Geology of Craig Quadrangle Alaska

Geology of the Craig Quadrangle Alaska By W. H. (30NDON

M I N E R A L R E S O U R C E S O F A L A S K A

G E O L O G I C A L S U R V E Y B U L L E T I N 1 1 0 8 - B

U N W E D STATES GOVERNMENT PRINTING OFFICE. WASHIN.GTON : 1961

UNITED STATES DEPARTMENT OF THE IIWERIOR

STEWART C. VDlkLLI Setretaw

GEOLOGICAL SURVEY

Thomaa B. Nolan. mtector

For M e by tho w a r n d e n t 0.8. Cmammmnt Mat!- Omw Wnshl*tMf 25, D.C.

CONTENTS

Location, , . , , , , - . - , - - - - - - - - - - - - - - - - - - - - - - - - - , , - . - , . , , , . , . ,+-- History of geologIe investigations-- - -- - -- - -, - -,- - ,- - -- - ,- - ,,, . ,, , Acknawledgrnents- - - -- --- - - - ---- ------ - -- ---- -. - , , , , , - . , , . . ,, . Gwgraph y and geomorphology- -- - - - - - - - - - - - - - - - - - - - - - - - - , - - + - - +

Descriptive p logy-- - - - - - - - - - - - - - - - - - - - - - - - . . - . . - - - - . -+ . , , , , - , - - - - - . Metamorphosed rocks of undetermined age- ------,-----------,--,

Wales group. , - . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -++- , - -+- - - - Bohist and limestone . - - - - - - - - - - - - - - - - - - - - - - - - - - - - + - - - - -

Greenstone, . . - - - - -, * - - - - -- - - - - -- - - -- - - - - - - - - + - - - * - , - - Wrangell-Revillagigedo belt of mekamorphie rock-- - - - + , -, ,, , ,

PhyUite, quartzite, and slah ------------,----------*-*--

Crystalline schist and phpllite ,---------------------*----

Pdeoroie ~ocks- -+ . . , - ,,A- ,-,--* + *+ - --------- ------- ---- -- --- - Ordovician and Silurian systems, undifferentiated --,--- - --- ---,

Graywaekmlete sequences -,,,--- --- ------- -- - ------ -- - * Volcanic rocks and condomerate-- . . . . . . . . . . . . . . . . . . . . . .

Middle and Upper GiLurian series, Silurian system- - - --- - -- - -- - Limestone and intraformrrtional conglomerate- -- - --- --- --- Upper gaywaeke-sandstone sequence- -- --- - -- --- - -- --- - -

Dwonisrnsptem -,-.---....+.----------------------------- Conglomerate-grapwanke sequence--- -- - --- -- - --- --- ----- Lower slate and volcanio racks ,,-,-.-------------------- Andedtic volcanic rocks ..-,..+.-,----------------------

Graywacke-tuff equence -...,,----------,--_----------- Upper shte and volcanic racka .,-.- .-----,--------- - ----- L i m ~ t o n e ---.--.,-.----......-,.,,.--.--,------------- Upper Devonian rocks-------.,+.,,-,_,_-,----------------

Mississippian system--- - --- - -- - - - - - - - , - - -- - --- - -- - - - ---- - -- Penoaylvanian (?) system - - - . . - . - - - , - . - - - - - - - - - - - - - - - - - - - - - - Permian systemu-----_--------*-*----+---~,-+-,-+---------

Meeazoic rock^. -- - - - - -- - -, - - ---- - - - - - -. -. , , . , - --- - - - --- - - --- Triassic system ---------,-------,----------*----*-+-,------

Jutmsic or C r e b n s systems --------.---. .,----.---------. Cenozoic rocks-- ------- - - - - ------,- -- - --- - - -. . . . , -. , -. - ,- - - - --

T e ~ i a r y ~ m m - - - - - - - - - - - - - - - - - * - * - * - * - - - - - , - - - - - - - - - - - - - Sandstone and conglomerate-- - - - - - - - - - - * - - - -- Volcanic tacks------------------------..,.------------

Quaternary system - - - - - - - - - - - - - - - - - - + - - - - - + - - -- - - - - ----- - -

Pam B-1

1 1 a 4 5 6 7 7 9 9 9 9

10 10 1 I 11 12 13 13 14 15 16 17 17 17 18 18 IS 20 20 21 21 21 21 22 22 22 23 23 24 24 25

N CONTENTS

Descriptive geologp--Contintred Intlvsiveilpleous rocks-----------------------------------------

Pre-hlesozoia intrusive rocka--- . . ,,, -, -,, . --- - -- --- -- ------ - Mmzoic intrusive mka ------- -,..,,+--+-------------------

Units Age and contact relationship- ,,- -- ,,- ,,-. - -- -- ----- - --- Rrlation to structure and mineral depoeih ,-.,,---,,-,----

PmbMesoeoEc intrusive rock~--- - - - - - -, . -- - -,-. ,, , --. , - - -- -- Stmeture, , , , - - - . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - . - - - - , . . - - - , , , , - - - -

Folding -----+-,------,,-----------------.+,,,-----...----,,_-

Princeof Walea @anticl ine----------------- .- . , , . -- . , ---- ,- &ymourposyneline----------------- , -----+---------- , ----+

FaultsysCma,.,,. . , . . ,-,-., ,---------------------,-,----,+----- -

Regional fault pattern - - - - - - - - - - - - - - - - - - - - - - - - - - ,+-- - -+- , , - -

Interpreted fsult pattern. .-.,--------------------,-,,--.,,, Mineral deposfts--------------------------------------------- , - . . - ,

MetdSic depita------.-,.,,.,--,,+,---------------.---+----,- Distribution of mines and prospecb ,,-----------------------. Occurrence of the metah- --,-------,,-------------------,--

Nonmetallic deposits--- -- - -- - . -. - -. ------A_. - ---- ----- --- - -- - ,- Selected bibliography - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - . - Inde~,,--,-----------~-------------------------------------------

PaKc PLATE 1. Geolom of Craig quadrangle, southeastern Atsska- - , - - -- - In p k e t Froms 1. Index map of Akaska, showing location of the Craig quadrangle, B-2

2. Sketch map of major structural features and most prominent auxiliary foIds aa pmviausly mapped or described in t he Craig q~adrangle..-,,,.,---------+---~------~, 30

MINERAL RESOURCES OF ALASKA

GEOLOGY OF THE CRAIG QUADRANGLE, ALASKA

The Grain quadrangle, in southeastern Alaska, lies enff rely within the T o n @ s ~ Nntlonat Fownt and includps a large part of Prince nf Wales Island, the la-t ialand of the Alexander Archlpelago, R~dlmentary, volcanic, and metamorphic lwcka of P~leozolc And Mpsomlc egr are expnswl as complexly folded and faulted sequences. Pnleuroir mcka occupy a broad geanticlinal area cnmprising Prince of Wnles Island and the I~lands to the NB~. Metamorphosed Yesoxoic rocks form a peosyncllnal area along and enst of Clarence Strait. Granitic and diw rftlc s k k e rind rnaaseg, mainly of Mesoeolc ape, intrnde the Paleozoic and Mesomlc TO&@. Remnanta of valcanlc rorka of Tertiary age exbt on Saems Island, and scattered areaR of Tertiary clAstic swks and Folctutlc m k s are ex- po~ed nmr Clarence Strait. Deposits of Quaternary age are mainly thin glacial deposits and narmw bands of 8trerlm alluvium.

The faWt pattern withln the q~ladrnople Is r ~ f k t e d hy well-defined major lineaments sttiklng northward to northwestward, and hg pnernllr less con- splcuous Ilnenr feature^ trending north~nrrt~vr.*rrl: and eastward. A compIex b i ~ t o q ~ of faaltl~g sepmee indicated beglnnlng in the Pnleomic, extending through the Mcmaoiq and Into Recmt t t rn~r r . Ln the pamt. there haa bPen production of or ex tenalve prmpecting f nr, meta1ZIc

rntnemI depoafta, incIuding the roppr end copper-iron deposfts of the Kamm Peninsula, Hettn Inlet, and Niblack anas, t h ~ gold dqmlta of Helm Bas, and the complex sulfide deposits of the Dolemi-Cbolmondelg Sound area. Otber noteworthy mineral occurrenw Inclnde the molghrl~nltc! ot Baker IsIand, the iron-~hrornium deposits of Mount Burnett, and the galen* of Coronation Island: ; tine Is not uncommon la mmplex sulfldc deposits. Some gold, stlrer, and palladium have been recovened as byproducts of baw-mrtnl mining. The ontg sign[- ftcant development of nometallic depodts bns been the p r o m t i n * for, and quarrying of, limmtone and ornamentnl marble.

The Craig qudrangle comprises nn area of about 7,000 aquare milea between Iat. 56' and 56" N., nnd lmg. 132O and 134°30' qT. It is one of the aoutheplzmost quadrangles of southeastern Alaska and lies

B-2 MINERAL RESOURCES OF ALASKA

about 16 miles rest of Ketchikan nnd 170 miles south of Juneau (fig. 1 ) . The qundmngle is entirely within the Tongnss National F o ~ e ~ t .

Systematic surveys and investigntions in muthenstem Alaska began with s very genernl recoi~naissance of the lietchikran district by A. H. Brooks in 1901. This reconnaissnnce included pnrts of the Craig qz~tidr~ngle. rl reconnaisstbnce of Kasaan Peninsula \rns made in 1904-05 by F. E. Wright and C. IT. TITrigllt. h 1907, C. W. Wright and Sidney Paige did reconnaissnnca mapping and mads short in- vestimtions on the Rasnan Peninsuln and Jumbo Bnsin nreas; the fieldwork was completed in 1908 by Wriglt. KO investigations took place other than brief mine visits until 1912 when E. F. Burchard studied the marble and gypsum msources in the Retchikan and Wran- plE districts. In 1913, P. S. Smith began stmtigrapl~ic studies in the Ketchikan

district. The work was continued and expnnded by T h d o m Chnpin through 1915 ta 1917 resulting in the mapping of the district south

: 2m 403 MILES

henam l.-In@ex map of Alaska mhowlng lomtlon d the Craig gnndrnngle.

GEOLOGY OF THE CRAIG QUADRANGLE, ALA8KA %3

of lnt. 55'40' N., nnd a report on the minernl deposits of the aren. Some pnIeonto10g-i~ investigations by Ed\\-in Kirk and others, denling mainly with Silurian Strata, mere coilducted in ln17. J. B. hlertie, Jr., investigated some iron ores of the lietcllikn~h district in 1917 nnd 1919. The work of Chapin was continned by -4. H, Duddington in 1921-25, their joint efforts resulting in pnblictht ion of U.S. GeoEogical Survey Bulletin 800 (1929). This geologic reconnnism~~ce mapping consisted largely of shoreline observntio~~s. Some large nrens re- mained unmapped, notably the interiors of central Prince of 'IITales Island and Cleveland Peninsuln, Coronation Ishnd, and m~l l pnrts of other islands.

After the work of Buddington and before 1941 rev little or no geologic investigation wns done by the Geologicnl Survey within the Crnig quadrangle. In 194148, inVestig~tions of rnanj7 mines and small areas were made to evaluate or search for deposits of various strategic metals including iron, copper, zinc, the platinum metals, nickel, and chromium. The Inrpd volume of these investigations was done in 1942-44 on Knsnan Peninsnla and vicinity by Tamer, Goddard, Walbn, Crault, T'Vnhrhaftig, and others who studied copper and iron deposits ; much of their work is unpuMfshd exmpt as open- file mahrinl. Molybdenum deposits on Bnbr Islnnd were investi- gnted in 1943 by G. D. Robinson. The nltramafic rocks of Mount Rurnett were investigated also in 1943 for nickel, chromium, and the platinum metals by G. C. Kennedy snd 3T. S. Walton, Jr. Copper rind iron deposits of Jumbo Basin on Retta Inlet were studied in 1904 by Kennedy. Zinc and Iead deposits of the Dora Lake a m wem reported upon by W. S. Twenhof~l. In some of these mining areas drilling ~ n d tfenching work 11-n~ done by the U.S. Rumu of Mines. The most recent investiptions and mapping by the Geological

Survey in Cmig qaadnlngle hare been by G. D. Rberlein nnd by C. L. Sainsbwry. In the field sensons of 194749, Eberlein completed detailed mrtpping of ITeceZa and Tuxek~n Zsl~nds, and some recan- naissance of other smaller anas (Ehrlein, oral communication, 1949). Spat field checks were mrtde by Eberlein, Sainsbury, nnd the writer as a brief monnaimnce in 1054, In 1954 nnd tR5.5, Swinsburg mnde reconnaissanw studies of pnrts of enstern Prince of Wales Island. Reconnaissance hm h e n made for rndionetire deposits by 6. R. Thus- ton and athers.

The object of the present compilation i s to nrmmnrize, consistent with the scale of plnte 1, the known geolnric dntn fmrn m R p and reports, and to supplement find modify locnlly this summntion with geologic interpretations f ~ o m ~ ~ c i n l photagrnphs, The re1 inbili ty of geologic data within this qundrangle varies; in areas previously

mapped, reliability depends upon the amount of basic data available and whether it is reconnaissance or detailed. (See compilation on 1 1.) In areas previously not mapped, reliability depends upon how well the criteria for identifying formations are expressed on aerinl photographs. The identification and extension of certain rock units are tenuous owing to the complexity of folding and faulting? tho lack of basic field data for some large areas, and to the mn~lking effects of vegetal cover, glaciation, and metamorphism. Spot field checks were made of some selected key points in 1954.

