23. MINERALOGICAL DATA FROM SITES 211, 212, 213, 214, AND 215 OF DEEP-SEADRILLING PROJECT LEG 22 AND ORIGIN OF NONCARBONATE

SEDIMENTS IN THE EQUATORIAL INDIAN OCEAN1

Kolla Venkatarathnam, Lamont-Doherty Geological Observatory, Columbia University, Palisades, New York

ABSTRACT

During the pre-late or middle Miocene times, basalt volcanicswere the main source of sediments in the eastern equatorialIndian Ocean. The alteration of these volcanics resulted in theformation of smectite, palygorskite, phillipsite, clinoptilolite, ormetahalloysite-kaolinite. This rather predominantly single sourceis contrasted with the diverse origins for the sediments in theeastern Indian Ocean during later times. These different sourcesare: the Indonesian silicic volcanic source resulting in the supplyof smectite and volcanic ash; the Ganges-Brahmaputra Riversource supplying the illite-chlorite-rich sediments; the aeoliantransport of kaolinite from western Australia; and the pelagicsiliceous skeletal remains that have settled to the sea floor fromthe overlying waters in the equatorial productivity zone. Inaddition, basalt volcanics continued to be the source of thesediments in certain areas even though their importance wasreduced. The diverse origins of the sediments during the lateCenozoic time are primarily the result of the northward move-ment of the Indo-Australian plate and the evolution of theeastern Indian Ocean—uplift of the Himalayas and the formationof the prominent subduction zone along the Indonesian islands—and certain paleoclimatological changes in the region during theMiocene and later.

INTRODUCTION

The objectives of this paper are: ( l ) to describe themineral composition of the sediments drilled by DSDP Leg22 at Sites 211,212,213, 214, and 215 and (2) in the lightof this information, to discuss the origin and dispersal ofsediments deposited through Cretaceous to Quaternarytimes in the equatorial eastern Indian Ocean. Except for thepreliminary data reported by Venkatarathnam and Biscaye(in press), no information is available on the mineralogy ofthe sediments deposited during the pre-Quaternary period inthe eastern Indian Ocean.

METHODS OF STUDY

The DSDP Leg 22 sites from which sediment sampleshave been chosen and analyzed are shown in Figure 1. Thepre-Quaternary cores analyzed by Venkatarathnam andBiscaye (in press) are also shown in this figure.

Sample preparation (as described in more detail byBiscaye, 1965), consisted of treating the sediments withsodium acetate (pH = 5.0) to dissolve calcium carbonate,with sodium dithionate-citrate to remove amorphous ironand manganese oxides, and with hot sodium carbonate todisaggregate particles cemented together by amorphoussilica and alumina.

The last treatment takes away only small amounts ofamorphous silica and will not affect much of the chert orsiliceous skeletal remains. After all the treatments, sedi-ments were size-fractioned by gravity settling and decantingof the <2µ size material; 2-20µ and >20µ size fractionswere separated by sieving. The <2µ size fractions werefreeze-dried, and thick clay pastes were made with a fewdrops of water and smeared on glass slides. Two or threeslides were thus prepared for each sample. All the clayslides were glycolated and some were heat-treated. The <2µsize fractions were analyzed on a Siemen's X-ray diffrac-tometer. Where the presence of palygorskite and a fewother minerals was suspected, the clays were also examinedunder the transmission and scanning electron microscopesfor confirmation of mineral identification (Plate 1).

The major clay mineral groups identified are smectite,kaolinite, illite, and chlorite. The method of estimatingthese minerals is as described by Biscaye (1965). In somesamples, palygorskite was found to be abundant. Nonclayminerals were also observed in small amounts in some ofthe <2µ fractions. These minerals were not taken intoaccount in the estimations of smectite, kaolinite, illite, andchlorite. In the case of one sample, 214-422, with an

Lamont-Doherty Geological Observatory contribution No.1961.

When a reference is made in text to a specific sample analyzed,it is done by mentioning only the core number of a particular holeand no other details about the section of the core, interval of thesection, etc., since only one sample per core was analyzed. All thedetails of each sample are noted in the tables.

489

K. VENKATARATHNAM

65'

5°

15'

25'

55°

Figure 1. Locations of DSDP Sites 211,212,213, 214 and 215 (underscored) and some pre-Quatemary piston cores.The mineral provinces shown in the map are from Venkatarathnam and Biscaye (in press).

abundant kaolinite type of mineral, an attempt was madeto distinguish the particular mineral species by X-raydiffraction and electron microscopy. The ratio of the 7Åand 4.47Å peak heights on the diffractograms is similar tothat of metahalloysite rather than kaolinite (Brindley,1961). The asymmetry and the rather wide distribution ofeach of these peaks indicate the presence also of somepoorly crystallized kaolinite. Electron microscopic exam-ination has revealed the presence of hexagonal as well asirregular shaped crystals (Plate 1, Figure 3). These observa-tions taken together indicate the presence of metahalloysiteand well to poorly crystallized kaolinite in the sample,21442.

In some samples rich in palygorskite, a peak at 10Åattributed to illite is present as a shoulder on the 10.6Åtreatment at 400 to 600° C does destroy the 10Å peak.

