7. SITE 188
The Shipboard Scientific Party1

SITE DATA
Date Occupied: 15-16 Aug 71.
Position:

53°45.2l'N
178°39.56'E.
Water Depth: 2649 meters.
Penetration: 638 meters.
Number of Holes: One.
Number of Cores: 18.
Total Core Recovered: 57.4 meters.
Acoustic Basement:

Depth: Greater than 1.0 sec andNature: Unknown
Velocity: Unknown.
Age of Oldest Sediment: Upper Miocene.
Basement: Unknown.

SUMMARY

Site 188 is located at the outer edge of the mid-slope
terrace on the western flank of Bowers Ridge, Bering Sea,
in water 2649 meters deep. The 638-meter thick sedimentary sequence drilled and cored consists basically of a
Pleistocene to upper upper Miocene (0-580 m) unconsolidated and semiconsolidated interbedded diatom ooze,
silt-rich diatom ooze, and diatomaceous silt overlying
mudstone (580-638 m) lacking diagnostic fossils. The upper
diatomaceous unit is similar to Unit A at Sites 184 and 185,
and the lower is similar to the mudstone sequence, Unit B,
at Site 184.
Variations in the relative abundance of diatoms andinorganic silt plus thin layers of volcanic ash, black sandand silt, and limestone occur throughout the upper 580
meters. Foraminiferal assemblages are typical of present
water depths.

1David W. Scholl, U.S. Geological Survey, Menlo Park, California; Joe S. Creager, University of Washington, Seattle, Washington; Robert E. Boyce, Scripps Institution of Oceanography, La
Jolla, California; Ronald J. Echols, University of Washington,
Seattle, Washington; Timothy J. Fullam, Standard Oil Company ofCalifornia, La Habra, California; John A. Grow, Massachusetts
Institute of Technology, Cambridge, Massachusetts; Itaru Koizumi,
Osaka University, Osaka, Japan; Homa J. Lee, Naval Civil Engineering Laboratory, Port Hueneme, California; Hsin Yi Ling, Universityof Washington, Seattle, Washington; Richard J. Stewart, Universityof Washington, Seattle, Washington; Peter R. Supko, Scripps
Institution of Oceanography, La Jolla, California; Thomas R.
Worsley, University of Washington, Seattle, Washington.

Except for a few thin sand layers, no evidence ofturbidite deposition was encountered at Site 188, hence it
seems unlikely that any part of the Neogene section was
deposited beneath the abyssal floor of the adjacent Bowers
Basin. Thus, the drilled section at Site 188 appears to be an
in situ pelagic and terrigenous blanket depositionally draped
over a deeper basement underlying the inner flank ofBowers Ridge (Ludwig et al., 1971a).
The prominent reflection horizon "P" noted by Ewing
et al. (1965) and Ludwig et al. (1971a; 1971b) in this area
is caused by the major lithologic transition at a subbottom
depth of 580 meters. This transition, from terrigenous-richdiatom ooze to terrigenous mudstone of late late Miocene
age takes place over a vertical thickness less than about 15
meters. A similar lithologic break was found at Sites 184
and 185 and also in deposits of late Miocene age. The BSR
beneath Umnak Plateau and the "P" horizon of Bowers
Ridge are thus equivalent to the top of a lithified
terrigenous sequence. However, the subbottom depth to
this lithified section is not everywhere a measure to a
stratigraphic level; the BSR is time transgressive and its
position and geometry is partly related to diagenetic
alteration of terrigenous-rich diatomaceous deposits ofearly late to late late Miocene age (see Scholl and Creager;
Stewart; Fullam et al.; all in this volume).
BACKGROUND AND OBJECTIVES
Description

Bowers Ridge is one of those rare bathymetric elementsthat is sharply arcuate in form and nearly closes on theprincipal structure (i.e., Aleutian Ridge) from which it
extends. Site 188 is located at a depth near 2600 meters on
the lower part of the westward-sloping inner flank of thisnorthward-looping ridge (Figure 1).
Acoustic reflection profiles crossing this flank reveal athick sequence of sedimentary beds covering an "acoustic
basement" at a subbottom depth near 2 km. This basement
can presumably be traced to exposure of deformed volcanicand siliceous sedimentary rocks underlying the shallowly
submerged summit of Bowers Ridge. The younger sedimentary deposits underlying the middle and lower parts of
the inner flank of the ridge can be traced downslope
beneath a thick (approximately 1 km) turbidite sequence
immediately underlying the flat floor of Bowers Basin.
Beneath the basin ward-sloping flank deposits, a prominent
reflection occurs at a subbottom depth near 600 meters,
this is horizon "P" of Ewing et al. (1965). Reflection
records of exceptional quality suggest that this reflecting
surface produces cross-bedding surfaces much as does the
BSR or Bottom-Simulating Reflector (see site reports for
184 and 185) beneath Umnak Plateau.

