6. SITE 215
The Shipboard Scientific Party1

ABSTRACT
Site 215 was drilled west of Ninetyeast Ridge in 5309 metersof water. The stratigraphic column in the area is 155.5 meters inthickness and is divided into four units, an upper radiolarian
diatom ooze of Quaternary to upper Miocene age, two thin
terrigenous silty clay layers of upper Miocene age, a 7-meter-thickbrown clay which corresponds with a 40-m.y. time interval, and acalcareous nannofossil ooze ranging from lower Eocene to
mid-Paleocene in age which includes an iron-oxide-rich zone at
the base. These are underlain by a fresh pillow basalt withintercalated baked calcareous ooze. Lithology and biostratigraphyof Site 215 closely resemble Site 213 which is on the opposite
side of Ninetyeast Ridge and suggest synchronous subsidence ofboth sites since the mid-Paleocene.
SITE DATA
Date Occupied: 13 Feb 72 (0334)
Date Departed: 15 Feb 72 (2018)
Time on Site: 64 hours 44 minutes
Position:lat 8°07.30'S
long 86°47.50'E
Water Depth (to rig floor):
5321 meters (Echo sounding)
5319 meters (Drill pipe)
Penetration: 175 meters
Number of Holes: 1
Number of Cores: 20
Total Length of Cored Section: 175 meters
Total Core Recovered: 113.3 meters
Acoustic Basement:
Depth: 155.5 meters
Nature: Basalt
Age of Oldest Sediment: Mid-Paleocene
Basement: Basalt

C. C. von der Borch, Flinders University, Bedford Park, South
Australia; J. G. Scláter, Scripps Institution of Oceanography, La
Jolla, California; S. Gartner, Jr., Rosenstiel School of Marine andAtmospheric Science, University of Miami, Coral Gables, Florida;
R. Hekinian, Centre Oceanologique de Bretagne, Brest, France; D. A.
Johnson, Woods Hole Oceanographic Institution, Woods Hole,
Massachusetts; B. McGowran, University of Adelaide, Adelaide,
South Australia; A. C. Pimm, Scripps Institution of Oceanography;
La Jolla, California; R. W. Thompson, Humboldt State College,
Arcata, California; J. J. Veevers, Macquarie University, North Ryde,
N.S.W., Australia; Lee S. Waterman, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts.

BACKGROUND AND OBJECTIVES
To complete the trio of sites on and either side of the
Ninetyeast Ridge, Site 215 was placed in the central Indian
Basin at 8°12'S, 86°5θ'E. The original site was pickedfurther to the south. However, because of the thin sediment
cover and the unclear nature of the magnetic anomalies, thesite was moved further north. Another factor involved in
the move north was the hope that some of the distal
sediments from the Bengal Fan could be sampled.
The site was selected on the basis of Scripps Institutionof Oceanography CIRCE V airgun profile run from the R/V
Argo. The region chosen was to the east of an area ofprominent east-west magnetic lineations identified by
McKenzie and Sclater (1971) as anomalies 28 through 33.
By extrapolating these anomalies eastward, it was
anticipated that the site was close to anomaly 29 and would
yield a basement age of 68 to 70 m.y. Due to the poor
character of the magnetic anomalies in the area selected, we
considered moving the site to the well-identified anomalies
further east. However, as this involved extra steaming, we
decided not to change the site.
The surface sediments in this slightly elevated area to thesouth of the fan are predominantly siliceous, though inmore elevated regions isolated calcareous Eocene sediments
have been recovered. With this rather scattered preliminary
evidence, it was anticipated that Site 215 would be
stratigraphically very similar to Site 213 and yield abasement age of some 7 to 12 m.y. older.
The actual site was selected at a depth of 5300 meters in
ponded sediments at the southernmost extremity of theBengal Fan (Figure 1). The CIRCE V airgun profile showed
three horizons, an uppermost transparent layer over an
acoustically opaque layer with many internal reflectors on
top of another transparent layer which appeared to drape
over what was thought to be basement. The incoming andoutgoing airgun records show these layers very clearly. The
sediment thickness of the top two units was close to 0.15

193

SITE 215

85°

86°

Figure 1. Bathymetry in vicinity of Site 215

194

SITE 215

to 0.20 sec with 0.05 sec of draped sediment overlying
acoustic basement.
The objectives of this site were (a) to obtain acontinuous core for stratigraphic and biostratigraphic
purposes, (b) to sample some of the distal fan sediments,and (c) to date the age of the basement for comparison
with the magnetically determined age.
OPERATIONS

The approach to Site 215 was made in an approximately
northward direction along the seismic reflection line run by
R/V Argo (CIRCE Expedition, Leg V). The site was chosen
in what appears as a basin of ponded and draped sediments
just beyond the distal end of the Bengal Abyssal Fan.
After the final choice of site was made, Glomar
Challenger reversed course and steamed back to the chosenarea at 5 knots. A lighted spar buoy was dropped and theseismic gear secured, after which the vessel returned to thebuoy. The beacon was dropped in 5309 meters of water.
A Smith 93 CJS, 4-cone chizzel-point bit was used andno drilling difficulties were encountered. Sediments drilledcomprise 155.5 meters of soft siliceous ooze, brown clay,
calcareous ooze, and chalk overlying basalt. The basalt was
drilled for 19.5 meters. A total of 175 meters of coring was
carried out resulting in 133.3 meters of sediment and rock,a recovery of 64.7% (see Table 1).