The identification of the illite mineral in such cases may bequestionable and is so indicated in Figure 1 and Table 1.

The procedures adopted in this mineralogical study aresimilar to those of Goldberg and Griffin (1970) andVenkatarathnam and Biscaye (in press), thus enablingdiscussion of the significance of the present results in thecontext of these earlier investigations on the Quaternaryand pre-Quaternary sediments of the eastern Indian Ocean.

The 2-20µ size fractions were X-rayed on a Norelcodiffractometer. Besides the minerals quartz and feldspar, anattempt was made to look for the presence of minerals suchas zeolites, cristobalite, barite, pyrite, magnetite, apatite,etc. The mineral peak heights in the X-ray tracings werecompared and correlated with the results of the micro-scopic counts of the minerals on the smear slides. Theminerals were then ranked according to an approximate

490

MINERALOGICAL DATA AND ORIGIN OF NONCARBONATE SEDIMENTS IN THE EQUATORIAL INDIAN OCEAN

TABLE 1Clay Mineral Composition of <2µ Size Fraction

Sample

211-1-3211-2-3211-3-4211-4-3211-6-5211-9-3211-12, CC211-14-1212-2-3212-5, CC212-10-5212-11-3212-14-5

212-15-3212-20, CC212-25-5212-29, CC212-33-3

212-35-2

212-37, CC

213-1-0213-2-5213-5-5213-7-5213-9-6213-11-5213-13-6213-15-6213-16-4

214-1-5

214-7-5

214-11-5

214-15-3

214-19-5

214-23-5

214-27-5214-31-5214-35-5214-37-2214-39-3214-41-3214-42, CC214-52, CC215-1-5215-3-5215-5-2215-8-3215-9-2215-10-2

215-11-5

215-15-4

215-17-1

Interval(cm)

0-100-100-100-100-100-108-10

12-190-10—

0-100-100-10

0-10-

0-10-

0-10

0-10

-

-

0-100-200-200-200-200-200-200-10

130-150

0-20

0-20

0-20

0-20

0-20

0-200-200-100-100-100-10--

0-200-200-200-200-200-20

0-20

0-20

73-80

Smectite(%)

7683776651221714

4774838279

6196998997

96

76

707070738875807979

54

63

70

78

91

80

7158—

>95%>95%>95%

->95%

646864885135

>95

>95

>95

v/p RatioSmectite

0.530.710.600.720.690.430.020.000.400.830.740.790.66

0.340.660.910.820.87

0.83

0.61

0.410.390.630.700.820.740.660.530.34

0.35

0.31

0.00

0.39

0.60

0.56

0.240.22-

0.730.750.92-

0.370.540.550.620.850.390.00

0.78

0.80

0.91

Illite(%)

108

1122355769(?)83 (?)126868

211153

4

23(?)

911

9837

131520

18

7

3

5

2

9

22(?)37(?)-

——--

138

116

43(?)63(?)

-

-

-

Kaolinite(%)

118

10457

113

4020

81112

172

—5

—

_

-

21182017

816551

26

30

22

11

5

7

42

--__

100-

171816

5—1

-

-

-

Chlorite(%)

22277

1423

__1

_—

_——1

—

_

-

___1

_12

—-

-

4

5

1

2

22

-—__9

-

557151

-

-

-

Age

Quat.Quat.Lt. Plio.Plio.Plio.Plio.Camp.

-

E. Plio.Lt. Mio.Lt. Mio.E.-M. MioE.-M. Mio

_M. Eoc.M. Eoc.(?)U. Cret.

(?)

(?)

Quat.Lt. Plio.E. Plio.Lt. Mio.M. Mio.(?)(?)

Remarks

—————

Abundant palygorskiteAbundant palygorskite

____

_—

Clinoptilolite traces_

Clinoptilolite traces

_

Considerable clinoptiloliteand poorly crystallizedmixed layer mineral present

______

Lt. Paleo. PalygorskiteLt. Paleo.

C)

Pleist.

Plio.

Lt. Mio.

Lt. Mio.

M. Mio.

E. Mio.

Oligo.Eoc.Paleo.Paleo.Paleo.Paleo.(?)Paleo.(?)Paleo.(?)Lt. Plio.E. Plio.Lt. Mio.Lt. Mio.E. Eoc.E. Eoc.

Paleo.

Paleo.

Paleo.

Palygorskite

-

-

-

-

Clinoptilolite considerable

Mixed layer mineral tracesPalygorskite and clinoptiloliteMostly palygorskite

____-

___

Abundant palygorskiteAbundant palygorskite

Clinoptilolite traces

Clinoptilolite traces

-

Lithology

Siliceous ooze with ashSiliceous ooze with ashSiliceous ooze with ashMicac. silty sand claySiliceous ooze (micac.)Silty sandHard brown clayBrown clayBrown clayNannofossil oozeNannofossil oozeNannofossil oozeNannofossil foraminifera

chalkBrown clayCalc. dark gray clayNannofossil chalkBrown clayNannofossil foraminifera

chalkNannofossil foraminiferachalk

Brown clay

Siliceous oozeSiliceous oozeSiliceous oozeSiliceous oozeBrown clayBrown clayBrown clayNannofossil oozeNannofossil ooze