291

SITE 188

washing from the sea floor to a subbottom depth of 638
meters. At approximately 580 meters mudstone was
encountered. This sedimentary rock correlates well with the
expected deepest reflector, the site target. Three more cores
were taken to assure us that the target had been reachedand that more drilling would not yield datable material.
Satisfied in this, the hole was terminated.
Using Matthews Tables, the sonic depth of 1380 frns wascorrected to 2607 meters giving a water depth of 2613
meters and a drill-floor depth of 2623 meters. This
compares with 2659 meters below drill floor established on
the basis of the first core collected containing sediment.
The 2659 meters below drill floor, or 2649 meters below
sea level, is the accepted depth for this site.
No difficulties were encountered in drilling this hole.
Diatomaceous silty clay was present from the bottom toabout 580 meters and mudstone and limestone were
present from 580 to 638 meters. Drilling and coring became
progressively harder with depth until the mudstone wasreached, after which drilling was significantly more difficult. A coring summary is given in Table 1.
LITHOSTRATIGRAPHY

Figure 1. Base map showing the location of Site 188,
Bowers Ridge.
Objectives

The principal reason for occupying Site 188 was todetermine the geologic implication of reflector "P". Specifically, is it (1) a variety or type of bottom-simulatingreflecting surface, possibly associated with gas and an
overlying clathrated section, or (2) a lithologic boundary
related to a fundamental change in style of sedimentation
over the flank of the ridge? Additionally, the possibility
that the ridge may have been formed as a result of late
Tertiary uplift (Ewing et al., 1965) can be assessed bydetermining the probable depositional position of the flankdeposits, i.e., are they in situ ridge deposits or uplifted
Bowers Basin units.
OPERATIONS
Pre- and Post-drilling Survey

Site 188 is located on the western flank of Bowers Ridgealong the track of the reference profile collected by G.G.
Shor on 26 Jul 70 (Figure 2). The site was approached witha ship's heading of 301 °T which was approximately theheading used in the collection of the reference profile. The
air-gun profile obtained during the approach (Figure 3) soclosely approximated the reference profile that the beacon
was dropped on the fly at 0300 on 15 Aug 71. The finallyaccepted position is: 53°45.2l'N; 178°39.56'E. No postdrilling survey was deemed necessary. A map showing theapproach and departure tracks plus the site location isshown in Figure 4.
Drilling Program

Site 188 was occupied from 0300 hrs 15 Aug 71 (beaconaway) until 1530 hrs 16 Aug 71 with alternating coring and292

At Site 188 two major lithologic units were sampled.
Unit A, from 0 to 580 meters below bottom is unconsolidated and semiconsolidated, interbedded diatom ooze,
silt-rich diatom ooze, and diatomaceous silt. Unit B, from
580 meters to the bottom of the hole is mudstone.
Unit A - 0 to 580 meters
Unit A extends from 0 to 580 meters below bottom andis unconsolidated and semiconsolidated olive gray diatom
ooze, silt- and clay-rich diatom ooze, and diatomaceous silt.
Thin layers of volcanic ash occur at 37 to 38 meters and284 meters. Black sands and silts occur at 30 to 34 meters,
100 meters, and 283 to 284 meters.
Thin (5-10 cm) limestone layers are present at 283
meters and 425 meters. The first occurrence of very hard,conchoidally fractured black mudstone was in the corecatcher of Core 14 at approximately 273 meters. A second
large fragment of the olive black mudstone was cored at
580 meters.
From the surface to about 315 meters Unit A is
unconsolidated, while from 315 to 573(?) meters it issemilithified with the exception of unconsolidated material
between 573 and 582 meters, which could be the result of
drilling disturbance.
Unit B - 582 to 638 meters
Unit B is olive black mudstone. Some fragments are very
hard, have a waxy luster, and a distinct conchoidal fracture.
In addition to clay, feldspar, pyrite, and muscovite, tracesof chlorite, zircon, and pyroxene were observed in samplesof the hard mudstone. The rest of the mudstone is thinly(regularly and irregularly) laminated with bands and lenses
1 mm to 3 cm thick. Traces of sponge spicules, radiolarians,
and foraminifers are present.
A 20-cm layer of light olive gray limestone occurs at 601
meters.

SITE 188

-3.5

-4.5

:

'-

1* t :sf*• l• $ ri
-

••

'

..