Geologic data for this compilation have been extracted from all availabls published and unpublished information and have been sup- plemented and modified by interpretation of mrtieal aerial photo- gr~phs of abut 1 : 40,000 scale (pl. 1). Several of the published references are now out of print. This text is based mainly upon U.S. Geological Survey Bulletin 800 (Buddington and Chapin, l929), a large part of which is reconnaissance confined chiefly to shoreline. Compilation of the geologic map along the shoreline is based mainly upon Bulletin 800, but inland mapping is mostly based upon inter- prehatian of aerial photographs. Detailed or samidetaiIed geoIogic mapphg and description cover small and scattered but important areas. These include the Heceta-Tuxekan Islands area (Ebarlein, written communication, 19491, part of Baker Island (Robinson, 19481, the Heth Inlet a m (Kennedy, 19517; Wright, 1915), IC.ns~an Peninsula (Wright, 1908, p. 7&9T, 116-128 ; 1915; Warner and others, 1980), and Mount Burnett (Kennedy and Walton, 1946). The work of Twenhofel and Sainsbury (1958) on the pattern of faults and lineaments in southeastern Alaska strengthens the photogeologic interpretation of a simiIar pattern in Craig quadrangle;. These reports and many others contain useful data w brief references, summations of previous information, or annual pro,oress reports on mines, quarri~, and prospects.

The selected bibliography represents those publications considered by the writer to be most useful in the compilntion of this text and map at the 1 : 250,000 scale. Many publicntions not Iisted were useful as spot checks of small areas. These include mine reports of the Territorial (Alaska) Department of Mines (now Almkrt Division of Mines and Minerds), reports of investigations by the U.S. Bureau of Mines, ma the annuaI mineral resources bulletins, open-file material, and unpublished information of the Geological Survey.

The writer is indebted to the publicntions previously mentioned for most of the information in this compilation. Further &owl-

GEOLOGY OF THE CRAIG QPhDRANGLE, ALASKA '13-5

d p e n t is extended to G. D. Eberleim and C. L. Sainsbury far gen- erous munsel in the field and in the office, especially regarding their field observations tlnd unpublished mapping, and to C. W. Merriam and J. T. Dutro, Jr., for preliminary examination of fossils. Some information on current mining activity has been supplied by the Territorial (Alaska) Department of Mines.

The largest part of the l ~ n d Rrea of Craig quadrangle is in Prince of Wales Island, the southernmost major idand of the Alexander Archipelago. This island is ~epnrated from Cleveland Peninsults and Etolin Idand by the broad oxpnnse of Clnrence Strait, and from the many large and small islands seaward by generally narrow imp- lar channels and straits.

Prince of Wales Island is characterized by rugged mountain g m p s of low to moderate relief, generally with altit~~des of 5,000 feet or less but IocalEy nearly 4,000 feet, as in the Copper Mountain area. The mountains are separated by steep-sided glncinl valleys and fiorda I)wp sounds and long arms of the Wit extend inlnnd, t~nd with tlle many small inlets and bays form an extr~rnely irregular mastline. Lakes a m abundant at the lowr?r altitudes ns well as in the many glacier-cawed m k basins. Streams nra mostly small and short. They hare the steep and imgular profile of the enrly stage of dream development. A few of the larger streams are tidal for short dis- tances from their mouths where gradients are low, and some flow through small tidal flats. The terrain of Cleveland Peninsula and the other islands af the quadrangle is similar to that of Prince of Wales Island.

The pornorphic deveIopment of the region has been strongly in- ffuencd by underlying rocks nnd the geologic pmcewes. Mmng t o p - graphically low amns or nrms of the sca occupy crest or trough lines of anticlinorial or syncli~~orinl structures. Frtrl l ls or shenr zones pmbably hnva determined pnrts of the courses of many present-day or preglacial streams. Different,inl erosion of underlying rock hns influenced the distribution of highland and lowland areas. Shoreline char~i~tarist~ics are affected largely by the composition md structure of the rocks. Intrusive rocks tend to form resistant headlands; lirne- stone tends to fomn F)locky sliorelines d e r e e x p o d to lw,l-e nction of the open sea, or regular shorelines where protected; deep water dose to shore is characteristic f n ei Zher situation. T h e widespmd volcanic rocks and tliinly interbedded m k s of different types commonly form dangerous offshore reefs nnd rngged coastlines,

680823 -1-2

Glaciation hw been the mmt signzcant factor in rnodifging the Irtnd. No premt-day glaciers exist but past glaciation by ice sheets and alpine glaciers hrnve had marked effwb. Pqglacial drainhge Lines were widened and deepened ta form V-shaped valleys and fiords ; mountain p k s and ridges were rounded and probably only a few of the highest peah stood above the lirnits of glaciation. Alpine glaciation has produced steep-walled cirques whose homhm-shaped rock basins are genemlIy occupied by k m s , and mrroundd by sharp ridges.

The climate of the mgiw is mild with a mean annual rainfall of 100 to 150 inches. The density of forest cover and undergrowth is typied of the rain forest of cold temperate regions. The dominantly conifer- ous p w t h mnsish mainly of hemlock? spmq and less abundant cedar, with spama intergrowths of deciduous traes such aa ash, cotton- wood, and alder. Undergrowth consists of berry bushes and devils- club. Muskeg is widely distributed especially in the lowlands and flatter parts of the upland amah where it occurs as patches within timbered areas or locally as bmd, swampy, nearly treeless expanses. !I%e timberline is commonly betwean altitudes of 1,200 and 2$00 feet.

!?hmportation into and within the qudrmgla ki limited to the use of b a t s and fioat planes. Most shoreline points are easily accessible to small boats and many deepwater channels and ~nchomgea exist for larger vessels. Charter and schedule service of small float and am- phibian plma is maintained from Kahilcan, the nearest distributing point t o the quadrangle. On Prince of Wales Island and Cleveland Peninsula, many lakes in the lowlands and a few in the uplands, ss well as protscted bays and inlets, are suitable for float-plane landings. Only a few ~ u c h lakes are suitable on the smaller islands, No 1 anding fields rare maintained in the quadrangle. Public roads are not developed except for one between Craig and Klawak. Private; mad9 exist as short mine or logging roads in various states of repair. Some of Ghese, ~ s p i s l l y logging roads, have been m n t l y constructed or im- proved and extended.

The larger settlements are HoIlis, Craig, Klawdr, and Hydaburg. Small groups of permanent residents live near sites of canning, lum- baring, and mining activity.

DEBCRIFTXVE GEOLOGY

Most of the sxpmed sedimentary and volcanic m k s are of Paleozoic a p . A smaller part of the bedrock comprises a belt of Mesozoic rocks as well as scattered remnants of the Cenozoic system. Igneous dikes, sills, atmks, and small batholithic masses cut the rocks of Paleomic and

GEOLOGY OF THE CRAIG QUADRANOLE, AW8Kh %7

Mesozoic aga, Much of the quadrangle area is covered by Pleistocene glacial drift of varying thickness. The lithology is widely varied bath gtratigraphicaIly and areally.

Sequences of thinly interbedded graywacke, tuff, conglomerate, lava flows, date, tuflaceoas or arkosic sandstone, limestone, and chert in varying combinations are characteristic of much of the Palmmio rock Volcenic rocks are abundant as are thick mtions of massive limestone within the Paleozoic rocks.

The composite stratipphic mlumn of the rocks exposed w i t h the Craig quadrangle indicates saveral unconformities. The column contains several unih whose stratigrnphic position is net thoroughly un- derstood, thus their relations are generalized. The lack of close and reliable correlatian of the atrata of the region as a whole, the facies, changes, the complexity resulting from several periods of folding and faulting, and the eflmts of regional and contact metamorphism, pm- vent clear interpretation.

Intrusive igneous rocks am widely distributed and are generally believed to be genetically related to the Coat Range batholith as outlying s~tellitic masses emplaced during Jurassic and Cretaceous tima. Emplacement of these bodies and the rnetmorphism asaaciated with it albred large a m of bedrock, superimposed new trends of structure, and possibly rnmked the evidence of previous igneous intrusion.

Metamorphomd rocks of undetermined age ham pwvious1y bean mapped as the Wales group in the southeastern part of the quadrangle and the WrangelI-Revillagigdo belt in the northeastern part. The original cla~tic and limy sedimentaq rocks, limestme, and wIcanic rocks have Seen transformed by regional and contact metamorphism to whist and phyllitq crystalline limestone and marble, and the schie- greenstone nnd other metavolcanic rocks now exposed. The ago of these metarnorphod rocks is commonly given as possible pm- Ordovician to Early Cretaceous and the grade of metamorphism is ~neral ly low.

The Walea p u p as mapped nnd described by Buddington and Chapin (1929, p. 45-49) for southeastern Alaska comprises four units. From oldest to youngsh they urn .e: (a) schist, (b) schist with inhr- bedded limestone m d slate, (c) a unit dominantly of limmdone, and (d) a unit dominantly of greenston& Only the last three units wem map@ in the Craig qnadmgle. Contncta ~ r s gradational, with inhrbedding of the dominmt rock types. In the Jumbo Basin s m

Ek-8 MINERAL RESOURCES OF ALAGKA

upper Hem Inlet, Kennedy (1953, p. 1, 5) distinguished two major divisions of the Wales group : folded metamorphosed IimRstom conformably overlain by calcareous schist and quartz-mica schist; and a greenstone unit with s small propartion of elastic m k s unconformably overlying the limestone and schist. Conhct metamorphism by intrusive igneous masses as well as regional metamorphism by tectonic forces hava obscured or complicated the original structure. The IVnleq group h h e n mapped in n bmnd balt in the south-

easten part of the quadrangle between Cholmondeley Sound and DoIomi nnd forms most of the rock between the sound and Hetta hlet to the west and southwst.. The belt is anticlinori~l with a north- mestwmd-trending axis. The northwestward extansion of this belt, as interpmted from aerial photopphs, has a similarity of top paphic errpmion to m b of the Wales group. Data concerning rock type are scant, but those given for the Marble Fieart claim (Brooks, 1002, p, 93) favor this northwestwad extension of the Wales group. The northern limit of the p u p is probably at or near a fault zone that trends eastward from the head of k a d e m Bay, The western limit of these rocks is isdehite on aerial photographs.

The Wales group is presumed by Buddington and Chapin (1989) to include the oldest stmts within the Craig quadrangle, and itn hrtm is nowhere exposed. The group is prohbly l~rgely of Ordovician and Silurian age, nnd probrrbly includes Devonian and possibly mme pmQrdovician mks. The few fossil fragments reported from this p u p are not d iap t i c (RuddingCon and Chapin, 1929, p. 49) and ages b a d upon comparison of rock types am tenuous at best. *She Wales group is unconformably overlsin En places by Devonian beds, in others by Silurian b d s with undetermined relations. The Walm is deformed and metamorphosed to a much greater degrea than known Silurian or younger mh.

Mineral deposits within the Wales p u p have been developed locally, and many minks in the Heth Inlet and Dolomi amas in the sontheastarn part of the quadmngle have been limited pdumrs. Gold-hearing veins are abundant in t.he schist of the Dolomi am. Copper and imn deposits are nssociated with skarn a t f i e contacts of limestone with intrusive ignwus masses near Heth Inlet. S c a t t ~ d sulfide deposits of lead, zinc, and other metals, and shear-zone deposits of copper h ~ v e b n prqmtd . Limestone is widely distributed and commercial deposits of marble have been prospected and quarried 16cally. Barite m u m in limestone on Lime Point, Hetta Inlet.

GEO-Y OF T E E CRAIG QUADRANGLE, ALASKA B-9

This unit compri~s mainly schist with some Iimestone and minor quarhitic and slaty beds. It is transitional to the overlying limestone. Kennedy (1953, p. 6) locally distinguishes calcareous schist and quartz-mica whist btween the next younger limsstoue unit and the greanstones, which are the youngest rocks of the Wales group. The schists am not everywhere present between the greenstone and the limestone units.

WIYELITONE

This unit is predominantly metamorphosed limestone with some interstratified schist and quartzite. Ths limestone is white to blue OF black, inhnsely folded and sheared, and commonIy metamorphosed to marble. The limestone in its upper part is intercalated with volcanic rocks and p a w into the p n s t o n e schist unit. Individual limestone sequences of this unit and those within the mhist range in thickness from Iws than 100 feet to mom than 1,000 feet (Wright, 1915, p. 30). Kennedy (1953) has suggested an nnmnfomit.y be- twgen the lirnestona unit and the overlying preenstone schist unit, According to R u d d i n g h and Chapin (1929) fossil fragments are not diqg-tostic, and comparison of rock types with thme of h o r n age is tsnuous but may indicate thnt some of the limestone intarcalated with the p n s t o n e schihist is of Silurian age; some lower I d 3

are possibly pm-Ordovician. Mapping of the limestone has been extended photop8010gically

northwmtward from the Hetta Inlet area on the hsis of similarity of topopphic expression to known limestone of the Wales. An ares north of Dolomi has likewise been interpreted to be mainly limestone on the hs is of vegetation pattern. Both interpretations am to some extent supported by mine and p r q w t reports.

This mit is pdominmtly schist- p n s t a n e derived from tuff, agglomerste,and bsalticand rhyciliticlnva flow. Interbedded slate and argillsceous rocks occur, and in the lower part of the unit, beds and lenw of limestone are common. The penstone unit has been extended with the limestone unit but its western extant is indeter- minable on aerial photopphs.

W Q ~ R E T C L L A Q I Q E D O BELT OF METAMOREHXC ROCKS

The Wmngell-Revillngigdo belt of metamorphic rocks roughly parallels the b t Range batholith east of this quadmngle. A small part of this belt crosses the northeastern corner of the Craig quadrangla

&lo MINERAL REBOURCEB OF A U K 4

and occupies the muth end of Etolin Island, as well ga much of Cleve- land Peninsula, Brownson Island, and Deer Island. The rockg have bgen mapped and described (nuddinghn and Chnpin, 1929, p. 49-55) in two units: phyllitic, quartzitic, and slaty m k s ; and crystalline schist and phyllite. This division was based on the degree of meh- morphism and amount of intrusion by igneous material as described by Wright and Wright (1908, pl. 2) ; no contradistinction was made by usa of aerial photogmphs. The belt has h e n intruded by many batholiths, stocks, sheets, and dikes probably genetically related to the Mesozoic intrusive m k s of the; Coast Range. The. metamorphic m k s are cut in many pIam by basalt sheets and dikes of Tertiary age, which are especially abundant near the area of Tertiary lava on Eagle Island.