Foraminifera-Nanno fossilooze

Foraminifera-Nannofossilooze

Foraminifera-Nannofossilooze

Foraminifera-Nannofossilooze

Foraminifera-Nannofossilooze

Foraminifera-Nannofossilooze

Nannofossil oozeNannofossil oozeGlauconite calcareniteGlauconite calcareniteGlauconite calcareniteCalcareniteLignite claysBrown claySiliceous oozeSiliceous oozeSiliceous oozeBrown clayBrown clayNannofossil ooze with

some clayNannofossil ooze with

some clayNannofossil ooze with

some clayBrown clay

491

K. VENKATARATHNAM

scale as: abundant (A, with >50%), common (C, with50%-10%), and traces (Tr, with < 10%). Microscopic exam-ination has, in particular, helped to identify and estimateglauconite, rock fragments, and palagonite grains.

The >20µ size fractions were examined only micro-scopically. Aggregates of mineral grains (other thanglauconite and pyrite aggregates) were identified as volcanicrock fragments or cristabolite, depending upon the opticalproperties. If the grains were present as individual minerals,they were separately identified and estimated. The arbitrarylimits chosen for abundances of the different constituents,are the same as for the 2-20µ size fractions.

RESULTS AND DISCUSSION

Venkatarathnam and Biscaye (in press) distinguished anumber of Quaternary clay mineral provinces in the easternIndian Ocean (Figure 1). Briefly, these provinces are:(1) The Deccan Province in the northwestern part of thearea characterized by abundant smectite clay derived fromthe Deccan trap soils; the sediment dispersal in the provinceis by surface water circulation and turbidity currents in thewestern Bay of Bengal. (2) The Ganges (illite-chlorite)Province extending to the south of the equator on bothsides of the Ninety east Ridge; turbidity currents havechiefly been responsible in the transport of these sediments.(3) The Indonesian Province with high smectite adjacent tothe Indonesian Islands, on the Cocos-Roo Rises, and on theNinetyeast Ridge between 5°N and 14°S. This province isinfluenced by aeolian transport of silicic volcanic ash fromthe Indonesian Island arc. (4) The Australian MineralProvince in the southern Wharton Basin and on theNinetyeast Ridge south of about 15°S, characterized byrelatively high amounts of kaolinite transported by aeolianprocess from the western Australian continent. (5) TheInter-Ridge Province between the Ninetyeast Ridge and themid-Indian Ridge south of about 5°S with a high amount ofsmectite derived in part from the mid-Indian Ridgevolcanism and in part from local submarine volcanics.

The mineralogical composition and the sources ofnoncarbonate sediments characteristic of the Quaternaryperiod have changed markedly during certain times in thepre-Quaternary period in the equatorial Indian Ocean.

Site 211

The Quaternary sediments (Cores 1 and 2) containabundant smectite and volcanic ash beds (Figure 2, Table1). This high smectite abundance persists into the latePliocene (Core 3) as well. In the sediments of early (?)Pliocene age (Cores 4, 6, and 9), however, a markedmineralogical change has occurred. These sediments havehigh amounts of illite and chlorite minerals in the <2µ sizefraction, and abundant quartz, colorless and brown micaswith small amounts of green amphibole and epidote in thecoarser fractions (Tables 2 and 3). Turbidites are frequentlypresent in these Pliocene sediments. (Scientific Staff, DSDPLeg 22,1972). Another change in mineral composition is inthe Cretaceous sediments (Cores 12 and 14) which containabundant palygorskite with small amounts of smectite(Table 1). The amounts of illite (?) among the nonpaly-gorskite clay minerals are high. In the coarser fractions ofthese cores, feldspar (with some sanidine) and amphibole

(green and basaltic hornblendes) are common, and volcanicrock fragments and palagonite grains are definitely present,though in traces. It should be noted that the samplesanalyzed from Cores 12 and 14 are from near a basalthorizon.

Amorphous siliceous skeletons are present in abundancein Cores 1,2, and 3 and in traces in Core 4. They are absentin the rest of the cores (Table 2).

It is inferred that the Upper Cretaceous sediments, richin palygorskite, are derived from the alteration of in situvolcanics. If the identification and therefore the estimationof illite in the Cretaceous sediments is correct, thismineral, like palygorskite, may also be of authigenic origin.In the early Pliocene, the Ganges-Brahmaputra Riversediments, rich in illite, chlorite, and the other mineralsdescribed, have been transported to the area of Site 211 byturbidity currents similar to the adjacent QuaternaryGanges Province (Figure 1). This source has been cut offdue to the tectonics in the region of Site 211 (see SiteReport) and was replaced in late Pliocene by smectite andsilicic volcanic ash sediments derived from the Indonesianarc. This arc has since continued to supply material to theregion. The study of the piston cores V19-155 and V19-154(Venkatarathnam and Biscaye, in press) south of Site 211,but from the same Quaternary province as the site,corroborates the inference of the basalt volcanic source forthe sediments in Late Cretaceous times as opposed to thesilicic Indonesian volcanic source in Quaternary times. Noillite- and chlorite-rich sediments were observed in thesepiston cores.