LITHOLOGIC SUMMARY
Introduction

Quaternary to mid-Paleocene sediment (151 meters) was
continuously cored from the sea floor down to acoustic
basement where a penetration of 24 meters into basaltic
pillow lava was accomplished (Figure 2).
The following lithologic units can be recognized:
Unit

Depth Below
Sea Floor (m)1Lithology

Age

Cores

0 to 64.5

Rad, diatom ooze,
clay-rich in places

Quaternary
to lateMiocene1-7

247.5 to 48.0
and72.0 to 74.0

Silty clay and clayeysilt

Late Miocene 6, 8

3

65.0 to 82.0

Clay-zeolitic inpart

LateMiocene to early
Eocene8,9Paleocene

9-17

482.0 to 151.0

Nanno ooze

4b149.0 to 151.0

Iron-oxide-rich nannoooze

5151.0 to 175+

Basalt16,17
MidPaleocene

17-20

TABLE 1
Coring Summary, Site 215
Depth fromDrill Floor

Core

Date
(Feb)

Time

(m)

1
2
3
4

13
13
13
13

1445
1618
1737
1900

5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

13
13
13
14
14
14
14
14
14
14
15
14
14
14
14
15

2020
2142
2300
0035
0235
0430
0620
0755
0935
1115
1305
1425
1600
2006
2255
0255

5319.0-5328.5
5328.5-5336.0
5336.0-5345.5
5345.5-5355.0
5355.0-5364.5
5364.5-5374.0
5374.0-5383.5
5383.5-5393.0
5393.0-5402.5
5402.5-5412.0
5412.0-5421.5
5421.5-5431.0
5431.0-5440.5
5440.5-5450.0
5450.0-5459.5
5459.5-5469.0
5469.0-5474.5
5474.5-5481.0
5481.0-5484.5
5484.5-5494.0

Total

Depth Below
Sea Floor
(m)

Cored
(m)

0-9.5
9.5-17.0
17.0-26.5
26.5-36.0

9.5
7.5
9.5
9.5

8.5
1.5
9.5
9.5

89
20
100
100

36.0-45.5
45.5-55.0
55.0-64.5
64.5-74.0
74.0-83.5
83.5-93.0
93.0-102.5
102.5-112.0
112.0-121.5
121.5-131.0
131.0-140.5
140.5-150.0
150.0-155.5
155.5-162.0
162.0-165.5
165.5-175.0

9.5
9.5
9.5
9.5
9.5
9.5
9.5
9.5
9.5
9.5
9.5
9.5
5.5
6.5
3.5
9.5

5.0
3.3
2.0
8.2
4.2
3.6
9.0
9.0
4.8
9.0
6.4
6.8
0.8
4.5
2.5
5.2

52
35
21
87
44
40
95
95
52
95
67
74
14
69
71
55

175.0

113.3

64.7

Recovered(m)

Recovery

Note: Sounding depth (to drill floor) = 5321 meters; drill pipe length to bottom = 5319 meters.

195

SITE 215

Unit 3-Clay (Cores 8,9)This unit comprises light brown spicule radiolarian
bearing clay in Core 8 and dark brown zeolite-rich clay inCore 9. The nonclay fraction (<20%) is biogenous(Radiolaria and sponge spicules) in Core 8 and iron-oxidemanganese(?) and phillipsite in Core 9.

SITE 215
8°07.3'S 86°47.5'E
5319m
QUAT.
U.PLIO.

Rad
L.PLIO.4

Diatom Ooze
UPPER

Silty Clay

.47.5
48

Zeol. Clay
Silty Clay
Zeol. Clay

-64.5
-72
74
-82

MIOC.
3 2=
LOWER l n
EOCENE I U
11
u,

-100

12

g 13 ~L. J Nanno Ooze
o

S 14
s! i5
4bz
5

16
17
18
19
20

FeO

J 49
151

Pillow Lava
BasaltT.D. 175 m; 20 cores;
133 m rec.

Figure 2. Lithologic units at Site 215.
Unit 1— Radiolarian Diatom Ooze (Cores 1-7)This unit is predominantly light yellowish brownradiolarian-diatom ooze with varying amounts of clay andsponge spicules. The only trend seen in this unit is anincrease in clay content with depth to reach 30% to 40%
near the base, with a corresponding decrease in siliceous
fossils. Abundant black streaking and mottling is due todrilling deformation of manganese-rich layers. Silicoflagellates and iron-oxide granules are always present insmall amounts (<2%). In Core 4 at a depth of 34 meters
small amounts (3%) of volcanic glass, mostly rhyolitic withsome basaltics, were seen through a 30-cm interval.

