135-83BA-2HSMEAR SLIDE SUMMARY (%):

Clay

COMPOSITION:

Accessory miner

ClayFeldsparForaminilorsGlassNannolossils

SITE 838 HOLE A CORE 2H CORED 3.7-13.2 mbsf 838A-2H 1


o 8

I P

10YR3/3To

10YR4/2

10YR3/2

10YR4/2

10YR4/3

10YR3/2

10YR4/3

Description


Major lithology: CLAYEYNANNOFOSSIL OOZE, very darkgrayish brown (10YR 3/2) to brown(10YR 4/3), generally structureless.Pumice clasts up to 18 mm in diameteroccur scattered throughout.

Minor lithology: VITRIC CLAYEYNANNOFOSSIL MIXED SEDIMENTpresent within burrow structures inSection 3,146-148 cm.

135838A-3HSMEAR SLIDE SUMMARY (%)

TEXTURE:

SandSillClay

COMPOSITION:

Accessory mineralClayForaminifers

2,130M

85105

s —520

5,8

M

9010

5

10

7,40M

101377

308

SITE 838 HOLE A CORE 3H CORED 13.2-22.7 mbsf 838A-3H


55 t F O

O

O

O i

10YR4/3

2.5Y

10YR4/3

10YR3/3

10YR4/3

Description


Major Irthology: CLAYEYNANNOFOSSIL OOZE, brown to darkbrown (10YR 4/3). generallystructureless. Scattered dasts includepumice fragments up to 3.3 cm indiameter and a rounded ash clast 2 cmin diameter (Section 2, 85 cm).

Minor lithologies: VITRIC SAND WITHFORAMS, grayish brown (2.5Y 5/2), innormally graded, planar-laminatedintervals from Section 2,109 cm, toSection 3,10 cm, and in Section 5,from 2 to 8 cm. Pumice clast, 2.5 cm indiameter, occurs at the scoured basalcontact in Section 3. The uppercontacts of these intervals aregradational with the overlying clayeynannofossil ooze. VITRIC CLAYEYNANNOFOSSIL MIXED SEDIMENT,very thin (2 mm) layer in Section 7,40cm. Distinct but irregular boundaries.May represent disrupted fine volcanicash layer.

135-83BA-4HSMEAR SLIDE SUMMARY (%):

TEXTURE:

SandSillClay

COMPOSITION:

Accessory minor;ClayFeldspar

1,100 3 , 8 00 D

eo3010

ils Tr10Tr

100

5

5,61D

100

Tr

6,73D

100

5

SITE 838 HOLE A CORE 4H CORED 22.7-32.2 mbsf 838A-1H jl 1

GraphicLith.

: L J. J. -•I A X J •

Structure

_ Ck. _

I P

2.5Y6\2

2.5Y5\2

10YR3/3To5Y

2.5/1

10YR4/3

Description

CLAYEY NANNOFOSSIL OOZE andVITRC SAND

Major lithologies: CLAYEYNANNOFOSSIL OOZE, dark brown(10YR 3/3 to 10YR 4/3), generallystructureless. Scattered clasts includepumice and mud clasts. VITRIC SAND,light brownish gray (2.5 Y 6/2) tograyish brown (2.5Y 5/2) and black (5Y2.5/1). Very coarse grained andmoderately well sorted, withsubrounded to angular grains. Threethin (4 to 9 cm), fining-upward beds areintβrbeddθd with clayey nannofossilooze in Section 4,27-135 cm. Adiscrete vitric volcanic sand bed occursin Section 5,22-72 cm.

Minor lithology: VITRIC SAND WITHCLAY AND FORAMS. Light brownishgray (2.5 Y 6/2). Structureless.

135 838A•5HSMEAR SLIDE SUMMARY (%):

TEXTURE:

SandSillClay

COMPOSITION:

Accessory minorsClay

0

100

ils 5

0 5, 50

454510

7

5.100D

801010

Tr10

SITE 838 HOLE

Met

er

;

0.5

I.U_

--

-

-

•

:

-

—

—

-

—

—

-

-

-

_

•

•

—

-

11

11

•

GraphicUth.

S S• l • • •

':''•':'••':'••':'

Sec

tion

—

4

—

5

—

7

X

Age

<D

<5o<P

Q.

%

A CORE

Structure

F

O 1

' F *

_ « _

= •O I F

t

5H

Dis

turb

>j

>

j!