' .. j,
j
j

•

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'

i-5.5

^_
j1

SJ

|

'l

l

i
!

i

l i e
\

••

N
t—6.5

Figure 2. S‰ 188 reference seismic reflection profile, obtained by G. G. Shore, 26 Jul 70.
PHYSICAL PROPERTIES

Physical properties measured at Site 188 include bulk
density, water content, natural gamma radiation, acoustic
velocity, vane shear strength, and residual pore waterpressure. Bulk density was measured with the GRAPE
system, calculated on the basis of shore laboratory watercontents, and, for the harder materials, measured by thewater displacement method.
The bulk densities are presented on a core basis opposite
the core summary sheets. Mean GRAPE densities, water
displacement densities, shore laboratory densities, andacoustic velocities are shown on the site summary sheet.
Bulk Density

GRAPE densities were obtained to a sediment depth ofabout 290 meters. Below this point the sediment was
broken and no longer filled the core liner completely.
Several water displacement densities were obtained for the
deeper material.
The measurements at Site 188 disclose a zone extending
from 0 to 600 meters which has a low, uniform density (1.3
to 1.4 g/cc). There is virtually no increase in density withdepth, indicating that the diatom ooze is practially incompressible. On a core level there is some variation depending
upon the clay and silt content. The more clayey sections
have densities about 15 percent higher than the nearly pureoozes. Also, the few ash layers are apparent as high-density
zones. At about 600 meters there is a sharp break in thetrend with the density increasing rapidly to 1.8 g/cm3.
Acoustic Velocity
The acoustic velocities measured with the Hamilton
Frame follow the same trend as the densities. A zone
extends from 0 to 600 meters over which the acoustic
velocity gradually, but very consistently, increases from1.55 to 1.65 km/sec. At 600 meters there is a sharp breakwith velocities increasing to 2.4-2.6 km/sec in the mudstone
and 4.5 km/sec in a layer of limestone.
Summary

The density and acoustic velocity measurements indicate
a uniform, low-density, low-velocity zone extending fromthe sea floor to a sediment depth of 600 meters. Below 600
meters, a zone of relatively high-density, high-acoustic

293

SITE 188

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time,
sec.
Figure 3. Glomar Challenger seismic reflection profile obtained on approach to Site 188.
velocity material is encountered. The density measurements
indicate that the diatom ooze of the upper zone is relatively
incompressible.
PALEONTOLOGY

Within the upper 300 meters of diatomaceous sediments(Cores 1 through 10), Pleistocene and late Pliocene age,nannofossils are found sparsely distributed through the firstsix cores. Species diversity of radiolarians and silicoflagellates decrease downward, and calcareous benthic foraminifera are present down to the level of Core 8. Solutioncorroded planktonic foraminiferal specimens are observed
above Core 5.
In the underlying early Pliocene and late Miocene
semilithified diatomaceous section (Cores 12 through 15),
radiolarians become rather scarce, but the number ofsilicoflagellate specimens as well as species increase. The
underlying mudstone unit failed to yield any index microfossils.

294

As in previous sites, the absence of all calcareous fossils
in the Pliocene section (Cores 8-11) is probably indicativeof an elevated carbonate compensation depth.
Foraminifera

In the Quaternary section (Cores 1-8) planktonic foraminifera vary from abundant to absent and calcareous
benthics are usually present. Above the core catcher ofCore 5, planktonic foraminiferal tests are more or lessuniformly corroded, but preservation of some of the tests
in the core catcher of Core 5 and the top and bottom (butnot the middle) of Core 6 is excellent.
In the Pliocene section (Cores 9-13) the only foraminiferan found is a probable new species oi Eggerella that also
occurs in the Scotia Sea area of the southern Atlantic
Ocean (Echols, 1971). It has a test that is insoluble in diluteHC1 and therefore unlike the calcareous tests of morphologically similar forms of Eggerella that are associated withthe calcareous faunas in the Quaternary section at this site.

SITE 188
178°35'E

1630L/16 AUG 71 DR

0322 L/15 AUG 71
C/C 119°02201/15 AUG 71
SAT NAV

53°40'N

Figure 4. Glomar Challenger approach and departure tracks, Site 188.

At the level of Core 12 the sediment becomes difficult
to disaggregate and in Cores 15 and 16 it hardens tomudstone; identifiable foraminifera have not been found inthese sediments, but fragments of arenaceous tests could bepresent in Core 17.
Populations of Globigerina pachyderma at this site
consist of dominantly sinistral form with relatively small
pores and a dominantly dextral form with large pores.
Populations are 96 to 100% sinistral to the bottom of Core
5. They are 85% sinistral in the core catcher of Core 5 andfrom there the frequency of sinistral forms appears to fall
off gradually with depth, becoming 75% at two levels inCore 6 and 40% in Core 7. The smaller populations of Core
8 are also dominantly dextral. The large-pored form appears
first down the core at the top of Core 5. According to
subdivisions based on diatoms at this site, the large-poredform appears first in middle middle Pleistocene, becoming
dominant in the upper lower Pleistocene.
A sand layer in Core 6, Section 1, Interval 80-82 cm, isrich in planktonic and benthic tests. The benthic fauna isdominated by Bulimina exilis; Uvigerina senticosa, Melonis
barleanus, Pùllenia bulloides, and two species of Globobulimina are common. These and other less common species are
typical of the present water depth at Site 188, therefore,
they provide no evidence that the sand layer is a turbidite.