Site 212This site is located in the Quaternary Australian Mineral

Province (Figure 1).Except in the Pliocene and to some extent in the upper

Miocene sediments (Cores 2 and 5), where kaolinite ispresent in relatively higher amounts, abundant smectite ispresent in the < 2µ size fractions in all the sediments of Site212 irrespective of lithology (Figure 2). In the coarsefractions, volcanic rock fragments, palagonite, feldspar, andquartz are either common or present in traces throughoutthe hole. However, in the 2-20µ fractions of calcareouschalks of the early-middle Miocene and the brown clays ofunknown age overlying the Eocene chalks (Cores 10, 11,and 15), the zeolite phillipsite is common (Table 2); in theEocene and Upper Cretaceous chalks and in the brownclays directly overlying the basalt, clinoptilolite is common.

Siliceous skeletal remains are abundant in the middleEocene chalk.

Though local submarine volcanics is the main source ofmuch of the sediments at Site 212, it appears that in lateMiocene and Pliocene times, detrital kaolinite has beensupplied to the area in greater abundances similar to theQuaternary. This observation is corroborated by the datareported by Venkatarathnam and Biscaye (in press) onpiston cores V20-163, RC 11-127, RC 11-137, RC 11-144,and RC 9-151 from the Australian Province. According toGill (1961), the present aridity and desert conditions inwestern Australia have developed during the last onemillion years. However, the temperature and humidity of

492

MINERALOGICAL DATA AND ORIGIN OF NONCARBONATE SEDIMENTS IN THE EQUATORIAL INDIAN OCEAN

O 111

< zOuαt. °

L. Pliocene

100'

c

c

Pli

oc

e

_

4OO

JSutw• \

211jr-o•-u -if

\r- si- IT — IT

ir•/ u -.i/. . ir

ui . ir . u• . u

i f - i / - ir- ir•

Ft Ft Ft

* Ci/i})' MINERAL

2 0 4 0 GO 8 0

CLAYEY SANO

CLAYEY SILT

Ouαt.

Upper

plio.

LPIio.

Upper

Mioc

M Mlioc.

K>O•

L. EocU. Pal.

213- I T - ir—ir-

- v — tr- t

—v — ir—tr-

LT—IT— I T - U

—u — I T — IT-

ir— ir — u•— i

—u•—ir —u•-

i r — I T — i r — u

—v — ir—ir-

tf—U — I T — U

— i / — ir — i r -

J — if — ir — u

- z — z —z —

- z - z - z -

-z— z - z —

- z - z ~ z -

–z-z-z-–z — z — z —

— z — z — z •

z - z - z -—_L_— _ I _ — _ 1 _ —

J. J. J L

-L J- J- J-i. -L-L -L

% CLAY MINERAL

20 40 60 80

NAN NO OOZECLAYNAN NO OOZE

Ft-Un

BASALT

<

SMECTITE

V

iI

214SU <Ti>J K MINERAL

20 40 60 80 100

212

FORAU

NANNO CHALK

PHILLIPS CLAY

NANNO CHAU!

FORAU

NANNO CHALK

CUNOPT.CLAYBASALT

% CLAY MINERAL

0 20 40 60 80 KX)

300

I L6LAUC.

NANNO CHALK

LIGNITE

CONGLOMERATE

SILTY SAND

BASALT

SILTY SAND

BASALT

BASALT

X

SMECTITE

AJSMECTITE

^^IM///////////J/W'l/M/

SMECTITE

•

Jm

me,mFigure 2. Variations of clay mineral abundances with stratigraphic age, lithology (taken from Scientific Staff, DSDP

Leg 22, 1972), and depth at Sites 211, 212, 213, and 214.

the climate in Australia were maximum in Miocene-Oligocene times, which might have led to the formation ofkaolinite soils. The optimum conditions for laterite devel-opment prevailed during the Pliocene (Gill, 1961). Thekaolinite-rich sediments in the Australian Province havethus probably been derived from Australia. The pre-Quaternary kaolinite, however, may not have reached inthis province by aeolian transport.

Site 213

This site is located in the Quaternary Indonesian MineralProvince similar to Site 211. In the <2µ size fractions,

smectite is the most abundant clay mineral throughout theentire hole, although slight increases in the amounts ofkaolinite are noticed in the uppermost part (Figure 2, Table1). In the upper Paleocene and Eocene calcareous ooze(Cores 15 and 16), palygorskite becomes a common mineralcomponent. In the coarser fractions of the sediments of themiddle Miocene and brown clays of unknown age overlyingthe lower Eocene calcareous ooze (Cores 9 and 11),phillipsite is a common mineral component. Both thepalygorskite and phillipsite minerals have associated withthem volcanic rock fragments and palagonite in con-siderable amounts. In addition, in Cores 15 and 16 (with