>

>>>>>>>>>>>>>>>

j

Sam

ple

S

S

S

Col

or

10YR4/3

2.5/1To5Y3/1

iY 2.5/1

CORED 32.2-41.7 mbsf

Description

VITRIC SAND

Major lithology: VITRIC SAND, black(5Y 2.5/1) to very dark gray (5Y 2.5Y3/1), normally graded intervals inSection 1, from 70 to 150 cm, and

Planar-lamination occurs in 2 cm thickintervals in Section 7 at 11 and 30 cm.Rounded dark brown to brown (10 YR4/3) mud clasts of clayey nannofossilooze (up to 4 cm in diameter), occur inSection 2 from 0 to 105 cm. Isolatedmud clasts occur in Section 4 at 20and 100 cm In an otherwisestructureless interval.

Minor lithology: CLAYEYNANNOFOSSIL OOZE, dark brown tobrown (10YR 4/3), generallystructureless. Mottling occurs at thegradational base of these intervals inSection 1 at 70 cm and Section 5 at 7cm.

838A-5H M 1

135838A-6HSMEAR SLIDE SUMMARY (%):

SITE 838 HOLE A CORE 6H CORED 41.7-51.2 mbsf 838A-6H , 1

1,80 2,95 6, 110 CC.3

COMPOSITION:

Accessory minorClayFeldspar

05] ^ Λ

GraphicLhh.

«

m±>W 7 1

Ag

e

Structure

= o

10YR5/3

10YR6/2

10YR6/1

Description

VOLCANIC GRAVEL and VITRICSAND

Major lithologiβs: VOLCANICGRAVEL, light gray to gray (5YR 6/1),generally structureless (partly due todrilling disturbance), and poorly sorted,containing mud clasts of clayeynannofossil ooze. VITRIC SAND, lightgray (10YR 6/1) to brownish gray (10YR 6/2), with thin- to medium-bedded,normally graded layers. Thin bedoccurs in Section 1,0 to 12 cm.CLAYEY NANNOFOSSIL OOZE,brown (10 YR 5/3). structureless.Occurs in Section 1,0-150 cm, as athin bed in Section 7,14-19 cm, and inSection CC.


135-838A-7HSMEAR SLIDE SUMMARY (%):

TEXTURE:

SandSillClay

COMPOSITION:

Accessory mineralsClayFeldspar

1,140 2,127D D

100

TrTrTr

100

35

10

SITE 838 HOLE

I M

eter

i j j

•

;

;

**

;

;

1

-:

GraphicLith.

v v*I I I<*:*:*V V**************V VV %• V ********&#V V

V V* * * ********VVV*******V**

v v••**************•••••-M••••4V V V

1 Sec

tion

1

—-2

—

3

4

5

6

T

A CORE 7H

Structure

MM* + F

iu tF

O

i ro

o

o

1 D

istu

rb!

!•

|

ii

iijI1!

!

i

ji|ijj

iijjji

i

jiiijj

iiiji

{j

Sam

ple

s

s

Col

or

10YR7/1

10YR6/1


Description

VOLCANIC GRAVEL

Major Iithoiogy: VOLCANIC GRAVEL,light gray (10YR 6/1 to 10YR 7/1),generally poorly sorted, withfining-upward intervals from 2 to 50 cmthick. Pebbles are very angular tosubrounded and up to 4 cm indiameter.

838A-7H ] 1

....

135-83 SASH

SMEAR SLIDE SUMMARY (%)

TEXTURE:

Sand

Sill

Clay

COMPOSITION:

Clay

Dokxi>tβ

Feldspar

2,44

D

100

ils Tr

100

Tr

3,20

D

2

98

Tr

35

Tr

Tr

5,50

D

10

90

30

SITE 838 HOLE A CORE 8H

GraphicLit*.

JL JLTf "L JLJLT••JL •I•T

CORED 60.7 - 70.2 mbsf 838A-8H : 1

Structure

I p

s

5Y5/1To

2.5Y5U

2.5Y5\4

5Y5/1To

2.5Y5U

10YR4/3

Description

VOLCANIC GRAVEL

Major lithologies: VOLCANICGRAVEL, gray (5Y 5/1), poorly sorted.Contains numerous clasts of clayeynannofossil ooze (up to 15 cm Indiameter), mafic rocks, and pumice (upto 7 cm in diameter). CLAYEYNANNOFOSSIL OOZE, brown to darkbrown (10YR 4/3) with mud clasts andoccasional mottling.

