafic metavolcanic rocks of the Black River area are similar in

appearance and composition to the metasedimentary and metavolcanic

rocks in the Manitouwadge area. There are differences however.

Unlike the Manitouwadge area iron formation is relatively rare in the

Black River area, conglomerates are present in the lower section of

the metasedimentary formation, and a pyroclastic-silicic metavol

canic formation occurs between the mafic and metavolcanic and

109

metasedimentary formations. These differences are believed

by the author to be due to facies changes and to the restrict

ion of the mafor centres of volcanic extrusion to the south

ern region between Marathon and White Lake.

In the Black River area, the pyroclastic-acid metavol-

canic farmation is of limited extent east-west, and it grades

into metasedimentary material to the west so that the mafic

metavolcanic formation in the -eastern and western parts of

the area abuts the metasedimentary formation. It is believed

that the pyroclastic-silicic metavolcanic formation is simi

larly restricted in the north-south direction so that in the

Manitouwadge area the metasediments lie directly upon the ma

fic metavolcanic formation. In all probability the base of the

metalogically to the base of the similar formation in the Man

itouwadge area. Sedimentary material may have accumulated in

the Manitouwadge area at a time of waning mafic volcanism and

during expulsion of silicic volcanic and pyroclastic material

and general absence of volcanic material in the wide belt north

of Manitouwadge may not be due solely to deep downfolding of the

volcanic material beneath the metasediments, but may be largely

due to the thinning and disappearance of the volcanic material

to the north.

The relative scarcity of iron formation in the Black River

area, compared with Manitouwadge, may be due to the fact that

conditions for accumulation have been more unsettled in the

no.

immediate vicinity of the sources of volcanic extrusion, and

possibly to the coarse clastic type of sedimentation occurring

in the Black River area as indicated by the presence of

conglomerates. Th-e—p-r-es-ette-e—o-f—appr"eTT±abie—strlphrd-es—in—t he-

Black—River^±r'orr^o"rmatTo

f acn-es- irf-f r'eirge ^ the.qp and the -an-v^mf-a^ge

-djz&¥r-~£omia1?to¥irr> The little iron formation found in the Black

River area is in part banded magnetite-quartz but abundant

pyrite and pyrrhotite are present and the iron formation is in

part slaty. The iron formation occurrences on the yon Klein

Property appear to be very local features and in one occurrence

the thin iron formation appears to be underlain by tuff and

overlain by a thin mafic flow which is interbedded in the

predominantly pyroclastic formation. The sulphides in the iron

formation may be replacement material but it is possible that

sulphide facies iron formation is present. The iron formation

in the Manitouwadge area (Pye 1957) is metamorphosed to banded

magnetite-amphibole-quartz and garnet-amphibole-epidote-magnetite-

quartz mineral assemblages and these mineral facies tend to

indicate that the original iron formation belonged essentially

to the oxide and iron silicate facies (James 1955)• The

occurrence of oxide and iron silicate facies of iron formation

in a predominantly sedimentary rock formation, as at Manitouwadge,

and of the banded magnetite and sulphide facies with volcanic

formations is typical of the eugeosynclinal Algoma Type iron

formation (Gross 1965).

In the Manitouwadge area the copper-zinc-lead orebodies

/ / /

are generally associated with muscovite-quartz schists, and

iron formation or related rocks (Pye 1957). They seem to occur

near the same stratigraphic level within t he metasedimentary

formation and comparing these orebodies with similar types in

other areas (McAllister 1959; Hutchinson 1965; Roscoe 1965;

Richards 1966; Vokes 1966) it is possible that they are of an

age and origin similar to the rocks in which they occur. Age

determinations on the Manitouwadge orebodies (Davis et al 1965)

and on the neighbouring metasediments (Lowdon 1961) indicate

that these have similar metamorphic ages. Iron formation and

muscovitic schists are present in the contemporaneous metavol-

canic-metasedimentary formations in the Black River area and

it is possible therefore that similar sulphide bodies are also

present.

Descriptions of Mineral Showings

Fairservice Occurrence (l)

A zinc occurrence was discovered in 1957 by

B. Fairservice of Manitouwadge who operates the trap line in

the Dotted Lake-Mobert Creek area. The occurrence is located

in mafic metavolcanic rocks about 400 feet east of the old

lumber company dam on the north arm of Dotted Lake. There are

a number of small pits scattered around the area in rusty zones

in the volcanic rocks and in white porphyritic (quartz and

feldspar) dikes which contain disseminated pyrite. At the main

occurrence there is a shallow pit about 4 feet square with two

other smaller pits about 5 and 10 feet to the west. A leucocratic

/ / : >

porphyry (quartz, feldspar) dike strikes N70°E across the

south end of the main pit and about 22 feet north of the dike

a rusty, horizontally striated, shear plane trends N70°E through

mafic metavolcanic hornblende gneiss and dips about 8l°S.

Between the shear plane and the porphyry dike and* north of the

shear plane for about 2 feet the rock is a very coarse-grained

rusty weathering garnetiferous amphibolite containing much

disseminated magnetite and light coloured amphibole. North

of the shear zone the garnetiferous rock grades into the normal

dark green medium-grained hornblende gneiss of the area. On

the south side of the shear plane and within 1 foot of it, 3

to 4 irregular stringers of massive black sphalerite up to 1

inch in thickness, trend roughly parallel to the shear plane.

The sphalerite stringers disappear quickly to the east and west.

They are absent in the small pit about 10 feet west of the main

pit and were not seen in outcrops just east of the pit. About

50 feet east of the main pit the garnetiferous material thins

to about I2 feet, and about 75 feet east of the pit both the

garnetiferous material and the shear plane peter out into rusty,

typical metavolcanic hornblende gneiss cut by a few thin rusty

quartz stringers. Except for a little disseminated pyrite in

the mafic metavolcanic rocks and leucocratic porphyry dikes no

other mineralization was observed in the surrounding rocks.

n the spring of 1965 about 170 claims were staked

covering the Fairservice occurrence and most of the metavolcanic d

rocks north and west of Dotte^ Lake. These claims were optioned

to Irish Copper Mines Ltd. and in May 1965 an electromagnetic

and magnetometer survey was flown over the claim area. The

/n.

electromagnetic survey indicated one good conductor and a

few very minor conductors but none over the zinc showing loca

tion. Ground checking of the airgeophysical survey was carried

out by the company in the late summer of 1965-

Kusins Occurrence (2)

A lead-zinc occurrence was discovered by R. and W. Kusins

in I963 as a result of geochemical soil sampling. The occurrence

is about 1500 feet north and 3000 feet west of the mouth of

Amwri Creek at the Black River. It can be reached by a poorly

marked trail starting on the west side of the Black River

opposite the mouth of the creek about 4500 feet north of Amwri

Creek. The occurrence is on the northwest side of a low ridge

and occurs in mafic metavolcanic laminated hornblende gneiss which

is bounded on the southeast by siliceous and migmatitic meta-

sedimentary or metapyroclastic material and on the northwest

by hornblende-biotite granodiorite of the Gowan Lake Pluton.

It is believed by the writer that a major west-northwest

trending fault lies about 1000 feet south of the showing (see

Map No. and 0/?St->/-t''e i/c &

In I964 T. and W. Kusins held five claims in the area,

Nos. T.B.104950 to 104954 inclusive, and the occurrence is just

within claim T.B.104951 about 650 feet south of the No.4 post.

At the time the occurrence was examined there were four pits

and a plan of these is shown in Pisrtre M>j<. The countryrock

around the pits is mafic metavolcanic, laminated hornblende

gneiss. Pits Nos. 1, 2 and 3 expose a rusty gossan zone about

1-foot thick, overlying a rusty, silicified pyritic zone up to

6 feet wide which parallels the foliation of the country rock,

trending N55°E and dipping about 50°NW. The three pits cover

a strike length of about 100 feet. The pyritic silicified

zone was not found in outcrops a short distance east of the

No.3 pit and west of the No.l pit the zone disappears beneath

a swamp. The light grey to white silicified zone contains

disseminated pyrite throughout and in addition seams of

massive pyrite up to 8 inches thick parallel the trend of the

zone. Thin seams of massive pyrite, about l/8 inch thick, a±s=» These cress cis fftf'^f /*yni'?e

cross+cut the silicified zone and the wide pyrite searns,th-at

strike about N65°W, and this is parallel to a major ^oint

direction in the surrounding country rocks. In parts of pits

Nos. 2 and 3 disseminated galena and sphalerite are mixed with

the disseminated pyrite. A grab sample taken from the No.2

pit by T. and ¥. Kusins and submitted to the Laboratory Branch,

Ontario Department of Mines contained 1.93 per cent zinc, 0.94

per cent lead, 0.64 ozs. per ton silver, and traces of copper

and gold. The No.4 pit is about 65 feet south of the other

three and exposes a second zone, about 22 feet wide, composed

of quartzo-feldspathic sericitic schist with 1/16 inch pyrite

layers paralleling the foliation of the schist. No galena or

sphalerite were observed in this pit.

As stated previously a major fault trending N65°W is

believed to be about 1000 feet south of the occurrence. Near

the occurrence the metavolcanics are fractured. In an outcrop

about 60 feet south of the No.l pit the metavolcanic rock is

cut by a zone of brecciated metavolcanic material striking

N70°W and about 150 feet south and slightly west of the pit the

metavolcanic rocks are highly fractured and the fractures filled

with carbonate and occasionally minor galena. The mineraliza

tion in the area may be related to faulting, however, as was

stated above, the main pyrite seams and silicified zone are

cross-cut by thin possibly remobilized, pyrite seams which

trend N65 W parallel to the main fault and joint direction in

the country rock. This suggests that the silicified zones and

main pyrite seams originated before the fracturing.

This showing was examined in 1963 by geologists of

The Mining Corporation of Canada Ltd. and Willroy Mines Ltd.

before trenching was done and the disseminated sphalerite-

galena found. The showing was later examined in 1965 by

geologists of The Consolidated Mining and Smelting Company of

Canada Ltd. (now Cominco Ltd.).

i/ on Klein Occurrences (3)

A number of occurrences of copper-nickel and copper-

lead-zinc mineralization were found in the area east and south

east of No.3 Lake by C. Von Klein and in 1962 a block of 52

claims enclosing these occurrences was optioned to Mclntyre

Porcupine Mines Ltd. At the time the property was examined by

Mclntyre Procupine Mines Ltd. there were four main occurrences.

A geological map of the claim area was prepared by the mining

company in 1962 and the occurrences numbered from 1 to 4. The

same system of numbering is used in the following descriptions.

II (e

Occurrence No. 1

This occurrence is located on the south side of the

Dead Otter Lake road about 2 mile east of No.3 Lake, on a

roughly east-west stretch of road (see rSste "'3 ). A pit has

been blasted in the outcrop. The mineralization consists of

pyrite with minor chalcopyrite and pyrrhotite disseminated in

a coarse-grained dark green amphibolite4 a d==b laBq5s==€«P*ih«

N . gr<5u-p=" iien:tijaja ^ . The

amphibolite is in contact to the south with a siliceous

garnetiferous gneiss exhibiting thin contorted lamination and

containing small, and possibly rotated, mafic inclusions. -Cc/

The mineralizafedban amphibolite is invaded by stringers of

quartzo-feldspathic material emanating from the siliceous gneiss

and although very little of the contact is exposed the mineral

ized amphibolite is thought to be an extra large inclusion

rafted in the siliceous gneiss which is probably welded tuff

material. A chip sample over a 2-foot section submitted for

assay by E.G. Pye, Resident Geologist, Ontario Department of

Mines, Port Arthur indicated a content of 0.42 per cent copper

and 0.18 per cent nickel.

Occurrence No. 2

^his occurrence, sometimes referred to as the main

occurrence, is exposed 1000 feet south and 300 feet east of the

No.l occurrence. Mineralization here appears to be similar

to that in the No.l Occurrence. Pyrite,chalcopyrite and

pyrrhotite are disseminated in a large irregularly shaped mass of

coarse-grained, dark green amphibolite which is in contact with

a rhyolite breccia at the only place where the contact is exposed.

Exposures are limited but the amphibolite is interpreted by

the writer as a large block rafted in a rhyolite breccia plug.

The matrix of the rhyolite breccia is faintly foliated, very

fine-grained and light pink in colour with abundant silvery

flecks of muscovite throughout, and consists of muscovite, quartz

and alkalic feldspar with minor biotite, chlorite, apatite and

epidote. The matrix cements together a great many angular,

mafic, hornblendic fragments and rhyolite blocks and the breccia

is intruded by younger granitic dikes (Photo Two, 2-foot

section, chip samples were taken from this occurrence by E.G. Pye,

Resident Geologist, Port Arthur, and assayed 0.33 and 0.31 per

cent copper and 0.17 and 0.41 per cent nickel sra ^ciCr-tM^ x

Occurrence No. 3

This occurrence is about 350 feet south of No.3 Lake

and 4 mile west of the Dead Otter Lake road. Mineralization

consists of finely disseminated pyrite and pyrrhotite with a

trace of chalcopyrite in a rusty shear zone about 22 feet wide

in a biotitic quartzite or metagreywacke containing thin mafic

hornblende layers. The shear zone is essentially parallel to

the foliation in the country rock, striking N65 E and dipping

about 80°N. A strike length of about 15 feet is exposed and

the shear seems to die out at the west end. The mineralization

is similar to that seen in the silicified zones in Kusins

m

occurrence. No assays are available on this material.

Occurrence No. 4

This occurrence is in the mafic metavolcanic rocks

just north of the contact with the pyroclastic-acid metavolcanic

rocks, and about 850 feet west and 300 feet north of the No.l

occurrence. Mineralization occurs as thin irregular stringers

containing pyrite, pyrrhotite and chalcopyrite with occasional

sphalerite and galena in a zone of fractured mafic metavolcanic

rock about 5 feet wide. The fracture zone trends roughly

east-west and dips about 85°S. While examining this showing

another small pit was found on the north side of a small creek,

about 250 feet east and 160 feet north, in similarly fractured

and mineralized mafic metavolcanic rocks.

J)$& -<~^.—---^ A Horizontal Loop E-M and Magnetometer ground geophy

sical survey was carried out by Mclntyre Procupine Mines Ltd.,

also in 1962, and six electromagnetic conductive zones were

outlined. These are shown on «Pi£r,fc.eA/0 . Four of these were A

weak conductors and the other two<> aefi'6&—en*d—r=a, were of moderate

strength. Zones A and B seem to be at the contacts of "thin

mafic flows within the predominantly pyroclastic-a-e-ird metavolcanic

rocks and zone C at the main contact between the latter rocks

and mafic metavolcanic rocks. The remaining zones all seem to

be within the mafic metavolcanic rocks. Zones B and C were

trenched (•Piafcs®' and £"), and the results of assayed samples

from these trenches are shown in &a&3*e "*?-tf6;',

U

//?