Unit 2-Silty Clay to Clayey Silt (Cores 6-8)
This unit forms two distinct beds of grayish brown togray sediment in Cores 6 and 8. The beds are estimated as
60-cm thick in Core 6 and 200-cm thick in Core 8. The baseof the beds is clearly defined as a sharp contact of gray silty
clay resting on light yellowish brown material from Unit 1.
The upper parts of the beds appear finer grained with apredominance of clay-size material and show a gradational
color change of grayish brown upwards into Unit 1
sediment. The composition of the silt sized fraction as
deduced from smear slides is predominantly (65%) feldspar(Refractive Index <1.55 i.e., sodic) with moderate (25%)
clay aggregates. The minor constituents include pale green
basic volcanic glass, hornblende, tourmaline, zircon,
epidote, calcite, and garnet.

196

Unit 4-Nannofossil Ooze (Cores 9-17)This unit is pale brown to yellowish brown nannofossil
ooze with a clay content ranging from 5% to 20%.
Foraminifera are rare, and dolomite and authigenic
carbonate only occur in trace amounts. In Cores 13 (114
meters) and 14 (122 meters) yellowish brown porcellanouschert nodules up to 5 cm across were recovered. The chert
is slightly calcareous and foraminiferal ghosts are visible inthin section. On polished surfaces burrow structures andchemical haloes (?) are visible.
Subunit 4b is identified on the basis of an abundance(~12%) of iron-oxide micronodules in the 1 meter of
sediment above the basalt. The sediment here is a darkbrown color and above this is transitional into a browncolor for 1 meter and then up into the typical lightyellowish brown of Unit 4. The sediment in the subunit
contains about 30% clay, but only a trace of authigenic
carbonate.
The basal contact zone with basalt was cored andconsists from top to bottom of about 1 to 2 cm of darkgrayish brown nannofossil chalk, a 1-mm-thick layer ofpure white chalk, a 1 to 2-mm thick yellow palagonite
layer, a dark brown fresh glass layer about 3 mm thick, andfinally fresh black volcanic glass in a 4 to 10-mm skinresting on the basalt of Unit 5. Neither of the chalks show
recrystallization of the nannofossils.
Unit 5-Basalt (Cores 17-20)

Unit 5 consists of a succession of about 14 basalt
pillows. The total amount of rocks recovered is 13.3
meters. These basaltic rocks have undergone various degrees
of seawater weathering effects. The pillowed structure of
the basaltic rocks is characterized by the occurrence of(1) glassy margins, (2) a less glassy variolitic transitionalzone, and (3) an innermost crystalline zone.
1) The glassy margin consists of basaltic glass
criss-crossed with veins of palagonite. Sometimes indurated
carbonate material (limestone <5 cm thick) occurs at
contact or intermixed with the basaltic glass. The limestone
contains mostly nannofossils, calcite, and traces of brownglass.
2) The less glassy variolitic margin is the transitionalzone between the glassy margin and the innermost
crystalline zone. This transitional zone is made up of
sheaf-like microlites and radiating Plagioclase laths and anabundantly weathered matrix consisting of a reddish browndark mesostasis comprising iron-ore-rich brown glass andpalagonite.
3) The crystalline rock is always found in the innermost
zone of the pillow lava; it is either partially weathered ormoderately fresh. These rocks are usually holocrystalline or
hypocrystalline, and their general texture varies between
subophitic and pilotaxitic, respectively.

SITE 215
CHEMICAL PROPERTIES

Nine pairs of contiguous 10-cm minicores and one"piece of sediment" were obtained from the first 17 cores
recovered at this site. Slope determinations were made on
all nine minicore samples, and one sample (215-1-5) wasused for temperature cycling experiments.
Data on slopes and the pH values obtained with thepunch-in (sediments) and flow-through (pore waters)
electrodes are given below:

SamplePH(punch-in)pH(flow-through)Temperature

215-1-5
215-3-5
215-5-2
215-8-3
215-9-2
215-10-2
215-11-5
215-13-3
215-15-4
215-17-1

7.21
7.16
7.18
7.17
7.34
7.40
7.24
7.36
7.40
—

7.30
7.13
7.29
7.46
7.26
7.23
7.01
7.19
7.32
7.12

25.0
26.0
25.9
26.0
26.0
26.2
26.1
26.2
26.2
26.0

BIOSTRATIGRAPHIC SUMMARY
GeneralDatable fossil assemblages were recovered throughout
the sedimentary section cored at Site 215. Cores 1 through8 yielded siliceous microfossils including radiolarians of
Neogene age, and which indicate a more or less complete
section from the late Miocene through the Quaternary.
Calcareous fossils are lacking in the above cores, althoughsome agglutinated benthonic foraminifera were recovered inCores 1 to 7. Core 9 is barren of fossils except at its basewhere it penetrated the top of a calcareous interval. The
calcareous section continues to the top of Core 17 andranges in age from the early Eocene at the base of Core 9 tothe mid-Paleocene in Core 17. This section contains bothplanktonic foraminifera and nannofossils, though somewhat
sparse near the base, in a more or less normal succession.
The unfossiliferous portion of Core 9 separates twointervals which differ in age by 40 m.y. As Core 9 consistsof less than 5 meters of sediment, a considerable hiatus
must be inferred even if a very low rate of brown clay
accumulation is assumed.
Foraminifera