Minor Ihhology: CLAY, reddish brown(5YR 5/4), occurs in Section 2 from 40to 47 cm.

135-B3βA•9HSMEAR SLIDE SUMMARY (%)

TEXTURE:

Sand

Sill

Clay

COMPOSITION:

Accessory minerals

Clay

Feldspar

Glass

Nannofossils

Radiolarians

1,56

D

100

Tr

95

Tr

5

TrTr

SMEAR SLIDE SUMMARY (%)

TEXTURE:

Sand

Siil

Clay

COMPOSITION:

Accessory minerals

Clay

Feldspar

6,110M

353530

22820

1,129 2,76D M

100

10

585

45505

331579

2,112D

100

10

585

3,113 5,9M M

100

TrTrTr100Tr

1090

Tr9010

Tr

SITE 838 HOLE

Met

er

;

0.5j

:

l.<>

-

-

-

-

-

—

z—

z---

—

--

-

-

—

-

-

GraphicLith.

[•:•:•."!

> Φ~Φ~Φ"

* » :

W.J• Φ Φ ΦΦ Φ Φ i

Se

ctio

n

•>

I —

3

4

—

6

Ti

Age

A COHb

Structure

O Φ

—

O*

<>

_ *II

0

III

O

F

o

9H

Dis

turb

iI

Sam

ple

S

S

s

s

5

S

S

Co

lor

10YR3/3

5YR2.5/2

2 5Y2/0

5YR3/3

2.5Y2/0


Description

VITRIC SAND

Major lithologies: VITRIC SAND, black(2.5 Y 2/0), fine- to coarse-grained.with common bedding and planarlaminae. In Section 2,0-30 cm bedsdip up to 45°. Common mud clasts andvolcanic clasts up to 5 cm in diameter,including indurated clasts in Section 1,140-145 cm, and Section 4,40-45 cm.Also occurs as thin interbed within clayin Section 1, 34-48 cm.MUD-SUPPORTED VOLCANICGRAVEL, black (2.5Y 2/0) gravel indark reddish brown (5YR 3/3) clayeynannofossil ooze matrix. Shows anoverall fining-upward sequence inSection 6, with gravel decreasing insize from 5 to 0.5 cm. CLAY, darkbrown (10YR 3/3), generallystructureless, occurs in Section 1,17-71 cm, Section 4, 75-80 cm. CLAYWITH FELDSPAR, dark reddish brown(5YR 5/6), occurs in Section 4,143 cm,through Section 5,150 cm. Generallystructureless, but containing somepebble-sized clasts.

Minor lithologies: SANDY CLAYMIXED SEDIMENT. Olive brown (2.5Y 4/4). Occurs in Section 4,100-120cm. Clast of CRYSTAL-RICH TUFFWITH FELDSPAR AND ZEOLITESoccurs in Section 4,110 cm.

838A-9H [I 1

135-83 BΛ-IOHSMEAR SLIDE SUMMARY (%):

SandSillClay

COMPOSITION:

Aceossory mineralsCalciloClayFeldsparGlassZoolilo

SITE 838 HOLE

Met

er

1.0;

-

-

-

-

-

-

-

—

-

:

—

;

;

In

;

—

—

-

J

Graphic

Lith.

• . •.• vr-•-•

*******

• m. ^ t\f i ^ ' .

; : : : : : : :

******** * * * * *

•~. ~. •~. •~

*******

K::::*******

Se

ctio

n

1

—

3

5

6

TC(

Φ

Φc

o—

1

A GORb

Structure

Φ

- O- -

Φ

- - -

- - -

Φ

Φ

Φ

Φ

10H

Dis

turb

|

i

Sam

ple

S

Co

lor

5Y4/3

5Y3/1

5Y3/1

2.5Y 7/C


Description

VITRIC SAND and VOLCANIC SANDYGRAVEL

Major lithologies: COARSE VITRICSAND, olive (5Y 4/3) to very dark gray(5Y 3/1). Marked by an overall upwardfining throughout Sections 1, 2, and 3.Thin bed occurs in Section 6, 0-13 cm.VOLCANIC SANDY GRAVEL, verydark gray (5Y 3/1). Pumice clastsoccur throughout Section 4 (maximumdiameter 4 cm) and Section 6(maximum diameter 6 cm). Vagueplanar bedding varying in thicknessfrom 1 to 16 cm occurs in Section 4.Sections 4, 5, and 6 are poorly sortedand generally structureless.