Mclntyre Porcupine Mines Ltd. drilled 28 diamond-

drill holes. Most of this drilling was concentrated around

occurrences No.2 and 4 while the electromagnetic conductive

zones were investigated with a few very short holes. The

drilling indicated that there was no immediate downward extension

of the mineralization at occurrences No.l and 2. Drilling on

occurrence No.4 indicated continued weak mineralization at

depth with a second weakly mineralized copper-zinc zone a short

distance north of the main zone, and a short hole drilled on

conducting Zone F indicated a narrow pyrite-pyrrhotite minera

lized zone with traces of chalcopyrite. No further work was

done by Mclntyre Porcupine Mines Ltd. and the option on the

claims was dropped.

In 1963 C. von Klein did some further prospecting

in the area and located two additional mineralized occurrences.

• he exact location of these showings is not known but it is

believed that the small pit found while examining occurrence

No.4 (page/^') is the No.5 showing mentioned in the 'Report on

the Pulfa Group of Claims' by V.Wierzbicki (File N0.63.E6).

In I964 Carravelle Mines Ltd. gained control of a

large block of claims designated as the Pulfa Group consisting

originally of 134 claims but later increased to 274 claims, and

including the von Klein claims and a large number of claims to

the east and west. C. von Klein carried out further prospecting

in the area during the summer of 1964 for the company and in

August I964 T. Garczynski collected soil and water samples for

geochemical analysis. In November I964 a preliminary evaluation

12.0>

based on photogeological, geophysical and all other available

information (File N0.63.E6) recommended that an airborne

geophysical survey be made of the claim group. In July, I965

an airborne magnetometer and Induced Pulse Transient (input)

electromagnetic survey was flown over the area. The results of

0. &. /y • this survey (File No.63.1693) indicated several well defined

A

groups of electromagnetic anomalies, trending essentially

parallel to the country rock structure, and generally within

the pyroclastic-acid metavolcanic rocks or the mafic metavolcanic

rocks immediately adjacent to them. These anomalous zones did

not occur over the four main occurrences examined by Mclntyre

Porcupine Mines Ltd. It was concluded that these groups of

anomalies were potentially more interesting than the main surface

occurrences and that they should be further investigated.

Geological mapping, ground geophysical surveys and drilling

were recommended. In April, 1966 Carravelle Mines Ltd. announced

(Carravelle Mines Ltd. Annual Report I965) that an agreement

had been made with Falconbridge Nickel Mines Ltd. to carry out zj f - further work on the property.

;/ -' o *-*'' "-^^""^ During mapping of the area a number of other small

\ 1 .'A'?** 1 ,.-«' mineralized occurrences were located but the majority of these

.^)>- -•-''rl,''-i( f appeared to contain only pyrite. Most of these consist of

narrow, rusty, pyritic shear zones in mafic metavolcanic rocks

most commonly striking parallel to the foliation in the country

rock. Examples of this type can be seen around the shores of

Theresa Lake, on the firetower trail from Dead Otter Lake and

on the east side of the Dead Otter Lake road about a mile

' £ /

northwards from the von Klein No.l occurrence. One band of

extensive pyrite mineralization which is not of this type is

exposed over a distance of about 9 000 feet between the Black

River and the Amwri Lake road, west of No.2 Lake. The pyrite

occurs as disseminations, streaks and small lenses in a

distinctive band of quartzo-feldspathic muscovite paragneiss

in contact with a band of pillowed mafic metavolcanic rocks

to the north. It is believed that some drilling was done in

1962 on this pyritic gneiss just south of the Amwri Lake road

but no information is available.

Two other occurrences were found which are—o-f*-*th*e*

No. 2 group—d-escrib ed—in—~the,~int r odu:c1fi~5*n""( pa g eT ™-)-.—-Tlxese

ife«o-&c«u.i,reB&es resemble the von Klein No.l and 2 occurrences

in that the host rock is similar but they occur in quite different

environments. One of these occurrences is in a railroad cut

at the north end of East Barbara Lake and appears to consist

entirely of abundant pyrite disseminated throughout a coarse

grained, dark green, amphibolitic metagabbro sheet intruding

the metasedimentary country rock. The second occurrence is

in a road cut on the Ontario Paper Company road about 2 mile

northeast of Morely Lake. The host rock is a coarse-grained,

biotitic, amphibolitic metagabbro, presumably isolated in the

granodiorite gneiss of the Black-Pic Batholith, however the

amphibolite outcrop is the only one for a considerable distance

and no contacts were seen. The metagabbro is cut in outcrop

by several thin mineralized fractures containing pyrite but in

loose blocks of this material blasted from the outcrop for road

IL2L

fill small pods of almost massive sulphides occurred in the

amphibolite adjacent to the fractures. These pods were up to

4 inches in diameter and contained pyrite, pyrrhotite and

chalcopyrite.

A trace of an entirely different type of mineraliza

tion was noted in an outcrop of garnetiferous metagabbro located

on the Ontario Paper Company road about 1^ miles east of the

south end of Agonzon Lake. This metagabbro is intruded by the

granodiorite gneiss of the Black-Pic Batholith and is cut by

late, rusty weathering fractures. The fractures are coated

with very minute cubes of pyrite and widely disseminated very

fine molybdenite grains. This was the only location within the

area where molybdenite was observed.

r\ &

The mineralized showings in the Black River area

seem to fall into three main groups^ (1) mineralization

occurring in shear and fracture zones in mafic metavolcanic

rocks and sometimes containing minor zinc, lead-zinc or

copper-lead-zinc values in addition to pyrite3 (2) mineral

ization occurring as stringers^ pods or disseminations in

massive amphibolitic metagabbro and sometimes containing

significant copper-nickel values in addition to pyrite3 and

(3) strata-bound disseminations and stringers of pyrite in

muscovite-quartz-feldspar gneiss. The Fairservice and Kusins

showings and the mineralized shear zones around Theresa Lake

/e-3

belong to the No. 1 group while both the No. 1 and No. 2 types

are found on the von Klein Property. The mineralization

northeast of Morley Lake and at the north end of East Barbara

Lake is of the No. 2 type.

Investigations on the von Klein Property have

indicated that the amphibolite type copper-nickel mineralization

(No. 2 type above) is restricted to the amphibolite which occurs

as small isolated blocks, and the Morley Lake and East Barbara

Lake also appear to be quife local. However the fact that

sulphide mineralization is present in the same rock type in at

least three different environments; isolated in a rhyolite

breccia, rafted in the granodiorite gneiss of the Black-Pic

Batholith and intruding the metasedimentary gneiss, suggests

that the mineralization in the amphibolite may be syngenetic.

Therefore the masses of intrusive amphibolitic metagabbro in

the area may be worthy of detailed study.

The No. 1 type mineralized fracture and shear zones

contain minor amounts of economically interesting minerals.

It is possible that the anomalous electro-vmagnetic zones

outlined by Carravelle Mines Limited are related to this type

since both the anomalies and the shear and fracture zones

trend parallel to the rock formations and occur near the

contacts between mafic metavolcanic flows and pyroclastic rocks.

Some of the anomalies are quite extensive and therefore may

contain significantly more valuable mineralization.

The No. 3 type of occurrence in the Black River area

contained only pyrite where examined but of the three types it

occurs in an environment most closely resembling that of the

Manitouwadge ore bodies. The mineralization occurs in a

horizon of muscovite, quartzo-feldspathic metasediment very

similar lithologically to the muscovite-quartz schists of the

Manitouwadge area. This mineralization extends over a

considerable strike length, much of it unexposed, and on the

basis of its similarity to Manitouwadge occurrences, detailed

examination would seem to be justified.

/x :>

Sc tc c. f'r J &c 'fc rv >< cc S •B-ibl- iogr.aph.y-

Bartley, M. W. and Page, T. W.

1957: A geological report on the Hemlo Area, Thunder Bay District, Ontario; Department of Industrial Development, Canadian Pacific Railway.

Davis, G. L., Tilton, G. R., Aldrich, L. T., Hart, S. R., and Steiger, R. H.

1965: Geochronology and Isotope^Geology; Annual Report of the Directi-e«- Geophysical Laboratory (1964-1965), Carnegie Institution pp. 165-171'.

Fahrig, W. F. and Wanless, R. K.

1963: Age Significance of Diabase Dyke swarms of the Canadian Shield: Nature, Vol. 200, No. 4910, 934.

Farrand, ¥. R.

196 : Former Shorelines in Western and Northern Lake Superior Basing University of Michigan Ph.D., Mic. 60-6866. University Microfilms Inc., Ann Arbor, Michigan.

Fyffe, W. S., Turner, F. J. and Verhoogen, J.

1959: Metamorphic Reactions and Metamorphic Facies} Geological Society of America. Memoir 73-

Gross, G.A.

1965: Geology of Iron Deposits in Canada, Vol. 1 General Geology and Evaluation of Iron Depositsj Geol&g-i-e-a-i Survey o# Canada, Economic Geolog'y Report No. 22.

Hutchinson, R. W.

1965: Genesis of Canadian Massive Sulphides Reconsidered by Comparison to Cyprus Deposits; Canadian Mining and Metallurgical Bulletin. Vol. 5$, No. 64I, pp. 236-300.

James, H. L.

1955: Zones of Regional Metamorphism in the Precambrian of Northern Michigan; Bull. of the Geological Society of America Vol. 66, No. 12, Pt. 1, pp. 1455-14SS.

iogr.aph.y-

Lowdon, J. A.

1961: Age Determinations by the Geological Survey of Canada Report 2. Isotopic Agesj Geol.egieai Survey—o£ Canada. Paper 6l-17v p. 607 " ^ > >

McAllister, A. L.

I960: Massive Sulphide Deposits in New Brunswick*, Canadian Mining and Metallurgical Bulletin,Vol. 63, pp. 50-60.

Milne, V. G.

1964: Geology of the Flanders Lake Area: Ontario Depajrtmo-nt, e£ Mines Geologioa-l Repeat, No. 2 1 . J

196 : Geology of t h e C i r rus Lake-Bamoos Lake Area. Ontar io Departflie-ftt. ef Mines, Gee/. (2cpf-

Pye, E. G.

1957: Geology of the Manitouwadge Areaj Ontario Department, of Mines, Afm-uai—R-eport. Vol. 66, ft. 8. (.PobUWcd i feo).

Richards, S. M.

1966: The Banded Iron Formations at Broken Hill, Australia and their relationship to the Lead-Zinc Orebodies;Economic Geology, Vol. 61, pp. 72-96.

Roscoe, S. M.

1965: Geochemical and Isotopic Studies, Noranda and Matagami Areas: The Canadian Mining and Metallurgical Bull.. Vol. 58, No. 641, pp. 965-971. '

Thomson, J. .E. - . — I D ^ i s V r i c T o £ (hunger DA.y ^

1931: Geology of the Heron Bay Area^A Ontar io Depa^fefaent. ef Mines, Aagu^l-ReporI , Vol. 40. f t . 2 , pp . 21-39.

1932: Geology of t h e Heron Bay-White Lake Area; Ontar io Department.-e€ Mines, A-nnua-1 Repopfes^ Vol; 4 1 , H. 6, pp . 34-47 . {.?M;$^d ^ '53).

/ ? /

Wanless, R. K., Stevens, R. D., Lachanche, G. R,, and Rimsaite, R. Y. H.

1965: Age Determinations and Geological Studies, Pt. 1 - Isotopic Ages, Report 5 J Geol&gi-eair-Survoy o£ Canada, Paper 64-17 (Pt. 1).

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PRELIMINARY GEOLOGICAL MAP No. P. 332

BLACK RIVER AREA NORTHWEST PART


Scale 1 inch t o ½ mile

N.T.S. Reference: 42D/16, 42E/1 , 42C./13, 42F/4 G.S.C.-O.D.M. Aeromagnetic Maps:

2157C, 215SG, 2163C, 2169c.

MARGINAL MOTES

In t roduc t ion : The area l i e s between l a t i t u d e s 48°45' and 49°07' and longitudes 85º32 ' and 86°05' in t he D i s t r i c t of Thunder Bay. The ea s t e rn l i m i t of the area follows t he west boundaries of Bryant, Atikameg and McGil l townships and the west l i m i t i s marked by the eas t boundary of Township 75 and corresponds t o t he eas t boundaries of pre l iminary maps Nos. P. 233 and P.235. Highway No. 614 t o Manitouwadje runs nor th -sou th through t h e cen t re of the area and the southern l i m i t of t he map i s about 4 miles nor th of the junc t ion between t h i s highway and Trans Canada Highway No. 17. The nor thern l i m i t of t he area corresponds t o t h e southern l i m i t of t he Manitouwadge Area Map No. 1957-8.

The Black River meanders roughly south-southwest through the cen t r e of t he area and l i e s in a r e l a t i v e l y wide low va l l ey f loored by th ick depos i t s of g l a c i o l a c u s t r i n e varved c lays and s i l t y sands with coarse sands and minor g r a v e l s . The rocks under lying t he area west of t h e Black River and north of Mobert Creek are predominantly g r a n i t i c . These g r a n i t e s are well exposed and high bare r i d g e s a re common. The t rend of t h e s e r idges i s con t ro l l ed by t h e g n e i s s o s i t y and j o i n t i n g and nor theas t - sou thwes t t r end ing va l l eys have been accentuated by g l a c i a l scour ing . In t h e Black River v a l l e y , Nama Creek v a l l e y , Wabikoba Lake and south White Lake areas d r i f t cover i s t h i c k and rock exposures a re few and s c a t t e r e d while in t he area between the Black River and Theresa and Dotted Lakes high bare r idges of metavolcanic rocks a re separa ted oy l a rge areas of low swampy ground. In t h i s l a t t e r region t he g r a n i t i c a reas in p a r t i c u l a r are poorly exposed and swampy.

The eas t e rn half of the area i s a c c e s s i b l e v ia Highway 17 and White Lake, Highway No. 614, Dead Otter Lake road, Ontar io Paper Co. t ruck road and t h e Black River . The western half and n o r t h e a s t e r n corner are a c c e s s i b l e via a number of lakes s u i t a b l e for f l o a t p lane l and ings . The nea res t a i rba se i s a t White River which i s approximately 40 miles e a s t -sou theas t of the a rea . !