The age of the rocb hm not been determind adquakly, and a diversity of opinion exist5 for the age of the belt as s whole. Budding- ton and Chapin (1929) state thnt Carboniferous and Triassic formations probably make up rt large part, but that the belt possibly mngw in age from Ordovician to Cret.mons. Wright and Wright (1908, p. 56) favomd a Carboniferous age for most of the crystalline whish and argillites.

Mineral d e p i t s are scnttered within the mehrnorphd rocks of the TVrangell-Rsvillagigedo belt. Base-metal sulfides are f w d locally in the more intensely metamorphosed rocks, and gold-quartz firssure vsins occur in phyllita and low-grade schist. Garnet and graphite mny occur in some places within this part of the beIt. Kya- nite and sillirnanite are economicaIly nnevaluated.

The rocks of this unit are dcsribed by Buddington and Chapin ( 1929) ns phyllilite, ~trgillacmus and mieaoeous phyllite, quartz phyl- lirte, foliated quartzite, and locally slate and limeat,one. Met~rnorphism is marked near the intrusive igneotts mamea at Union Bay and Enton Point on Emmt Sound, and the contorted, a h e a d , and baked rocks are cut by splite di'kes or quartz ~einlets.

The crystalline schist, phyllih, and pdat iona between are more highly metamorphosed in p e r a l than the rocks of the preceding unit. The stratigmphic relnt,ion to lthe preceding unit is not known. Large r n m of quartz diorite and p n i t i s mks intrude these rocks. Quartz schist with intarcalated kganite schist predominates north of Eaton Point. Phyllitic schist on Deer Island, in the northeast corner of the mapped area, contains some sillimanite.

GEOLOGY OF THE C W G QUADRANGLE, ALASKA B-11

Virtually all the stratified sedimentary and volcanic rocks of Princa of Wales Island and the islands to the west are of Paleozoic age. The Walm -up of metamorphic rocks probably is largely or ~ntilwl y Palmzoic, but cornlation with Paleozoic units of existing geologic maps has not been established. Interbedded elastic rocks of various lithologies with or without volcanic rocks, characterize much of the Ordovician, Silurian, and Devonian systems. Conspimow strati- graphically are the thick massive limestonw of the Silurian and De- vonian systems, and the acattemd remnants of the limestone and chert of the Mississippian, Pennsylvanian ( 7) , and Permian systema Vol- canic rocks and m i a t e d tuffaoeous sedimentary rocks represent thick sequences of the Devonian system, and are sparsely distributed within the Ordovician and Silurian systems. Unusually thick but discon- tinuous conglomerate lenses and beds exist within the Silurian limestone.

The Ordovician system and lower part of the Silurian system corn- priw mainly indurated graywacke and slate within which locally and at different horizons volcanic rocks are mappable, These rocks are widespread in the northern half of Craig quadrangle and form a belt across DalZ Island. The mapping of the rocks is extended ta the ertst

by comparing temne expression with that of known formations on aria1 photographs, These rocks have been mapped and described as time-stmtigraphic units by Buddington and Chapin (1929) who divided the gmywacke-slah sequence into Ordovician and Silurian with the reservation that each possibly contained parts of the other. The sequences are thinly bedded, closely h isoclinally foIded, m d corn- pIexly faulted. The similarity between faunally identified Ordovician and Lower Silurian rocks, both structurally and lithologically, makes their mp~ration as map units vary tenuous with the sparse faunal data available.

Mineral deposits reportsd within the graywacke-slab wquence are few and widely scattered. Small sulfide deposits containing copper, lead, gold, and silver have been reported on DalZ IsIand. A copper prospect in a shsar-zone deposit is located near Swmtwater Lake on Prince of Wales Island. Buddington and Chapin (1929) suggest that the apparent slparsity of deposits may be in keeping with a like sparsity of intrusive rocks.

B-12 NINE- RESOURCES OF ALASKA

n e s e sequenw are mapped and described by Buddington and Chapin (1929, p. 74-77, and 81-82) as indurated thin-bedded p y - wacke and dark to black slab with varying amounts of thinly interbedded black chert, conglomemhe, and h e y bda. Andesitic volcanic rocks occur at various zones but are mappable only locally. The total thickness of these sequences is undetermined but they contain mveml thousand feet of Ordovician strata alone.

Age of parts of the mquenees has been assigned at widely separated points. Ruedemann {h Buddington and Chapin, 1929, p. 74) identified fauna of several h w e r and Middle Ordovician locrtlities. Lower Ordovician graptolites are described from slate partinga in the thin- layered black chert md graywacke of Lulu and San Fernando &lands and the island barrier of Big Salt hh. On tbesa islands, Middle Ordovician pptolites are reported from gmywacke md black slate. A L w e r Silurian age is assigned by Ruedemann (in Buddingtan and Chapin, 1929, p. 82) to the dark to black grttptolitia slate and graywacke mapped previously on Sttn Fernando, Lulu, Dall, Hmta, and Noyes Islands. On Hmta Island strata previously mapped as Si- lurian contain Silurian and Middle Ordovician pptolites at di fpemnt horizons. These mks are mapped by Eberlein (written communication, 1949) as marse-pined pywacke f d e s (sandstone, conglomerate, and breccia) and fine-grained graywmke facies (siltstone, mudstone, and he-grained sandstone).

The position and conformity of the contact between Ordovician and Silurian strata within the gmywacke-slate quence has not been &stab- lishd. Smith (1939, p. 12) suggests that the absence of recognizable Upper Ordovician strata probably indicates a marked unconformity representing Lwte Ordovician and perhaps mme of Early Silurian time. On Heoettt Island, no break in the graywacke-slate wquenca kas been o h w e d between Middle Ordovician and similar Early Silurian strata, both faunally identified, but disconformity is a distinct p s i - bility ,

The base of thie Ordovician-Silurian wquence l-m not been obmmed. The upper eontsct is varied and where observed is marked by genemlly unmnfonnable or faulted relationships. Angular ununleonformities am mported with Devonian rocks on San Fernando Island and with conglomerate at Sarkar Cove on El Capitan Passage. The conglumerats is probably a basal unit within the Silurian limestone. Mississippian stmh and Devonian volcanic rmks overlie Ordovician stmta. west of Big Salt Lake either uncanformably or through faulting. The tx3- quence is overlain by Silurian limestone on Hwta Island with no appamt anguIar mmnf~rmity.

This unit as mapped and described by Buddingkn and Chapb ! 1929) comprises nndesitic lava1 flo~rs locally with pillow structure, rmnglomerate wntaining Inva nncl limestone, nnd minor amounts of p g w a c k g black slafm, limestone, and tufT. The maximum total thick- ]less is about 3 , O feet. I t is only locnllg conspictrous rind the propor- tion of conglomerate to volcanic mks varies greatly. Eberlein (written mmnaunication, 1949) mapped similnr volcnnic rocks within his Ordovician-Silurian graywacke-slats qucnca . Typical roch of this unit m u r on El Capitm and Rosciuska Islands. Similar rocks m u r elsewhere in several zones within the grnywacke-slab sequence of Ordovician and Early Silurian aga on Prince of ?Vales Island but are generally not mappable at this scala. Thie unit has pmvjously been mapped on the east side of Princa of Wales I~lland and is so mapped in this report although it may h better described as a graywacke-slate Wuence mi t h varying proportions of volcanic rock.

Age assignment of the separate areas of vdc~n ic rocks varies. Smith (1939) grouped them as Lower Silurian conformnhle with overlying mks. The andesitic volcanic rocks fire described by Bud- dingtan and Chapin (1929) as lmnlly partly contempmneous with the massive Silurian limestone. Elsewhere they are iint,err,~lated with Lower Ordovician slate (Kosciusko Pslnnd) , wit 11 Middle Orclovicinn p y w a c k e and graptolitic slate in the base of the volcanic section (El Capitttn Island). They also occur between the Silurian limestone and the Ordovician graywach-slate sequence. S trat-rt previously mapped near Thorns Bay ~s Ordovician dztttes and gm;ymnckcs have h . n included with this unit Fauna collectd near Thorne Ray by Sains- bury (1960) in the summer of 1955 indicate n Silurian age. Some strata mapped as Devonian slate, volcani~ rocks, and andesitic volcanic rock, both south and west of Kmnn Ray may be Silurian or older (Sainsbury, 01x1 mmmunimtion February 25, 195B).

Middle and Upper Silariatn &mta comprise s thick section of massive limestone containing htrnformation~l congl~memte beds nnd Senses and overl~in by a thick gmywacke-sandstone sequence, These zrtmta, have been mapped and described by Buddingbon and Chnpin (1929, p. 8%-94) and discussed by Smith (1939, p. 15-16), They were mapped in detniI by Eberlein (written communication, 1949) in Llle

IIecets, and Tuxekan Islands area. Strata of known Silurian age are mapped in a broad northwest-

ward-trending synclinorinm occupying Kosciusko, Receta, and Tuxe- m a a a 0--81--e


kan Islands and extending onto Prince of Wales Island ; smaller exposures occur on DJI Island. The general distribution of the Silurixn formntions reflects the northmestward trend of dominant folding in mutheastern Alaska. The Tuxeknn sgnclina trends more ensterly as it extends onto Prince of Wales Island. The mapping of Silurian formations l lns been extended enst,wxrd by photointerpretation nnd bnsic assumptions and interpretations are: the Silurian m- quence eastn~ard is similar to that an E-Teceta and Tuxek~n Islands; extensive faulting, pprobnbly with do~vntl~row to the west, has probably helped to restrict the upper graywacke-sanhtone squence to the Tuxekan Passnge and 'Pu'aukati Ray area.

No mention of metallic mineral deposits within the Middle and Upper Silurian series is found in the literatnre. High-calcium limestone and commerical marble deposits have been developed and prospected locally, notably on Dall and Marble Islands. Quarries and prospects of limestone and ornamental marble on Ddl, Heceta, Kosciusko, Marble, nnd Orr Islands have been describd in detail by Burchard (1920) and Roehm (1946, p. 1155).

LIYEBMWE AD rwrmromaomfi UOX[~~OHEEATE

Thew rocks have been mapped and described by Buddington and Chapin (1029) limestone and locally intercalated coarse conglomerate, and sandy or argillaceous beds. The intercalated beds and lenses include coarse congllomernte, thin-layered limmtone, nodular or shaly limestone, and some shale and andstone. The coarse clastic rocks are mmt common in the middle part of the limestone section but occur at all lemls including the bass and top. Eberlein (written communication, 1947) ~ t i m n t e s a thickness of 17,000 feet or more, including 2,700 feet of clast,ic rocks, in his work on Haeettl. and Tuxe- kan Islands, The rna~ive limestone is widely dishribukd on the west side of Prince of Wales Island, on Receta, Tuxekan, Kosciusko, and nearby islands. It occurs as two bmd #belts on Dall Island, and locally on Noyes Island. Limestone-marble, not, previously mapped south of Coco Harbor on Dall Island, is here mapped tentatively as Silurian and overliw Wales penschist. The intraformational conglomerate beds are most prominent on Hecettt, Tuxehn, and Kos- ciusko Tdands. Rrtsal conglomerate occurs at Sarkttr Cove, and conglomerate seems to underlie limestone on Orr Tsland, possibly unconformably. Mapping of limest1one areas has been extended into Prince of Wales Island by interpretation of aerial the main criterion being the prevalence o f den= timber stands on limestone terrzna. The belt across Dxll Island between Reef Point and Diver Islands mema to have the typical topographic expression of

GEOLOGY OF THE CRAIG QUADRANGLE, ALASKA %I5

limestone but previously has be6n mapped in two psrts separated by overlying Devonian volcanic rocks. The massive limestone on Coro- nation Island is arbitrarily mapped as Silurian on the assumption that it corrasponds to the limestone of Kosciusko and Heceta Islands across the, axis of the Kuiu anticlinoriurn of B u d d i n e n and Chapin ( 1929, p. 3071, which exposes supposed Ordovician strata on Warren Island.

The limestone hrtg hen grouped with Middle Silurian m k s by Smith (1939), and Silurian fossils have been reported from several localities in the limestone (Buddington and Chapin, 1929, p. 9*-94;). T ~ B lower contact of the limestone may mark a general unccmfomity, which in places is markedly angular with the Ordovician mks . The limestone and conglomerate conformably overlie volcanic rocks locally according to Smith (1930) and Buddington and Chapin (1929). The upper contact of the limestone with the overlying grqtywacke- andstone sequence may be mostly conformable. The limestone on Dall Island is locally overlain hy Devoninn volcanic socks.

This sequence is mapped and described by Buddingtan nnd Chapin (1829) as predominantly green-gray graywacke, locally red, greenish- gray and gray sandstone, or interbedded conglomerate and sandstone, or shale. The thickness is 5,000 feet or more. Along Karheen Pas- sage, Eberlein (written communication, 1949) distinguished a platy limestone and a thin-bedded to massive limestone within the sequence. The sequence is most conspic~~ous in the troughs of synclinal structures along Naukati Bay, Karheen Passage, and on Kosciusko Islmd ; it extends for an unknown distnnw. into Prince of Wales Island. The outcrops mapped in this report are probably bounded not far inland by northward-trending fa-tilts downthrown to the west. This m- q~lence is mentioned but not rnnpped by Ruddington and Chapin (1929) as occurring on the south end of Marble Island. Its ragged &omline expmion contrmts with the more regular expression where l irnbne forms the shoreline.