Minor lithology: VITRIC CLAYEY SILT,dark grayish brown (2.5Y 4/2) occurs inSection 1, 0-22 cm. Containsabundant rounded clasts of induratedclaystone up to 8 cm in diameter.

838A-10H 1

135-838A-11H

SMEAR SLIDE SUMMARY (%):

Sand

Sill

Clay

Accessory i

Clay

Feldspar

SITE 838 HOLE

I M

eter

1

:

1.0

_;:-

:

:

j—

—:

--

-I

-

II11

1II |

-

-

—

z

GraphicLith.

m.>*****•*v v1*1*1*1*•t i i<> vm ,J KW I;i; : :;

nV VbV Vv vΦ Φ Φ 4

• 4h Φ Φ Φ

rΦ%V» Φ Φ Φ>x xΦ"Φ"Φ*4

V Λ*Φ* *Φ*4

1 S

θct

ion

l

•j

2

3

4

-

_

6

X

1 A

ge

1

1o51

S§:

A CORE

Structure

_ _ _

_ _ _

11H

| D

istu

rb |

jj|!j

jji

i!

jjii!j

jjijij

i

j

iiiiii

jjiit

Sam

ple

S

Co

lor

5Y3/1

5Y5/1To5Y

4/1

5Y5/1


Description

VOLCANIC GRAVEL

Major lithologiθs: VOLCANIC

GRAVEL, generally structureless.

composed of a mixture of poorly sortedpumice and angular mafic hyaloclastiteclasts that range in size from 0.5 to 3cm. Indurated mudclasts occur inSection 2, 100 cm, and Section 6, 20

cm. COARSE VITRIC SAND, generallycoarse and poorly sorted; similar incomposition to the vitric volcanic

gravel.


838A-11H 1

838A 12X NO RECOVERY


13&838A-14XSMEAR SLIDE SUMMARY (%):

Clay

COMPOSITION:

SITE 838 HOLE A CORE 14X CORED 113.9-118.5 mbsf 838A-14X ; 1

Accessory minerals TiClay 3<FeldsparGlass 55

Met

er GraphicLith.

~ ~ ~ ~

Sec

tion

1

Ag

e

Structure

Dis

turb

Sam

ple

s

Co

lor

2.5Y5/4

Description

VITRIC CLAYEY SILTSTONE WITHFELDSPAR

Major lithology: VITRIC CLAYEYSILTSTONE WITH FELDSPAR, lightolive brown (2.5Y 5/4), planar- andcross-laminatθd in the upper 16 cm ofthe core.


45—j

SO—|

55—:

SO—

β 5 —

7 0 —

7 5 —

8 0 —

8 5 —

9 0 —

100

105

110

SIS

120

!25

130

\ 135

140

145

150

135-838A-15XSMEAR SLIDE SUMMARY (%):

SandSillClay

COMPOSITION:

SITE 838 HOLE A CORE 15X CORED 1 1 8 . 5 - 1 2 3 . 1 mt>sf 838A-16X ! 1 838A-17X I CC

Accessory minerals 5Clay 4!Feldspar 11Glass 2!Rock fragment 1!

135-83BA-16XSMEAR SLIDE SUMMARY (%)

TEXTURE:

SandSillClay

COMPOSITION:

CarbonalβGoothileMagnelileNalrdilePlagioclasePyroxeneSmeclite

1.3

D

98

2

-

2

Tr

115εTr76

135-83BA-17XSMEAR SLIDE SUMMARY (%):

COMPOSITION:

CarbonateForaminilorsGoolhilβNalrolilePlagioclasePyroxeneSmβctilo

T

G

11717

Met

er |

:

GraphicLith.