Calcareous Nannoflora

At Site 188, only the topmost six cores (130 m) werefossiliferous with respect to calcareous nannoplankton.
Species diversity is expectably low and the only diagnostic
species found for this entirely Pleistocene sequence were afew partially dissolved specimens of Gephyrocapsa sp. andEmiliania cf. huxleyi in Core 4. Core 5 was conspicously
richer in nannoplankton than other cores, although most
specimens were Coccolithus pelagicus.

Radiolaria and Silicoflagellates

Occurrence of Radiolaria is discussed in Chapter 28(Ling, this volume). Cores 1 and 2 yield a typical Bering Sea(surface sediments) fauna. Eucyrtidium tumidulum wasrecovered in Core 3 and rare occurrence of Druppatractus
acquilonius {=Stylacontarium acquilonium in this paper)
was noted in Core 7. Radiolarians are rather scarcethroughout the Pliocene and upper Miocene sections andare essentially absent below Core 15.
Stratigraphic distribution of silicoflagellates from thissite is similar to those of previous sites. Like radiolarians,
silicoflagellates are also absent below Core 15.

295

SITE 188

CORRELATION BETWEEN REFLECTION PROFILEAND STRATIGRAPHIC COLUMNTABLE 1
Coring Summary — Site188
Recovered

Cored Interval
Below Bottom

Cored

Core

(m)

(m)

(m)

(%)

1
2
Wash
3
Wash

0-1
1-10

1
9

1.0
4.5

100.0
50.0

30-39

9

9.1

101.0

59-68

9

3.1

34.0

87-96

9

2.5

27.0

124-133

9

5.3

58.0

7

171-180

9

9.5

105.0

Wash
8
Wash

227-236

9

9.5

105.0

9
10
Wash
11
Wash

283-292292-293

9
1

4.5
0.1

50.0
10.0

330-339

9

1.1

12.0

12
Wash
13
Wash
14

425-434

9

1.2

13.0

527-536

9

2.1

23.0

564-573

9

1.3

14.0

573-582582-591

9
9

1.7
CC

18.0
0.0

601-610

9

0.9

10.0

629-638

9

CC

0.0

146

57.4

39.3

4
Wash
5
Wash
6
Wash

15
16
Wash
17
Wash
18

Diatoms
Although diatoms are still abundant and well preserved
within the upper unit of diatomaceous sediments, decreasein abundancy was noticed in comparison with previous
sites. Occurrence of diatom taxa at this site is shown in
Table 6, Chapter 30.

296

The reflection profile, taken by G.G. Shor on the R/VMelville (1970), which was used to select Site 188, is shownin Figure 5 along with the stratigraphic column andphysical properties. The reflection profile was taken on acourse of 287°T (to the right) and was very close to the
Glomar Challenger's course of 296°T. The only strong
reflector on the record is at a depth of 0.72 sec and nobasement can be seen although the penetration is at least
1.0 sec. While there are numerous thin reflectors within thecolumn above 0.72 sec, the lithology of these upper units is
a moderately homogenous diatom ooze with various
amounts of silt and clay. Consequently, there is no clear
correlation between the upper lithologic subunits and theseminor reflectors. The prominent reflector at 0.72 sec is the
mudstone. Density and velocity plots also show only one
major discontinuity at the top of the mudstone.
Interval velocities for Unit A are near 1.6 km/sec
according to shipboard measurements, in agreement withthat (1.62 km/sec) calculated by reflection time andmeasured drill distance.

REFERENCES
Echols, R.D., 1971. Distribution of foraminifera in sediments of the Scotia Sea area, Antarctic waters. In
Antarctic Oceanology I, Reid, J.L. (Ed.). Am. Geophys.
Union, Antarctic Res. Ser. 15, 93.
Ewing, M., Ludwig, W.J. and Ewing, J., 1965. Oceanic
structural history of the Bering Sea. J. Geophys. Res.
70(18), 4593.
Ludwig, W.J., Murauchi, S., Den, N., Ewing, M., Hotta, H.,
Houtz, R.E., Yoshii, T., Asanuma, T., Hagiwara, K.,
Sato, T. and Ando, S., 1971a. Structure of Bowers
Ridge, Bering Sea. J. Geophys. Res. 76(26), 6350.
Ludwig, W.J., Houtz, R.E. and Ewing, M., 1971b. Sediment
distribution in the Bering Sea: Bowers Ridge, Shirshov
Ridge, and enclosed basins, J. Geophys. Res. 76(26),6367.