Cores 1 to 7 contain sporadic occurrences of deep-water
agglutinated benthonics. One planktonic in Core 4 indicatesan age of Pliocene (Zone N.19) or younger.
A lower Tertiary planktonic foraminiferal section was
encountered fading out fast in Core 9. Cores 10 and 11
contain rich and well-preserved assemblages identified
throughout (10-1 to 11, CC) as Zone P.6b (lowest lower
Eocene). It would seem from the poor material of Core 9that the record ends within Zone P.7.

Core 12, Section 1 differs markedly from Cores 11 and
10 in having a quite diverse benthonic assemblage (seebelow) but poor planktonics. These are sufficient toindicate a late Paleocene age (Zones P.5 to P.6a). A top to
Planorotalites pseudomenardii in Core 13, Section 1 marks
the top of Zone P.4, and the rest of the assemblage
supports this identification. Zone P.4 continues down to
the top of the basalt in Core 17, Section 1. The mostimportant change in the interval from Core 13 to Core 17,
Section 1 occurs within Core 16, where a relatively good
assemblage (in terms of specimen numbers and lack ofcorrosion) dominated by abundant Subbotina spp. appears
somewhat suddenly in the core catcher and continues intoCore 17, Section 1. This matches well the downward
increase in iron-rich clay.
The pelagic limestone in Core 17, CC contains a poor
assemblage, but indicates clearly the mid-Paleocene(Zone P.3) age.
From Core 9 to Core 17, Section 1 there are marked
variations in content and preservation. These variations
range from (1) abundant, well-preserved planktonics, few
and small benthonics, little clay or fish remain to (2) few orvery few and corroded to fragmented planktonics, robust,often strongly calcified (in growth), and common
benthonics variable in preservation, substantial clay, andfish remains. The former is exemplified by Cores 10 and 11,
the latter by Cores 9, CC and Core 15; Core 16, CC andCore 17, Section 1 contain both benthonics and goodplanktonics. The explanation for the inverse relationshipbetween the calcareous planktonics and benthonics appears
to lie in the composition and age indications of the latter:
species of Nuttallinella, Gyroidinoides, Anomalinoides,
Cibicides, Oridorsalis, Marssonella, etc. are of SenonianMaastrichtian aspect rather than Paleocene and are known
from carbonate shelf facies. Other benthonics (e.g.,
Nuttallides) are lower Tertiary. Since no Cretaceousplanktonics have been found and the Paleocene biostratigraphic record in Core 12 to Section 17-1, though it could
be better, shows no evidence of mixing or inversion, it
might be concluded that some part of this section (alsoCore 9) is material stripped from a high on which normal
marine benthonics flourished, but planktonics did notaccumulate (in the Upper Cretaceous at any rate they may
well have in the Paleocene). If the estimated 2-m.y. intervalof Zone P.4 extends from Core 13, Section 4 to Core 17,
Section 1 (a minimum), then the accumulation rate is of
the order of 20 m/m.y.—rather high, particularly in a
calcareous section showing so much corrosion andfragmentation of foraminiferal tests. A tentative figure of
12 m/m.y. for Cores 9, CC to 11, CC puts the lower Eocene
clayey material in the same class, since Cores 10 and 11
contain relatively little clay. It would seem that thesefigures support the foraminiferal evidence for redeposition,and it could be inferred that some nearby part of the
Ninetyeast Ridge was topographically very shallow during
the Late Cretaceous. Finally, the great dominance ofsubbotinids over acarininids and globorotalids in Core 16,
CC and Core 17, Section 1 may indicate an "extratropical"
environment at about 58 m.y. In any case, the grosscomposition contrasts sharply with that in Cores 10 and 11(lower Eocene).