Mineral Explora t ion: Since t he discovery of t he orebodies in t he Manitouwadge area in 1953 the whole d i s t r i c t gene ra l ly has been regarded with : i n t e r e s t . Claims have been staked and res taked at var ious t imes , mostly along a b e l t extending no r theas t from Valley Lake t o Dead Ot ter Lake. Extensive new s tak ing was done in t he sp r ing of 1965 in t he area nor th , south, and west of Dotted and Dead Otter Lakes. In 1965 most of t h e ground between Dotted Lake, Theresa Lake and t h e Black River was covered by s t a k i n g . In 1962 McIntyre Porcupine Mines Ltd. surveyed and d r i l l e d a 52 claim area enclosing t h e Von Klein (No.3) copper -n icke l showing j u s t eas t of Summers Lake on Highway No. 614. In 1963, some d r i l l i n g was done by Mining Corpor a t i o n of Canada Ltd. in the area between Amwri Lake and t h e Black River about ½ t o 1 mile eas t of t h e r i v e r and in l a t e 1963 T. and W, Kusins uncovered a l e ad -z inc showing (No.2) between the Black River and Valley Lake, about ¾ mile west of the r i v e r . The Kusins showing was examined in 1965 by Cominco. In January 1966 Carave l le Mines Ltd. held a l a r g e block of more than 100 claims enc los ing t h e Von Klein copper-n ickel showing and extending from Theresa Lake in the eas t t o Highway No. 614 on the west , south of Dead Otter Lake. Also, I r i s h Copper Mines Ltd. held two blocks of claims north of Dotted Lake enclos ing a zinc showing (No.4) s taked by B. Fa i r se rv i ce . -Both companies flew geophysical surveys during t h e summer of 1965 and follow-up work i s con t inu ing .

General Geology: The nor thern half and western p a r t s of t he area a re underl a i n e s s e n t i a l l y by g r a n i t e gne isses and younger massive g r a n i t i c rocks i n t rud ing t he se g n e i s s e s . The younger massive g r a n i t i c rocks (6) have a r e l a t i v e l y high magnetic response and the genera l o u t l i n e of i n t r u s i o n s of t h i s ma te r i a l can be determined from aeromagnetic maps (Maps 2157G, 2158G, and 2168G). In t h e sou theas t qua r t e r of the area eas t of the Black River , the rocks cons i s t of a folded s e r i e s of b i o t i t e - q u a r t z - f e l d s p a r p a r a g n e i s s e s , conglomerates, hornblendic metatuffs and metavolcanic hornblende gne isses in t ruded by s e r p e n t i n i t e , amphibo l i t i c metagabbro, and massive g r a n i t i c rocks . The metasedimentary and metavolcanic rocks extend as a narrow 1 ½ mile wide b e l t from south of Valley Lake, nor theastwards t o Highway No. 614 where t he b e l t swings eas t and widens to about 6 miles due to fo ld ing of the metavolcanic rocks on the nor th s i d e of t he b e l t . These rocks s t r i k e eastwards between Highway No. 614 and Theresa Lake and then swing southeas t through White Lake t o Highway No. 17. The flow rocks are predominantly mafic hornblendic gne isses of formerly pillowed b a s a l t i c or a n d e s i t i c c h a r a c t e r . Po rphyr i t i c d a c i t e p i l low lavas occur west of t h e r a i l r o a d t r ack around Pinegrove Lake and d a c i t i c flow b r e c c i a , r h y o l i t e b r e c c i a , metarhyo--l i t e , tu f f and agglomerate a re exposed south of t he amphibol i t i c metavolcanic rocks , eas t and southwest of Summers Lake. Iron formation, which gives r i s e to a s t rong magnetic anomaly i s exposed on t h e northwest s i d e of the mafic metavolcanic r idge between Amwri Lake and the Black River and on the southeas t s ide of t h i s metavolcanic r i d g e , a band of p y r i t i c muscovit ic meta-arkose extends from west of the Black River eas t t o Phi l Lake. The pyro-c l a s t i c fac ies t e rmina te j u s t eas t of Theresa Lake and the mafic metavolcanic rocks then l i e in contac t with conglomeratic metasediments t o t h e south . The metasedimentary and metavolcanic rocks are in t ruded by g r a n i t e s , meta-gabbroic amphiboli te s h e e t s , s e r p e n t i n i t e l enses and fe ldspar porphyry, amph ibo l i t i c , and d a c i t e d ikes . Large l e n t i c u l a r bodies of s e r p e n t i n i t e are exposed at t h r e e l o c a t i o n s ; on t he no r theas t shore of Dotted Lake, a t the north end of Theresa Lake, and in Spruce Bay on the west s ide of White Lake. All these bodies give r i s e t o marked magnetic anomalies (Map 2168G). The youngest rocks in t he area appear t o be t he d iabases which form dikes i n t rud ing a l l t he p rev ious ly mentioned formations.

S t r u c t u r e : The metasedimentary-metavolcanic b e l t of rocks r ep re sen t s t he southern limb of a roughly e a s t - n o r t h e a s t t r end ing an t i c l i no r ium. The south s ide of the be l t c o n s i s t s of metasediments and in t h i s sec t ion the a n t i c l i n a l limb i s s l i g h t l y overturned to the south . The metavolcanic s ec t ion on the north s i d e of the b e l t i s thickened by r e p e t i t i o n caused by folding about an e a s t - n o r t h e a s t t r e n d i n g a n t i c l i n e centred on Dead Otter Lake and a paral l e l sync l ine ly ing on t h e north s ide of Dotted Lake. These fo lds plunge westwards, the plunge being about 20° near Roger Lake and s teepening westwards t o almost v e r t i c a l at Highway No. 614. At t he nor th contac t of the metasedimentary-metavolcanic b e l t t h e f o l i a t i o n of the g r a n i t e gne i s ses dips s t e ep ly south beneath the metavolcanic rocks but progress ing no r th wards t h e dips g radua l ly shallow u n t i l , about 2 miles north of the contact the d ips are very shallow and in many p laces h o r i z o n t a l . The f l a t dip of the f o l i a t i o n p e r s i s t s northwards t o wi th in 3 miles of Manitouwadge where the f o l i a t i o n s t a r t s to dip predominantly north between 30° and 70°, beneath the metavolcanic rocks of t he Manitouwadge sync l i ne .

Economic Geology: The b i o t i t e - q u a r t z - f e l d s p a r pa ragne i s ses of t h e Black River area a re s i m i l a r in appearance and composition to the metasedimentary gne i s ses of t he Manitouwadge a rea . Unlike the Manitouwadge area , however, i ron formation i s r e l a t i v e l y r a r e and was found in only two l o c a l i t i e s ; one between Amwri Lake and the Black River , c lose t o t h e g r a n i t e contac t and the o ther in the region of the Von Klein copper -n icke l showing (No.3) . Both t he se occurrences conta in p y r i t e and p y r r h o t i t e . The most economically i n t e r e s t i n g f ea tu re in t he area i s a band of predominantly p y r o c l a s t i c m a t e r i a l , a ssoc ia ted with some s i l i c e o u s metasedimentary and in te rmedia te to acid flow rocks , which extends from midway between Valley Lake and the Black River , eas t -nor theas twards for about 6 miles to Highway No. 614, j u s t south of Summers Lake, then eastwards t o north of Musher Lake and southeas t t o Theresa Lake. The rocks in t h i s band are c h a r a c t e r i s t i c a l l y ga rne t i f e rous hornblende meta tuffs and agglomerates, s i l i c e o u s b i o t i t e gne i s se s , and muscovite gne i s ses f requent ly high in p y r i t e . The l ead -z inc showing of T. and W. Kusins (No.2) i s in metavolcanic hornblende gne iss at t h e southwest end of t h i s band. S i l i c i f i e d , p y r i t i c , n o r t h e a s t - t r e n d i n g zones occur in t he hornblende gne iss and in one of t h e s e , small pods of s p h a l e r i t e and galena occur with the p y r i t e . T. and W. Kusins r e p o r t tha t a grab sample gave on ana ly s i s 1.93 per cent z inc , 0.94 per cent lead and O.64 oz. s i l v e r per t on . A major f au l t t r e n d i n g N65°W i s bel ieved to occur about 1,000 fee t southwest of t he showing.

The Von Klein copper-nickel occurrences (No.3) are located about halfway along t h e p y r o c l a s t i c band about 1½ miles northwest of Musher Lake. The rocks in t h e v i c i n i t y of the showings are acid to i n t e r mediate flow rocks , b r e c c i a s and p y r o c l a s t i c rocks in t ruded by d a c i t i c fe ldspar porphyry, b i o t i t e g r a n i t e , muscovite g r a n i t e and t a l c o s e u l t r a -bas ic dikes There are s eve ra l su lphide showings and, in what appear t o be the two r i c h e s t zones, c h a l c o p y r i t e - p y r r h o t i t e - p y r i t e m i n e r a l i z a t i o n seems to be confined to two s e p a r a t e , l a rge blocks of coarse -gra ined amphibol i te ; one apparent ly i s ra f ted in a r h y o l i t e b recc ia (2d) plug and the other is in r h y o l i t e or acid welded tu f f (2 fg) . Minera l i za t ion in t h e surrounding m uscov i t e -b io t i t e gne isses i s minor. Some other showings with coppcr-nickel values occur in shear zones in the mafic pi l low lavas ( l a ) and ga rne t i f e rous agglomerates (2g) on the nor th s ide of t he p y r o c l a s t i c band. A geologica l map of a 52-claim block was prepared by Mclntyre Porcupine Mines Ltd. in 1962 and some d r i l l i n g was done at t h a t t ime . The d r i l l i n g was concentra ted mainly on t he two main sur face showings and t h i s ind ica ted l i t t l e con t inu i ty to the mineral ized amphibol i te b locks . A number of e lec t romagnet ic anomal i e s unre la ted t o the two main showings were noted but these were examined only s u p e r f i c i a l l y . In 1965 Carave l l e Mines Ltd. ou t l ined severa l more e lec t romagnet ic anomalies and considered t ha t these might r e l a t e to .he shear zone type of mine ra l i z a t i on 0.1 t h e p rope r ty . This i n v e s t i g a t i o n i s cont inuing .

A small zinc showing (No.4) was loca ted by B. F a i r s e r v i c e in the mafic metavolcanic hornblende gne isses north of Dotted Lake and t h i s prooer ty was under examination by I r i s h Copper Mines Ltd. in 1965. The showing c o n s i s t s of 3 or 4 seams of massive s p h a l e r i t e up t o 1 inch in width in a shor t rus ty shear zone up t o 4 fee t wide and about 50 feet long. No other mine ra l i za t i on was noted in t h e l o c a l i t y except for minor p y r i t e in some quar tz fe ldspar porphyry dikes which i n t rude t he hornblende g n e i s s e s .

Traces of mine ra l i z a t i on were noted in t h r e e o ther l o c a l i t i e s . On Highway No. 614 and on t h e r a i l r o a d t r a c k opposi te the nor th end of East Barbara Lake a narrow band of massive and laminated metagabbro i s i n t e r -layered with the pa ragne i s s . Disseminated p y r i t e i s no t i c eab l e in the coarse-gra ined metagabbro on the r a i l r o a d t rack and on Highway No. 614. The laminated metagabbro outcrop on the eas t s i d e of the road i s cut by a t h i n 1-inch t o 4-inch seam of black ear thy weathered ma te r i a l conta in ing p v r i t e . A second small showing was located on the Ontario Paper Company road opposi te the north end of Morely Lake. The road cu t s through a small outcrop of amphibol i te metagabbro in a genera l ly d r i f t - cove red a rea . The amphiboli te con ta ins a l i t t l e disseminated p y r i t e and i s cut by s ca t t e r ed t h in ru s ty f r a c t u r e s con ta in ing occasional small blebs of p y r i t e . On the west s ide of t he road a loose block b la s t ed from the outcrop shows loca l shear ing along a r u s t y f r a c t u r e and assoc ia ted with t h i s a small 4 to 6-inch diameter pod of massive p y r r h o t i t e , cha l copyr i t e and p y r i t e . The t h i r d l o c a l i t y i s a small outcrop of game t i f erous amphibol i te 0.1 the Ontario Paper Company road eas t of t he south end of Agoazoa Lake Widely s c a t t e r e d , t h i n , rus ty p y r i t e - c o a t e d f r a c t u r e s cut the rock and l o c a l l y a t h i n veneer of molybdenite coa t s t he f r a c t u r e s .

LEGEND FOR P . 3 3 2 - P . 3 3 5

PHANEROZOIC CENOZOIC

PLEISTOCENE AND RECENT V a r v e d c l a y , s i l t y s a n d , s a n d a n d g r a v e l

U n c o n f o r m i t y PRECAMBRIAN

PROTEROZOIC KEWEENAWAN

8a - D i a b a s e ( d i k e s ) 8b - P o r p h y r i t i c d i a b a s e ( d i k e s )

I n t r u s i v e C o n t a c t

ARCHEAN

POST-TECTONIC CRANITIC ROCKS

7a - B i o t i t e g r a n i t e 7b - B i o t i t e g r a n i t e ( d i k e s ) 7 c - F e l d s p a r p o r p h y r y ( d i k e s ) 7d - L e u c o c r a t i c b i o t i t e g r a n i t e ( d i k e s ) 7 e - A p l i t e a n d p e g m a t i t e ( d i k e s ) 7 f - M u s c o v i t e g r a n i t e ( d i k e s ) 7 g - L a m p r o p h y r e 7h - H e m a t i t i z e d , a l b i t i z e d g r a n i t e 7k - X e n o l i t h i c g r a n i t e

6a - H o r n b l e n d e - b i o t i t e q u a r t z m o n z o n i t e 6b - P o r p h y r i t i c b i o t i t e - q u a r t z m o n z o n i t e 6 c - A u g i t e q u a r t z m o n z o n i t e 6d - B i o t i t i c a u g i t e q u a r t z m o n z o n i t e 6 e - H y b r i d d i o r i t e 6 f - H o r n b l e n d e - f e l d s p a r p o r p h y r y ( d i k e s ) 6 g - A u g i t e s y e n i t e ( d i k e s )

6h - H e m a t i t i z e d , a l b i t i z e d q u a r t z m o n z o n i t e

I n t r u s i v e C o n t a c t GRANITIC GNEISSES

5a - H o r n b l e n d e - b i o t i t e g r a n i t e g n e i s s 5b - B i o t i t e g r a n i t e g n e i s s 5c - F e l d s p a r a u g e n g n e i s s 5d - M i g m a t i t e 5 e - X e n o l i t h i c g r a n i t e g n e i s s 5f - H y b r i d g r a n i t e g n e i s s