Sec

tion

X

Ag

e

Structure

= -u-

Dis

turb

$

s

Co

lor

2.5Y4/4

Description

VITRIC SANDSTONE and VITRICCLAYEY SILTSTONE

Major lithologtes: VITRICSANDSTONE, olive brown (2.5Y 4/4),with faint planar laminae, from 0 to 9cm. VITRIC CLAYEY SILTSTONE,very dark grayish brown (10YR 3/2),structureless, from 9 to 16 cm.GRANULAR VITRIC SANDSTONE,olive brown (2.5Y 4/4), with faint planarlaminae, from 16 to 32 cm. Mean grainsize is 2 to 3 mm


SITE 838 HOLE A C O R E 16X CORED 1 2 3 . 1 - 1 3 2 . 8 mbsf


2.5Y4/4

Description

VOLCANIC CONGLOMERATE

Major lithology: VOLCANICCONGLOMERATE, olive brown (2.5Y4/4), grain-supported and induratedgravel, with faint planar stratification.Maximum gravel size is 1 c m Basalcontact with underlying siltstone issharply defined. VITRIC CLAYEYSILTSTONE, dark olive (5Y 4/3) withthin planar lamination. Black dβndritβs,probably of manganese oxide, occur at67 cm. Cross lamination occurs from49 to 51 cm.


SITE 838 HOLE A CORE 17X CORED 1 3 2 . 8 - 1 4 2 . 4 mbsf

GraphicLith. Structure Description

VOLCANIC CONGLOMERATE

Major lithology: VOLCANICCONGLOMERATE, olive brown (2.5Y4/4), thinly bedded, planar stratified,grain-supported with granule-sizedgrains up to 0.5 cm in diameter. Basalcontact is sharply defined with loadcasts. Occurs with alternating layers ofmedium- to coarse-grained vitricsandstone.




s

I0-

I5-

20-

25-

30-

35-

4 0 —

4 5 —

5 0 — !

tat*

6 0 —

β 5 —

7 0 —

75

βo—

8 5 —

9 0 —

9 5 —

I00—

105—

HO—

115—

! 2 0 —

185—

130—

135—

140—

1*45 '•"""

ISO—

εα-

25

30

35

40

45

50

55

SO

65

70

75

80

8 5 —

30

9 5 —

100

105—

110—

115

120—

125

130

135—

140 —

145—I

: (50—I

2 5 — —

3 0 — '. —

35--™" "•"™

4 0 — . —

SO— —

SS— —

g f j — - •

S D • "" "™™™

7 0 — —

7 5 — —

8 0 — —•

85"™— -™T

5HJ—— ^ ^

I—I ^95—IL_ SOS

—i 115

— ; J20

—! 125

; 130

!!35

! ;I4O

ii45

im•

135-838A20H

SMEAR SLIDE SUMMARY (%):

Clay

COMPOSITION:

Accessory I

Feldspar

SITE 838 HOLE A CORE 20H CORED 152.1 -153.8 mbsf 838A-20H 1 CC 838B-9R I CC 838B-10R CC

Met

er

0.5;

GraphicLith.

I

Se

ctio

n

1

<

iStructure i

if

r

Sar

πp

le

s

Co

lor

2.5Y2/0

5Y4/1

2.5Y 2,'Q

Description

VOLCANIC GRAVEL

Major lithology: VOLCANIC GRAVEL,black (2.5Y 2/0), moderate to wellsorted with angular clasts, showing anupward-fining trend. Contains up to95% basaltic fragments, with minorquantities of pumice and greensiltstone. Some black glass withconchoidal fractures (hyaloclastite)occurs. Clasts are up to 4 cm indiameter in Section CC.

Minor lithology: VITRIC SAND WITHACCESSORY MINERALS, dark gray(5Y 4/1), structureless.

838B1W WASH CORE

838B 2R Entire core was given to paleontologists.

838B 3R NO RECOVERY

838B 4R HARD ROCK

838B 5R THROUGH 8R NO RECOVERY

SITE 838 HOLE B CORE 9R CORED 210.9-220.6 mbsf

Met

er

-

GraphicLith.

Sec

tion

JC

Ag

e

StructureD

istu

rb

>S

amp

le

Co

lor

5Y6/2

Description

VITRIC CLAYEY SILTSTONE

Major lithology: VITRIC CLAYEYSILTSTONE, light olive gray (5Y 6/2),structureless.


SITE 838 HOLE B CORE 10R CORED 220.6 - 230.2 mbsf

Met

er GraphicLith.

mm mm mm -

Sec

tion

Ag

e

Structure

^ =

Dis

turb

Sam

ple

Co

lor

Description


Major lithology: VITRIC CLAYEYSILTSTONE, olive (5Y 4/4), thinlylaminated with alternating dark- andlight-colored banding.



Met

er |

;

GraphicLith.