197

SITE 215

Nannofossils
Calcareous nannofossils were recovered at Site 215 fromnear the base of Core 9 through Core 17. The preservation
is variable, but datable assemblages are present throughout
the interval. The bottom of Core 9 is assignable to theTribrachiatus orthostylus Zone of early Eocene age. Core
10 and Sections 1 and 2 of Core 11 also are of early Eocene
age, probably assignable to the Discoaster diastypus Zone.
From Section 3, Core 11 through the top of Section 2,
Core 13, the late Paleocene Discoaster multiradiatus Zone isrepresented. Additional Paleocene zones are present asfollows: Core 10, Section 2 to Core 14, Section
A—Discoaster mohleri Zone; Core 14, Section 4 to Core 17,
Section 1, ~90 cm—Heliolithus kleinpelli Zone; basal partof Core 17—Fasciculithus tympaniformis Zone.
The nannofossil assemblages in the calcareous intervalfrom Cores 9 through 17 are for the most part of normal
diversity with fair to good preservation except at the top
and bottom of the calcareous interval where solution
effects are strongly manifested. Only the most solutionresistant species remain at the top where the calcareous
section grades into the barren deep-sea clays above.
Similarly poor preservation and low diversity characterize
the calcareous nannofossil assemblage immediately above
basement.
Radiolaria
At Site 215 Radiolaria are common and well-preservedin Cores 1 through 7. In Core 8 Radiolaria are few to rare
and moderately to poorly preserved. No identifiable
Radiolaria were encountered between the bottom of Core 8
and the base of the sediment at the basalt contact, although
trace amounts of siliceous debris were observed in a few
samples.
The Radiolaria in Cores 1 through 8 range in age from
Quaternary through upper Miocene. The following zonal
boundaries can be recognized: The base of the Quaternarylies within Core 1, between Samples 215-1-4, 130-132 cm
and 215-1-5, 70-72 cm. The base of the Pterocanium
prismatium Zone is between Samples 215-2-1, 53-55 cm
and 215-2, CC. The base of the Spongaster pentas Zone is
between Sample 215-5-3, 70-72 cm and 215-5, CC. Thebase of the Stichocorys peregrina Zone lies between
Samples 215-7, CC and 215-8-1, 90-92 cm. The
Ommatartus penultimus Zone appears to be missing at thissite, since the base of this zone occurs at approximately thesame level as the base of the Stichocorys peregrina Zone.
The base of the Ommatartus antepenultimus Zone occurs
in the interval below Core 8 in which radiolaria are absent
or unidentifiable. The earliest identifiable radiolarianassemblage at Site 215 is at Sample 215-8-5, 78-80 cm andappears to be in the upper Ommatartus antepenultimus
Zone.
CORRELATION OF REFLECTION PROFILEAND STRATIGRAPHIC COLUMN
Site 215 is near the distal portion of the Bengal Fan. The
seismic profile approaching the site from the south shows
irregular outcropping acoustic basement with small basinsof ponded sediment. Immediately north of the site the198smooth, graded surface of the Bengal Fan begins, risingsteadily to the north. Site 215 is situated in what appearson the single available crossing to be a basin approximately
4 nautical miles in length, containing up to 0.25 sec of
sediment. Surface sediment at the site is at a slightly higher
level than the surface of obvious Bengal Fan sediments tothe north. However, deeper layers within the "basin" maybe continuous with fan sediments.
Details of the seismic reflection record at Site 215(Figure 3) show an upper, acoustically transparent zone ofponded sediments 0.06 sec in thickness. This is underlain
by a zone of ponded sediments characterized by asuccession of well-defined reflectors which resemble theBengal Fan turbidites. At the drill site, this zone is only
about 0.005 sec thick, over a basement high, but nearby itreaches a thickness of 0.1 sec. Lowermost zone on theseismic profile consists of an acoustically transparent layer
0.1 sec in thickness which is draped over the irregularacoustic basement (3).
The upper acoustically transparent zone on the record
represents a 46-meter-thick Radiolaria diatom ooze unit,
with an interval velocity of 1.5 km/sec. The underlying thinzone of acoustically layered sediment may represent a
28-meter section which is bounded at the top and bottom
by thin terrigenous silty clays and clayey silts, separated byclayey Radiolaria diatom ooze. This unit is tentatively
considered to be distal Bengal Fan sediments, possibly of
turbidite origin. The basal acoustically transparent drapedzone correlates with the thick nannofossil ooze to chalk
unit which overlies basalt.
Overall sediment thickness at the drilling site is 155.5
meters, represented by 0.18 sec on the seismic profile.
From these observations, the overall interval velocity ofSite 214 is 1.7 km/sec.
Depth of reflections and interval velocities are as
follows:

Reflector

2-Way Time
(sec)

Depth
(m)

Interval Velocity(km/sec)

0
0.06
0.18

0
46
151

1.5
1.8

1.7

SUMMARY AND CONCLUSIONS
Site 215 is situated in the central Indian Ocean Basin ina water depth of 5309 meters, approximately 240 km westof the median line of Ninetyeast Ridge. The hole wasdrilled in what appears on one crossing to be an 18-km-longbasin of ponded and draped sediments up to 0.25 sec thick.
The basin is separated by basement highs from the distal
portion of the Bengal Fan to the north.
The 175 meters of sediment and rock drilled at Site 215
is divisible into five lithologic units. The lowermost unit
consists of a succession of pillow basalts with mid-Indian
Ocean Ridge affinities. This typical sea-floor basalt isoverlain by 1 meter of mid-Paleocene iron-oxide-richnannofossil ooze which is in turn overlain by a 70-meter
unit of nannofossil ooze and thin cherts of mid-Paleocene