5g - H e m a t i t i z e d , a l b i t i z e d g r a n i t e g n e i s s

I n t r u s i v e C o n t a c t MAFIC AND ULTRAMAFIC INTRUSIVE ROCKS

4 a - A m p h i b o l i t i c m e t a g a b b r o 4b - S e r p e n t i n i t e 4 c - G a b b r o 4d - T a l c o s e r o c k ( d i k e s ) 4 e - A n o r t h o s i t i c g n e i s s


METASEDIMENTARY ROCKS

3 a - C o n g l o m e r a t e a n d f i n e l y l a m i n a t e d g r e y w a c k e

3b - P y r i t i c a n d ( o r ) m u s c o v i t e - q u a r t z - f e l d s p a r g n e i s s

3 c - B i o t i t e - q u a r t z - f e l d s p a r p a r a g n e i s s 3d - F e l d s p a t h i z e d o r m i g m a t i t i c m e t a s e d i m e n t s

o r t u f f 3 e - G a r n e t - b i o t i t e s c h i s t 3 f - K y a n i t e - g a r n e t - q u a r t z - f e l d s p a r g n e i s s 3g - M e t a - a r k o s e

INTERMEDIATE TO S I L I C I C METAVOLCANICS, PYROCLASTIC ROCKS AND METASEDIMENTS

2 a - P o r p h y r i t i c d a c i t e ( f l o w s ) 2b - D a c i t e f l o w b r e c c i a 2 c - P i l l o w l a v a 2d - R h y o l i t e b r e c c i a 2 e - M e t a r h y o l i t e 2f - I n t e r m e d i a t e t o s i l i c i c w e l d e d t u f f

o r f l o w b r e c c i a 2g - A g g l o m e r a t e , t u f f , g r e y w a c k e 2h - I r o n f o r m a t i o n 2 j - B i o t i t e g n e i s s 2k - M i g m a t i t e

MAFIC TO INTERMEDIATE METAVOLCANIC ROCKS

l a - M e d i u m - t o f i n e - g r a i n e d , m a s s i v e a n d g n e i s s i c a m p h i b o l i t e

l b - M e d i u m - t o c o a r s e - g r a i n e d , m a s s i v e a n d g n e i s s i c a m p h i b o l i t e

l c - L a m i n a t e d h o r n b l e n d e g n e i s s 1d - P i l l o w l a v a l e - H e m a t i t i z e d , e p i d o t i z e d m e t a v o l c a n i c r o c k 1f - M i g m a t i t e .

SYMBOLS FOR P . 3 3 2 - P . 3 3 5

M u s k e g o r s w a m p .

R i v e r , c r e e k , s t r e a m , R = r a p i d s ; F = f a l l s .

R a i l w a y .

E l e c t r i c p o w e r t r a n s m i s s i o n l i n e .

H i g h w a y .

T r a i l , p o r t a g e , w i n t e r r o a d .

G l a c i a l s t r i a e .

D r i f t f e a t u r e s .

S m a l l r o c k o u t c r o p .

B o u n d a r y o f r o c k o u t c r o p .

G e o l o g i c a l b o u n d a r y , d e f i n e d

G e o l o g i c a l b o u n d a r y , a p p r o x i m a t e .

G e o l o g i c a l b o u n d a r y , a s s u m e d .

G e o l o g i c a l b o u n d a r y a s i n d i c a t e d b y g e o p h y s i c a l d a t a .

S t r i k e a n d d i p ; d i r e c t i o n o f t o p u n k n o w n .

S t r i k e a n d v e r t i c a l d i p ; d i r e c t i o n o f t o p u n k n o w n .

D i r e c t i o n i n w h i c h l a v a f l o w s f a c e a s i n d i c a t e d b y s h a p e o f p i l l o w s .

S y n c l i n a l a x i s .

A n t i c l i n a l a x i s .

D i r e c t i o n o f p l u n g e o f f o l d a x i s , c r e s t l i n e o r t r o u g h l i n e .

S t r i k e a n d d i p o f s c h i s t o s i t y .

S t r i k e o f v e r t i c a l s c h i s t o s i t y .

S t r i k e a n d d i p o f g n e i s s o s i t y .

S t r i k e o f v e r t i c a l g n e i s s o s i t y .

H o r i z o n t a l g n e i s s o s i t y .

S t r a t i f o r m f o l i a t i o n , d i p u n k n o w n .

L i n e a t i o n ( p l u n g e k n o w n , p l u n g e u n k n o w n ) .

D r a g - f o l d s . ( A r r o w i n d i c a t e s d i r e c t i o n o f p l u n g e ) .

Wide s h e a r z o n e .

F a u l t , i n d i c a t e d o r a s s u m e d .

L i n e a m e n t .

L o c a t i o n o f m i n i n g p r o p e r t y .

B u i l d i n g .

G r a v e l p i t .

D r i l l h o l e , i n c l i n a t i o n u n k n o w n .

N e t w o r k o f q u a r t z v e i n s .

S u l p h i d e m i n e r a l i z a t i o n .

M a g n e t i c a t t r a c t i o n .

D i k e s .

F i r e t o w e r .

MINERAL OCCURRENCES REFERENCE

Cu C o p p e r c p C h a l c o p y r i t e mo M o l y b d e n i t e Ni N i c k e l

Pb L e a d p y P y r i t e p o P y r r h o t i t e Zn Z i n c

LIST OF PROPERTIES

1 . M i n i n g C o r p o r a t i o n o f C a n a d a L t d . ( 1 9 6 2 ) . 2 . K u s i n s p r o p e r t y ( C o m i n c o 1 9 6 5 ) . 3 . Von K l e i n p r o p e r t y ( M c l n t y r e P o r c u p i n e M i n e s L t d . 1 9 6 2 ;

C a r a b c l l e M i n e s L t d . 1 0 6 5 ) -4 . F a i r s e r v i c e p r o p e r t y ( T r i s h C o p p e r M i n e s L t d . 1 9 0 5 ) .

SOURCES OF INFORMATION

G e o l o g y b y V . G . M i l n e a n d a s s i s t a n t s 1 9 6 4 , 1 9 6 5 . A s s e s s m e n t f i l e N o . 6 3 - 1 2 1 0 , O n t a r i o D e p t . M i n e s . O n t a r i o D e p t . M i n e s , V o l . XXXI , 1 9 3 2 , p t . 6 O n t a r i o D e p t . M i n e s , V o l . LXVT, 1 9 5 7 , p t . 8 . G e o l o g i c a l R e p o r t o n t h e H e m l o a r e a , D e p t . o f I n d u s t r i a l D e v e l o p m e n t ,

C a n a d i a n P a c i f i c R a i l w a y , 1 9 5 7 .

B a s e map f r o m m a p s o f F o r e s t R e s o u r c e s I n v e n t o r y , O n t a r i o D e p a r t m e n t of L a n d s a n d F o r e s t s , w i t h a d d i t i o n a l i n f o r m a t i o n b y V . G . M i l n e .

I s s u e d 1 9 6 6 .



BLACK RIVER AREA NORTHEAST PART


Scale 1 inch t o ½ mile

N.T.S. Reference: 42C/13, 42F/4 G.S.C.-O.D.M. Aeromagnetic Maps: 216SG, 2169G.

MARGINAL NOTES

I n t r o d u c t i o n : The area l i e s between l a t i t u d e s 48º45' and 49°07' and long i tudes 85°32' and 86°05' in t he D i s t r i c t of Thunder Bay. The ea s t e rn l imi t of t h e area follows t h e west boundaries of Bryant, Atikameg and McGi l l townships and the west l i m i t i s marked by the eas t boundary of Township 75 and corresponds t o t h e eas t boundaries of pre l iminary maps Nos. P. 233 and P. 235- Highway No. 614 t o Manitouwadge runs nor th - sou th through t h e cen t re of t he area and the southern l i m i t of t h e map i s about 4 miles nor th of the j unc t i on between t h i s highway and Trans Canada Highway No. 17. The northern l i m i t of the area corresponds t o t h e southern l i m i t of t he Manitouwadge Area Map No. 1957-8.

The Black River meanders roughly south-southwest through the cen t r e of t he area and l i e s in a r e l a t i v e l y wide low va l l ey f loored by t h i c k depos i t s of g l a c i o l a c u s t r i n e varved c lays and s i l t y sands with coarse sands and minor g r a v e l s . The rocks under lying the area west of t h e Black River and nor th of Mobert Creek are predominantly g r a n i t i c . These g r a n i t e s are well exposed and high bare r i dges a re common. The t rend of t he se r idges i s con t ro l l ed by t he g n e i s s o s i t y and j o i n t i n g and nor theas t - southwes t t r end ing va l l eys have been accentuated by g l a c i a l scour ing . In t h e Black Rive v a l l e y , Nama Creek v a l l e y , Wabikoba Lake and south White Lake areas d r i f t cover i s t h i c k and rock exposures a re few and s c a t t e r e d while in t h e area between t h e Black River and Theresa and Dotted Lakes high ba re r idges of metavolcanic rocks a re separa ted by l a r g e a reas of low swampy round. In t h i s l a t t e r region the g r a n i t i c areas in p a r t i c u l a r a re poorly exposed and swampy.

The eas t e rn ha l f of the area i s a c c e s s i b l e v ia Highway 17 and White Lake, Highway No. 614, Dead Otter Lake road, Ontar io Paper Co. t ruck road and t h e Black River . The western ha l f and no r thea s t e rn corner are a c c e s s i b l e via a number of lakes s u i t a b l e for f l o a t p lane l and ings . The nearest a i rba se i s a t White River which i s approximately 40 miles e a s t -southeast of the a rea .

Mineral Explora t ion: Since t he discovery of the orebodies in the Manitouwadge area in 1953 the whole d i s t r i c t gene ra l ly has been regarded with i n t e r e s t . Claims have been staked and res taked at var ious t imes , mostly along a b e l t extending no r theas t from Valley Lake t o Dead Otter Lake. Extensive new s t ak ing was done in t h e spr ing of 1965 in the area nor th , south , and west of Dotted and Dead Ot ter Lakes. In 1965 most of t h e ground between Dotted Lake, Theresa Lake and t h e Black River was covered by s t ak ing . In 1962 McIntryre Porcupine Mines Ltd. surveyed and d r i l l e d a 52 claim area

enc lo s ing the Von Klein (No.3) copper -n icke l showing j u s t eas t of Summers Lake on Highway No. 614. In 1963, some d r i l l i n g was done by Mining Corpo-r a t i o n of Canada Ltd. in t he area between Amwri Lake and t h e Black River about ½ to 1 mile eas t of the r i v e r and in l a t e 1963 T. and W. Kusins uncovered a l e ad -z inc showing (No.2) between t he Black River and Valley Lake, about ¾ mile west of t he r i v e r . The Kusins showing was examined in 1965 by Cominco. In January 1966 Carave l le Mines Ltd. held a l a r g e block of more than 100 claims enclos ing the Von Klein copper-n ickel showing and extending from Theresa Lake in t h e eas t t o Highway No. 614 on t h e west , south of Dead Ot ter Lake. Also, I r i s h Copper Mines Ltd. held two blocks of claims nor th of Dotted Lake enclos ing a zinc showing (No.4) s taked by B. F a i r s e r v i c e . Both companies flew geophysical surveys during t h e summer of 1965 and follow-up work i s con t inu ing .

General Geology: The nor thern half and western p a r t s of t he area a re underl a i n e s s e n t i a l l y by g r a n i t e gne i s ses and younger massive g r a n i t i c rocks i n t r u d i n g t he se g n e i s s e s . The younger massive g r a n i t i c rocks (6) have a r e l a t i v e l y high magnetic response and the genera l o u t l i n e of i n t r u s i o n s of t h j s ma te r i a l can be determined from aeromagnetic maps (Maps 2157G, 2158G, and 2168G). In t h e sou theas t quar te r of t he area eas t of the Black River, the rocks cons i s t of a folded s e r i e s of b i o t i t e - q u a r t z - f e l d s p a r pa ragne i s ses , conglomerates , hornblendic meta tuffs and metavolcanic hornblende gne isses in t ruded by s e r p e n t i n i t e , amphibo l i t i c metagabbro, and massive g r a n i t i c rocks . The metasedimentary and metavolcanic rocks extend as a narrow 1 2 mile wide b e l t from south of Valley Lake, nor theas twards t o Highway No. 614 where t h e b e l t swings eas t and widens to about 6 miles due t o folding of t h e metavolcanic rocks on t h e nor th s i d e of the b e l t . These rocks s t r i k e eastwards between Highway No. 614 and Theresa Lake and then swing southeast through White Lake t o Highway No. 17. The flow rocks are predominantly mafic hornblendic gne i s ses of formerly pil lowed b a s a l t i c or a n d e s i t i c c h a r a c t e r . Po rphyr i t i c d a c i t e p i l low lavas occur west of the r a i l r o a d t rack around Pinegrove l a k e and d a c i t i c flow b r e c c i a , r h y o l i t e b r e c c i a , metarhyo--- l i t e , tu f f and agglomerate a re exposed south of the amphibol i t ic metavolcanic rocks , eas t and southwest of Summers Lake. Iron formation, which gives r i s e to a s t rong magnetic anomaly i s exposed 0:1 t he northwest s ide of the mafic metavolcanic r idge between Amwri Lake and the Black River and on the southeas t s ide of t h i s metavolcanic r i d g e , a band of p y r i t i c muscovit ic meta-arkose extends from west of the Black River eas t t o Phi l Lake. The pyro-c l a s t i c f a d e s t e rmina te j u s t eas t of Theresa Lake and the mafic metavolcanic rocks then l i e in contac t with conglomeratic metasediments t o t h e south . The metasedimentary and metavolcanic rocks are in t ruded by g r a n i t e s , meta-gabbroic amphiboli te s h e e t s , s e r p e n t i n i t e lenses and fe ldspar porphyry, amph ibo l i t i c , and d a c i t e d ikes . Large l e n t i c u l a r bodies of s e r p e n t i n i t e are exposed at t h r e e l o c a t i o n s ; on the nor theas t shore of Dotted Lake, at the north end of Theresa Lake, and in Spruce Bay on the west s ide of White Lake. All these bodies give r i s e t o marked magnetic anomalies (Map 2168G). The youngest rocks in_the area appear t o be t h e d iabases which form dikes in t rud ing a l l the previously mentioned format ions .