493

TABLE 2Mineral Composition of the 2-20µ Size Fraction

Interval Diffracting AmorphousSample (cm) Material Material

Diffracting Material Vole.Rock_ Vole. Clay

Mica Clinoptilolite Phillipsite Quartz Feldspar Palagonite Age Remarks Lithology

211-1-3211-2-3211-3-4211-4-3

211-6-5

211-9-3

211-12, CC

211-14-1

212-2-3212-5,CC212-10-5212-11-3212-14-5212-15-3212-20,CC212-25-5212-29,CC

212-33-3212-35-2212-37,CC

213-1-0213-2-5213-5-5213-7-5213-9-6213-11-5213-13-6213-15-6

0-100-100-100-10

0-10

0-10

8-10

12-19

0-10—

0-100-100-100-10—

0-10-

0-100-10

- •

_

0-100-200-200-200-200-200-20

TrTr

Tr-CA

A

A

A

A

AAAAAA

TrAA

AAA

TrCC

Tr-CCAAA

AAATi

-

-

-

_

_—___—

A—Tr

—-

AC

C-AAC__

—TrTr

Tr-C

C

c

Tr

_

Tr-CTr—_TrTr——Tr

TrTr-_TrTr__—_

_TrTr_———A

Tr

ATrA_———_

-_

214-1-5214-7-5214-11-5214-15-3214-19-5214-23-5214-27-5214-31-5214-35-5

0-10

130-1500-200-200-200-200-200-200-200-10

TrTrTrTrTrAAA

Tr

AAAAA

TrC

TrA

C(glauc)

—--

Tr-C

Tr

Tr

_

-

Tr-CACC

TrTr-CTr-

r(?)

—--

_TrTrTrCA

Tr(?)Tr

Tr

————AA

Tr_

CC

cA

A

A

A

.A

C-ACCCAA

TrTr

C-A

Tr-CC-AC

Tr-CCCC

Tr-CTrC

Tr

Tr

TrTrTrTrTrTrTrC_

TrTr—

Tr

Tr

Tr

Tr-C(somesanidine)Tr-C

TrTrCC

TrC

TrTrC

(sanidine?)

TrC

Tr

TrTr-CTr-CTrTrTr

Tr-CA

(sanidine)A

(sanidine)

TrTrTrTr-

TrTrTr

_

———-

-

-

Tr

-

Tr-CTr

Tr-CTr-C

CC

TrTrTr

TrTrTr

__--

TrTrC

Tr

Tr

——

Tr—

TrTrAA

Quat.Quat.Lt. Plio.Plio.

Püo.

Plio.

Camp.

-

E. Plio.Lt. Mio.Lt. Mio.E.-M. Mio.E.-M. Mio.

(?)M. Eoc.M Eoc.

(?)

U. Cret.(?)(?)

Quat.Lt. Plio.E. Plio.Lt. Mio.M. Mio.

(?)(?)

Lt. Paleo.

Lt. Paleo.

Pleisto.Püo.Lt. Mio.Lt. Mio.M. Mio.E. Mio.Oügo.EocenePaleo.

Shards: C_

Shards: TrShards & amphibole: TrChlorite: TrAmphibole: TrChlorite: TrAmphibole: TrChlorite: TrGreen & basalt hornblende: Tr-CPalygorskite: Tr

-

__

__

Cristobaüte: TrCristobaüte: TrCristobalite: Tr

__-

_—

Cristobalite (?): TrCristobalite (?): TrCristobaüte (?)

—_—

—

__——_——

Palygorskite: Tr_

MINERALOGICAL DATA AND ORIGIN OF NONCARBONATE SEDIMENTS IN THE EQUATORIAL INDIAN OCEAN

i i i i i SS

o o-60 O

< Ü duo ö

o o,2 ,2

o o o ε a.2 6 o -2 d dS a a s ° °J di J J W w

0) Q QJ>

I ( J

I I

I I

I I I I

1 '

i i < i i i i i i i < <

J2 H a >, i i fi i i i i i i

0-10

•37

-2

0-10

•39

-3

0-10

-41-

342.C

C52

,CC

•* < t •<a

CN <N CN

0-20

0-20

0-20

0-20

0-20

0-20

•1-5

-3-5

•5-

2-8

-3•

9-2

•10

-2

IT) >/*5 Vi >O >O U0

fSNNMNN

0-20

11-5

0-20

15-4

i o

0-20

17-1

in

palygorskite), abundant sanidine has been observed. On theother hand, in the sediments of late Miocene and youngerages, palagonite is either absent or present only in traces.Amorphous siliceous skeletal remains are abundant in theseyounger sediments.

The fine and coarse fraction mineralogy describedindicates that during the pre-middle Miocene, basaltvolcanics was the main source of the sediments. In thesediments of late Miocene and younger ages, even thoughsmectite is abundant, basaltic palagonite and rock frag-ments are present either in traces or absent in contrast tothe higher abundances of these components in earlier times.This suggests that the silicic Indonesian volcanics character-istic of the Quaternary may have been a source since thelate Miocene.

Site 214

This site is located in the Australian Province on theNinetyeast Ridge, but near the border with the IndonesianProvince (Figure 1). The Pliocene and upper Miocenesediments (Cores 1, 7, and 11) have relatively higheramounts of kaolinite (Figure 2, Table 1). Smectite ispresent in high amounts in these sediments, but itsabundance is relatively higher in middle and lower Miocene,and Oligocene sediments (Cores 19, 23, and 27). Paly-gorskite begins to show up in the late Eocene (Core 31) andbecomes abundant in the lower Eocene-Paleocene sedi-ments (Core 35). In Cores 37, 39, and 41 of Paleocene age,smectite is again abundant. In Core 42 of Paleocene (?) age,in a lignite sample, metahalloysite-kaolinite mineral layersbecome abundant; further down in the hole in Core 52,smectite is abundant.