SITE 215

SECS
6

SITE 215
c/c toreciptocal

meters- 0
Radiolarian diatom
ooze

CM

Thin terrigenous
silty clays
Zeolitic brown clay
-7

100
Nanno ooze

Pillow basalt

Nautical Miles

Figure 3. Correlation of reflection profile and stratigraphic column at Site 215.
to early Eocene age. Seven meters of barren zeolitic brown
clay, corresponding to a 40-m.y. time interval, lies above
the nannofossil ooze and is succeeded by upper Miocene
terrigenous silts and clays. The uppermost unit at Site 215
is a 70-meter-thick radiolarian-diatom ooze of upper
Miocene to Quaternary age.
The stratigraphy and biostratigraphy of Site 215 imply
subsidence accompanying sea-floor spreading in a fashion

very similar to Site 213 which is situated on the opposite
side of the Ninetyeast Ridge. The major difference between
these two sites is the occurrence of upper Miocene
terrigenous silts and clays at Site 215 which probably
represent distal turbidites of the Bengal Fan.
The oldest nannofossils and foraminifera, which were
found with the basalts at the base of Core 17, give an age
between 58 and 60 m.y. for the crust at this site. They are

199

SITE 215

significantly younger than the age of the crust of 72 m.y.
given by the beginning of magnetic anomaly 31 to the west
(McKenzie and Sclater, 1971) which is at the same latitude.
Apparently the oceanic crust just to the west of the
Ninetyeast Ridge is younger than the crust west of 86°E.
Thus, there must be a major fracture zone unidentified
from topography running parallel to the Ninetyeast Ridgealong 86°E offsetting the oceanic crust of the same age
some 6° to 8° to the south. Though some 350 km to thenorth of Site 214, Site 215 has a basement age of 58 to 60

200m.y. which, though probably slightly older, is still close to
the Paleocene age of the basal sediments at Site 214. Thissimilarity and the possible existence of the fracture zone at
86°E are discussed further in the regional synthesis chapter.
REFERENCE

McKenzie, D. P. and Sclater, J. G., 1971. The evolution of
the Indian Ocean since the Late Cretaceous: Geophys. J.
Roy. Astro. Soc, v. 25, p. 439-528.

S1teZl5

HoleCore 1

Cored Interval: 0-9.5 m

Site215

LITHOLOGIC DESCRIPTION

RAD DIATOM OOZE
dark yellowish brown 10YR4/4 soupy
Diatoms
50%
Rads
25%
Clay and Spicules
25%
RAD DIATOM OOZE
light yellowish brown 10YR6/4
to yellowish brown 10YR5/4
Diatoms
50%
Rads
30%
Spicules10*
Silicoflag.
2%
FeO grains
2%
Opaques1%
Clay5%
with abundant streaks and mottles
of very dark grayish brown
10YR3/2 to black 10YR2.5/1 - Mn
rich

Hole

Core 2

Cored I n t e r v a l : 9.5-17 in

LITHOLOGIC DESCRIPTION

RAD DIATOM OOZE
yellowish brown 10YR5/4 w i t habundant streaks and mottles
o f black 10YR2.5/1 - Mn r i c hSite 215

Hole

Core 3

Cored Interval.- 17-26.5 m

S i t e 215

Core 4

Cored I n t e r v a l : 2 6 . 5 - 3 6 m

LITHOLOGIC DESCRIPTION

LITHOLOGIC DESCRIPTIONRAD CLAY RICH DIATOM OOZE
brown 10YR5/3
Diatoms
Clay
Rads
SpiculesHole

l i g h t yellowish brown 10YR6/4
6058
25%
10%
5%

RAD CLAY RICH DIATOM OOZE
pale brown 10YR6/3
Diatoms
60%
Rads
15%
Clay
20%
Spicules5%some black streaking e . g . 17-24
cm, 40-50 cm and patches o fdarker color 10YR6/2 e . g . 84 cm
which i s RAD RICH DIATOM CLAY

CLAY RAD RICH DIATOM OOZE
moderately f i r m , l i g h t yellowish
brown 10YR6/4 w i t h traces o fbrown 10YR5/3
Diatoms
60£
Rads
20X
Clay
162
Spicules2%
Silicoflag.
2%

Clay
45%
Diatoms
35%
Rads
20%
l i g h t brownish gray 2.5Y6/4
with few smears o f grayish brown
2.5Y5/2

Sections 3 , 4 , 5, 6
l i g h t yellowish brown with
abundant black streaks andpatches o f brownl i g h t yellowish brown 10YR6/4
with dark smears a t 74-85, 95102, 120-122, and 142 cm.