S t r u c t u r e : The metasedimentary-metavolcanic be l t of rocks r e p r e s e n t s t he southern limb of a roughly e a s t - n o r t h e a s t t r end ing a n t i c l i n o r i u m . The south s ide of the b e l t c o n s i s t s of metasediments and in t h i s sec t ion t h e a n t i c l i n a l limb i s s l i g h t l y overturned to the south . The metavolcanic s ec t i on on the north s i d e of the b e l t i s thickened by r e p e t i t i o n caused by folding about an e a s t - n o r t h e a s t t r end ing a n t i c l i n e centred on Dead Otter Lake and a paral l e l sync l ine ly ing on t h e north s i d e of Dotted Lake. These folds plunge westwards, t he plunge being about 20° near Roger lake and steepening westwards t o almost v e r t i c a l at Highway No. 614. At t he north contact of the metasedimentary-metavolcanic belt t h e f o l i a t i o n of t he g r a n i t e gne isses dips s teeply south beneath the metavolcanic rocks but progress ing nor th wards the dips gradual ly shallow u n t i l , about 2 miles north of the contact the d ips a re very shallow and in many places h o r i z o n t a l . The f l a t dip of the f o l i a t i o n p e r s i s t s northwards t o wi th in 3 miles of Manitouwadge where the f o l i a t i o n s t a r t s to dip predominantly north between 30° and 70°, beneath the metavolcanic rocks of t he Manitouwadge sync l i nc .

Economic Geology: The b i o t i t e - q u a r t z - f e l d s p a r pa ragne i s ses of t he Black River area arc s i m i l a r in appearance and composition t o the metasedimentary gne i s ses of the Manitouwadge area . Un l ike the Manitouwadge a rea , however, i ron formation i s r e l a t i v e l y r a r e and was found in only two l o c a l i t i e s ; one between Amwri Lake and the Black River , c lose to t h e g r a n i t e contac t and the o ther in the region of t he Von K l e i n copper-n ickel showing (No.3). Both t he se occurrences conta in p y r i t e and p y r r h o t i t e . The most economically i n t e r e s t i n g f ea tu re in t he area i s a band of predominantly p y r o c l a s t i c m a t e r i a l , a ssoc ia ted with some s i l i c e o u s metasedimentary and in te rmedia te to acid flow rocks , which extends from midway between Valley Lake and the Black R i v e r , eas t -nor theas twards for about 6 miles to Highway No. 614, j u s t south of Summers Lake, then eastwards t o nor th of Musher Lake and southeas t t o Theresa l a k e . The rocks in t h i s band are c h a r a c t e r i s t i c a l l y ga rne t i f e rous , hornblende meta tuffs and agglomerates, s i l i c e o u s b i o t i t e gne i s se s , and muscovite gne i s ses f requent ly high in p y r i t e . The lead-z inc showing of T. and W. Kusins (No.2) is in metavolcanic hornblende gneiss a t t he southwest end of t h i s band. S i l i c i f i e d , p y r i t i c , n o r t h e a s t - t r e n d i n g zones occur in the hornblende gne iss and in one of t h e s e , small pods of s p h a l e r i t e and galena occur with the p y r i t e . T. and W. Kusins r e p o r t tha t a grab sample gave on a n a l y s i s 1.93 per cent z inc , 0.94 per cent lead and 0.64 oz. s i l v e r per t on . A major f a u l t t r e n d i n g N65°W i s bel ieved to occur about 1,000 fee t southwest of t h e showing.

The Von Klein copper-nickel occurrences (No.3) are loca ted about halfway along t he p y r o c l a s t i c band about 1½ miles northwest of Musher Lake. The rocks in t he v i c i n i t y of t he showings are acid to i n t e r mediate flow rocks , b r e c c i a s and p y r o c l a s t i c rocks in t ruded by d a c i t i c fe ldspar porphyry, b i o t i t e g r a n i t e , muscovite g r a n i t e and t a l c o s e u l t r a -bas ic d i k e s . There are s eve ra l su lphide showings and, in what appear t o be the two r i c h e s t zones, c h a l c o p y r i t e - p y r r h o t i t e - p y r i t e m i n e r a l i z a t i o n seems to be confined to two s e p a r a t e , l a rge blocks of coarse -gra ined amphibol i te ; one apparent ly i s ra f t ed in a r h y o l i t e b r ecc i a (2d) plug and the other i s in r h y o l i t e or acid welded tu f f (2 fg ) . Minera l i za t ion in t h e surrounding m u s c o v i t e - b i o t i t e gne isses i s minor. Some other showings with copper-nickel values occur in shear zones in the mafic p i l low lavas (1a) and ga rne t i f e rous Agglomerates (2g) on t h e nor th s ide of t h e p y r o c l a s t i c band. A geological map of a 52-claim block was prepared by McIntyre Porcupine Mines Ltd. in 1962 and some d r i l l i n g was done at t h a t t ime . The d r i l l i n g was concentra ted mainly on t h e two main sur face showings and t h i s ind ica ted l i t t l e con t inu i ty to t he mineral ized amphibol i te b locks . A number of e lec t romagnet ic anomal i e s unre la ted t o t he two main showings were noted but these were examined only s u p e r f i c i a l l y . In 1965 Carave l l e Mines Ltd. ou t l ined severa l more e lec t romagnet ic anomalies and considered t ha t t he se might r e l a t e to the shear zone type of m i n e r a l i z a t i o n on t h e p rope r ty . This i n v e s t i g a t i o n i s cont inuing .

A small zinc showing (No.4) was loca ted by B. F a i r s e r v i c e in the mafic metavolcanic hornblende gne i s ses north of Dotted Lake and t h i s proper ty was under examination by I r i s h Copper Mines Ltd. in 1965. The showing c o n s i s t s of 3 or 4 seams of massive s p h a l e r i t e up t o 1 inch in width in a shor t r u s t y shear zone up t o 4 fee t wide and about 50 fee t long. No other m ine ra l i z a t i on was noted in t h e l o c a l i t y except for minor p y r i t e m some quar tz f e l d 3 p a r porphyry dikes which i n t rude t he hornblende gne i s s e s .

Traces of m i n e r a l i z a t i o n were noted in t h r e e o ther l o c a l i t i e s . On Highway No. 614 and on t h e r a i l r o a d t r a c k opposi te the nor th end of East Barbara Lake a narrow band of massive and laminated metagabbro i s i n t e r -layered with t he pa ragne i s s . Disseminated p y r i t e i s no t i c eab l e in the c o a r s e - g a i n e d metagabbro on t h e r a i l r o a d t rack and on Highway No. 614. The laminated metagabbro outcrop on the eas t s ide of the road i s cut by a t h i n 1-inch t o 4-inch seam of black ear thy weathered ma te r i a l conta in ing p y r i t e . A second small showing was located on the Ontario Paper Company road oppos i te t h e nor th end of Morely Lake. The road cu t s through a small outcrop of amphibol i te metagabbro in a genera l ly d r i f t - cove red area. The amphibol i te con ta ins a l i t t l e disseminated p y r i t e and i s cut by s c a t t e r e d t h i n , rus ty f r a c t u r e s con ta in ing occas ional small b lebs of p y r i t e . On the west s ide of t h e road a loose block b la s t ed from the outcrop shows loca l shear ing along a rus ty f r a c t u r e and assoc ia ted with t h i s a small 4 to 6-inch diameter pod of massive p y r r h o t i t e , cha l copyr i t e and p y r i t e . the t h i r d l o c a l i t y i s a small outcrop of ga rne t i f e rous amphibol i te on t he Ontario Paper Company road eas t of t h e south end of Agoazoa Lake. Widely s c a t t e r e d , t h i n , rus ty p y r i t e - c o a t e d f r a c t u r e s cut the rock and l o c a l l y a t h i n veneer of molybdenite coa t s the f r a c t u r e s .

LEGEND FOR P . 3 3 2 - P . 3 3 5

PHANEROZOIC CEN0ZOIC

PLEISTOCENE AND RECENT V a r v e d c l a y , s i l t y s a n d , s a n d a n d g r a v e l

U n c o n f o r m i t y PRECAMBRIAN


8 a - D i a b a s e ( d i k e s ) 8b - P o r p h y r i t i c d i a b a s e ( d i k e s )


ARCHEAN

POST-TECTONIC GRANITIC ROCKS

7a - B i o t i t e g r a n i t e 7b - B i o t i t e g r a n i t e ( d i k e s ) 7 c - F e l d s p a r p o r p h y r y ( d i k e s ) 7d - L e u c o c r a t i c b i o t i t e g r a n i t e ( d i k e s ) 7 e - A p l i t e a n d p e g m a t i t e ( d i k e s ) 7 f - M u s c o v i t e g r a n i t e ( d i k e s ) 7 g - L a m p r o p h y r e 7h - H e m a t i t i z e d , a l b i t i z e d g r a n i t e 7k - X e n o l i t h i c g r a n i t e

6a - H o r n b l e n d e - b i o t i t e q u a r t z m o n z o n i t e 6b - P o r p h y r i t i c b i o t i t e - q u a r t z m o n z o n i t e 6 c - A u g i t e q u a r t z m o n z o n i t e 6d - B i o t i t i c a u g i t e q u a r t z m o n z o n i t e 6 e - H y b r i d d i o r i t e 6 f - H o r n b l e n d e - f e l d s p a r p o r p h y r y ( d i k e s ) 6 g - A u g i t e s y e n i t e ( d i k e s )



5 a - H o r n b l e n d e - b i o t i t e g r a n i t e g n e i s s 5b - B i o t i t e g r a n i t e g n e i s s 5c - F e l d s p a r a u g e n g n e i s s 5d - M i g m a t i t e 5 e - X e n o l i t h i c g r a n i t e g n e i s s 5f - H y b r i d g r a n i t e g n e i s s



4 a - A m p h i b o l i t i c m e t a g a b b r o 4b - S e r p e n t i n i t e 4 c - G a b b r o 4d - T a l c o s e r o c k ( d i k e s ) 4 e - A n o r t h o s i t i c g n e i s s



3a - C o n g l o m e r a t e a n d f i n e l y l a m i n a t e d g r e y w a c k e

3b - P y r i t i c a n d ( o r ) m u s c o v i t e - q u a r t z - f e l d s p a r g n e i s s

3 c - B i o t i t e - q u a r t z - f e l d s p a r p a r a g n e i s s 3d - F e l d s p a t h i z e d o r m i g m a t i t i c m e t a s e d i m e n t s

o r t u f f 3 e - G a r n e t - b i o t i t e s c h i s t 3 f - K y a n i t e - g a r n e t - q u a r t z - f e l d s p a r g n e i s s 3 g - M e t a - a r k o s e

INTERMEDIATE TO S I L I C I C METAVOLCANICS, PYROCLASTIC ROCKS AND METASEDIMENTS

2 a - P o r p h y r i t i c d a c i t e ( f l o w s ) 2b - D a c i t e f l o w b r e c c i a 2 c - P i l l o w l a v a 2d - R h y o l i t e b r e c c i a 2 e - M e t a r h y o l i t e 2 f - I n t e r m e d i a t e t o s i l i c i c w e l d e d t u f f

o r f l o w b r e c c i a 2 g - A g g l o m e r a t e , t u f f , g r e y w a c k e 2h - I r o n f o r m a t i o n 2 j - B i o t i t e g n e i s s 2k - M i g m a t i t e


l a - M e d i u m - t o f i n e - g r a i n e d , m a s s i v e a n d g n e i s s i c a m p h i b o l i t e

l b - M e d i u m - t o c o a r s e - g r a i n e d , m a s s i v e a n d g n e i s s i c a m p h i b o l i t e

l c - L a m i n a t e d h o r n b l e n d e g n e i s s 1d - P i l l o w l a v a l e - H e m a t i t i z e d , e p i d o t i z e d m e t a v o l c a n i c r o c k 1f - M i g m a t i t e

SYMBOLS FOR P . 3,32 - P . 3 3 5

Muskeg o r swamp.


R a i l w a y .

E l e c t r i c power t r a n s m i s s i o n l i n e .

Highway.


G l a c i a l s t r i a e -


Smal l r o c k o u t c r o p .

Boundary of r o c k o u t c r o p .



G e o l o g i c a l b o u n d a r y , assumed.

G e o l o g i c a l b o u n d a r y a s i n d i c a t e d by g e o p h y s i c a l d a t a .

S t r i k e and d i p ; d i r e c t i o n of t o p unknown.

S t r i k e and v e r t i c a l d i p ; d i r e c t i o n of t o p unknown.

D i r e c t i o n i n which l a v a f l ows f a c e a s i n d i c a t e d by s h a p e of p i l l o w s .



D i r e c t i o n of p l u n g e of f o l d a x i s , c r e s t l i n e o r t r o u g h l i n e .

S t r i k e and d i p of S c h i s t o s i t y .

S t r i k e of v e r t i c a l s c h i s t o s i t y .

S t r i k e and d i p of g n e i s s o s i t y .

S t r i k e of v e r t i c a l g n e i s s o s i t y .


S t r a t i f o r m f o l i a t i o n , d i p unknown.

L i n e a t i o n ( p l u n g e Known, p l u n g e u n k n o w n ) .

D r a g - f o l d s . (Arrow i n d i c a t e s d i r e c t i o n of p l u n g e ) .


F a u l t , i n d i c a t e d o r a s sumed .

L i n e a m e n t .

L o c a t i o n of m i n i n g p r o p e r t y .

B u i l d i n g .

G r a v e l p i t .

D r i l l h o l e , i n c l i n a t i o n unknown.

Network of q u a r t z v e i n s .



D i k e s .

F i r e t o w e r .


Cu C o p p e r c p C h a l c o p y r i t e mo M o l y b d e n i t e N i N i c k e l

Pb L e a d p y P y r i t e p o P y r r h o t i t e Zn Z i n c

L I S T OF PROPERTIES

1 . M i n i n g C o r p o r a t i o n o f C a n a d a L t d . ( 1 9 6 2 ) . 2 . K u s i n s p r o p e r t y ( C o m i n c o 1 9 6 5 ) . 3 . Von K l e i n p r o p e r t y ( M c l n t y r e P o r c u p i n e M i n e s L t d . 1 9 6 2 ;

C a r a b e l l e M i n e s L t d . 1 9 6 5 ) . 4 . F a i r s e r v i c e p r o p e r t y ( I r i s h C o p p e r M i n e s L t d . I 9 6 5 ) .


G e o l o g y b y V . G . M i l n e a n d a s s i s t a n t s 1 9 6 4 , 1 9 6 5 . A s s e s s m e n t f i l e N o . 6 3 - 1 2 1 0 , O n t a r i o D e p t . M i n e s . O n t a r i o D e p t . M i n e s , V o l . XXXI, 1 9 3 2 , p t . 6 O n t a r i o D e p t . M i n e s , V o l . L X V I , 1 9 5 7 , p t . 8 . G e o l o g i c a l R e p o r t o n t h e H e m l o a r e a , D e p t . o f I n d u s t r i a l D e v e l o p m e n t ,

C a n a d i a n P a c i f i c R a i l w a y , 1 9 5 7 .