The age of these beds on Heccta and Kosciusko Islands is indicated by Kirk and Amsden (1952, p. 53-54) in their descriptions of an Upper Silurian Brachiopod fauna. The lower contact of the ss- quence is questionably confomab,ble to the massive Silurian limestone. The quenca has not been previously mapped in contact with younger rocks. Lirnsstone was interpreted from aerial photogmphs as overlying the sequence at one locality enst of Tuxekan Passaga and was later verified by field checking; this limestone is probably Middle Devonian. A marked stratigraphic gap in Middle Devonian roeh is implied by both Smith (1939) and Buddington mid Chapin (1929).


Units of the Devonian system xre widespread and have been mapped and described by Buddington and Chapin (1929, p. 94109) a d later discussed by Smith (1939, p. 19). Data htlve been compiled in some- what more detail by Eberlein (written communciation, 1949) along South Arm of Cholmondeley Sound, by Warner and others (1960) on Kasmn Peninsula, and by Robinson (1946, p. 31) on Baker Island. Stratigraphic relations within the Devonian rocks are not closely or reliably established because of stmcturaI complexity, lack of detailed study, scarcity of fossils, and facies changes. The general stratigraphic: ~uccession has been sumrnarimd in three asmbIages, but the composite sequence is nowhere exposed. Tba lower memblage mainly comprises mafic volcanic Bows and breccias and locally elastic dimentaw rocks. The middle assemblage is mainly interbedded pyroclastic and sedimentary rocks including some black slate and fossiliferous limestone, which contain more volcanic material khan the younger rocks. The lower part of the upper assemblage consists of conglomerate, slate, graywacke, and voleanic rocks, and the upper part of massive limatone.

Strata of Devonian age occupy most of the southern synclinorial pro~ncs of Buddington and C h ~ p i n (1929), which includes much of Psirim of Wales Island, a large part of Dall, Baker, Noyes, Suemez, and Sukkwan Islands, and the islands of San Alberta Ray. The strueturn of the Devonian rocks is complex-isoclinal folding is corn- mon, aa in the Devonian (?) of Kasaan Peninsula ; general overturn- ing of stmta is characteristic over wide areas, for example, south of Dolomi. Locally the Devonian rocks may be partly cosxtsnsive with parts of the Wales group.

Field investigations in the summer of 1955 near Kasaan Bay indicate that part of the strata previously mapped as Devonian is ac- tuaIly of Early Silurian age, and geologic relatiens south of ICasaan Bay strongly suggest that same strata am of Silurian age or older ( Saiwbury , om1 mmmunimtion, Februarg 25,1956). In ~xtending the mapping of Devonian rocks by aerial photograph

inbrpretation into previously unmrtpped central Prince of Wales Island only a vary tentative separation of map units is inhnded, and this is based solely on t o p o g ~ p h i c sjmilari ty to known Devonian units.

A Middle or Upper Devonian ~ g e I s indicated by fossils collechd from the sequences st rntigr~pl~ically above the lower nssembl age of predominantly volcanic rocks. Precise relations between the sequences of the Devonian as a whole nre not well established. The lower contact of the system is known in places to be markedly unconformable with Silurian or oIder rocks.

Mineral d e p j ts are widely distributed in the a1 tend volcnnic fl oms and breccias, and in the bIack slate, gmyw~cke, nncl conglomerate of Middle Devonian age. They occur as contact-metamorphic deposits of copper and iron, shear-zone deposits of copper nnd other rnetnb, and fissure-vein deposits of p I d and other metals. The Upper Devonian strata are not known to be minernljmd. The development of mines and prospects in some awns has k e n extensive. Kasaan Penin- sula has long been noted for its copper-iron and copper ores, and n unique copper-palladium deposit, The FTolli s nnd Grnni te hfoltntni n areas have many gold mines and prospects. Ocrurrences of rnotybde- nite on Baker Island are notable, Qrnnrnentnl rnrtrble nnd limestone are quarried locally in the Dolomi and Jlickmnn Rng arens. Rnrite has been noted on the sout8heast end of St. Ignace Island.

This quence is mapped by Buddington and Chnpin (1929) a ~ s

mainly conglomerate and gr~ywncko or snndstone with n totnl thickness of 2,000 feet or more. These rock~l nm expos~,cl nlong Snn Clhristo- val Ghannel, on San Fernando, Lulu, nnd Rlnnqaixnl Islnnds, and on th0 islands and north side of San Alberto T3~y.

The sequence has been grouped with the Middle Devoni nn nf t hough fmsils are not abundant. Thc lower contact is uncollformnble with Silurian or older mks nnrl the sequence seems t,o pinch out nt the head of San Alberta Bay. The upper contact, wl~ere observed is with the overIying massive limestone. On the north end of T ~ l u Island the conglornemte is overlain by fosiliferoua limestone of untlssignecl nge ; relation of the sequenm to other Devonian units hns not been demonstrated.

LO- BLATE OOLCAIPfC1 ROOM

This unit is rnnpped on t . 1 ~ northenst, end of Noyes TsIsnd by Bud- dington and Chnpin (1929) ns ir'tterhdded sltlte, lirn~stane, chert, and volcanic rocks including tuff and breccia. A Middle Devonian age for fossils from the limpstone within this unit was given by Kirk (in Raddingtan nnd Chnpin, 1929, p. 105). Contact relations have not been described.

blCDzSITIC voLeaane aacxs

The lower dorninnntly volcanic mLr aw dmcri ld by nt~dclinflon rind Chnpin (1999) ns ruldesitic larn flows, hreccii~, and tuff, lwnlly including cmglmemte ~ind rhyol i t fc I2vn flow-s. Tlle conzlometv te is made np mainly of limestone nnd nntksite fmprnents. Tlle l:t~-a is h e graind, dens^, green to gmy, nnd interktdwl miti1 coarse b~w- ia locnlly of a flow type. Submarine deposition of part of the I-o?c;lnic

B-18 MINERAL RESOURCE6 OF AWlSgA

rocks is indicated by pillow stmctum in the lava. Total thickness is about 2,000 feet. These m h mupy I m p parts of Noyes, Baker, Suemez, Sukkman, Dall, and Prince of Wales I~lands. In southern Prince of IVttles Lland the volcanic rocks occupy the cores of anti- dim1 stmctures, that are rnnerally overturned to the northeast and flanked by younger slates nnd volcnnir, rocks. Mapping the extension of t h w volcanic roch on Prince of Wnles Island by photointerpm- tation is tenuous.

The volcanic rocks have been grouped with the Middle Dewnian mks but thag may be partly Silarjnn pnrticul~lrly ~ l s mapped east of Big Salt Lake. According to earlier work the lower contact is nnconformable with Silurian or older mh, and the upper cuntwt is conformable with overlying s l ~ t e and volmnic mks bnt the relation to younger mks is not well known.

A unit predominantly of p y wneke and kuflaceous beds is mapped locally by Buddington and Chapin (1929) on Suemez Island and amall islands in the Maarelle p u p . Drark slate, and conglornemte of limestone and andmite fragments are included. The unit mny be equivalent !t part of the slate, and volcanic rocks next described. Aerial photopphs indicate a similar belt of rocke northwest of Port Xefngio between the ~nderlying anlclesitic volcanic rock and the over- ly ing Uppr Devonian rocks. The topographic expression and vegw tntion pnttern appRm to be simiIar to that of the b l t along the northern slope of Suemez Idand.

The unit is groupecl with m k s of Middle Devonian am and over- lias the andesitic volanic rocks, probably conformably. It underlim the Upper Devonian rocks, pmbnbly unoonformably.

The rocks of this sequenca are mapped and descriw by Buddington and Chepin (1929) as n n d ~ i t i c p n to p a y tuff, lwl ly oonglome- rah, sIIbtB, limestone, and some chert. Associated volcanic rocks include minor amounts of andesitic lava, breccia, and tuff. They give the total thickness as mom t h ~ n 2,400 feet. The volcanic material decreases lipward in the squence. Limestone in places is particularly sbundant and interbedded with greenstone, siltstone, quadeite, p y - wacke and wngllomerate as on Kasaan Peninsula. Robinson (1946, p. 31) indicates that the mka of Buker Idand are arenamus and calmmus argillites ~ n d aq$lwenus rocks wit11 some marble and tuf- f acems be&. Along Klakas Inlet, F'hrlain (written cxrmmunication,

1949) hm mapped a sequence of banded siliceous sandstone and siltstone with locally wide bands of voImnic and pymlastic rucks and agglomerah; at the northern end of the inlet these rocks grade into tuffaceow IomIIy conglomeratic graywacke-sandstone. On Hasaan Peninsula, Warner and Goddard (1960) suggest that sill-like intrusive 'bodies of Triassic ~p have metamorphosed the strata and locally form most of the bedrock This suggestion contrasts with earlier ideas that the sequence eonsidered of interlayend metamorphosed volcanic rocks (greenstone) and conglomerate, graywacke, tuff, and limestone. The sequence is widely distributed and forms a large part of the Mrock of Sukkwan Island and Prince of Wdes Island south and WE& of Kasaan Peninsula. In the southeastern p ~ r t of the quadrangle the sequence occupies the troughs of synclines overturned to the northeast and is underlain by older andesitic volcanic rocks.

The Middle Devonian we of this sequence has previously been assigned from faunal analysis, but, only Iocally. The lower contact is described as gradationally conformable with underlying volcanic rocks and unmnformable with underlying mks of the Wales group.

The Devonian lirnmtone is described by Buddington and Chapin (1929) as uniform, g a y or white limestone, locally with sandy or argillaceous hds, mom than 600 feet thick. Eberlein (written communication, 1949) mapped it near Karheen Passage as argillaceous limestono with interbed'ded shale. The limestone is exposed on some islands in San Alberto Ray (notably Wadleigh and Fish Egg Islands), on islands in Trocadsro and Kasaan Bays, on Prince of Wales Island near Craig and Klnwak Lake, and on San Fernando Island. From the study of aerial photographs, a small area east of Tuxekan Passage was interpreted as limestone; and later verified by a field check. Its stratigraphic position overlying the Upper Silurian g a y wacke-sandstone quence and a, tentative identification of fauna (C. W. Merriam, oral mmmunication, April 1955) indicate a probable Devonian age. Another small a m of limestane was mapped by photointerpretation east of Craig.

The age of this richly fossilifemus limestane has been established faunsIIy as Xddle Devonian in many places in S&n Alberto Bay and the Klawak Inlet area, the Coronados Islands, and Kasnan Bray. On Ham Island in Karheen Pwlssage silicified fossils are abundant. The limestone is locally unconformabls with underlying units of Silurian or older rocks. Contact relations with underlying Devonian or Upper Silurian rocks is nowhere dearly demonstrahd but a gen-

'B-20 MINERAL RESOUFEFS OF ALASKA

era1 unoonformity seems indiwtd. The actual contact with the overlying Upper Devonian rocks has nowhem been observed.

Upper Devoninn rocks am not extensive but are mapped by Bud- d h e n and Chapin as limestone with dmreous sandstone m d some conglomerata and srgillite interbedded, or as volcanic rocks including basalt, andesits, and tuff. Thickness is given as about 1,000 feet. The rocks occupy most of Ssn Juan Bautista, Island, pwt of Suemez TsImd, and some islands in Tmcadem Say.

The Late Devonian age of the rocks on San Juan Bautista and Suemez Islands was assigned on the; basis of m ~ h e fossils and locally fossil plants (Btlddington and Chapin, 1929, p. 107-109). The na- tare of the contacts is not clearly defined. Both upper and lower contacts am probably nnconformable.

T h e Mississippian rocks of Craig quadrsngIe o c m in a few scab bred small areas. The outcrops probably represent only a part of the Mississippian sequence ns known for sou the^ Alaska as a whole. The system is mapped and dwcribed by Buddington and Chrtpin (1989, p. 110) and described by Smith (1939, p. 26). A thin sequence of basal conglomerate and calcnmus sskose i~ overlain by coarsely crystalline highly f osilif emus 1 f mestone interbedded with thin-bedded black chert. The limestone is in turn overlain by a sequence of interbedded chert, dense p y quartzite, cherty 1 imdone, and thin-Iayerwl chert. A thickness 06 about 1,000 feet is repre- senM by these beds, but the whole sequenm is not present in all outcrops.

Mississippian m h crop ont in We Klawak area, occupying all or parts of many islands in Trocadero Bay, and occurring alwg HIawak Inlet, find in parts of Snemez and Shelikof Islands. Structnally, the rwks m p out in the troughs of synclines. In the Klawak area they am folded along a north-south axis and cross folded along east- west tbxes; they may be overhrned to the west. Photointerpretation indicates that Mississippian outcrops are probably bounded by a fault south of Point Bocas on Suemez Tsland.

Tha Mississippian age of the mks is based upon fmih from Sheli- kof, Suemez, Madre de Dioa, and the Coronadm Islands as well as many Poc~lities in the Xflawak area. (Buddington and Chapin, 1929, p. 110-117) ; t.he m k s have been as iped to the upper pnrt of the Mississippian by Girty (in Smith, 1939, p. 26$, The Misgssippian rocks overlie the Upper Devonian system on Snemez IsIand but the

contact is not descrihd in d e t d and no angular unconformity has been obmmd. Pennsyhni an ( B ) limestone overlies the Mississip- pian limestone on S helikof IsIand.

Rock of the hnsylvanian system may occur in one locality in the quadrangle. The stmta, briefly described by Bnddingtm and Chapin (1929, p. 117) and Smith (1939, p. 261, were mapped with rocks of the Permian sysbem by Buddington and Chapin. Massive white limestone 100 feet or more thick occurs on the southwest end of Shelikof Island in Soda Bay. Fnuna of the limestone seemed indicative of the Pennsylvnnian and was m assigned tentatively by Gidy (in Buddington and Chapin, 1929, p. 117). This limestone overlies the Mississippian limestone with no apparent stratigraphic breek.