SITE 188

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Q
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oo

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I

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(Si

1 I

r-^ C\J C\J CM

fi-'
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SILT
RICH

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σ

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5

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BEARINGoo

12

SEMILITHIFIED
CLAY& SILT
RICH

O

o

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0
0

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DOLHOLETERMINATED

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Figure 5. Correlation of seismic reflection profile with physical properties and lithologic column, Site 188.

297

to

00
DENSITY(gm/cc)Mean GRAPE Density, +Shore Laboratory Density, x
Water Displacement Density,

DEPTH
LITHOLOGIC DESCRIPTION

local interbeds ofblack volcanic sands,
volcanic ash, andlimestone.0

2.0

DENSITY(gm/cc)Mean GRAPE Density, +Shore Laboratory Density, x
Water Displacement Density,

COMPRESSIONALWAVE
VELOCITY(km/sec)
5

2.0

(m)

LITHOLOGIC DESCRIPTION

induration increasing

UNIT A(see sheet 1)

UNIT A
DIATOM OOZE,o l i v e gray, withvariable terrigenous
admixture, a t times
with the sedimentachieving thecomposition o f
diatomaceous
silty clay

.0

2.0

COMPRESSIONALWAVE
VELOCITY(km/sec)j

2.0

SITE 188

DENSITY(gm/cc)Mean GRAPE Density, +Shore Laboratory Density, >Water Displacement Density,
DEPTH
(m)

LITHOLOGIC DESCRIPTION•'Δ

f
UNIT B
MUDSTONE, black,thinly laminated withbands and lenses 1-3 cm
thick

.0

2.0

COMPRESSIONALWAVE
VELOCITY(km/sec)SITE 188
Site 188

Hole

Core 1

Cored I n t e r v a l : 0 - 1

FOSSILCHARACTER

LITHOLOGY

LITHOLOGIC DESCRIPTIONVOID

SILT RICH, SPICULE RICH CLAYEY DIATOM OOZE
olive gray (5Y 3/2)

0.5-

107
125

105-110 cm FORAM BEARING DIATOM OOZE
moderate olive brown

Core
CatcherR M(S) Distephanus octangulatus
Site 188

Hole
FOSSILCHARACTER

Core 2

Cored Interval:1-10

LITHOLOGIC DESCRIPTION

LITHOLOGY

0.5—

56

1. SILT, CLAY, SPICULE BEARING DIATOM OOZE
grayish olive (10Y 4/2)

1.0-120

-75

-75

Core
Catcher
Explanatory notes in Chapter 1

300

2. SILT BEARING, CLAYEY DIATOM OOZE
olive gray (5Y 3/2)

Slide 1-56
65% diatoms
25% clay
10% silt

Slide 1-120
85% diatoms
10% clay
5% silt

Slides 2-75, 3-75
80% diatoms
10% clay
10% quartz, feldspar
sponge spiculesSITE 188

WET-BULK DENSITY, gm/cc
1
2
3
POROSITY,%
100
0

SECTIONCM
Grain
Density

i

M
On

1-

-25

2-

-50
3-

4-

-75

-100

7-

-125

8-

9- 1
1—150

-

188-1-1 188-2-1 188-2-2 188-2-3

301

SITE 188
Site 188

Hole

Core 3

Cored I n t e r v a l : 3 0 - 3 9

FOSSILCHARACTER

LITHOLOGIC DESCRIPTION

LITHOLOGY

0.575
olive gray(5Y 4/2)

1.0-132

Basic lithology, sections 1-4-75

SILT and CLAY RICH DIATOM OOZE
75% diatoms

olive gray(5Y 4/1 - 5Y 3/2)

sec. 1, 128-139 cm Blacksand admixed with diatom ooze
(45% diatoms)
sec. 3, 100-110 cm Slightly
darker, admixture of silt

sec. 4, 140-148 cm DIATOM
OOZE, 85% diatoms-75

dark olive gray(5Y 3/2)

142

olive gray(5Y 4/2)-40

XR 4-120
94% amorph.
1% quartz
2% plag.
1% mica
1% chlor.
TR pyrite

SPICULE BEARING, SILT, CLAY RICH DIATOM OOZE
light olive gray, 80% diatoms

-80
115
145
42

SPICULE, SILT, CLAY RICH DIATOM OOZE
olive gray (5Y 3/2) 65% diatoms
SILT and CLAY BEARING DIATOM OOZE
moderate olive brown (5Y 4/4) 85% diatoms
SILT and CLAY RICH DIATOM OOZE
olive gray {5Y 4/2 - 3/2) 80% diatoms
DIATOM OOZE olive (5Y 4/3)
VITRIC ASH olive gray (5Y 4/2)
mixed: SILT and CLAY RICH DIATOM OOZEand DIATOM OOZE
olive-olive gray (5Y 4/2 - 4/3)