B a s e map f r o m m a p s o f F o r e s t R e s o u r c e s I n v e n t o r y , O n t a r i o D e p a r t m e n t o f L a n d s a n d F o r e s t s , w i t h a d d i t i o n a l i n f o r m a t i o n b y V . G . M i l n e .

I s s u e d 1 9 6 6 .



BLACK RIVER AREA SOUTHWEST PART


S c a l e 1 i n c h t o ½ m i l e

N . T . S . R e f e r e n c e : 4 2 D / 1 6 , 42C/13 G .S .C . -O .D.M. A e r o m a g n e t i c Maps: 2157G, 2168G.

MARGINAL NOTES

In t roduc t ion : The area l i e s between l a t i t u d e s 48°45' and 49°07' and long i tudes 85°32' and 86°05' i n t he D i s t r i c t of Thunder Bay. The e a s t e r n l i m i t of t h e area follows t h e west boundaries of Bryant, Atikameg and McGi l l townships and the west l i m i t i s marked by the eas t boundary of Township 75 and corresponds t o t he eas t boundaries of p re l iminary maps Nos. P. 233 and P.235- Highway No. 614 t o Manitouwadge runs nor th -sou th through t h e cen t re of t h e area and t h e southern l i m i t of t h e map i s about 4 miles nor th of the junc t ion between t h i s highway and Trans Canada Highway No. 17. The northern l i m i t of t he area corresponds t o t h e southern l i m i t of t he Manitouwadge Area Map No. 1957-8.

The Black River meanders roughly south-southwest through the cen t r e of t h e area and l i e s in a r e l a t i v e l y wide low va l l ey f loored by th i ck depos i t s of g l a c i o l a c u s t r i n e varved c lays and s i l t y sands with coarse sands and minor g r a v e l s . The rocks under ly ing t h e area west of t h e Black River and nor th of Mobert Creek are predominantly g r a n i t i c . These g r a n i t e s are well exposed and high bare r i d g e s a re common. The t r end of t he se r idges i s c o n t r o l l e d by t h e g n e i s s o s i t y and j o i n t i n g and nor theas t - southwes t t r end ing va l l eys have been accentuated by g l a c i a l scour ing . In t h e Black River v a l l e y , Nama Creek v a l l e y , Wabikoba Lake and south White Lake areas d r i f t cover i s t h i c k and rock exposures a re few and s c a t t e r e d whi le in t h e area between t he Black River and Theresa and Dotted Lakes high ba re r idges of metavolcanic rocks are separa ted by l a r g e a reas of low swampy ground. In t h i s l a t t e r region the g r a n i t i c a reas in p a r t i c u l a r a re poorly exposed and swampy.

The eas t e rn ha l f of t h e area i s a c c e s s i b l e v ia Highway 17 and White Lake, Highway No. 614, Dead Ot ter Lake road, Ontario Paper Co. t ruck road and t h e Black River . The western half and no r theas t e rn corner are a c c e s s i b l e via a number of l akes s u i t a b l e for f l o a t p lane l and ings . The neares t a i rba se i s a t White River which i s approximately 4° miles e a s t -southeas t of t h e a rea .

Mineral Explora t ion : Since t he discovery of t h e orebodies in the Manitouwadge area in 1953 the whole d i s t r i c t gene ra l ly has been regarded with i n t e r e s t . Claims have been s taked and res taked a t va r ious t imes , mostly along a b e l t extending no r theas t from Valley Lake t o Dead Otter Lake. Extensive new s t ak ing was done in t h e s p r i n g of 1965 in t he area nor th , south, and west of Dotted and Dead Ot ter Lakes. In 1965 most of t h e ground between Dotted Lake, Theresa Lake and t h e Black River was covered by s t ak ing . In 1962 McIntyre Porcupine Mines Ltd. surveyed and d r i l l e d a 52 claim area enclosing the Von Klein (No.3) copper -n icke l showing j u s t ea s t of Summers Lake on Highway No. 614. In 1963, some d r i l l i n g was done by Mining Corpor a t i o n of Canada Ltd. in t he area between Amwri Lake and t h e Black River about ½ t o 1 mile eas t of t h e r i v e r and in l a t e 1963 T. and W. Kusins uncovered a l e ad -z inc showing (No.2) between t he Black River and Valley Lake, about ¾ mile west of the r i v e r . The Kusins showing was examined in 1965 by Cominco. In January 1966 Carave l le Mines Ltd. held a l a r g e block of more than 100 claims enc los ing t h e Von Klein copper -n icke l showing and extending from Theresa Lake in t h e eas t t o Highway No. 614 on the west , south of Dead Otter Lake. Also, I r i s h Copper Mines Ltd. held two blocks of claims nor th of Dotted Lake enclos ing a z inc showing (No.4) staked by B. F a i r s e r v i c e . Both companies flew geophysical surveys during t h e summer of I965 and follow-up work i s con t inu ing .

General Geology: The nor thern ha l f and western p a r t s of t he area a r e underl a i n e s s e n t i a l l y by g r a n i t e gne i s ses and younger massive g r a n i t i c rocks i n t r u d i n g t he se g n e i s s e s . The younger massive g r a n i t i c rocks (6) have a r e l a t i v e l y high magnetic response and the genera l o u t l i n e of i n t r u s i o n s of t h i s ma te r i a l can be determined from aeromagnetic maps (Maps 2157G, 215SG, and 2168G). In t h e sou theas t quar te r of the area eas t of t he Black River , the rocks cons i s t of a folded s e r i e s of b i o t i t e - q u a r t z - f e l d s p a r pa ragne i s se s , conglomerates, hornblendic meta tuffs and metavolcanic hornblende gne isses in t ruded by s e r p e n t i n i t e , amphibo l i t i c metagabbro, and massive g r a n i t i c rocks . The metasedimentary and metavolcanic rocks extend as a narrow 1 ½ mile wide b e l t from south of Valley Lake, nor theas twards t o Highway No. 614 where t h e b e l t swings eas t and widens to about 6 miles due t o fo lding of t h e metavolcanic rocks on t h e nor th s i d e of the b e l t . These rocks s t r i k e eastwards between Highway No. 614 and Theresa Lake and then swing southeas t through White Lake t o Highway No. 17. The flow rocks are predominantly mafic hornblendic gne i s ses of formerly pillowed b a s a l t i c or a n d e s i t i c c h a r a c t e r . Po rphyr i t i c d a c i t e p i l low lavas occur west of t he r a i l r o a d t r ack around Pinegrove Lake and d a c i t i c flow b recc i a , r h y o l i t e b r e c c i a , metarhyo--l i t e , t u f f and agglomerate a re exposed south of t he amphibol i t ic metavolcanic rocks , eas t and southwest of Summers Lake. Iron formation, which gives r i s e to a s t rong magnetic anomaly i s exposed on t h e northwest s i d e of the mafic metavolcanic r idge between Amwri Lake and t h e Black River and on the southeas t s ide of t h i s metavolcanic r i d g e , a band of p y r i t i c muscovit ic meta-arkose extends from west of the Black River eas t t o Phi l Lake. The pyroc l a s t i c f ac i e s t e rmina te j u s t eas t of Theresa Lake and the mafic metavolcanic rocks then l i e in contac t with conglomeratic metasediments t o t h e south . The metasedimentary and metavolcanic rocks are in t ruded by g r a n i t e s , meta-gabbroic amphibol i te s h e e t s , s e r p e n t i n i t e l enses and fe ldspar porphyry, amphibo l i t i c , and d a c i t e d ikes . Large l e n t i c u l a r bodies of s e r p e n t i n i t e are exposed at t h r e e l o c a t i o n s ; on t he nor theas t shore of Dotted Lake, at the nor th end of Theresa Lake, and in Spruce Bay on the west s i d e of White Lake. All these bodies give r i s e t o marked magnetic anomalies (Map 2168G). The youngest rocks in t he area appear t o be t h e d iabases which form dikes i n t rud ing a l l the p rev ious ly mentioned formations.

S t r u c t u r e : The metasedimentary-metavolcanic b e l t of rocks r e p r e s e n t s the southern limb of a roughly e a s t - n o r t h e a s t t r end ing a n t i c l i n o r i u m . The south s ide of the b e l t c o n s i s t s of metasediments and in t h i s s ec t ion t h e a n t i c l i n a l limb i s s l i g h t l y overturned to the south . The metavolcanic s e c t i o n on the north s i d e of the b e l t i s thickened by r e p e t i t i o n caused by folding about an e a s t - n o r t h e a s t t r e n d i n g a n t i c l i n e centred on Dead Otter Lake and a paral l e l sync l ine ly ing on the north s i d e of Dotted Lake. These folds plunge westwards, the plunge being about 20° near Roger Lake and s teepening westwards t o almost v e r t i c a l at Highway No. 614. At t he north contact of the metasedimentary-metavolcanic b e l t t h e f o l i a t i o n of t he g r a n i t e gne isses dips s t e e p l y south beneath the metavolcanic rocks but progress ing nor th wards t h e dips g radua l ly shallow u n t i l , about 2 miles nor th of t h e contact the d ips are very shallow and in many p laces h o r i z o n t a l . The f l a t dip of the f o l i a t i o n p e r s i s t s northwards to wi th in 3 miles of Manitouwadge where the f o l i a t i o n s t a r t s to dip predominantly north between 30° and 70°, beneath the metavolcanic rocks of t h e Manitouwadge s y n c l i n e .

Economic Geology: The b i o t i t e - q u a r t z - f e l d s p a r pa ragne i s ses of t he Black River area are s i m i l a r in appearance and composition t o the metasedimentary gne isses of the Manitouwadge a rea . Unlike the Manitouwadge a rea , however, i ron formation i s r e l a t i v e l y r a r e and was found in only two l o c a l i t i e s ; one between Amwri Lake and the Black River , c lose t o t h e g r a n i t e contac t and the o ther in t h e region of the Von Klein copper-nickel showing (No. 3 ) . Both t h e s e occurrences conta in p y r i t e and p y r r h o t i t e . The most economically i n t e r e s t i n g f ea tu re in the area i s a band of predominantly p y r o c l a s t i c m a t e r i a l , assoc ia ted with some s i l i c e o u s metasedimentary and in te rmedia te t o acid flow rocks , which extends from midway between Valley Lake and the Black River , eas t -nor theas twards for about 6 miles to Highway No. 614, j u s t south of Summers Lake, then eastwards to north of Musher Lake and southeas t t o Theresa Lake. The rocks in t h i s band are c h a r a c t e r i s t i c a l l y ga rne t i f e rous hornblende metatuffs and agglomerates, s i l i c e o u s b i o t i t e gne i s se s , and muscovite gne isses f requent ly high in p y r i t e . The l ead -z inc showing of T. and W. Kusins (No.2) i s in metavolcanic hornblende gneiss at t h e southwest end of t h i s band. S i l i c i f i e d , p y r i t i c , n o r t h e a s t - t r e n d i n g zones occur in t he hornblende gneiss and in one of t h e s e , small pods of s p h a l e r i t e and galena occur with the p y r i t e . T. and W. Kusins r e p o r t tha t a grab sample gave on ana ly s i s 1.93 per cent z inc , 0.94 per cent lead and 0.64 oz. s i l v e r per t on . A major f a u l t t r e n d i n g N65°W i s bel ieved t o occur about 1,000 fee t southwest of the showing.

The Von Klein copper-nickel occurrences .(No.3) arc located about halfway along t h e p y r o c l a s t i c band about 1½ miles northwest of Musher Lake. The rocks in t h e v i c i n i t y of the showings are acid to i n t e r mediate flow rocks , b r e c c i a s and p y r o c l a s t i c rocks in t ruded by d a c i t i c fe ldspar porphyry, b i o t i t e g r a n i t e , muscovite g r a n i t e and t a l c o s e u l t r a -bas i c d i k e s . There are s eve ra l su lphide showings and, in what appear t o be the two r i c h e s t zones, c h a l c o p y r i t e - p y r r h o t i t e - p y r i t e mine ra l i za t i on seems to be confined to two s e p a r a t e , l a rge blocks of coarse -gra ined amphibol i te ; one apparent ly i s ra f ted in a r h y o l i t e b recc ia (2d) plug and the o ther i s in r h y o l i t e or acid welded tu f f (2 fg) . Minera l i za t ion in t h e surrounding muscov i t e -b io t i t e gne isses i s minor. Some other showings with copper-nickel values occur in shear zones in the mafic p i l low lavas ( l a ) and ga rne t i f e rous agglomerates (2g) on the nor th s ide of t h e p y r o c i a s t i c band. A geological map of a 52-claim block was prepared by Mclntyre Porcupine Mines Ltd. in 1962 and some d r i l l i n g was done a t t h a t t ime . The d r i l l i n g was concentrated mainly on the two main surface showings and t h i s ind ica ted l i t t l e con t inu i ty to t he mineral ized amphiboli te b locks . A number of e lec t romagnet ic anomal i e s unre la ted t o t h e two main showings were noted but these were examined only s u p e r f i c i a l l y . In 1965 Carave l l e Mines Ltd. ou t l ined severa l move e lec t romagnet ic anomalies and considered t h a t t he se might r e l a t e to the shear zone type of m i n e r a l i z a t i o n on the p rope r ty . This i n v e s t i g a t i o n i s cont inuing .

A small zinc showing (No.4) was loca ted by B. F a i r s e r v i c e in the mafic metavolcanic hornblende gne i s ses north of Dotted Lake and t h i s proper ty was under examination by I r i s h Copper Mines Ltd. in 1965. The showing c o n s i s t s of 3 or 4 seams of massive s p h a l e r i t e up t o 1 inch in width in a shor t rus ty shear zone up t o 4 fee t wide and about 50 fee t long. No other mine ra l i za t i on was noted in t h e l o c a l i t y except for minor p y r i t e in some quar tz fe ldspar porphyry dikes which in t rude the hornblende gne i s se s .