In the coarse fractions in the sediments of middleMiocene and younger ages (Cores 19, 15, 11, 7, and 1),siliceous skeletal remains are abundant, but are absent inthe older sediments. Phillipsite is abundant in the lowerMiocene and Oligocene sediments (Cores 23 and 27).Though clinoptilolite is common in Core 23 (earlyMiocene), this zeolite is more abundant in Core 31 ofmiddle Eocene and Core 42 (rich in lignite) of Paleocene (?)ages (Table 2). Pyrite is a common component in Cores 41and 42. Starting from Core 23, volcanic rock fragments andpalagonite become more and more abundant towards thebottom of the hole. Basaltic hornblende is abundant inCore 52 (Paleocene ?) immediately above the basalt.Smectite is the abundant clay mineral in the materials ofdredge RC 14-6D from the Ninetyeast Ridge. This dredgeconsists of mudstones, limestones, and altered volcanicrocks of Cretaceous-Eocene age.

The source of kaolinite in sediments of late Miocene andPliocene age is probably similar to that of Site 212. Themetahalloysite-kaolinite of Paleocene (?) age was, however,of a different origin. It appears that basalt volcanics andtheir alteration products were the main source of theminerals during the pre-middle Miocene. Yet the differentminerals—smectite, palygorskite, phillipsite, clinoptilolite,and kaolinite—have been formed at different stratigraphichorizons. These minerals are probably the result of differ-ent environmental conditions prevailing at different times.The metahalloysite-kaolinite minerals in the Paleocene (?)sediments have developed from volcanics and smectite.

495

K. VENKATARATHNAM

TABLE 3Mineral Composition of >2µ Size Fractions

TABLE 3 - Continued

SampleInterval

(cm) Mineral Abundances Age

211-1-3

211-2-3211-3-4

211-4-3

211-6-5

211-9-3211-12-, CC

211-14-1212-2-3

212-5, CC

0-10

0-100-10

0-10

0-10

0-108-10

12-190-10

212-10-5

212-11-3

212-14-5

212-15-3

212-20, CC

212-25-5

212-29, CC

212-33-3

212-35-2

212-37, CC

213-1-0

213-2-5

213-5-5213-7-5213-9-6

213-11-5213-13-6

213-15-6

213-16-4

0-10

0-10

0-10

0-10

-

0-10

-

0-10

0-10

-

0-10

0-20

0-200-200-20

0-200-20

0-20

0-10

Siliceous skeletons (Radiolariaand diatoms): A; terr. minerals:Tr; glass shards: TrSiliceous skeletons: ASiliceous skeletons: A; terr. min-erals: Tr; glass shards: TrSiliceous skeletons: Tr to com-mon; terr. minerals-mainly quartzand mica with hornblende andepidote: Tr; phillipsite: TrTerr, minerals (mainly quartz andmica with hornblende in traces):A; phillipsite: TrAs in Core 6Feldspar (mainly Plagioclase withsome K-feldspar): A; volcanicrock fragments and palagonite:TrFeldspar and quartz: AVolcanic rock fragments andpalagonite: A; quartz and feld-spar: C; phillipsite: TrPalagonite (and magnetite): A;phillipsite: C; feldspar andquartz: TrPalagonite and volcanic rockfragments: A; phillipsite: TrPalagonite and volcanic clay: A;phillipsite: Tr; feldspar: TrPalagonite and volcanic clay: A;phillipsite: Tr; feldspar: TrPalagonite, volcanic rock frag-ments (and magnetite): A;feldspar: TrSiliceous skeletons: A; palago-nite: C; feldspar and phillips-ite: TrFeldspar: C; clinoptilolite: Tr-C; palagonite and magnetite:TrRock fragments and palago-nite: A; feldspar: CRock fragments and palagonite:C; feldspar: Tr-C; clinoptilo-lite: CRock fragments and palago-nite: A; feldspar: C; quartz: TrClinoptilolite: A; feldsparand palagonite: Tr

Siliceous skeletons: A; feld-spar and palagonite: TrSiliceous skeletons: A; feld-spar, quartz, and palagonite: TrSiliceous skeletons: ASiliceous skeletons: ASiliceous skeletons: C; phillips-ite: C; palagonite and volcanicrock fragments: C; feldspar: TrPhillipsite: A; palagonite: Tr-CPalagonite, volcanic rock frag-ments, and clay; A; feldspar andphillipsite: TrPalagonite and volcanic rockfragments: A; feldspar (sani-dine): C; phillipsite: TrPalagonite and volcanic frag-ments (palygorskite): A; feld-spar (sanidine): C

Quat.

Lt. Plio.

E. Plio.Lt. Mio.M. Mio.

Lt.Paleo.

Lt. Paleo.

SampleInterval

(cm) Mineral Abundances Age

Quat.

Quat.Lt. Plio.

Plio.

Plio.

Plio.Camp.

E. Plio.

Lt. Mio.

Lt. Mio.

E.-M. Mio.

E.-M. Mio.