SPONGE SPICULE RAD RICH CLAY
DIATOM OOZE
Diatoms
40%
Clay
35%
Rads
15%
Spicules10%

ASH BEARING RAD RICH CLAY DIATOM
OOZE
l i g h t brownish gray 2.5Y6/2
Diatoms
40%
Clay
32%
Rads
20%
Volcanic glass (mostly
rhyolitic, somebasaltic)3%
Spicules5%
10YR6/4 with streaking o f 2.5Y6/2
between 60 and 90 cm
patches o f brown 10YR5/3 from90-130 cm
Quar 27, Plag 6, Kaol 19, Mica 24,
Mont 24

Site 215

Hole

Site 215

Cored Interval:36-45.5 m

Hole

Cored Interval; 45.5-55 m

FOSSILCHARACTERFOSSILCHARACTER

LITHOLOGIC DESCRIPTION

LITHOLOGIC DESCRIPTION

l i g h t yellowish brown 10YR6/4
mixed w i t h brown 1OYR5/3,
few black specks from 0-30 cm

l i g h t yellowish
brown 10YR6/4
down t o brown
10YR5/3, 107-110
cm very dark gray
10YR3/1 pocket
SILTY CLAY
grayish brown 10YR5/4, s i l t
f r a c t i o n mainly carbonate withfeldspar and hornblende
Clay
702J
Silt
30*

pale brown 10YR6/3 with few
patches o f 10YR6/4

l i g h t yellowish
brown 10YR6/4
VOI_D
pale brown
10YR6/3

10YR6/4 w i t hstreaks o f gray
10YR5/1

10YR6/4
RAD RICH DIATOM CLAY
Clay
Diatoms
Rads
SpiculesSilicoflag.
FeO
Phillipsite

CLAY
gray 10YR5/1, s i l t fraction mainly
feldspar, rare quartz (?) andbasic glass.
Clay
80?
Silt
20%

105-150 very watery40%
X-ray a t 47.80 m Quar 20, Feld 2 , Plag 4 , Mica 6 1 ,Chio 6, Mont 720%
2%

Site 215

Hole

Cored Interval:55-64.5 m

FOSSILCHARACTER
LITHOLOGIC DESCRIPTION

Explanatory notes in Chapter 1

l i g h t yellowish
brown 10YR6/4=l-÷=O=

97-105 patchesof l i g h t gray
5Y7/2
10YR6/4

CLAY DIATOM RAD OOZE
pale brown 10YR6/3
Rads
Diatoms
Clay
SpiculesSilicoflag.
Basic volcanic glass pale green

40%

;os
28%
1%
1%
Tr.

X-ray a t 57.10 m Quar 2 8 , Plag 8 , Kaol 1 6 , M1ca 2 8 ,Mont 20
Explanatory notes in Chapter 1

Site 215

Hole

Core 8

Cored I n t e r v a l : 6 4 . 5 - 7 4 m

Site 215

Hole

Core 9

Cored I n t e r v a l : 74-83.5 m

LITHOLOGIC DESCRIPTION

LITHOLOGIC DESCRIPTION

very dark gray
10YR3/1 grading
down to darkbrown 10YR3/3

CLAY
mostly l i g h t brown 7.5YR6/4
with mixed very pale brown
10YR7/3 yellow brown 10YR5/4
Clay
902
Rads
5%
Spicules3%
Feldspar, volcanic
glass, FeO, s i l i c o flag.
2%

ZEOLITE RICH CLAY and FeO/Mn(?)
r i c h i n places, smear pale
brown 10YR6/3 77-85 cm
Clay
803!
FeO/Mn(?)
10*
Phillipsite
10%
Nannosmottled brown
10YR5/3

Tr•dark brown 7.5YR4/2 changing
from 70 to 90 cm to brown 10YR5/3
with blotches of very pale brown
10YR7/3 near base Section 3.
CLAY RICH NANNO OOZE
Nannos70%
Clay
20%
Calcite fragments
9%
FeO
1%
X - r a y a t 74.40 m Quar 1 0 , Feld 8 , Mica 6 , Mont 1 3 ,Paly 3 6 , P h i l 27
X - r a y a t 7 6 . 1 0 m Quar 8 , Paly 91
X - r a y a t 77.40 m Quar 7 , Paly 8 9 , H a l i 5

S i t e 215

HoleCore 10

Cored I n t e r v a l : 8 3 . 5 - 9 3 . 0 m

LITHOLOGIC DESCRIPTION

pale yellow 2.5Y7/4

CLAY RICH NANNO OOZE
2.5Y7/4
NannosClay
Calcite fragments mostly rectangular
FeO

80%
15%
5%
Tr.

white 2.5Y8/2,
f i r m and s o f talternations

becoming f i r m e r

CLAY BEARING NANNO OOZE
NannosClay
C a l c i t e fragments
Foram
Carbonate rhombs
FeO

84%
10%
5%
1%
Tr.
Tr.

Site 215

Hole

Core 11Site 215

Cored I n t e r v a l : 93-102.5 m

LITHOLOGIC DESCRIPTIONNANNO OOZE
very pale brown 16YR8/4 withsmears and pockets of white
Nanπos
92%
Clay
5%
Foram
3%
Dolomite
Tr.
Authigenic carbonate
Tr.
Rads
Tr.