FERMI4N SPsmm

The Permian system is represented in only one locality in the quadrangle nnd hrts been mapped and described by Ruddingt,on md Ghapin (1929, p. 118) and discussed by Smith (1939, p. 26). On ths eastam tip of Swemez Tsland about 300 feet of clos~ly folded blue and gmy limestone is described by Chapin ns part of the upper division of the two Permian units mapped in southeastern Alaska. Fossils were identified by Girty (in Rtrddingkon and Chapin, 1929, p. 129). The Permian rocks omrlie Upper Devonian m d older stratn probably unmnformably.

~ O Z O L C ItOCgEC

The Mesozoic era ja represented only in the northeastern comer of the quadrangle where the systems comprise metavolcanic and metasedimentary m k s . A generrlll hintus involving a11 or most of the Triassic system probably exists. ~lthough in ndjacent quadrangles to the north and east, thick sections of Triasqic metavolcanic and metasedimentary rocks crop out. The metamorphosed vobrtnic and sedimentary rocks of Jurassic or Cretnceons a@ originated mainly as flows and pyrwlnstic rocks.

Triassic strata are not mapped as such in Craig quadrangle but mcur in adjoining quadrangles to the north and to the east. An area tm small to mnp at the head of Clover Bay, eastern Prince of Wales Island, comprises graywncke of probable Triassic or younger nge and

was reported tu be infolded with Devonian limestone irnd mng10merate by Markin ( 1926, p. 73-74).

Jurassic and Cretaceous r+ if both m r , have not been separated in lCraig quadrangle. The m b have been described and mapped as Jurassic or Cretaceous by Buddmgton and Chapin (1929, p. 163,186) and discussed by Smith (1929, p. 4&41,48). The rocks are described as dominantly volcanic; that is: schistose greenstong breccia with intercalated tu$ agglomerate, lava flows, asmiated with black data and pywacke . Generdly the black slate is intercalated in the greenstone in variable proportions. In some other parts of mutheastern Alaska, units of predominantly sedimentary rocks are mapped both above and below the groennstons.

These rnetavolcanic and metasedimentary rocks occupy Onslow Island and the ~outhw-rn part of Cleveland Peninsula with syn- clina! dructure overturned to the southw&. The rocks are highly metamorphosed ttnd schistose snd have been intruded by large masses of igneous rock that are m i a M with the Mwozoic period of intrusion. No specific basis axi& for distingnishmg the Jurassic from the

Cretaceous ayatem over wide are- of southeastern Mash, according to Smith (1939). Martin (1926) specified that the d s of the two systems differ in d e p of metamorphism and am slightly diflerent in fossil content scms a pronoun& unconformity. Buddington and Chapin (1929) did not concur with m definite a separation on the basis of what was hown of the rocks. As mapped, the Jurassic and Cretaceous rocke may include parts of older systems. The lower ern- tact is generally believed b be unconformable with Triassic or older rocks, but relations are not clearly demonstrated on Clweland Peninsula.

Minerd deposits in the greenstones are prominent in a belt along He1 m Bay, mainly as gold-bearing fimm veins.

cmm1c BOCK8

Ths ~ n o z u i c era is mpresenkd by mItemd remnants of Terkiary clastic and volcanic rocks, and by Quaternary glacial deposits in sddi- tion to thoae uncmsoliclated deposits flow being formed as a result of subaerial weathering or submarine deposition.

The Tertiarg sgstRm comprises scat ted remnants of c k t i c and 1-01canic rocks mostly confined to a narrow trough and the valleys

GEOLOGY OF THE CRAIG QUADRANGLE, ALASKA B-23

leading into it. Thii outcrop belt roughly corresponds to the Seymour gmspdine of Payne (1955) in b i g quadrangle. The Tertiary rocks of southeastern Alaska have been rnspped and described by Budding- ton and Chapin (1929, p. 26S215) and discussed by Smith (1939, p. 58, 59, 79). The clttstic rocks near Union Bay are described briefly by Kennedy and Walton (1946, p. 81). Other small areas northwest of K ~ m n Bay (Sainsbury, oral mmunication, 1956) have been mported but not mapped.

Tertiary clastic rocks contain coal smms or lignitic material in places, but these nre not wmmercially significant. Metallifemus deposits are not h o r n in m i a t i o n with Tertiary rocks; their d a m - tion ptdates the genera1 period of rnineralimtion.

Clastic nonmarine sedimentary roh-san&tone to boulder con- glornerak-crop out at Coal Bay and at Union Bay. Sandstone with thin coal seams occupies a smalI basin at h l Bay. The rocks am largely covered by gIacial material ; they have a maximum total Ihicknes9 of abut 100 feet, and are commonly flat lying or dip 1 5 O or less. As mapped, the area shown indicates probable distribution, not actual known outcrop. At Union Hay, Goarse boulder conglomerate locally grades inta p r l y sorted sandstone.

Time relations among the scattered remnants of Tertiary clastic rocks in southmstern Alaska have not been satisfactorily worked out. They a m generally regarded as nonmarine and of Eocene age on the basis of plant fmsils; they rest with angular unconformity upon older mks.

voLemc mcm

The Tertiary bk7altic, andwitic, and rhyofitic flows and pymclastic mks, tuffs, and breccias are awciahd with minor mounts of inbr- bedded sedimentary material. A largo part of tho volcanic m k is probably the result of fissure eruptions that filled existing valleys, for emmpla, the basaltic and andesitic flows and pyroclastic mch of Eagle Idand. On Suemm Island, basalt, andesite, rhyolite, and obsi- dian Bows occupy a large area; thin coal seams have been rsported from the northern part.

The Tertiary volcanic m k s of southeastern Alaska are genemlly regarded as Eocene and rest with angular unconformity on older racks. d possible Pliocene age is postulated (Buddington and Chapin, 1929, p. 271) for the volcrtnic d s of Svemez Island on the basis of their position and lithologic similarity to those. af Graham Island, British Columbia. Their topographic expression indicates an ttge clehitely predating the last glaciation at the head of Arena Cove.

B-24 MINERAL REBOURCES OF ALASKA

The Quaternary deposits of southeastern Alasks have h e n described in general terms (nuddington and Chapin, 1929, p. 275-281; Smith, 1039, p. 66-67; nnd others) but they have not been mapped or described in detail. Quaternary deposits have been mapped in this report by photogeologic methods and nre not md-divided. Mineral deposits are not commonly mciated with the Quakrnary deposits. Buddington and Chapin (1929, p 355) reported small placer deposits in eluvium resulting from wenthering of gold-bearing rocks along the mest side of Helm Bay. Fxonornic value of sand and gravel is undetermined.

Vev little data are available concerning them deposits, and the tapgraphic forms of the glacial features are not, sufficiently definite for identification and classification by means of aerial photographs. Bmoks (1902, p. 33) indicated that morainic material mas observed at fow localities and in very limited quantities, but t h ~ t evidence of glaciation at low altitudes is present in nearly every part of the Retchiknn mining district. Well-developed cirques indicate that past glacintion reached 2,000 feet or more on certnin p n k s of Prince of Wales Island. I.Iomever, the scouring action of slpine glaciers during the waning stages of the glacia1 period i s nlso r~flected in the cirques at altitudes of 400 feet or les~ as on certnin islrlnds west of Prince of TVnIw Island Most valley bottoms are covered by varying thicknesses of glncial debris or valley drift. Thin veneers of glacial debris mny be expected nearly everywhere except on the highest peaks. Small, s c n t h d deposits af stratified g a v e l and sand are undoubtedly p m n t but probahly notin abundance.

Certain pmtulntions about Quaternary deposits may be made on the basis of aerial photographic study of topography : 1. The flat to gently sIoping bottoms of broad U-shaped valleys, such as those of the 1-Inrris River and Andersen Creek, are andoubtedly occupied by relntivoly deep deposits from melted valley glnciers. T h e deposits in upper parts of valleys probably b p r to a thin veneer over sco~~red bedmck, and many of the valleys terminate in criques.

2. Mast of the broad valley of the Thorne River is -pied by drum- linlike features, nlmost certainly of glacial origin bec~use rnmtfy till and but very little bdrock occurs below an altitude of 200. feet (Sainsbury, written cornrnunicntion, Jnly 1955) Parts of the brond mddle area southward fmm the head of Trmdera Bay to the heads

of Sods Bay and South Pass seem to contain similar glacial features.

3. A broad flat area drained by Staney Creek may once hnve been covered by a temporary glacinl lake if an ice dnm were formed in Tuxekan Passage. Such a lake may have overflowed to the northwest toward Naukati Bay, or it may have been connected to another flooded area near the head of Naukati Bay. Deposits in such an a m would be silts and clays beneath ra swampy surface with a pe- ripheral belt of deltaic sand and p v e l which would have been deposited by streams entering a relatively quiet lak~ from surround- ing mountains.

Suficial deposits formed during late stages of glaciation or after the glacial epoch are unevaluated. Subaerial weathering in place, landsIides, and creep have created eluvial and residual deposits of soil and talus, Large stream systems are not deve1oped in the quad* rangla, but fine sand and silt have built up tidal deltaa and flats locally, for example, at the mouth of Staney Creek. Some sorting and con- centmtian of g1miaI material to sand and pave1 bars by streams is probable but large deposits are not to be expected. Well-developed h h deposits are also uncommon. Elevated marine terraces and benches of clay, sand, and gravel have been noted at different levels up to altitudes of 600 feet throughout southeastern Alaska (Budding- ton and Chapin, 1929, p. 216). Quaternary volcanic rocks, although known not far to the north and east, are not known in Craig quadrangle.

WBUSrVX IGKEOUS gOCKB

Intrusive igeneous r+ks are common and widespread in the Craig quadrangle as batholiths, stocks, and smaller masses such as dikes and sib. Most of these intrusions were probahly emplaced during Jur- assic and Cretaceous time nnd are. genetically related to Coast Range intrusions. Despite some evidence of pre-Mesozoic intrusions their location and period of intrusion is conjectuml. Some small tabular mas- have been assigned to the Tertiary by several field workers.

No outcrops of pre-Mesozoic intrusive rocks are known, but p n i t i c pebblas and cobbles in the conglomwates of Silurian and Devonian age must be explained by one or more of the following: the existence of Early or pre-Silurian intrusive m k s a3 yet unproved ; the former existenca of such intrusive rmks, which could have been subsequently

&% bRMERAL RESOURCES OF W K A

eroded: or assimilnted by Blesoxoic intrusive rucks ; or glacial trans- portation. The role of glncintion is controversial.

Intrusive igneous mks of the M m o i c era, g.enernlly associated with the Coast Rnnge intrusions, aro widely distributed in the Craig qundmngle. The scope of this report, and lack of detailed infoma- tion within the area allows only a general dwription and classification of the intrusive igneous rocks. Those of southeastern Alaska have been described and mapped by Buddington and Chapin (1029, p. 173-2531, and their work and that of others discussed by Smith (1939, p. 8). More detail4 studies have been carried on locally (Wright, 1915; Robinson, 104%; Kennedy and Walton, 1946; and Kennedy, 1853). Most, intrusive masses have been cansidered as outlying aatsllitic bodies related to the h t e Jurassic and Early Cretaceous Coast Range intrusions to the east. They are mostly dioritic, but granitic und ultramsfic rocks nre not common. Younger dikes, commonly diabase or nplite and locally pegmatite, may be of Mesozoic age but some are of Tertinry age.

The following division of igneous intrusive r& has been used in this compilaLion : 1. Granite nnd granitic rocks as mapped by Buddington and Chapin

(1999) occur aa stocks throughout the Alexander Archipelago but form a minor part of the igneous complex. The mapped mks lie within the Wranpll-Revillagigdo belt of metamorphic m k a where granite porphyry underlies a large part of Etolin Island, and forms the small islands near D m Islafid. The Etolin Island masa probsbly includes a large amount of rocks more rnafic in composition than true granite. Elsewhere small bodies of gmnite and syanite are known but are not of rnappabla size. Pegmatitio and aplitic facies occur mainly as tubular intm~iva bodja within both igneous mck and adjamt country rock.

2, Dioritic racks include panodiorih, quartz diorite, and diorite and their variants. Gabbro, diorite, and rocks of intermediate cam- position occur as arnnlI m a w s and margins1 vsriants. Diorite forms the l a r p t park of the igneous mas= of Prince of Wales Island and adjoining islands. Quartz diorite is one of the pre- dominant igneous rocks on Dall Island and northeast of CEarenoe Strait. Granodiorite is less common but forms the bulk of some irnportsnt igneous bodies such as that of the Copper Mountain

GEOLOGY OF T R E CRAla QUADRANGLE, ALA8Kh %g

area. In the Rasam Peninsula area, Warner and others (1060) locally distinguished an early diorite end a late granodiorite.

3. Mafic and ultramafic rocks include dunite, pyroxenite, hornblendite, md rnarginnl variants of pbbm and other rocks of intermediate composition. The ultrarnafic rocks occur as stmh and silk but masses of mappable size are few. In Craig quadmngle the pymxenite ~ n d nsstxiated rocks of the Mount Burnett and K M ~ R Bay areas, find the ~zltramnfic rocks of Helm Bay and muthem Sukkwan lsland are noteworthy. Elsewhere mall masses or marginal variants of more silicic igneous mks am tm small ta map.

4. An interpreted unit has been mapped, p i M y of igneous intrusive m.b or a complex of igneous and metamorphic rocks. This unit, RS intarpreted frm aerial photographs, is extended from previously mapped igneous boclies, or comprises separate and strictly interpretive amas on phte I. Possible extensions of igneous bodies have been indic~tsd on Prince of Nrtles Island: northeast of Thorne River, and on Cleveland Peninsuln northwest of Helm Bag on the basis of similarity of surficid chnr- acteristics and fmctum pattern. By the same criteria, igneous intrusive mks am indicated in l a p areas east of Kogish Moan- tain and in the Black Bear Lake area on Prince of Wmles Island. Smaller amas interpmted as either wholly or partly intrusive igneous m k include those near Emerald Bay on Emat Sound, nerrr Salmon Lake, near the head o f Polk Inlet, and on Suemez Island. The presence of any large nren of intrusive rock un Noyes Island is questionable, but scant information indicates first, possibility.