~ ~~ *" ~~

Sec

tion |

1

Ag

e

|

Structure

Dis

turb

|

Φ

I<T>

Co

lor

5Y5/3

Description


Major lithology: VITRIC CLAYEYSILTSTONE, olive gray (5Y 4/2), withsubanguiar igneous Irthic fragmentsand rounded intraclasts. The sedimentis strongly mottled throughout due tobioturbation. Light-colored (calcareous)and dark-colored (clay-silt-rich)mottling occurs.


Met

er

-

GraphicLith.

Se

ctio

n

1

Ag

e

Structure

\

Dis

turb

>

Sam

ple

Co

lor

5GY 6/1

Description


Major lithology: VITRIC CLAYEYSILTSTONE, greenish gray (5GY 6/1),locally calcareous and extensivelybioturbated. Calcareous materialoccurs within burrows.



Met

er GraphicLith.

--TZJZJZ.

Sec

tion

1A

ge

Structure

i= """ 5

Dis

turb

Sam

ple

Co

lor

5GY6/1

Description


Major lithology: VITRIC CLAYEYSILTSTONE, greenish gray (5GY 6/1),highly bioturbated and locallyforam-bearing, with local planarlamination and load dasts.


838B-11R;j 1 : 838B-12R;] 1

s-H^^•— 5-

ISO

SITE 838

cm0

§.25 8" δ

σCO•σ

£g.

CO

50 -

100 -

150 - I

135-838B-4R-1

APHYRIC BASALT

Piece 1

CONTACTS: None.PHENOCRYSTS:

Plagioclase: Trace-1%; 0.5 to 1 mm; euhedral, single crystals.GROUNDMASS: Aphanitic to glassy.VESICLES: 10%-25%; <0.4-1 mm; rounded to irregular; distributed throughout; rarely

cavities to 2.5 mm; density and shape varies from piece to piece; one has about 25%rounded 1 mm vesicles, one has 10% elongate 0.5-1 mm vesicles; other two haveabout 15% very small to 1 mm vesicles giving them a very high groundmass porosityMiaroles: Vesicle fillings and surface coatings of calcite, zeolites, and principallyanhydrite (?-granular, striated, and cleaved crystals); also thin white spots on surfacemay be cryptocrystalline silica.

COLOR: 2.5YR 5/0 to 3/0 gray to very dark gray.STRUCTURE: None.ALTERATION: None to slight.VEINS/FRACTURES: None.ADDITIONAL COMMENTS: Only four pebbles in core; could be clasts or flow rubble. Most

interesting features are small, angular lithic clasts in the largest piece. These are 1-10mm in size, about 1%-2% total of the piece and the largest has a very fine graineddiabasic texture. Two of the pieces in the working half have similar lithic clasts. Traceamounts of olivine phenocrysts tentatively identified. Samples are pebbles withinsedimentary Unit III.

950

SITE 838

135-838A-6H-04 (13-15 cm) OBSERVER: SHE

ROCK NAME: Sparsely phyric plagioclase pumice

GRAIN SIZE: Glassy to microcrystalline

TEXTURE: Pumiceous

WHERE SAMPLED: Sedimentary Unit IIC

PRIMARY

MINERALOGY

PHENOCRYSTSPlagioclase

Quartz?

GROUNDMASSOpaques

Mesostasis

PERCENT PERCENT SIZEPRESENT ORIGINAL (mm)

COMPO-SITION

1 1 0.2-0.8 AnlO-20

tr tr <O.l

tr tr <O.l

15-25 15-25 n/a

MORPHOLOGY

anhedral to euhedral oscillatory zoning, sodic rims on some,glass inclusions rare

anhedral small fragments

anhedral most of these may be contamination asthey appear to be most common in whatwas original void space, some do appearto occur in the glass

n/a typical pumiceous glass network, fewcrystallites; there has been a lot ofobscuring infilling and it is hard toidentify the glassy framework

VESICLES/ SIZECAVITIES PERCENT LOCATION (mm)Vesicles 70-80 everywhere <0.1-1.7

FILLING

none

SHAPE COMMENTSrounded, no alteration fillingirregular, but a lot of dust andor debris in vesicles andelongate cavities, probably from

sediments andmanufacture

COMMENTS: Slide is of a pumice clast from the sedimentary section. There is a lot of dust, dirt and debris in the voidsand vesicles probably from the sediment host and the thin section manufacture; hard to describe much detailbecause of the crushing and breakage. Sample is fresh.