Hole

Corel2

Cored Interval: 102.5-112 m

LITHOLOGIC DESCRIPTION

CLAY RICH NANNO OOZE
very pale brown 10YR7/3
with few pockets o f white
10YR8/2. At approx. 20 cm
i n t e r v a l s are firmer zones
2-3 cm t h i c kNannos
Clay
Foram

79%
20%
1%

Site 215

Hole

Corel3

S i t e 215

Cored I n t e r v a l : 112-121.5 m

HoleCore 14

Cored I n t e r v a l : 121.5-131 m

LITHOLOGIC DESCRIPTION

LITHOLOGIC DESCRIPTION

105 107~
117-120

CLAY RICH NANNO OOZE
very pale brown 1OYR7/4
Nannos85%
Clay15%
few white blebs throughout
Chert nodule yellowish brown
10YR5/4 porcellanous shows
burrows and chemical a l t e r a t i o n
fragment 5 cm across.

Chert nodules brown 1OYR5/3 andvery dark gray 10YR3/1 with white
chalky r i n d in places.

95-105 to 130-135 zones
o f white mottles

CLAY RICH NANNO OOZE
very pale brown 10YR7/3 withfew scattered white pockets up
to 1 cm across, every 10-50 cm
get 5 cm thick more l i t h i f i e dzone

white 10YR8/1
chalk zone

CLAY RICH NANNO CHALKSite 215

Hole

Core15Site 215

Cored I n t e r v a l : 131-140.5 m

HoleCorelβCored Interval: 140.5-150 m

LITHOLOGIC DESCRIPTION

LITHOLOGIC DESCRIPTIONNANNO OOZE
l i g h t yellowish brown 10YR6/4 withsparse specks o f white
CLAY RICH NANNO OOZE
very pale brown 10YR7/4
w i t h rare white streaks
Nannos
Clay
FeO

85%
1458
U

to

o

Site 215

Hole

Core 17Site 215

Cored Interval: 150-155.5 m

00

Hole

Core 19

Cored Interval: 162-165.5

FOSSILCHARACTERFOSSILCHARACTER
LITHOLOGIC DESCRIPTION

LITHOLOGIC DESCRIPTIONBASALT
Holocrystaiiine unweatheredcoarse grained rock, medium darkgray N4. Subophitic texture no
phenocrysts.
Plagioclase40*
Clinopyroxene
40*
Iron
10*
Chi on" t i c material
10*

IRON OXIDE RICH CLAY NANNO OOZE
dark"grayish brown 10YR4/3
CONTACT ZONE

dark brownglassy palagonite

dark grayish brown
nanπo chalk as
above but hard
yellow a l t e r e dpalagonite

glassy zone
bordered byweathered basalt

black volcanicglassbasalt70-110 cm calcite
veins

BASALT-weatheredvarioiitic texture
Plagioclase in matrix
30%
Microphenocrysts
Plagioclase
1*
Reddish brown mesostasis 69%

Core
CatcherSite 215

Core
CatcherSite 215

Hole

Core 18

2-12 cm black
glass

white 10YR7/2 limestone withpalagonite - yellow fragments
1-3 inn numerous fresh blackglass fragments <l mm
IRON OXIDE RICH NANNO CHALK

Hole

Core20Cored Interval: 165.5-175 m

FOSSILCHARACTER
LITHOLOGIC DESCRIPTION

Cored Interval: 155.5-162 m

FOSSILCHARACTER
100-120 cm calcite veining
100-130 cm basalt is moderately fresh

LITHOLOGIC DESCRIPTION

limestone bordered by basaltic
glass then chilled margin ofglassy basalt

glassy zone

glassy zone

BASALT
partially weathered olive gray
5Y4/1
Plagioclase in matrix
55*
Dark brown mesostasis
35*
Olivine ?
3*
Calcite3*
bordered Pyroxene1*
by finer Plag. micro, phenocrysts 1%
weathered Palagonite
lit
basaltglassy zone with weathered finer basalt on each side

120-150 cm one side of core comprises basaltic glass
glassy limestone and palagonite
glass with weathered borders of fine basalt

glass with weathered borders of fine basalt
glassy zone
glass with weathered borders of fine basalt
small edge of glass at 35 cm
glass with weathered borders of fine basalt

Core
CatcherCore
Catcher

Explanatory notes in Chapter 1

Explanatory notes 1n Chapter 1

SITE 215

0 cm

25

50

75

100

125

150

215-16-1
215-16-2
215-16-3
215-16-4
Photos for Cores 1 to 15 not available.

215-16-5

215-17-1
209

SITE 215

215210215-18-2

215-18-3

215-19-1
215-20-1

SITE 215

0 cm

25

50

75

100

125

150

215-20-2

215-20-3

215-20-4
211