M. Eoc.

M. Eoc.

U. Cret.

214-1-5214-7-5214-11-5214-15-3

214-19-5

214-23-5

214-27-5

214-31-5

214-35-5

214-37-2

214-39-3

214-41-3

214-42, CC

214-52, CC

215-1-5215-3-5215-5-2

215-8-3

215-9-2

215-10-2215-11-5

215-15-4

215-17-1

130-1500-200-200-20

0-20

0-20

0-20

0-20

0-10

0-10

0-10

0-10

-

0-200-200-20

0-20

0-20

0-200-20

0-20

73-80

Siliceous skeletons: A Pleist.Siliceous skeletons: A Plioc.Siliceous skeletons: A Lt. Mio.Siliceous skeletons: A; palago- Lt. Mio.nite: TrSiliceous skeletons: A; palago- M. Mio.nite: TrRock fragments and palagonite: E. Mio.C; phillipsite and feldspar: TrRock fragments and palagonite: Olig.A; feldspar: C; phillipsite: Tr-CVolcanic rock fragments and Eoc.palagonite: A; feldspar: TrVolcanic rock fragments and Paleo.palagonite: A;glauconite: CVolcanic rock and palagonite: Paleo.C; siliceous skeletons: Tr;magnetite: TrVolcanic rock and palagonite: C; Paleo.siliceous skeletons: Tr; magne-tite: TrVolcanic clay fragments and Paleo.(?)palagonite: A;pyrite: Tr;feldspar: TrVolcanic clay and palagonite: A; Paleo.(?)feldspar: TrVolcanic fragments and palago- Paleo.(?)nite: C; basalt hornblende: A;magnetite: TrSiliceous skeletons: A Lt. Plio.Siliceous skeletons: A E. Plio.Siliceous skeletons: A; palago- Lt. Mio.nite; TrSiliceous skeletons: A; palago- Lt. Mio.nite and volcanic fragments: CVolcanic rock fragments and E. Eoc.palagonite: C; palygorskite andchert: A; phillipsite: TrNo sample E. Eoc.Volcanic fragments and palago- Paleo.nite: C; clinoptilolite andchert: C; feldspar: TrVolcanic fragments and palago- Paleo.nite: C; clinoptilolite andchert: C; feldspar: TrVolcanic fragments and palago- Paleo.nite: A

During the Paleocene, part of the Ninety east Ridge in thearea of Site 214 existed as an island or was very shallowwith lagoonal conditions which favored the production ofabundant organic matter. This organic matter subsequentlybecame lignite (Scientific Staff, 1972). Low pH and Ehconditions existed at Site 214 as a consequence of thepresence of abundant organic matter. These conditionswould transform the volcanogenic smectite into kaolinite-metahalloysite by a process similar to that described byCarroll and Hathaway (1963). These same conditions wouldalso have produced the observed pyrite.

The origin of zeolites and palygorskite will be discussedlater.

Site 215

This site is located on the border between the Indone-sian and the Inter-Ridge provinces (Figure 1).

496

MINERALOGICAL DATA AND ORIGIN OF NONCARBONATE SEDIMENTS IN THE EQUATORIAL INDIAN OCEAN

Smectite is the abundant clay mineral throughout thishole except in Cores 9 and 10 (early Eocene) wherepalygorskite is present in high amounts (Figure 3). In thecoarser fractions, phillipsite is present in traces in thesediments of late Miocene and younger ages, but absent inthe older sediments. In the older sediments (Cores 8,9,10,11, 15, and 17),palagonite and volcanic rock fragments arecommon or abundant. Chert fragments and abundantclinoptilotite are present in Cores 11 and 15 of Paleoceneage.

The mineralogy of Site 215 thus reflects a volcanicinfluence from the Paleocene to Quaternary, but basaltvolcanics were more important as a source in pre-lateMiocene times. In the younger sediments Indonesianvolcanics may have provided a source of material.

Palygorskite

This mineral occurs in certain Upper Cretaceous, Paleo-cene, and Eocene calcareous sediments and brown clays inSites 211, 213, 214, and 215. The X-ray tracings showrelatively poorly to well crystallized palygorskite. In thepalygorskite-rich sediments smectite is present in lowamounts and is poorly crystallized (crystallinity was meas-ured by Biscaye's, 1965, v/p ratio method). Smectite isabundant in the sediments just above or below palygorskitehorizons. In the coarse fractions, usually volcanic rockfragments and palagonite, sometimes chert and sanidine areassociated with palygorskite; zeolites are occasionallycommon.

The genesis of palygorskite in the deep sea is no doubtrelated to the alteration of volcanics (von Rad and Röch,1972; Bonatti and Joensuu, 1968) possibly with smectiteacting as an intermediary. In places, the palygorskite claysoccur near basalts and basal iron-oxide-rich sediments ofprobable hydrothermal origin (see von der Borch and Rex,1970). Elsewhere, the stratigraphic position of palygorskiteis far above the basalt basement and separated from it bysediments without palygorskite. In the latter cases, volcanicrock fragments and palagonite grains occur both in sedi-ments with or without palygorskite. With the available data,it is not known whether the magnesium ions required tocombine with silica released from the alteration of volcanicsand palagonite have been supplied from hydrothermalsources (Bonatti and Joensuu, 1968) or from seawater(Hathaway and Sachs, 1965). In either case, the genesis ofpalygorskite as opposed to zeolites in certain sediments andat particular stratigraphic horizons is not clear.