ROCK NAME: Sparsely plagioclase phyric pumice


TEXTURE: Pumiceous

WHERE SAMPLED: Sedimentary Unit IIC

PRIMARYMINERALOGY


Quartz

Amphibole

Magnetite

PERCENTPRESENT

1-2

tr

tr

tr

PERCENTORIGINAL

1-2

tr

tr

tr

SIZE(mm)

0.15-1

0.05-0

0.3

0.05-0

.2

. 6

.1

COMPO-SITION

An30?

GROUNDMASSMesostasis 15-20 15-20 n/a

Magnetite

Sulfides

tr tr to 0.010 mm

tr tr 0.002 mm

MORPHOLOGY

subhedral toeuhedralanhedral tosubhedraleuhedral tosubhedraleuhedral tosubhedral

n/a

anhedral

andehdral

oscillatory zoned with sodic rims; 10-20micron glass and fluid inclusionsmany with rounded and irregular edges

pleochroic in pale greens

prominent ilmenite lamellae in some.

mostly glassy, some birefringent spots

may be crystallites; hard to tell withamount of fine grained debris scattered

throughout slidebright fragments in groundmass; many maybe contaminants in fillyellow bright spots in glass

VESICLES/CAVITIESVesicles

SIZEPERCENT LOCATION (mm)80? everywhere 0.02-1.5

FILLINGnone

SHAPE

round,elongate,orirregular

may be primary sedimentary debrisCOMMENTS: No visible alteration but a lot of dust and debris in vesicles and cavities;and shattering produced in thin section preparation. Sample is fresh.

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SITE 838


ROCK NAME: Moderately phyric olivine-plagioclase basalt


TEXTURE: Vesicular, porphyritic

WHERE SAMPLED: Sedimentary Unit IID

PRIMARYMINERALOGY


COMPO-SITION

PHENOCRYSTSPlagioclase 2-3

Olivine

Clinopyroxene

GROUNDMASSMesostasis

1 1 0.15-0.3

tr tr 0.1

75-85 75-85 n/a

MORPHOLOGY

anhedral to euhedral small fragments tend to be angular andanhedral; one large glomerocryst (3 mm)of 8 grains; minor glass inclusions insome grainssmall fragments tend to be anhedral.Quench textures are common,sector zoned

euhedral, subhedraland skeletaleuhedral

n/a various amounts (1-5% rarely to 20%)microlites and crystallites ofplagioclase and pyroxene; most piecesvery glassy, some with devitrified andvariolitic groundmass


SIZEPERCENT LOCATION (mm)10-20 throughout 0.01-0.2

FILLINGnone

SHAPE COMMENTSround to rarely flattened andovoid elongate, one piece

is graded from flatand elongate to roundvesicles across its1.5 mm width

Slide is a grain mount of very coarse sand (0.5-3 mm) from a volcanic breccia unit. Some of the smallestplagioclase microlites have short swallowtail terminations that bend outwards; these look like the abundantcrystallites found in the nannofossil slides from the core; all of the pieces are very fresh; the pieces arebasically the same rock type though they vary in groundmass crystallinity, phenocryst %, degree ofdevitrification. Many of the vesicles are filled with opaque fragments (probably polishing grit), nogroundmass opaques are evident. Sample is fresh.

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SITE 838

135-838A-20H-CC (0-10 cm) OBSERVER: SHE

ROCK NAME: Aphyric to sparsely phyric plagioclase basalt


TEXTURE: Felty to pilotaxitic

WHERE SAMPLED: Sedimentary Unit III

PRIMARYMINERALOGY


Clinopyroxene


COMPO-SITION

tr-3 tr-3 0.3-1.4 An501

tr-1 tr-1 0.1-0.4

Magnetite tr-1 tr-1 0.05-0.15

tr tr 0.2


Magnetite

75-80 n/a

MORPHOLOGY

euhedral, rarelysubhedral

subhedral, euhedralto skeletal

broken euhedralgrain

n/a

small, anhedral

zoned to sodic rims, rare glassinclusions; most common in one piece;single crystals in associated withopaquescommonly twinned; glass inclusions insome; one basal section has 1/3 of itscore filled with a clear glass inclusionwith 4 spinel or magnetites growing fromthe pyroxene into the glassisolated and associated with plagioclasein clumps of up to 6 grains; it isgray-white and isotropic with includedgrains of a white, anisotropic mineral(in reflected light)a single grain in one of the pieces

plagioclase, pyroxene crystallinte(<O.Ol m ) abundant, though density andsize varies from piece to piece; apronounced alignment of microlites;often wrapped around phenocrystsscattered thorughout; many appear to bein voids and ar likely contamination;some seem to occur in the glass