Core
Catcher
Explanatory notes in Chapter 1

302

SITE 188

WET-BULK DENSITY, gm/cc
1
2
3

SECTION

CM

ro

Grain
Density

POROSITY,%
100
0

I2b
''I

Jai

l
1-

-25

2-

-50

3-

4-75

5-

-100

6-

7-

-125

8-

9- 1
L-150

188-3-1 188-3-2 188-3-3 188-3-4 188-3-5 188-3-6

303

SITE 188
Site 188

Hole

Core 4

Cored Interval:59-68

LITHOLOGIC DESCRIPTION

-140

-75

-84

Explanatory notes in Chapter 1

304

SILT and CLAY BEARING DIATOM OOZE
olive (5Y 4/4)
90% diatoms
5% clay
3% silt
2% carbonate (forams and nannos)

SILTY DIATOM OOZE
light olive gray (5Y 5/2)
75% diatoms
25% silt

SITE 188

WET-BULK DENSITY, gm/cc
SECTION

CM

ro

3 §»

M
ù-i

1-1

2-1

1-50

"

hioo

1-125

1—150

188-4-1 188-4-2 188-4-3

305

SITE 188
S i t e 188

HoleCore 5

Cored I n t e r v a l : 87-96

FOSSILCHARACTER

LITHOLOGIC DESCRIPTION

LITHOLOGY

0.5 —

VOID

1.0-

VOID
SILT BEARING DIATOM OOZE
light olive gray (5Y 5/2)
-80

Slide 2-80
85% diatoms
10% silt
5% carbonate (forams and nannos)

VOID

CLAY and SILT BEARING DIATOM OOZE
light olive gray (5Y 5/2)
VOID

no
Core
Catcher
Explanatory notes in Chapter 1

306

Slide 3-110
80% diatoms
10% silt
5% clay
3% sponge spiculesCore Catcher
D c G
PF A G

BF C
N _ _
R R M
S R M

SITE 188

WET-BULK DENSITY, gm/cc
1
2
3
11

i i i 1 i i i i i i i i > i i

POROSITY,%
100
0

i

SECTION
CM

11

ro

Grain
Density
-32 u
M
ù-i

l-

-25

2-

-50

3-

à
4-75

5-

-100

6-

7-

-125

8-

9-1
"-150

188-5-1 188-5-2 188-5-3

307

SITE 188
Site 188

Hole

Core 6

Cored I n t e r v a l : 1 2 4 - 1 3 3

FOSSILCHARACTER
LITHOLOGY

LITHOLOGIC DESCRIPTION

VOID
0.5—
SAND remnants of a layer; graded ?
1.0-

CLAY RICH DIATOMACEOUS SILT; grayish
olive (10Y 4/2); 60% silt, 25% diatoms,
15% clay; small (1 mm) sponge at 4 cm
sec. 2.

DIATOM OOZE; moderate olive brown (5Y 4/4)
vr r‰cr

DIATOMACEOUS SILT; grayish olive
DIATOM OOZE; moderate olive brown (5Y 4/4)
grading to light olive brown (5Y 5/6). Sponge
at 145 cm, sec. 2-75

CLAY RICH DIATOMACEOUS SILT; grayish olive(TOY 4/2); grading downward to DIATOM OOZE,
olive brown (5Y 5/6); sand at upper contact.
Core Catcher
D A G

Core
Catcher
Explanatory notes in Chapter 1

308

97%
TR
1%
U
λ%

XR 3-20, •i-40, 3-70
150
I 50% 84% amorph. TR
calcite45',
5% 4% quartz TR
4%
5% plag.
TR
6% 4% mica

N _ _
R
M
S
F M
PF A M
BF F
LL.

80

CLAY RICH DIATOMACEOUS SILT; grayish
olive (TOY 4/2); grades downward touniform SILTY DIATOM OOZE; diatoms
range from 25 to 70%.

1 I0
chlor.
1% mont.
1% pyrite
TR amphib
haliteSITE 188

WET-BULK DENSITY, gm/cc
I
2
3
I1 i i i I i i i i i

POROSITY,%
100
0' • ' iSECTIONCM' > ' iro

Grain
Density
M
0-1

1-

-25

2-

-50

3-

4-75

5-

-100

6-

7-

-125

8-

9- 1
L-150

188-6-1 188-6-2 188-6-3 188-6-4

309

SITE 188
Site 188

Hole

Core 7

Cored Interval:171-180

LITHOLOGIC DESCRIPTION

zone of pure diatom oozejBasic l i t h o l o g y
SILT BEARING to SILTY DIATOM OOZE
grayish olive (10Y 4/2)

streaks and pods of DIATOM OOZE
l i g h t o l i v e brown (5Y 5/6)

f o s s i l fragments
XR 3-80
87% amorph.