Most of the intrusive masses ore complexes of mks of m~era1 wm- positions, peneralEy with indefinite and gradational contacts. Mar- ginat variant# such as gabhm-diorite, gnbbro, and hornblendite are not uncommon within both the ultmm~fic ~ n d dioritic gmmps. Various composition syrnhls are used in mapping the complex m s m s (pF. 1 ) where information shows approximate distribution, but the gmdfitional contacts nnd Iwk of jniormation generally pm- cludes s breakdown. Previously mapped contacts have been slightly changed in places where Inter information or aerial-photographic study m m e d ta justify the change. Detailed descriptions of local areas of intrusive rocks incIud~ Mount Burnett (Kennedy and Walton, 1946$, the Het,h Inlet nwn. (Wright, 1915 ; ICennedy, 1953), &saan Peninsula (Wright, 1915; Warner and others, l960), and B&er Island (Robinson, 1946). On Coronation Island the mapped exknt

B-2& MINERAL RESOlJRaS OF ALAi3KA

of htmsiva rock is based on photointerpretation and rather incan- sistent early sketch mapping.

Several epiFtod~ of igneous intrusion wers more or less continuous within one general perid embracing the late part of the Jumssic and the early part of the Cretaceous periods. Contact relations batween igneous bodiw and the order of their intrusion are broad and complex. Published data indicate that intrusion by the larger stocklike bodies progressed from the more mafic to the more silicic rocks; the dtrmafio rocks were cut by gabbro and dioritic mks, and the more silicic mernhra ef the dioritic p u p cut the more msfic ones. The granitic p u p in general is p ~ b a b l y the young& of the massive igneous racks. Aplite and pegmatitic dikes are associated with the dioritic and granitic rocks hrnpmphym dikes cut all other mks of the igneous complex, but their rtge assignment to the Masozoic or the Cencnoic era is problematical. Marginal variants, either of more mafic or more silici~ mla am fairly common, For wmmplg gabbra may occur marginal to either diorita or the ultramafic rocks, and d i o ~ h may have marginal vari~nts of either quartz diorite or gaWm.

The emplacement of the Mesozoic intrusive tidim and the omganie movements asmiatad with it had a marked effect upon the country rock and structures existing at the time. Met~morphism, contact and regional, cwvertad mcks to gneiss and scbist, and limestone to cryskid- line limestone and marble. Folding amxiated with intrusion superimposed the now-dominant northwcstwxrd trend of structures upon the pravious northwad and northeastward trends. Faulting and bmiation acmmpmying intrusion resulted in faults and shear zones, many of which have formed channels for ore-bearing solutions and contain valuable minmal dsposik The genetic relation of the intrusive m b b ore depdtion in southoastern Alaska has been gen- emUy recognized,

Post-Mesozoic igneous intrusive mks the quadrangla are present only a3 dikes and sills associated with the extrusion of lava. Some di~bam dikes not related to volcanic rocks are 'believed by Sainsbury (written cummaniation, 1958) to be Tertiary. Dikes and silIs granit,ic to basaltic in composition but most corn-

manly basaltic or nndesitic, cut country rock adjacent to certnin Ter- tiary flows and locally am of Tertiary age, cutting bnsal parts of

Tertiary mquenca Notably abundant are the tabular igneous bodies-dikes and sill-f ~outhern Etolin Idand and the southern end of Onslow Island. Elsewhere, some larnprophyre dikes that cut country rock and Mesozoic intrusive masses sre probably of Ter- tiary w. A few small Tertiary igneous instrusive masses have been noted but not mapped in southeastern Alaska. The mass nearest to Craig quadrangle is the granite porphyry of Zarembo Teland.

STRUCTURE

mmmo Folding waa significant during at lead three periods as indicated by

trends of major and minor fold ses, The oldest folding, that of the Ordovician ~ n d Zower Silurian strata, is most comnody isocIinal with northward strike and vertical or steep eastward dips and suggests a pm-Middle Silurian period of folding. At the close of the Paleozoic era, pre-Mesozoic rocks were folded with northeastward-tmnding axes a m d i n g to Wright and Wright, (1906, p. 39). The dominant folding of the rocks of southeastern Alaska occurred during the Mesozoic era when rocks including Jurassic and possibly some Cretacmus strata were folded with northwestward-t,rending axes. This later and dominant folding partly or totally obliterated prevjous trends of folding or was superimposed on thcm, rewIting in very complicated structure. Evidence of a, Tertiary period of warping along nearly cast-west axes is known in some parts of soutlleastern Alnskn but is not obvious in this quadrangle. In the Jumbo Basin area on Hettn Inlet east-west cross folds may be either a result of Tertiary folding or contempo- raneaus with earlier north-south trends (Kennedy, 1953, p. 13).

Two major tedanic eIernents are shown by Payne (1955). (See also this report, fig. 2.) The most prominent, the Prince of Wales gemticline, is described as a linear positive element where IittIe or no sedimentation took place or where uplift nnd subquent erosion occurred dnring the Mesozoic em and later periods. Its axis corresponds roughly to that of the Princa of TVnles-Kuiu anticlinorir~m ns described by Buddinen and Chapin (1929, p. 304714). The Seyrnourgeosyn- cline is described as a linear neptive element in which sediments ac- cumulated during and after the Mesozoic period. Its axis corresponds closely to that of the Keku-Gravina synclinorium of Buddinfinn and Chapin (1929, p. 300).

The Prince of Wales gemticline has n northwestward axial trend through Prince of Walles Island. The pnticline occupies the whole

island and thme to the west, and exposes Paleozaic rocZrs throughout m& of the area. Five large shctrtral pmvinm roughly defmed by Buddington and Chapin (1929) include: (1) Kuiu anticlinoriurn; (2) Kosciusko-Texekan-Heceta synelines; (3) a central anticlorial province; (4) a southern s~rnclinorial provinca divided into two parts by the Dolomi-Sulzer anticlinorium; and (5) a southern anticlinorium of which only the northern part falls within the quadrangle fig. 8). The Hashmarof anticlinorium, sketchily described, lies east of the main anticlinorial axis on the north border of the quadrangle. It extends southward an unknown disttlnce, is compIexly folded with a general northward plunge, and exposes mostly Ordovician strata with same infoldd Silurian rocks,

P'room 2 . 4 e t c h map of mafor structurnl features and molrt prombent anxllfafy Iol& an prevlou~ls mapped or d e h b e d la the Crnjg quad rand^. Lcmtlon d axel and ioldlug mostly dlagramnatlc reaturea nre numbered atcurdtag t o the iollowlng out- line : A. Prince of Wale# geanticline (Payne, 1956). PrIacc ot Wales-Kula antldlnorhrm of

Buddl~gton and C h a p l ~ (1929) ; inclsdea Kashevaroi antlcllnorlnm ( a ) : 1. Kuiu antlcllnorlurn. 2. Koscin~ko-Tuxeknn-Heceta spndrne% 3. Centrnl mntlclinorlrl province (Inclnden Ban Prrnmndo antlclinorlum). 4. Soutbera Ryncllnorlum : a, central tlynctlnorl~l provllrm ; b, DoIomCBnlsar anti-

clirrarium ; c, ~outhern nyacl1norM province. 5. BoutWm antictlnorlum (northern part only).

8. 8eymour goe6gnctine (Pame, 1955). mu-tfrariaa aynellnorium uf Bndllw$on nnd Chapln (1829).

The Keh-Gravina eynclinorium of Buddington and Chapin (1929) coincidm roughly with the Seymour geosyncline of Pttyne (1955) and trenda northwestward with its axis crossing the south end of Cleve- land Peninsula. The structure is closely folded and overturned towand the southwest. Mesozoic greenstones and small isolated remnants of Tertiary rocksoccupy its trough.

Many linear features are interpreted from aerial photographs as the trams of pmibla faults, major joints, or shear zones. Recogni- tion cribria for ~ u c h tram include topographic vegetation and stream alinements, Fault control has been suggested for certain river valleys, straits, and fiords of southeastern Alaska; these major alinements are termed L'linmment8." It is assumed in this mport that on -rid photographs the skill maller and less conspicuous tmm representing sheared or brecciated zones can be delineated where erosion by m s and ather agents baa pmgresd along the relative1y weak zones. Field evidence has confirmed locally that many of these trams do repraent faults or shear zones, but most have not been field checked. Little or no inf omation on dimtion or magnitude of f d t movement has bmn mmded by field workers, and recognizable criteria for such interpretation is lacking on the aerial photographs of the well-forested terrane. The aame is true of the type of faulting, for although most minor alinements linesm probably repmnt high-angle faults, soma thrust f aufting is very probable, Mowment along the faults amrd- ing to past interpmtations has m u & throughout a large span of geologic time. Much faulting and brecciation is attributed to disturb a n m during the Mesozoic era, and to gentle folding and warping dnring Tertiary time.

The pattern of major lineaments related to faulting muthmst8m Alwka has been discussed by Twenhofel and Ssinsbury (2958) and analyzed with mpect to h o r n field relations. They describe the well-defined major linerwnmts as striking northward and northwestward. In southeastern Alaska they say northward-trending faults marked by northward-trending lineaments have s complex history of movement before h h Cretaceous time;, during the TerLiav period, and possibly in R e n t time. The northwestward-trending fadts cut and are later than intrusive mks relatad to Coast Range intrusions but are also mmtly pm-Tertiary. They further state that less mnspicuow dinemmts, not forming 8x1 integral part of the major

lineaments, fona two systems : one of northeastward- and northwest- wadtrending linear f ea tuw and one of norbhward- and eastward- trending linear features. The first is the more prominent and older of the two minor systems; the northward- and eastward-trending system is Cenozoic in age and not we11 developed in south&em Alaska. Within these t w o systems, the northwestward- and northward-trending linsars f e a t u ~ are the mmt prominently e x p d , whereas those trending eastward and northemt.ward are relatively ill defined. h l i z a t i o n of certain mineral deposits near major f au1t.s h been noted by many workers in the region. A strong rslation seems indicrttd between the combination of igneous activit-y, northwestward-Ming regional faults, and the localization of m i n d d e p i &

Mast of Craig quadrangla lies between two major lineaments, one ~triking northwestward along Cl~mnce Strait and the other striking northward along the southwad extension of Chatham Strait. T h e following parqpphs am b d on the interp~tations made in this report.

A northerly trend of linear featnns diverging slightly southward is conspicuously eqresseiE on Prinm of Wales Island west of Tharne River and north of A n d e m Creek and the Klawak area, and may be related to the major lineament along Chatham Strait extended. Lem conspicuous linear features are on Coronation, Sukkw~n, EtoFin, and San Fernando islands, and some small parts of aouthern Prince of Wales Island. Northward-trending linear features are well de- h e d in the p n i t i e and dioritic m k s of Etolin and Sukban Islanda; associated faults are probably of Late Cretaceous or Cenozoic age.

A nodhwestward trend of Iinear features is most conspicuously exprassed on Cleveland Peninsula and aIong the east side of Prince of WaIes Island particularIy east of the weI1-expressed lineament extending northwestward from Karta Bay (here named the Thorne River lineament). Smaller aretla with this trend less conspicuously expmsed include Heceta, Om, Kosciusko, and Snkhan Islands. On the aerial photographs of southern Cleveland Peninsula linear featurn that are conspicuous elsewhere cannot be t n d across an ill-defined araa of ultrarnafic rocks commonly considend closely related to batholithic intrusive rocks of JIggozoic age, Therefore, latest movements along these faulb most probably occurred during Late Jurwsic or Early Cretaceous time. A structural relation to the regional trend along Clarence Strait seems o b ~ o u s .

Westward- or or&-north~estwal.d-trending linear features are dominant on Prince of Wales Islnnd southward from the Andersen Creek-Salmon Lake area, and nlso on a large part of Dall Island, Reasonably well defined linear features of this system appear between Staney Creek and Thorne River. Tho linear features trending west- northwest are probably correlative with the fault zone reported (Bud- din- and Chapin, 1929, p. 39) along Roeas de Pinas and San Christoval #amel. The mast continuous linear feature of this system extends from the North Arm af Mojrn Somd west-northwestward to Hetta Inlet where a fault =ems to cut the Mesozoic intrusive rocks, thence westward, but less distinctly expressed, to Soda BayLy. This feature seems to connect with one that c r m s Suemgz Island and that mms to have no expression across an ares of Tertiary lava Rows. If assumptions are correct concerning continuity of the feature and its relations to Aows and Mesozoic intrusive rocks as they appear on aerial photographs, then the age of associated f nults is most probably Late Cmtaceous to Early Tertiary. Kennedy (1953, p. 13) maps no major faults in the Hetta Inlet amti, but states that faults of n few hundred feet in dfspltl~ement may h associated with east-west cross warping. A well-defined zone of linear fetitum extends between the heads of Hettai Inlet and Trocadero Bay, and closely corresponds in trend to f ~ u l t s and shear zones reported at some mines and prospects along this zone. Another less conspicuous zone passes westward from the Salmon Lake area.

Northeastw~d-trending linear features are nowhere dominant but appear on Heceta Island, northern Dall Island, and along e a r n Prince of Wales Island.