VESICLES/ SIZECAVITIES PERCENT LOCATION (mm)Vesicles 3-20 throughout 0.02-1

FILLINGnone

SHAPE COMMENTSsmall ones the most phyric piece isround, the least vesicular; thelarger are other two pieces areelongate less phyric and

similarly vesicular

COMMENTS: Slide is three pebbles mounted together, all angular, glassy, 0.8-1.0 cm long, very fresh; pieces differsomewhat: the phenocryst description refers to the least vesicular piece; one of the more vesicular pieces isaphyric, the other sparsely phyric with the single olivine phenocryst. Sample is fresh.

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SITE 838

135-838B-4R-01 (0-6 cm) OBSERVER: KRI

ROCK NAME: Sparsely phyric plagioclase basalt

GRAIN SIZE: Fine grained

TEXTURE: Vesicular, porphyritic


PRIMARY PERCENT PERCENT SIZEMINERALOGY PRESENT ORIGINAL (mm)

PHENOCRYSTSPlagioclase 1-2 1-2 0.2-1.0

Clinopyroxene tr-1 tr-1 <0.5

COMPO-SITION


Magnetite

Sulfides

40

1-2

tr

40

1-2

tr

n/a

<O.l

<0.03

SECONDARY REPLACING/MINERALOGY PERCENT FILLINGFine grained 1-2 replacing mesostasisclays

MORPHOLOGY

euhedral

euhedral

groundmass

equant to skeletal

globules

tabular, mostly isolated grains, somewith distinct sodic rimsone grain has a 0.1 mm melt inclusion incenter

extremely fresh; dominantly glassy withplagioclase and ?clinopyroxenecrystallites discernibleilmenite lamellae in many of the larger,equant grainsmost are either at vesicle margins orassociated with plagioclase phenocrysts

COMMENTSthere are a few small patches of the groundmass which show asmall degree of breakdown to fine grained green-brown clays.


SIZEPERCENT LOCATION (mm)55-60 throughout <4mm

FILLINGempty

SHAPE COMMENTSround to most large vesicleselongate are highly elongate

one is 4x0.5mm);small ones arerounded

Comments: A pebble within Sedimentary Unit III.

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SITE 838

135-838B-4R-01 (0-2 cm) OBSERVER: KRI

ROCK NAME: Sparsely phyric plagioclase basalt

GRAIN SIZE: Fine grained

TEXTURE: Porphyritic, vesicular


PRIMARYMINERALOGY


COMPO-SITION

PHENOCRYSTSPlagioclase 1-2 1-2 <O.8Clinopyroxene tr tr <0.4

GROUNDMASSPlagioclase 10-12 10-12 <0.2

Mesostasis 20 n / a

SECONDARY REPLACING/MINERALOGY PERCENT FILLINGFine grained 20 replacing mesostasisclays

MORPHOLOGY

euhedral-subhedralsubhedral

euhedral

interstitial

some have abundant melt inclusionsoccur in glomeroporphyritic clusterswith plagioclase

skeletal microlites, randomly orientedexcept around lithic fragmentlargely broken down to fine grainedclays; some clinopyroxene crystallitesand small euhedral magnetites can bediscerned

COMMENTSgroundmass in the lithic fragment is more broken down thanthat in the host


PERCENT LOCATION40-45 throughout

SIZE(mm)<0.8mm

FILLINGempty

SHAPE COMMENTSirregular high porosity due

to abundance ofsmall vesiclesthroughout section

COMMENTS: This section contains a lithic fragment about one cm across which is aphyric basalt with slightly largerplagioclase microlites than the host, relatively sharp boundaries with the host, and some alignment of the plagioclasemicrolites in the host surrounding the fragment. The fragment is aphyric, less vesicular, and contains moreinterstitial magnetite than the host, but overall the texture and mineralogy are similar in the two rocktypes. There are several other 1-3 mm fragments in this sample which are probably highly altered lithicfragments, but one may be a pseudomorph of a phenocryst.

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SITE 838 HOLE A CORE 1H CORED 0.0-3.7 mbsf SMEAR SLIDE ...

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