Traces of m i n e r a l i z a t i o n were noted in t h r e e o ther l o c a l i t i e s . On Highway No. 614 and on the r a i l r o a d t r a c k opposi te the north end of East Barbara Lake a narrow band of massive and laminated metagabbro i s i n t e r -layered with t he pa ragne i s s . Disseminated p y r i t e i s no t i ceab le in the coarse-gra ined metagabbro on the r a i l r o a d t rack and on Highway No. 614. The laminated metagabbro outcrop on the eas t s ide of the road i s cut by a t h i n 1-inch t o 4-inch seam of black ear thy weathered mater ia l conta in ing p y r i t e . A second small showing was located on the Ontario Paper Company road opposi te the north end of Morely Lake. The road cu t s through a small outcrop of amphibol i te metagabbro in a genera l ly d r i f t - cove red area . The amphiboli te con ta ins a l i t t l e disseminated p y r i t e and i s cut by s ca t t e r ed t h i n ru s ty f r a c t u r e s con ta in ing occasional small b lebs of p y r i t e . On the west s ide of t he road a loose block b las ted from t h e outcrop shows loca l shear ing along a ru s ty f r a c t u r e and assoc ia ted with t h i s a small 4 to 6-inch diameter pod of massive p y r r h o t i t e , cha lcopyr i t c and p y r i t e . The t h i r d l o c a l i t y i s a small outcrop of ga rne t i f e rous amphiboli te on the Ontario Paper Company road eas t of the south end of Agoazoa Lake. Widely s c a t t e r e d , t h i n , rus ty p y r i t e - c o a t e d f r a c t u r e s cut t he rock and loca l ly a t h i n veneer of molybdenite coa t s the f r a c t u r e s .

LEGEND FOR P. 3.32 - P. 335

PHANEROZOIC CENOZOIC

PLEISTOCENE AND RECENT Varved c l a y , s i l t y s a n d , sand and g r a v e l

U n c o n f o r m i t y PR ECAMBRIAN




ARCHEAN


7a - B i o t i t e g r a n i t e 7b - B i o t i t e g r a n i t e ( d i k e s ) 7c - F e l d s p a r p o r p h y r y ( d i k e s ) 7d - L e u c o c r a t i c b i o t i t e g r a n i t e ( d i k e s ) 7e - A p l i t e and p e g m a t i t e ( d i k e s ) 7f - M u s c o v i t e g r a n i t e ( d i k e s ) 7g - Lamprophyre 7h - H e m a t i t i z e d , a l b i t i z e d g r a n i t e 7k - X e n o l i t h i c g r a n i t e

6a - H o r n b l e n d e - b i o t i t e q u a r t z m o n z o n i t e 6b - P o r p h y r i t i c b i o t i t e - q u a r t z m o n z o n i t e 6c - A u g i t e q u a r t z m o n z o n i t e 6d - B i o t i t i c a u g i t e q u a r t z m o n z o n i t e 6e - H y b r i d d i o r i t e 6f - H o r n b l e n d e - f e l d s p a r p o r p h y r y ( d i k e s ) 6g - A u g i t e s y e n i t e ( d i k e s )



5a - H o r n b l e n d e - b i o t i t e g r a n i t e g n e i s s 5b - B i o t i t e g r a n i t e g n e i s s 5c - F e l d s p a r augen g n e i s s 5d - M i g m a t i t e 5e - X e n o l i t h i c g r a n i t e g n e i s s 5f - H y b r i d g r a n i t e g n e i s s



4a - A m p h i b o l i t i c m e t a g a b b r o 4b - S e r p e n t i n i t e 4c - Gabbro 4d - T a l c o s e r o c k ( d i k e s ) 4e - A n o r t h o s i t i c g n e i s s



3a - C o n g l o m e r a t e and f i n e l y l a m i n a t e d g reywacke

3b - P y r i t i c and ( o r ) m u s c o v i t e - q u a r t z - f e l d s p a r g n e i s s

3c - B i o t i t e - q u a r t z - f e l d s p a r p a r a g n e i s s 3d - F e l d s p a t h i z e d o r m i g m a t i t i c m e t a s e d i m e n t s

o r t u f f 3e - G a r n e t - b i o t i t e s c h i s t 3f - K y a n i t e - g a r n e t - q u a r t z - f e l d s p a r g n e i s s 3g - M e t a - a r k o s e

INTERMEDIATE TO SILICIC METAVOLCANICS, PYROCLASTIC ROCKS AND METASEDIMENTS

2a - P o r p h y r i t i c d a c i t e ( f l o w s ) 2b - D a c i t e f low b r e c c i a 2c - P i l l o w l a v a 2d - R h y o l i t e b r e c c i a 2e - M e t a r h y o l i t e 2f - I n t e r m e d i a t e t o s i l i c i c w e l d e d t u f f

or f low b r e c c i a 2g - A g g l o m e r a t e , t u f f , g r eywacke 2h - I r o n f o r m a t i o n 2 j - B i o t i t e g n e i s s 2k - M i g m a t i t e


l a - Medium-to f i n e - g r a i n e d , m a s s i v e and g n e i s s i c a m p h i b o l i t e

l b - Medium-to c o a r s e - g r a i n e d , m a s s i v e and g n e i s s i c a m p h i b o l i t e

1c - Lamina ted h o r n b l e n d e g n e i s s 1d - P i l l o w l a v a 1e - H e m a t i t i z e d , e p i d o t i z e d m e t a v o l c a n i c r o c k 1f - M i g m a t i t e

SYMBOLS FOR P. 332 - P . 335

Muskeg o r swamp.


R a i l w a y .

E l e c t r i c power t r a n s m i s s i o n 1 i n e .

Highway.




Smal l r o c k o u t c r o p .




G e o l o g i c a l b o u n d a r y , a s sumed .

G e o l o g i c a l b o u n d a r y a s i n d i c a t e d by g e o p h y s i c a l d a t a .



D i r e c t i o n i n which l a v a f l o w s f a c e a s i n d i c a t e d by s h a p e of p i l l o w s .




S t r i k e and d i p of s c h i s t o s i t y .






L i n e a t i o n ( p l u n g e known, p l u n g e u n k n o w n ) .




L i n e a m e n t .


B u i l d i n g .

G r a v e l p i t .





D i k e s .

F i r e t o w e r .


Cu Copper cp C h a l c o p y r i t e mo M o l y b d e n i t e Ni N i c k e l

Pb Lead py P y r i t e po P y r r h o t i t e Zn Zinc

LIST OF PROPERTIES

1 . M i n i n g C o r p o r a t i o n of Canada L t d . ( 1 9 6 2 ) . 2. K u s i n s p r o p e r t y (Cominco 1965). 3 . Von K l e i n p r o p e r t y ( M c l n t y r e P o r c u p i n e Mines L t d . 1962;

C a r a b e l l e Mines L t d . 1 9 6 5 ) . 4 . F a i r s e r v i c e p r o p e r t y ( I r i s h Copper Mines L t d . 1 9 6 5 ) .


Geology by V.G. M i l n e and a s s i s t a n t s 1964 , 1965. Assessmen t f i l e No. 6 3 - 1 2 1 0 , O n t a r i o Dep t . M i n e s . O n t a r i o D e p t . M i n e s , V o l . XXXI, 1 9 3 2 , p t . 6 O n t a r i o D e p t . M i n e s , V o l . LXVI, 1957 , p t . 8 . G e o l o g i c a l R e p o r t on t h e Hemlo a r e a , Dep t . of I n d u s t r i a l Deve lopmen t ,

Canad i an P a c i f i c R a i l w a y , 1 9 5 7 .

Base map from maps of F o r e s t R e s o u r c e s I n v e n t o r y , O n t a r i o Depa r tmen t of Lands and F o r e s t s , w i t h a d d i t i o n a l i n f o r m a t i o n by V.G. M i l n e .

I s s u e d 1966 .


PRELIMINARY GEOLOGICAL MAP No. P. 3 3 5

BLACK RIVER AREA SOUTHEAST PART


S c a l e 1 inch t o ½ m i l e

N . T . S . R e f e r e n c e : 4 2 C / 1 3 G . S . C . - O . D . M . A e r o m a g n e t i c Map: 2168G.

MARGINAL NOTES

In t roduc t ion The area l i e s between l a t i t u d e s 48°45 ' and 49°07' and l ong i -tudes 85°32' and 8 6 ° 0 5 ' , i n the D i s t r i c t of Thunder Bay. The e a s t e r n l i m i t of the area follows t h e west boundaries of Bryant , Atikameg and McGi l l townships and the west l i m i t i s marked by the eas t boundary of Township 75 and corresponds t o t h e eas t boundaries of p re l iminary maps Nos. P. 233 and P.235. Highway No. 614 t o Manitouwadge runs nor th - sou th through t h e c e n t r e of the area and t h e southern l i m i t of t h e map i s about 4 mi les nor th of t h e j unc t ion between t h i s highway and Trans Canada Highway No. 17. The nor thern l i m i t of t h e area corresponds t o t h e southern l i m i t of the Manitouwadge Area Map No. 1957-8.

The Black River meanders roughly south-southwest through the c e n t r e of t h e area and l i e s in a r e l a t i v e l y wide low va l l ey f loored by t h i ck depos i t s of g l a c i o l a c u s t r i n e varved c lays and s i l t y sands with coarse sands and minor g r a v e l s . The rocks under ly ing the area west of t h e Black River and nor th of Mobert Creek a re predominantly g r a n i t i c . These g r a n i t e s a re well exposed and high bare r i d g e s a re common. The t rend of t h e s e r idges i s con t ro l l ed by t h e g n e i s s o s i t y and j o i n t i n g and nor theas t - southwes t t r e n d i n g v a l l e y s have been accentuated by g l a c i a l scour ing . In t h e Black River v a l l e y , Nama Creek v a l l e y , Wabikoba Lake and south White Lake areas d r i f t cover i s t h i c k and rock exposures a re few and s c a t t e r e d while in t h e area between t h e Black River and Theresa and Dotted Lakes high ba re r i d g e s of metavolcanic rocks a re separa ted by l a r g e a reas of low swampy ground. In t h i s l a t t e r region t h e g r a n i t i c a reas in p a r t i c u l a r a re poorly exposed and swampy.

The eas t e rn ha l f of t h e area i s a c c e s s i b l e via Highway 17 and White Lake, Highway No. 614, Dead Otter Lake road, Ontar io Paper Co. t ruck road and the Black River . The western half and n o r t h e a s t e r n corner a re a c c e s s i b l e via a number of l akes s u i t a b l e for f l o a t plane l and ings . The neares t a i r b a s e i s a t White River which i s approximately 40 mi les e a s t -sou theas t of the a r ea .

Mineral Explora t ion : Since t h e d iscovery of t h e orebodies in the Manitouwadge area in 1953 the whole d i s t r i c t gene ra l l y has been regarded with i n t e r e s t . Claims have been staked and res taked a t va r ious t imes , mostly along a b e l t extending no r thea s t from Valley Lake t o Dead Otter Lake. Extensive new s t ak ing was done in t h e sp r ing of 1965 in t h e area nor th , sou th , and west of Dotted and Dead Ot te r Lakes. In 1965 most of t h e ground between Dotted Lake, Theresa Lake and t h e Black River was covered by s t a k i n g . In 1962 McIntyre Porcupine Mines Ltd. surveyed and d r i l l e d a 52 claim area enclos ing t h e Von Klein (No.3) copper -n icke l showing j u s t eas t of Summers Lake on Highway No. 614. In 1963, some d r i l l i n g was done by Mining Corpor a t i o n of Canada Ltd. in the area between Amwri Lake and t h e Black River about ½ t o 1 mile ea s t of t h e r i v e r and i n l a t e 1963 T. and W. Kusins uncovered a l e a d - z i n c showing (No.2) between the Black River and Valley Lake, about ¾ mile west of t h e r i v e r . The Kusins showing was examined in I965 by Cominco. In January 1966 Caravel le Mines Ltd. held a l a r g e block of more than 100 claims enclos ing t h e Von Klein copper-n ickel showing and extending from Theresa Lake in t h e ea s t t o Highway No. 614 on t h e west, south of Dead Ot ter Lake. Also, I r i s h Copper Mines Ltd. held two blocks of c laims nor th of Dotted Lake enclos ing a z inc showing (No.4) s taked by B. F a i r s e r v i c e . Both companies flew geophysical surveys during t h e summer of 1965 and fol low-up work i s con t inu ing .

General Geology: The nor thern half and western p a r t s of t h e area a re underl a i n e s s e n t i a l l y by g r a n i t e gne i sses and younger massive g r a n i t i c rocks i n t r u d i n g these g n e i s s e s . The younger massive g r a n i t i c rocks (6) have a r e l a t i v e l y high magnetic response and t h e general o u t l i n e of i n t r u s i o n s of t h i s m a t e r i a l can be determined from aeromagnetic maps (Maps 2157G, 21586. and 2168G). In t h e sou theas t qua r t e r of t h e area eas t of the Black River , t he rocks cons i s t of a folded s e r i e s of b i o t i t e - q u a r t z - f e l d s p a r p a r a g n e i s s e s , conglomerates , hornblendic metatuffs and metavolcanic hornblende gne isses in t ruded by s e r p e n t i n i t e , amphibo l i t i c metagabbro, and massive g r a n i t i c rocks . The metasedimentary and metavolcanic rocks extend as a narrow 1 ½ mile wide b e l t from south of Valley Lake, nor theastwards t o Highway No. 614 where the b e l t swings eas t and widens to about 6 miles due to fo lding of t h e metavolcanic rocks on the nor th s i d e of the b e l t . These rocks s t r ike-eastwards between Highway No. 614 and Theresa Lake and chen swing southeas t through White Lake t o Highway No. 17. The flow rocks a re predominantly mafic hornblendic gne i sses of formerly pil lowed b a s a l t i c or a n d e s i t i c c h a r a c t e r . Po rphy r i t i c d a c i t e p i l low lavas occur west of t h e r a i l r o a d t rack around Pinegrove Lake and d a c i t i c flow b recc i a , r h y o l i t c b r e c c i a , metarhyo— l i t e , t u f f and agglomerate are exposed south of t h e amphibol i t i c metavolcanic rocks , eas t and southwest of Summers Lake. Tron formation, which gives r i s e to a s trong magnetic anomaly i s exposed on t h e northwest s i d e of t h e mafic metavolcanic r idge between Amwri Lake and t h e Black River and on t h e sou theas t s ide of t h i s metavolcanic r i d g e , a band of p y r i t i c muscovit ic m e t a -arkose extends from west of t h e Black River eas t t o Phil Lake. The pyro-c l a s t i c f a c i e s t e rmina te j u s t e a s t of Theresa Lake and the mafic metavolcanic rocks then l i e in contac t with conglomerat ic metasediments t o t h e south . The metasedimentary and metavolcanic rocks are in t ruded by g r a n i t e s , meta-gabbroic amphiboli te s h e e t s , s e r p e n t i n i t e l enses and fe ldspar porphyry, amph ibo l i t i c , and dacite" d ike s . Large l e n t i c u l a r bodies of s e r p e n t i n i t e are exposed a t t h r e e l o c a t i o n s ; on t h e no r theas t shore of Dotted Lake, a t t he north end of Theresa Lake, and in Spruce Bay on t h e west s i d e of White Lake. All these bodies give r i s e t o marked magnetic anomalies (Map 2168G). The youngest rocks in t h e area appear to be the d iabases which form d ikes i n t rud ing a l l t he p rev ious ly mentioned formations.