MINERAL DEPOSITS

Metallic deposits are widespread in the Craig quadrangle. The major factors in localization of deposits seem to be the proximity of igneous intrusive bodies and the presence of fissures and shear zones, A genetic relationship of metallization to the Mesozoic intrusive rmh has bmu postulated for a large pwt of the metallic deposits of southeastern Alaska by many workers. A close spatial relation with fnults and shear zones exists for mnny deposits. RoFk type and struct~lra locttlIy have influenced the type or form of deposit, such as: s k m and replmemenk deposits within limestone; the relation between ultra- ~ R A C rocks and certain uncommon elements (Pd, Ti, Cr, Ni) ; and the relation between gold cwxurrencea and greenstone. Metallization has taken place within a variety of rocks in the quadrangle; however,

deposit3 are notably scam on a large part of westam Prince of WaIes Island and adjacent islands where igneous intrusions are not as mm- mon in strata of Ordovician to Devonian age. The most important types of ore deposits w i t h the quadmqle

am the contact-metammatic copper and iron deposits of Hetts Inlet and Kasaan Peninsula, and deposits formed by hydrothermal prooeases such ss cavity filling and replacement as iimm veins, shear- zone deposits, breccia fillings, and replmment deposits. Copper deposits in shear zones, and sulfide deposits of one or several metals in fissure veins are widespread. Notable locally are breccia fillings (Dolomi ares), complex lode deposits (Salt Chuck and Rha.gyam mines), and impregnation zonw of molybdenite, Known placer de- posih are local and insignificant.

The mines and pmqwch may mnmuiently be p p e d within distinct are= 02 development for similar metala as follows: Kassan Peninsula-Karta Bay (copper and copper-iron deposits) ; Hetta Inlet deposits (mainly copper) ; Niblack-North Arm (Moim Sound area deposits (mainly capper) ; the gold deposits- of Helm Bay on Cleveland Peninsula ; Dolomi-Cholmondeley Somd area depafts (gold, silver, lead, zinc) ; and the Hollis-Granita Mountain-Pin Peak ama gold deposits. A h a 1 gronp includes mines and gmsph not; within these a m Mmy writers have clescribad the mining arms and individual mines and prmpwts (sea "Selected bibliographyy7).

Kmmn P ~ K w t r s Bay -.-The minw and prospecte of Kamn Peninsula am contact-metasomtic deposits of copper and iron at or near the contact of instrusive rocks with country rock. The deposits, chiefly magnetite and chalcopyrita, commonly replace caI- camus rocks, limestone, and greenstone. Fissure-vein, replacement, and dissprminsted capper sulfide deposita with srndl gold and silver content also ocmr. For a few miles on either side of Thome River, shear-zone deposits are fairly common. !l%e complex lode depaeit at Salt Chuck Mine is unique in that appraciable palladium has been produced. Many of tbs mines of this a m ham been dmribed in detail (Warner and others, 1960 ; Wright, 1915).

Rat tQ I&t area.-Contact-metasomtic deposits of copper and iron are localized at; the contact between m t r y rock+specially the limestons-and igneous intrusive rocks of Jumbo, Copper, Bill ia, and Green Manster Mountains. CThaIcopyrite and magnetite a m the chief ore minerals, Shear-mne, &sum-vh, and disseminatd deposits occur farther from the; intrusive masses. Small amounts of gold,

GEOLOGY OF THE Cam QUADRANGLE, ALAS= B-35

dm, I d , and zinc are moverable locally. Several mines of the area b v e been dmribed in detail (Kennedy, 1958 ; Wright, 1915).

Ilri!3bkkiVrth Am (Y& X d ) --The minw and prospects of this area are located chiefly in shear-zone and fissere-vein deposits of copper sulfides with varying mounts of gold, silver, lead, and zinc.

H e h Bay arm m C'b.ow P&muZa-Th~ gold mines and prospects along the west side of Helm Bay rrra loc&ted mainly on fimm-vein deposits in panstone schist. Gold 00c:urs free in quartz or combined with sulfides. Small placer deposits have been reported locally (Buddington and Chapin, 1923, p. 355).

Dobd-CiWZmmdeI..y S d ma7Salfide deposits of gold, silver, lead, zinc, and m e of copper am I d z e d in mins or as replacement dewits along &ear zones and fissures; b d a veins and replm- mant deposits are the common types. The chief are minerah are galena, sphalerite, and of silver md copper, and some free gold.

0 t h ~ ~ . - - O t h ~ r mxttered m i n e d deposits are m d y sulfides of mpper, lead, zinc, or molybdenum. Vein d e p i Q locally contain free gold or gold combined with snlfides. At Mount Bur- nett, an nltmrnrsfio intrusive- mass conkins pods m d im@r hdiw of the oxides of chromium and iroa The a m is mapped d de scribed in detail by Kennedy and Walton, (1946). Molybdenite, occurring as impregnations or in quartz veinlets, is noteworthy on Baker and Noyes Islands. The mUPrenCevg on Baker Island have been mapped and described in detail (&binson, 1946). A close spatid relation is noteworthy between photointerpmted faults and shear zonas md many sulfide deposits in shear zones or b m i a veins. Among these are the copper deposits the Big Harbor mine, at the Nancy claim, and the lead deposits on Coronation Island.

C;r,M.-Gold occurs either combined with the sulfides of other metals {iron, copper, lead, zinc, and silver) or as free gold. The deposits moat mmmody are quartz veina and sulfide impregnation zones Eo a greater or lesser d p controlled by shear zonas and ksures. Mmt areas of prospecting and development are within the greenstones of the Helm Bay area and in the black daty argillite of the Hollis- Granite Mountain sma. Moderate amounts of gold have bean recovered from wntact-metamorphic deposits locdly, ~ n d small amounts Rave been recovered from residnal deposits m l t i n g from weathering of gold-baring veins dong the west side of HeIm Bay. Pohntial

placer deposits are thought by several writers to have, been dissipated or c a v e d as a result of glacial action.

Copper.-The copper mines of Prince of Wales Island have pro- d u d mom than 27 million pounds of metallic copper, mainly be- twaen 1906 and 1918. A large part, of the copper was produced from the contact-mehmorphic deposits of h t m n Peninsula and Heth Inlet where magnetite, chalcopyrite, and p e t s comprise the chief om minerals. Bornite is an ore mineral in the Salt Chuck deposit. Copper deposits in fissure veins and shear zones am widely distributed throughout ths quadrangle ; chalcopyrite is the chief ore mineral but other sulfides and oxides are present locally, Secondarg copper minerals am nowhere in sufficient quantity to be mined without the primary sulfides.

Jm-The iron deposits of Kasaan Peninsula and Hetta Inlet a m contact-mebmorphic deposita in which magnetite is the chief aoarca of the metd. They are commonly small d e p i t s of high-grade om containing negligible amounts of titanium and phosphorus but much sulfur. Large pyrite deposits occur Imally as in the complex d e p i t s of the Khayyam mine. Titanifemus magnetite forms a large poten- timl source within the Mount Burnett mafic intrusiveboiEy.

Silver, lead, and eim.-Potentially workable d e p i t s of silver, lead, and zinc are not plentiful. Deposits of the sulfides of these elements are most abundant in the Dolomi-Cholmondely Sound area in fissure veins, breccia veins, and replacement deposits. Small amounts of silver, lead, and zinc have been recovered as byproducts of copper and gold mining. The isolated lead occurrence on Coronation Island is noteworthy.

itfolybdenm.-Scakted deposits of molybdenite have h e n r s parted within the quadrangle. Small amounts of the mineral occur in contact-metamo~hic d e p i t s , fissure veins in dioritie rocks, and ~9 disseminations in schist. The low-grade deposits of Brtker Island are ddescribed in detail by Robinson (1946). M' lnor accurrenms are mprted in the Hetta Inlet area, on Kasaan Peninsula, and on Noyes Island.

0 t h m~-PdIadium has been -red from the Salt Chuck mine in m i a t i o n with complex sulfide deposits disseminated in g a b h and ppxenita Kennedy and Walton (1948) state that further investigation of ultramafic rocks may reveal minable qnmti- ties of the platinum metals. The composite stock of ultramafic mks comprising Mount Burnett

wntains small bodies of chrurnih. T h e d e p i t s are of inferior grade (Kennedy and Waltun, 1946).

Nickel has k n ~porkd only as tracm in soma sulfide deposits. It m u m in mme ultramafir: m h of southemtarn Alaska but is not mporkd within those of Craig qndrangle. Bismuth in small quantities w u m at some mines on Cleveland Peninsula (Wright and Wright, 1908).

Not far to tha south in the Dixon Entrance quadrangle, recent dis- coverim of primary uranium and thorium minerals m i a M with hematite and minor m n d a r y uranium minerals indicats the possibility of similar deposits in the Craig quadrangle. A reconnsissa.nm of many mines in the Craig qurtdrangle indicated no potentialities for high-grade uranium o m {Houston, 1952 p. 1&17).

The most commercially impoant nonmetallic deposits are those of marble and limestone. Marble deposits have been prospected and quarried in wveral areas where limestone has been metamorphosed b mrbls suitable for dmrative building stone. These deposits are dwcribed in detail in the Rolorni-Dickmnn Bny area, and on Ddl, Marble, Hem&, and Kosciusko Islands by Burchard (1913, 1920). The only recently operated limestone quarry is at View Cove, DalI Is- land. A vast m e w e of high-calcium limestone' is the massive Sil- urian limestone expmed over much of Heceta, Tuxelcan, and Kwia- sko Islands, the western part of Prince of Walm Island, and many a d j m t smaller islands. The most raeent work of the Geological Survey involving this limestone has been the mapping of Hecetn and Turrekm islands by G. D. Eberlein in 194749. Within the quad- ranglq large masses of p n i t i c and diorirtic intrusive rock exist. Their potentialities for building stone have not been evaluated nl- though the central parts of thew m a w should provide g o d possibil- ities where crosscutting dikes are not too numerous.

Bitminous material m u m as a cementing agent in a fetid biaclastic limestone k i a on some small islands in Tuxekan Passage, 1 mile or less south of the tip of Tuxekan Island. Labratory tests by the Ge~logical S n m q have indicated that khis material is probably not a petroleum deivat ive. Other nonmetallic deposits are few md sca t ted . Barite occurs

as replmment d e p i t s on Lime Point (Hetta Inlet), find a minor amount has been reported in a fissure vein on Ste. I p a c e Island. Gmphita occurs IocaIIy in m n l I quantities in carbonaceous slate, phyllits, ar schist, but no l a w concentrations have been reported. Refractory m~terials h ~ v e been reported but are unevaluated as to grade or meme; dunite is described at Mount Burnett (Kennedy

and Walton, 1846, p. 84) and siIIimanite i s reported on the southern end of Deer Island (Buddington and Chnpin, 1929, p. 335).

SELECTED BZBLIOQRAPHY

Brooks A. H., 1902, Prellmlnary report, an the Ketchikan mining dhtrict. Blaslra : U.8. Qml. Surrey Prof. P a ~ r 1,120 p.

Buddington, & R, 1923 Mineral deposits of the Wrangell district, southeastern AIfiBka : U.8. Geol. Snrvey Bnll. 739.

Buddington, A. El,, and Chapin, Theodore, l!ZB, Geology and mineral dewits of southeastern Alaska : U.8. Geol. Survey Bull. 800,393 p.

Burchard, E. F., 1913, Marble resource8 of Ketchikm and Wrangell &strSctrr [Alaska1 : U.S. Geol. Survey Bull. 5 4 2 4 , p. 52-71. 1920, Marble resources of southeastern Alaska: 17,s. GeoL Buwey Bnll.

682,118 p. Cappa, S. R., 1M1, Glaciation In Alaska: U.S. Beol. 8nmey Prof. Paper 17bA,

p. 1-8. Chapln, Theodore, 1910, Minlng developmenb in mutheastern Alaska: U.8. -1.

8arrey Bull. 642, - 1018, AZining developments in KetchIBan and Wrangell mfnlag dietrich [Alaska] : U.S. Geol. Survey Bull. 662-B, p. -75. - 1919, Mining developments in KetchFkan dlatrict [AImh]: U.S. Geol.

Survey Bull. 69B, p. 85-89. Eonston, 3. R., 1912 Soatbeastern Alaska, gL 4 of PreUminary 8urnmary of

reconnais~ance for uranium in Alaska, 1951 : W.8 . Geol. 'Survey Circ. 1% Kennedy, G. C., 1953, Geology and mineral depwlts of Jumbo Basin, south-

eastern AIamka : U.S. Geol. Survey Prof. Paper 251,46 p. Kennedy, a. C.. and Walton, M. S., Jr., 1996, Geology ana asmlated mineral

deposits of some ultrabasic rock bodies in southeastern & , l a s h : U.S. Geol. Survey Bnll. 941-D, p. S(CS3.

Kirk, Edwfa, and Amsden, T. W., 1952, Upper Silurian bmchippoda from south- eamern Alaska : U.S. Geol. Surrey Prof. Paper 2SS-C.

Martin, G. C., 1928, Mesmofc stratigraphy of Alaska : U:S. QeoL B u m q gpll. T76.

Meree, J. B., Jr., 1919, Lode mlninp in h e Juneau and pAdkran distdcts CAhaknl: U.S. Wl. Survey Bull. 714-3, p 1OS128.

Payne, T. U., X I S , Meaozoic and Cenozoic tectonic elements of &ask& : U.8. -1. Survey Miw. Geol. Inv. Map 1-84.

Robinson, G. D., 1948, Molybdenum invdgatlons In southeastern Alaska: 0.8. GeoL Barvey BulL 947-B, p. 31-38.

Roehm, J. C., 1946, Some high calcium Iimestone dewits in southenatern A W : Terr. Ahska, Dept. Mines Pamph. no. 6, p. 1 4 .

Sahburg, C. L., 1960, Geology of part of Prince of Walm Tsland, U s k a : U.H. Ueol. Bnrveg Bull. l m H , p. 2!3%362.

Bmitb, P. S., 1914, M e mining in the Ketcbikan reglon [Alaaka] : U.S. Geol. 8urvey Bull. 992-B, p 7- - 1939, Areal geology of Alaska : U.S. Qeol. Sumy Prof. Paper 192,100 p. - 104% Occarrences of molybdenam minerals in Alaaka : U.B. 3.1. Hurvey

BuL 9264. p. 16S16& Twenhofel, W. s., 1- Some lead-zinc and zinc-copper deposit@ of the Ketchlkan

and wale^ districts, A l a a : U.S. Gml. 8 B m e y Bull. W, p. 7STS.