2% quartz
5% p l a g .
2% mica
1% c h l o r .
3% mont.
1% p y r i t eCore Catcher:
D A G
PF A M
BF C
N
C M
R
R M
S
R M

310

SITE 188

WET-BULK DENSITY, gm/cc
1
2
3

SECTIONCM

11 i i •i i i i • i " < > > i ' • ' i

POROSITY,%
100
0

ro

Grain
Density

-32 o

M
O-i

1-

-25

2-

-50
3CQ

4-75
CJ3
O

O
Q-

5-

o

-100

6-

7-

-125

.

8-

9- 1
1—150

188-7-1 188-7-2 188-7-3 188-7-4 188-7-5 188-7-6

311

SITE 188
S i t e 188

HoleCore 8

Cored Interval:227-236

LITHOLOGIC DESCRIPTION

312

SITE 188

WET-BULK DENSITY, gm/cc
1
2
3

SECTIONCM

POROSITY,%
100
I

ro

Grain
Density-a2 «1 i i i i i i i i i

i

i

i

i

j

1-

-50
3-

4-75

5-

-100

6-

7-

-125

8-

g-J
-150

188-8-1 188-8-2 188-8-3 188-8-4 188-8-5 188-8-6

313

SITE 188
Site 188

Hole

Core 9

Cored Interval;283-292

LITHOLOGIC DESCRIPTION

.30
35
-75
-96
-129

LIMESTONE (calcite cemented diatoms)
Slides 1-35, 1-75
85% diatoms
10% clay
VITRIC ASH~5% silt
SAND-20
Basic lithology
CLAY and/or SILT BEARING DIATOM OOZE
olive gray (5Y 4/2 - 5/2)

-45
-80

-145
VITRIC ASH light gray
(N7)
-85

Site 188

Hole
FOSSILCHARACTER

Core 10

Explanatory notes in Chapter 1

314

XR 3-70 3-100
88%
amorph.
2%quartz
3%
plag.
2%
mica
1%
chlor.
4%
mont.
TR
TR
pyri teamphib.
TR

Cored Interval: 292-293

LITHOLOGYCore
Catcher

Slide 3-85
95% diatoms
5% silt and clay

LITHOLOGIC DESCRIPTIONSILT BEARING DIATOM OOZE
95% diatoms
5% silt
TR carbonate and/or clay

SITE 188

WET-BULK DENSITY, gm/cc
I
2
3
I1 i i i I i> i' ' ' i" >POROSITY,*
100
0

SECTION
CM
- 0

i
Grain
Density
-32 u
3
o

Mil

M
O-i

1-

-25

-50

4-75

5-

-100

6-

7-

-125

8-

g_
-150

188-9-1 188-9-2 188-9-3

315

SITE 188
S i t e 188

HoleCore 11

Cored I n t e r v a l : 3 3 0 - 3 3 9

FOSSILCHARACTER

LITHOLOGY

LITHOLOGIC DESCRIPTION

VOID
-41

0.5—

Basic lithology
SILT BEARING DIATOM OOZE
brownish gray (10YR 4/1)
80 - 90% diatoms
irregular lenses and pods of DIATOM OOZE, Core Catcher
light olive gray (5Y 6/1), and PYRITE
D A G
BEARING DIATOM OOZE, dark olive grayPF (5YR 3/1)
BF R
N
- R R M
S
R M

1.0—

Core
CatcherSite 188

Hole
FOSSILCHARACTER

Core 12

Cored Interval.-425-434

LITHOLOGY

LITHOLOGIC DESCRIPTIONVOIDLIMESTONE yellowish gray (5Y 7/2)
0.5-

1.0-

Core
Catcher

Explanatory notes in Chapter 1

316

-93

Basic lithology
CLAY BEARING, SILTY RICH DIATOM OOZE
grayish olive (10Y 4/2)
Slide 1-93
75% diatoms
20% silt
5% clay*(D) Thalassiosira zabelinae(S) Ammodochium rectangulare

XR i-πo80% amorph. 2% chlor.
2% mont.
5% quartz
1% pyrite
7% plag.
TR amphib
4% micaSITE 188

WET-BULK DENSITY, gm/cc
1
2
3| i i i iI i i ' ' I ' ' ' ' I

POROSITY,*
100
0

' «

SECTION
CM
-0

M

Grain
Density
M
On

I-

-25

2-

-50
3-

4-75

5-

-100

7-

-125

-150

188-11-1 188-12-1

317

SITE 188
S i t e 188

HoleCore 13

Cored I n t e r v a l : 527-536

FOSSILCHARACTER

LITHOLOGIC DESCRIPTION

LITHOLOGY

VOID

0.5-

1.0--

SILT and CLAY RICH DIATOM OOZE
grayish olive (10Y 4/2) to lightolive gray (5Y 5/2)

-nogenerally uniform but with a few
burrows and scattered sponge remains
-75
-125

pod of
CLAY RICH
DIATOM OOZE

75 - 85% diatoms
5 - 15% clay
0 - 20%silt

Core Catcher

D C G

N _ _
R R M
S F M

Core
Catcher(S) Ebriopsis antiqua (without spine)
Hole

Site 188

Core 14

Cored Interval:564-573

FOSSILCHARACTER
LITHOLOGIC DESCRIPTION

LITHOLOGY

XR 1-130
84% amorph.
3% quartz
6% plag.