Zeolites

This study shows that phillipsite occurs both in calcar-eous sediments and brown clays and is restricted mostly toMiocene and younger sediments, but sometimes to Oligo-cene sediments. Clinoptilolite, on the other hand, is moreabundant in Eocene and older sediments—calcareous oozeand in one case lignitic clay. The temporal distribution ofthe two zeolites is similar to that reported by Venka-tarathnam and Biscaye (in preparation) from a study ofabout 70 piston cores in the Indian Ocean.

Abundant smectite, volcanic fragments, and palagoniteare associated with both types of zeolites. From thispreliminary examination, it appears there is no difference inthe type of associated volcanics. If the chemical composi-tion of the volcanics associated with both these zeolites isthe same, it may be that the formation of clinoptilolite(richer in silica than phillipsite) is due to the mobilizationof excess silica during Eocene-Cretaceous times. The altera-tion of volcanics appears, however, a prerequisite for theformation of both phillipsite and clinoptilolite.

ACKNOWLEDGMENTS

The author thanks Dr. A. C. Pimm for making DSDP Leg22 samples available and Drs. Pierre Biscaye and StephenEittriem for the critical reading of the manuscript andhelpful suggestions. This work was carried out under theOffice of Naval Research Contract No. N00014-67-A-0108-0004.

REFERENCES

Biscaye, P. E., 1965. Mineralogy and sedimentation ofrecent deep-sea clay in the Atlantic Ocean and adjacentsea and oceans; Geol. Soc. Am. Bull., v. 76, p. 803-832.

Bonatti, E. and Joensuu, O., 1968. Palygorskite from theAtlantic deep-sea sediments: Am. Mineralogist, v. 53, p.975-983.

Brindley, A. W., 1961. Kaolinite, sepentine and kindredminerals. In The X-ray identification and crystal struc-tures of clay minerals, Brown, G., (Ed.): London(Mineralogical Society, Clay Minerals Group), p. 51-131.

Carroll, D. and Hathaway, J. C, 1963. Mineralogy ofselected soils from Guam: U.S. Geol. Survey Prof. Paper403-F,p. 1-53.

Gill, E. D., 1961. The climates of Gondawanaland inKainozoic times. In Descriptive paleoclimatology. Nairn,A. E. M., (Ed.): New York (Interscience), p. 332-354.

Goldberg, E. D. and Griffin, J. J., 1970. The sediments ofthe northern Indian Ocean: Deep-Sea Res., v. 17, p.513-537.

Hathaway, J. D. and Sachs, P. L., 1965. Sepiolite andclinoptilolite from the Middle Atlantic Ridge: Am.Mineralogist, v. 50, p. 852-867.

Scientific Staff, 1972. Deep-Sea Drilling Project, Leg 22:Geotimes, vol. 17, p. 15-17.

Venkatarathnam, K. and Biscaye, P. E., in press. Claymineralogy and sedimentation in the eastern IndianOcean: Deep Sea Res.

, in preparation, Deep-sea zeolites: Variations inspace and time in the sediments of the Indian Ocean:submitted to Marine Geol.

von der Borch, C. C. and Rex. R. W., 1970. Amorphousiron oxide precipitates cored during Leg V, DSDP; InMcManus, D. A., Burns, R. E., et al., Initial Reports ofthe Deep Sea Drilling Project, Volume V: Washington(U.S. Government Printing Office), p. 541-544.

von Rad, U. and Röch, H., 1972. Mineralogy and origin ofclay minerals, silica and authigenic silicates in Leg 14sediments: In Hayes, D. E., Pimm, A. C, et al., InitialReports of the Deep Sea Drilling Project, Volume XIV:Washington (U.S. Government Printing Office), p.727-751.

497

K. VENKATARATHNAM

COQILU

UJ h-O LU< ^ 215

QüötTU. Plio.

L Plio.

UpperMioc.

LowerEocene

lOO<

cα>oo

- I T - I T - LT-

LJ• - I T - IT - σ

- L T — I T - L T -

L T - LT - L T — If

- L T - L T - L T -

L T - IT - LT - LT

- U" — LT — U —

I T - Ul - L T - U

- I f — i r - i r -

-L _L _!_ _L

Fe Fe Fe'

RAD.

DIATOMOOZE

CLAY

NANNO OOZE

CLAY

Feo

BASALT

% CLA Y MINERAL20 40 60 80

Figure 3. Variations of clay mineral abundances with stratigraphic age, lithology, and depth at Site 215.

100

498

K. VENKATARATHNAM

PLATE 1

(Magnification X 16,000)

Figure 1 Palygorskite from Sample 214-35 -5,0-10 cm.

Figure 2 Palygorskite from Sample 215-10-2,0-20 cm.

Figure 3 Kaolinite minerals from Sample 21442, CC.

500

MINERALOGICAL DATA AND ORIGIN OF NONCARBONATE SEDIMENTS IN THE EQUATORIAL INDIAN OCEAN

PLATE 1

501