GEOLOGY OF 'PKE CRAIG QTJADWGLE, ALASKA m g

Twenhofel, W. S., R e d , ,T. C., and G a h , B. O., 1949, Some mfnecal investlga- Zions In southeastern A l a ~ k a : U.B. Geol. Survey Bull 963-4 ip. 1-4s

Twenhofel, W. S., and Ralnsbury, C. L,, 1958, Fault patterns in mtheastern Alaska : Geol. Soc. America Bull., v. 69, no. 11, p. 1431-144!L

Warner, L. d, Gddard, E. N., and otbera, 1980, Iron and copper deposit8 of Kaman Peninsula, Prince of Walm Idand, southeastern Alaska : U.S. -1. Survey Bnll. 101)0,136 p*

Wrlghe, C. W., ISM. Nonmetdllc depmita of mutheastern Alaska: U.S. M I . Snwey Bnll. 28-1, p. 5 W . - 1BM. Lode mining in southeastern Alaska, and nwmekalliteroua mlneral remum of southeastern Alaska : U.S. Oeol. Survey Bull. 314, p. 47-81.

-XW, Lode mining in outh he astern Almka, and the building stones md materials of sontheastern Alaska : U.S. Geol. Survey Bull. 345. - 1909, l ining in southeastern dlaaka : U.8. Geol. Survey Bnll. 379, p. 87- 88. - 1915, Geology and are deposits of Copper Mouataln and Eaaann Peninsula, Alaska: n.S, Geol. S m e y Prof. Paper $7,110 p.

Wright, F. E., and Wright, C. W, 1908, M e mhlng In southeaatem Alaska: U.S. Geot. Samey Bull. 284.

-I=, The Kekhikan and Wmngell mlnlng dl~tricts Alaska : U.B. Fleol. h r v e s Boll. 347,210 p.

INDEX

A P e e A m t f ................................. B-6 Awlal pbb@mpha, a la mapping.. 3 $ S 8, 10, 11,

1414lf&l%l9.N,27,~,Sa,33 An- Omk ........................... 24,3a, 83 AreeeQuve .................................. ?a

B

Bbb? f h d , intmal~ ................ R ............................ mapping oL $16 18

mo1~bdentrmdeposlts---------------8~17785.3s Barlte ................................... 8, IT, 37 Blg Ksrboe mlne ............................. an Blg Ralt hk ................................ Is Aillle Mountdn .............................. 34 Black Bear Take ............................. 27 DImqnlznI faland. ........................... 17 Bomu do Flnaa ............................... s8 Rnrnlte .......................................

............................. P1romvn Inland 10

"

Devonisn s9stem-kmtlnuad a m Vpwr Dovonlan r m t ~ .., ............. ... B-m u ~ w r nlsb m d w h i o mb ............ I$-18

MokmsnTJa~ ................................ 17, 87 . M v e r b h d a .............*.+................ 14 hbrniam ..............+..... ~,l@,l?,S$&,w, rn DolomlBulaer antIeIlnmlaa~ ................. a0 Darn b k e m& sinc and lssd d e W t a ....... 8 h m l l n l l k e k n h ......................... 24

E Ea~lahsnd .................................. 2a ~t mpltan ~aland ............................ la EI Capitan ........................... la Emerald Bag ................................. 27 Emdt Sound ................................ a7

bland ,............+. .a*...... 6 , 8 1 28.29,

P Fndta.age ..... ............................. $ 4 1

effeetonr&&Um -+.-------.------ 6, 81 ..................... m m n m $11 14, 16, m, 32

Cirque! ...................................... 424 Clamnm Btralt ............................. "= Cleveland Pwhnsalll ......... 4 CHmste ...................................... .................................. Clover BI J .

Cod .......................................... 28.87 Coal Bay ., .................................. am Em btbolltb, rrhtm I I-

= in-m mclcr-*----------- 7*qqz - r r e .................................

Copper 1Momtdu .......................... 4 24 84 Corondm Lslsnds 19, 20 ............................ coronation L ~ I W ~ .............. ... B, EL^, 8% 85, ae C d E , -La O, Is ................................

D

mn r a l a a ~ ............ 11, t ~ i - 1 , ri&ia, ~&%Bs.$I ............................ Dear Islaad... lo, H, $8 aevonjsn *, mddfla w l d 0 m&l .... 17-18 ............................... S& extent I@-20 ........ m r i g h m e r a ~ a p h s sapuenm 17

................................. hdl s 14 if, 19 graywscbtu~ mqwnce .................. 1s llmemne ................................. 19 lower slnh and valeanin mcb ............ 17 mineral depxita, ........................ 11 8tratigrapble relatlm ................. 1617, 18 atructnre .............................. 14 18, I9 tbicknes ........... ... ............ 17,18,1Q, 20

0 u a h k . .......... 8n L . . * . . * 10 OWmI drVt ....,.., ... ....,............ 7 , N 18, OladaElsb, a matal., ..,................ W tfladatlon ........................ 4, 4 8,28,24,26.28 Omaite M m t a i e ........................ 17, N, S6 Ornphlte ..................................... 1 4 37 Green ?.roaster Momhh .................... 34

H Rm Island*..*.....+.*+*.+**landlandlandlandland..-landlandlandlandlandlandland l8 ................................. Hark- RIvar a Uwta Wand ............. a,4, 12 18,14,!6,?n%Xi, a7 ........................... Helm Bay %24,27,,84, 36

..................................... Ilcmatlte 37 Ijctm rol*tam, ~ o p w r d IronBeWk.. $4, 84B

.......................... l?It'U~Ivcl melts- 21, 34 Hnmt [catrm ............................. s8

........................... rmi~ptng of.... 4, 8 .......................... m h o r d Bepod& 8

........................... ~ o l l l s , Alnska B, 17~84.86 ............................ H~daburg, Alaskn 6

I IndusMtp .................................... 6

........... Intrualve * m a mh, we- Zs. m.23, P dforltic ................................... 29 gmnbte and mltik ..................... 26

B-41

parr f n ~ ~ * C o n ~

..-... h-gdnnit------------+------- ..... m85c mid u l m - - - - - - - - - - - + - - %'

mlntlon ro o ~ e deWClrm-----------+-

J

~ ~ ~ w ~ ~ ~ ~ ~ t s - - - - - - - 481 - fnlds- ............................... ag - P ~ K oL---. --....---....-........... % 8, B

f o r m i c or C m m W # ~ L ............. 22

K KMkm m. ............................ 16, la Kerta Bay -----_-----_-.-_------------------- a, w

............... Kaaasn Bay.- .-,... 1% 14 19,23,21 Kasaau Penlosalh mpper and imn deposle.. a,

17 84, 86 ........................... l a w a s m& n,34

...................... mapping of $4 1% 1&1g ..................... K ~ b r w o f aatlclinorlum a0 .................. Keku-QraVioa a y a b d m 28

Ketchlkan dlatrlct ........................... 28.24

Pam MbkmMam- ..................... S P n -.*...................*.......... Mdraktmd Z3,I .......................... Afolybdenlb t t , % a d , ~ Mount Rumstt-. .................... k Z , S 5 , 1

N Nancpawm ................................ #a ............................. N B U M B ~ Y - 14,1b,24 Niblack-North A r m sree ..................... ah .................. Noyes lalaad lg IR I?, 18.37, Bs. $8

0 ................................ o a d o w ~ aa,m O"v'"an and m ' l a w n-ms. smd extant. 11% 22

Id's-.-------------------------------- 111 1% 18 immb*b ms~m.---..----.... 11~1% 18

.......................... mimral dawsita 11 ........ 0 dr 8 wstem, @rstlgrephlo t e b t h k . 1?,18 ................................. 6tmdute I1

................................. thlclmess 4 18 YoImnic rock8 a d eEb-te---------- la .................................... 0- I s b a 14,82

-

I4

~ a m n m ..................... ~ , I ~ , I ~ , I S , = , ~ S Lime Point ................................... a37 ~ h e s m m ~ a . . 4, n, n .............................. h l t i I g h d . . ................................ la, 17

M MdmU8DIwIsland ........................ m

..................... structure 16 14 16 18,28,30 PrInceoiwBh-Kdnmmum----------

Q

m, mirmral & ~ b .. M ....... - demdta-. .................... %25 Recent d e W t P . .,.,-.,-,--......_-- ZS

MaOlwZLts.. .................................. * m Marble ............................. !&B,1417, I & = XTarblo&artehtm .......................... B Mmrbls Ishnd-. ........................... 1% 16, n Meuwlle group otbIm& ..................... 18 Mcmls, blmuth .............................. 3i*

chmmlum .............................. & q33 Eopwr. ...................... & 8,11,11, W W 80 @old ............... ... 8.10,ll.l7,22.Z4,as,34.35 Iron ............................ 3,417,34.35,38

........................... Icud. 3. b 11,M. 8% 38 motyWauim ......... ....- ......... 3, 17,35, 30 nickel .................................... 3,37 pnlladiam ............................. 17.M.36

.......................**.. platlnum gmup a,36 allver ............................... I L 34, a 36 umniumand thorinm... ................ 37 cino ............................... 3,aWWaB

Mebtammphlsm ............................... 7,10 MhemI dewaih.. .. 8,8,10.11,14, l i . a,%, 82,#-3A Mlws, clrrrent actlPlty ....................... d

d c v ~ l o ~ m ~ n t . . . .......................... 17 dl*lbutlon ........................... sa,8a-8cr pmvlo~sa rnrnnndsmna .................. 2 3 , 1 pmductim ............................... 8,%4

R Reslmt.-----.--..---------------------- 14

6 St. I p a m Idmd --------,+-+-+----*--.--+-- 17, S7 B a l m w l a k e ??,m Salt Chnch r n k ..----....-..-,.------------ 9(, 36 S~rr hiberto Bsy --_.-------_-.,---------- I6,lf, 18 SanCrlstovalChmnel ....................... 17,m E m ~ s m d o a n t t c ~ n m ................. 90 .................. S a n Fernando Island. 4 lf,lQ, SP San ~ u a n BsuUats I&& ..................... 33 Snrkar Cove .................................. 12.14 Peymorv~eosyncUm --.--------------.--- 23,28,YI

............................... Shellkot Island ZU, 21 Shoreline. charsctsrlstb, relation to amctunr

and mmposlUm 01 rocks --.--.-+. 4 16 S l l l i d b ................................... 14% Slludm sysbm, ~ 1 a x t e n L ................. 18.14

fodh .... ...,-..-..---.-..--IsIsIsIsIsIsIsIsIsIsIs IS. 15 lime- und intrsmrmatlaaal tmglom-

........................... emta.. l+la mlttf~raldepostts ......................... 14

........... atratlgtaphic relatIonsi 14,lB. 17,18, 19 gtmttpmphlorehMon8 .................... 15

INDEX

B w t h P w ................................... ZS Bphalerlts .................................... 35 swmy Creak ................................. 2 x 3 3 ....................... Gtraams, dsvabpmtnt 5,8,25 .......................... relaliontofn~hs 6 3 1

............... Rtruetnrcs, 8ntIelinal....... 19,88.30 anticUnd.. ........................ 6, A, IS. Su 8wckMb .................. 15 ,1S ,20 ,~SSu3 31 ................... S ~ C M O ~ 4 EA 16 s,m, a1 hend ............................ 24, W, 81,31.33

B U ~ W Z I F ~ S U ~ ,.---..,...,. ... 1% la. a, n, n, aa B u k k m IsbM ..................... 18,18, IB,27,32 ButAde deposlta .-,+.......+...-..+- 8,14 1E,W 85 ewoetwatar LKb ----.---.-...-*- ...a*...-... 11

T M ........................................ 6 Te mm?a-,...-.-..---*. ....................... as Tertlnrp $yc&tam --.---.--..-----+*++----.----- Zl Thorne Bay .................................. 13 Thorne River ....----.------ ?4,2?,S'P, 8&34 Thome River !inenmaat ,-,.-.---.---..-...- 82 Torr~NatIwslForedt !l Transportatlw ..-.-----..---..-.---..--.-- .., 6 Trisssic system -+.-_._.._..---------------.--- PI-= Tmcarlem Bay ....................... 8, lP, 10,2483 ........................ Tnxekm Island-. 3,/ 1197 T u x e k m Passam .......... ..++-+--- 14 14 1Q,% 37 ............................ Turekan sj'nclh 14

VaUeya, g W . ........................... .. 6,624 Vegetsttm ................................... 0 Wew Cove ................................... Bf ............ V o I d c mka, we-.. 19 l?,IB,p 1% 83

miner81 deposlb -.......+..-,-...---.,. 17 ............. wuww .., ~ ~ , ~ ~ n , ~ ~ , z s , a a

stratlgrsphic mlatlDDI ,.-...----- q 12,16,l&, 18

W .............................. Wadlelgh I s h d 10 ....................... W e l c s ~ p , ~ g e 7,8,9,11,16

aml er-t .............................. S,Q, 16 Rreenskme unit ........................... 9,14 llmcsVlne unit ............................ 0 mineral d a m t s .......................... 8 mh1st and llmeptone odt ............... .. u stratlprsphto rolatimrs ...----...+-.---- 8.1118 structure ................................. 8 kuwnrnphlo s r p m d m ~ ,,-,----.--..--. & 9

W m n I s b d ..........--_---------.-+----. II WrangeIl-RevllWgedQ &-It. ........... ... 7 , l O

areal ertent ............................... 9,10 mstahe schlsb md ph ylllta adtit. ....... 10 intrusl*~s mcks ........................... 1& W mined deposits ....-..........--_.-.---- 10 phyllite. quartzita, and && unit- ------- 10

Geology of Craig Quadrangle Alaska

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