\ S t r u c t u r e : The metasedimentary-metavolcanic b e l t of rocks r e p r e s e n t s the southern limb of a roughly e a s t - n o r t h e a s t t r end ing an t i c l i no r ium. The south s i d e of the b e l t c o n s i s t s of metasediments and in t h i s s ec t ion t h e a n t i c l i n a l limb i s s l i g h t l y overturned to the sou th . The metavolcanic s ec t ion on t h e north s i d e of the b e l t i s thickened by r e p e t i t i o n caused by folding about an e a s t - n o r t h e a s t t r e n d i n g a n t i c l i n e centred on Dead Ot ter Lake and a paral l e l sync l ine ly ing on t h e north s i d e of Dotted Lake. These fo lds plunge westwards, t he plunge being about 20° near Roger Lake and s teepening westwards t o almost v e r t i c a l a t Highway No. 614. At t h e nor th con tac t of the metasedimentary-metavolcanic b e l t t h e f o l i a t i o n of the g r a n i t e gne i s se s dips s t e e p l y south beneath the metavolcanic rocks but p rogress ing nor th wards the d ips g radua l ly shallow u n t i l , about 2 mi les nor th of t h e contac t t h e d ips are very shallow and in many p laces h o r i z o n t a l . The f l a t d ip of the f o l i a t i o n p e r s i s t s northwards t o wi th in 3 miles of Manitouwadge where the f o l i a t i o n s t a r t s to dip predominantly north between 30° and 70°, beneath t h e metavolcanic rocks of t h e Manitouwadge s y n c l i n e .

Economic Geology: The b i o t i t e - q u a r t z - f e l d s p a r pa ragne i s ses of t h e Black River area are s i m i l a r in appearance and composition t o t the metasedimentary gne i s ses of t h e Manitouwadge a rea . Unlike t h e Manitouwadge a rea , however, iron formation i s r e l a t i v e l y r a r e and was found in only two l o c a l i t i e s ; one between Amwri lake and the Black River , c lose to t h e g r a n i t e contac t and the o ther in t h e reg ion of the Von Klein copper-n ickel showing (No.3). Both t h e s e occurrences conta in p y r i t e and p y r r h o t i t e . The most economically i n t e r e s t i n g f e a t u r e in t h e area i s a band of predominantly p y r o c l a s t i c m a t e r i a l , a s soc ia t ed with some s i l i c e o u s metasedimentary and in t e rmed ia t e t o acid flow rocks , which extends from midway between Valley Lake and t h e Black River , eas t -nor theas twards for about 6 miles to Highway No. 614, j u s t south of Summers Lake, then eastwards to north of Musher Lake and southeas t t o Theresa Lake. The rocks in t h i s band are c h a r a c t e r i s t i c a l l y ga rne t i f e rous hornblende metatuffs and agglomerates , s i l i c e o u s b i o t i t e gne i s s e s , and muscovite gne i sses f requent ly high in p y r i t e . The l e ad -z inc showing of T. and W. Kusins (No. 2) i s in metavolcanic hornblende gne i s s at t he southwest end of t h i s band. S i l i c i f i e d , p y r i t i c , n o r t h e a s t - t r e n d i n g zones occur in the hornblende gne i s s and in one of t h e s e , small pods of s p h a l e r i t e and galena occur with the p y r i t e . T. and W. Kusins r epo r t tha t a grab sample gave on a n a l y s i s 1.93 per cent z i n c , 0.94 per cent l ead and 0.64 oz. s i l v e r per t on . A major f a u l t t r e n d i n g N65°W i s bel ieved to occur about 1,000 fee t southwest of the showing.

The Von Klein copper-n ickel occurrences (No.3) are loca ted about halfway along t h e p y r o c l a s t i c band about 1½ miles northwest of Musher Lake. The rocks in the v i c i n i t y of the showings a re acid to i n t e r mediate flow rocks , b r e c c i a s and p y r o c l a s t i c rocks in t ruded by d a c i t i c f e ldspar porphyry, b i o t i t e g r a n i t e , muscovite g r a n i t e and t a l c o s e u l t r a -bas ic d i k e s . There are s e v e r a l su lphide showings and, in what appear t o be t h e two r i c h e s t zones, c h a l c o p y r i t e - p y r r h o t i t e - p y r i t e m i n e r a l i z a t i o n seems t o be confined to two s e p a r a t e , l a rge blocks of coarse-gra ined amphibol i te ; one apparent ly i s ra f ted in a r h y o l i t e b recc ia (2d) plug and the o ther i s in r h y o l i t e or acid welded t u f f (2 fg ) . Mine ra l i za t ion in the surrounding m u s c o v i t e - b i o t i t e gne i sses i s minor. Some o ther showings with copper-nickel va lues occur in shear zones in the mafic p i l low lavas ( l a ) and g a r n e t i f e r o u s agglomerates (2g) on t h e nor th s ide of t h e p y r o c l a s t i c band. A geologica l map of a 52-claim block was prepared by McIntyre Porcupine Mines Ltd. in 1962 and some d r i l l i n g was done a t t h a t t ime. The d r i l l i n g was concentra ted mainly on the two main sur face showings and t h i s ind ica ted l i t t l e c o n t i n u i t y to t h e mineral ized amphibol i te b locks . A number of e lec t romagnet ic anomal i e s unre la ted t o t h e two main showings were noted but t hese were examined only s u p e r f i c i a l l y . In 1965 Carave l l e Mines Ltd. ou t l ined severa l more e lec t romagnet ic anomalies and considered t h a t t hese might r e l a t e to the shear zone type of m i n e r a l i z a t i o n on t h e p rope r ty . This i n v e s t i g a t i o n i s con t inu ing .

A small zinc showing (No.4) was located by B. F a i r s e r v i c e in the mafic metavolcanic hornblende gne i sses north of Dotted Lake and t h i s p roper ty was under examination by I r i s h Copper Mines Ltd. in I965. The showing c o n s i s t s of 3 or 4 seams of massive s p h a l e r i t e up t o 1 inch in width in a shor t rus ty shear zone up t o 4 feet wide and about 50 fee t long . No other mine ra l i za t i on was noted in t h e l o c a l i t y except for minor p y r i t e in some quar tz f e ldspa r porphyry d ikes which i n t rude t h e hornblende g n e i s s e s .

Traces of m i n e r a l i z a t i o n were noted in t h r e e o ther l o c a l i t i e s . On Highway No. 614 and on t h e r a i l r o a d t r a c k opposi te the north end of East Barbara Lake a narrow band of massive and laminated metagabbro i s i n t e r -layered with the pa r agne i s s . Disseminated p y r i t e i s no t i ceab le in the coarse-gra ined metagabbro on t h e r a i l r o a d t rack and on Highway No. 614-The laminated metagabbro outcrop on t h e eas t s i d e of the road i s cut by a t h i n 1-inch t o 4-inch seam of black ear thy weathered ma te r i a l conta in ing p y r i t e . A second small showing was located on the Ontario Paper Company road oppos i te t h e north end of Morely Lake. The road cu t s through a small outcrop of amphibol i te metagabbro in a gene ra l ly d r i f t - cove red area . The amphibol i te con t a in s a l i t t l e disseminated p y r i t e and i s cut by s c a t t e r e d , t h i n , rus ty f r a c t u r e s con ta in ing occasional small b lebs of p y r i t e . On t h e west s ide of t h e road a loose block b las ted from t h e outcrop shows loca l shear ing along a rus ty f r a c t u r e and assoc ia ted with t h i s a small 4 t o 6-inch diameter pod of massive p y r r h o t i t e , cha l copy r i t e and p y r i t e . The t h i r d l o c a l i t y i s a small outcrop of g a r n e t i f e r o u s amphibol i te on the Ontario Paper Company road eas t of t h e south end of Agonzon Lake. Widely s c a t t e r e d , t h i n , rus ty p y r i t c - c o a t e d f r a c t u r e s cut the rock and l o c a l l y a t h i n veneer of molybdenite coa t s the f r a c t u r e s .

LEGEND FOR P. 33 2 - P. 335

FHAN EROZOIC CENOZOIC

PLEISTOCENE AND RECENT Varved c l a y , s i l t y s a n d , s a n d and g r a v e l

Unconfo rmi ty PRECAMBRIAN

PR0TEROZOIC KEWEENAWAN



ARCHEAN


7a - B i o t i t e g r a n i t e 7b - B i o t i t e g r a n i t e ( d i k e s ) 7c - F e l d s p a r p o r p h y r y ( d i k e s ) 7d - L e u c o c r a t i c b i o t i t e g r a n i t e ( d i k e s ) 7e - A p l i t e and p e g m a t i t e ( d i k e s ) 7f - M u s c o v i t e g r a n i t e ( d i k e s ) 7g - Lamprophyre 7h - H e m a t i t i z e d , a l b i t i z e d g r a n i t e 7k - X e n o l i t h i c g r a n i t e

6a - H o r n b l e n d e - b i o t i t e q u a r t z m o n z o n i t e 6b - P o r p h y r i t i c b i q t i t e - q u a r t z m o n z o n i t e 6c - A u g i t e q u a r t z m o n z o n i t e 6d - B i o t i t i c a u g i t e q u a r t z m o n z o n i t e 6e - Hybr id d i o r i t e 6f - H o r n b l e n d e - f e l d s p a r p o r p h y r y ( d i k e s ) 6g - A u g i t e s y e n i t e ( d i k e s )



5 a - H o r n b l e n d e - b i o t i t e g r a n i t e g n e i s s 5b - D i o t i t e g r a n i t e g n e i s s 5 c - F e l d s p a r augen g n e i s s 5d - M i g m a t i t e 5 e - X e n o l i t h i c g r a n i t e g n e i s s 5f - H y b r i d g r a n i t e g n e i s s 5g - H e m a t i t i z e d , a l b i t i z e d g r a n i t e g n e i s s


MAFIC AND ULTRAMAFIC INTRUSIVE ROCKS

4a - A m p h i b o l i t i c m e t a g a b b r o 4b - S e r p e n t i n i t e 4c - Gabbro 4d - T a l c o s e r o c k ( d i k e s ) 4e - A n o r t h o s i t i c g n e i s s

Intrusive Contact


3a - C o n g l o m e r a t e and f i n e l y l a m i n a t e d g reywacke

3b - P y r i t i c and ( o r ) m u s c o v i t e - q u a r t z - f e l d s p a r g n e i s s

3c - B i o t i t e - q u a r t z - f e l d s p a r p a r a g n e i s s 3d - F e l d s p a t h i z e d o r m i g m a t i t i c m e t a s e d i m e n t s

o r t u f f 3e - G a r n e t - b i o t i t e s c h i s t 3f - K y a n i t e - g a r n e t - q u a r t z - f e l d s p a r g n e i s s 3g - M e t a - a r k o s e

INTERMEDIATE TO SILICIC METAVOLCANICS, PYROCLASTIC ROCKS AND METASEDIMENTS

2a - P o r p h y r i t i c d a c i t e ( f l o w s ) 2b - D a c i t e f l ow b r e c c i a 2c - P i l l o w l a v a 2d - R h y o l i t e b r e c c i a 2e - M e t a r h y o l i t e 2f - I n t e r m e d i a t e t o s i l i c i c w e l d e d t u f f

o r f low b r e c c i a 2g - A g g l o m e r a t e , t u f f , g r e y w a c k e 2h - I r o n f o r m a t i o n 2 j - B i o t i t e g n e i s s 2k - M i g m a t i t e


l a - Medium-to f i n e - g r a i n e d , m a s s i v e and g n e i s s i c a m p h i b o l i t e

l b - Medium-to c o a r s e - g r a i n e d , m a s s i v e and g n e i s s i c a m p h i b o l i t e

1c - Lamina ted h o r n b l e n d e g n e i s s 1d - P i l l o w l a v a 1e - H e m a t i t i z e d , e p i d o t i z e d m e t a v o l c a n i c r o c k 1f - M i g m a t i t e

SYMBOLS FOR P. 332 - P . 335

Muskeg o r swamp.


R a i l w a y .

E l e c t r i c power t r a n s m i s s i o n 1 i n e .

Highway.




Sma l l r o c k o u t c r o p .


G e o l o g i c a l b o u n d a r y , d e f i n e d .


G e o l o g i c a l b o u n d a r y , a ssumed .

G e o l o g i c a l bounda ry a s i n d i c a t e d by g e o p h y s i c a l d a t a .



D i r e c t i o n i n which l a v a f l o w s f a c e a s i n d i c a t e d by s h a p e of p i l l o w s .




S t r i k e and d i p of s c h i s t o s i t y .






L i n e a t i o n ( p l u n g e known, p l u n g e u n k n o w n ) .




L i n e a m e n t .


B u i l d i n g .

G r a v e l p i t .





D i k e s .

F i r e t o w e r .


Cu . Copper cp C h a l c o p y r i t e mo M o l y b d e n i t e Ni N i c k e l

Pb Lead py P y r i t e po P y r r h o t i t e Zn . Z inc

LIST OK PROPERTIES

1 . M i n i n g C o r p o r a t i o n of Canada L t d . ( 1 9 6 2 ) . 2. K u s i n s p r o p e r t y (Cominco 1965). 3 . Von K l e i n p r o p e r t y ( M c l n t y r e P o r c u p i n e Mines L t d . 1962;

C a r a b e l l e Mines L t d . 1 9 6 5 ) . 4 . F a i r s e r v i c e p r o p e r t y ( I r i s h Copper Mines L t d . 1 9 6 5 ) .


Geology by V.G. M i l n e and a s s i s t a n t s 1964 , 1965. A s s e s s m e n t f i l e No. 6 3 - 1 2 1 0 , O n t a r i o D e p t . M i n e s . O n t a r i o Dept . M i n e s , V o l . XXXI, 1 9 3 2 , p t . 6 O n t a r i o D e p t . M i n e s , V o l . LXVI, 1 9 5 7 , p t . 8 . G e o l o g i c a l R e p o r t on t h e Hemlo a r e a , Dep t . of I n d u s t r i a l D e v e l o p m e n t ,

C a n a d i a n P a c i f i c R a i l w a y , 1957-

Base map from maps of F o r e s t R e s o u r c e s I n v e n t o r y , O n t a r i o Depa r tmen t of Lands and F o r e s t s , w i t h a d d i t i o n a l i n f o r m a t i o n by V.G. M i l n e .

I s s u e d 1966 .

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