VOID
0.5-80
1.0-

•r-

CT

Core
Catcher

Explanatory notes in Chapter 1

318

105

— ?-

SILT RICH DIATOM OOZE
moderate olive brown (5Y 4/4)
pyrite associated with diatoms (up to 15% pyrite) 1% chlor.
semi-lithified
3% mont.
1% p y r i t e
TR h a l i t ecore catcher sample contains small ( 3 x 2 x 1 c m )fragments of hard MUDSTONE, olive blackSITE 188

WET-BULK DENSITY, gm/cc
1
2
3
11 11 1 1 1 i i < i i

POROSITY,*100
0•>i » » »SECTION

CM
-0

i

Grain
Density
M

On

1-

-25

2-

-50

3-

-75

5-

-100
6-

7-

-125

8-

9-1

-150

188-13-1 188-13-2 188-14-1

319

SITE 188
Site 188

Hole

Core 15

Cored Interval;573-582

FOSSILCHARACTER
LITHOLOGY

LITHOLOGIC DESCRIPTION

VOID

0.5—

1.0—
CLAY BEARING SILT RICH DIATOM OOZE
light olive brown (5Y 5/6)
Slide 2-80
70% diatoms, 25% silt, 5% clay

-80
-130
Core
Catcher

XR 2-120
Core Catcher
93% amorph.
D A G
TR calcite
PF
1% quartz
BF _4% plag.
N _ TR mica
R R M
MUDSTONE olive black (5Y 2/1)
λ% chlorite
S R M
1% mont.
SILT and CLAY BEARING DIATOM OOZE
dusky yellowish brown (10YR 2/2) TR pyri te
Slide 2-130
85% diatoms, 10% silt, 5% clay

core catcher sample contains fragmentsof mudstone similar to that insection 2

Explanatory notes in Chapter 1

320

LITHO.SAMPLE

DEFORMATIONCoreCatcherl : l : 1 : 1

P
M

LITHOLOGY

1 : i : I : 1: 1 : 1 : I!
: i : 1 : i :: I : i : 1 :!1: 1 : 1 : i
1 : 1 : 1 :1

R
R

Cored Interval:582-591

METERS

PRES.

D
N
R
S

Core 16

SECTIONABUND.

Hole
FOSSILCHARACTERFOSSIL

ZONE

AGE

Site 188

LITHOLOGIC DESCRIPTIONMUDSTONEolive gray (5Y 4/1)
fragments

SITE 188

WET-BULK DENSITY, gm/cc
1
2
3( i i i i | i i i i I i i ' ' M 'Grain
Density

POROSITY,*
100

0

I

SECTION

CM
rθ

' I

i

i

i

I 1

On

1-

h-25

2-

-50
3-

4-75

6-

-100

7-

-125

8-

9- 1
-150

188-15-1 188-15-2

321

SITE 188

LITHOLOGY

LITHO.SAMPLE |Cored I n t e r v a l ; 601-610

METERSPRES.

ABUND.

FOSSILZONE

AGE

SECTION

Core 17

FOSSILCHARACTER

DEFORMATION

Hole

Site

VOID
D
R
S

R M

0.5—

1

- J- -J- -L
-1—

-JL-

1.0-

Core
Catcher

PRES.

ABUND.

FOSSILZONE

AGEMETERS

Core 18

FOSSILCHARACTER

LITHOLOGY

LITHOLOGIC DESCRIPTION

i

i

i

i

D
Core
N
CatcherR
S
Explanatory notes in Chapter 1

XR 1-80, 1-90, 1-100
41%
87% 84% amorph.
55%
dolomite
1%TR
1SK quartz
DOLOMITE light olive gray (5Y 5/2)
1]J 1 2 J
cristo.
2A
I io
1A
pi a g .
TR
mica
TR
TR
chlor.
MUDSTONE black (5Y 2/2)
TR
mont.
TR
TR
clinop.
few scattered sponge remainsTRTR
pyriterare diatom fragments, largely
dissolved and unidentifiable

Cored Interval:629-638

LITHO.SAMPLEHoleSECTION

Site 188-135-\

DEFORMATION

' PF
BF R
N
R
S

LITHOLOGIC DESCRIPTION

322

MUDSTONE olive black (5Y 3/1)

SITE 188
WET-BULK DENSITY, gm/cc
1

2

POROSITY,%
100
0

SECTION

3

CM

r-o

Grain
Density

M
O-l

H

3-1

hioo

7-\

1-125

9-1

L-150

188-17-1

323