11. SITE 53
Shipboard Scientific Party1

SITE DATA

Occupied: July 13-16, 1969.
Position: Sediment apron on flank of Iwo Jima Ridge:
Latitude: 18° 02.0'N.
Longitude: 141° 11.5'E.
Water Depth: 4629 meters.
Hole 53.0: Eight cores.
Hole 53.1: Three cores.
Hole 53.2: One core.
Total Depth: 201 meters in Oligocene or Lower Miocene basalt and limestone.

Honshu Ridge by Menard, 1964). Farther west lies aless well-defined ridge which is the northward extensionof the Yap Arc. Still farther west lies the well defined
Palau Ridge, forming the eastern boundary of thewestern Philippine Sea (Chapter 20, Figure 1).
The general crustal structure as revealed by refraction
seismology is discussed by Murauchi et al. (1968). The
structure of the Philippine Sea is in general much likethat of the Pacific: The Mohorovicic discontinuity liesat depths of 10 to 16 kilometers. A layer 3 (6.4 to 7.2
km/sec) is generally 4 to 6 kilometers thick, but locallythinner. A layer 2 (4.0 to 6.0' km/sec) varies in thickness,but its base is generally 6 to 8 kilometers below sea level;
it outcrops widely in the western Philippine Basin.

MAIN RESULTS

A sequence of Miocene pumice ash beds of mixed
andesitic and basaltic composition laps onto an OligoMiocene volcanic complex of basalt flows and interbedded baked pink and brown limestones of pelagic
origin.
The history of basaltic lava flows, followed by Miocene
explosive vulcanism, is similar to that recorded in Guam
(Tracey, 1964) except that some sediments and volcanics there extend back to the Eocene. These findings
suggest that the crust of the eastern Philippine Sea may
have originated in Tertiary time, long after the crust of
the adjacent western Pacific which is at least as old as
Early Cretaceous.
BACKGROUND

The Mariana Trench and the associated island arc separate the Philippine Sea from the Pacific Ocean. The
Philippine Sea consists of a number of subsidiary basins
separated by ridges, trending mainly north-south (Figures 1, 2). From east to west are recognized (1) the
Mariana Ridge proper, with its many emergent islands;(2) the Iwo Jima Ridge (Hess 1949) (also known asWest Mariana Ridge by Karig (in press); and Southl

B. C. Heezen, Lamont-Doherty Geological Observatory; A. G.
Fischer, Princeton University; R. E. Boyce, Scripps Institutionof Oceanography; D. Bukry, U.S.G.S. La Jolla; R. G. Douglas,
Case Western Reserve University; R. E. Garrison, Universityof California, Santa Cruz; S. A. Kling, Cities Service Oil Company; V. Krasheninnikov, Academy of Sciences of the U.S.S.R.;
A. P. Lisitzin, Academy of Sciences of the U.S.S.R.; A. C.
Pimm, Scripps Institution of Oceanography.

Almost all of the eastern and some of the westernparts of the Philippine Basin are underlain by rocks
showing velocities of 3 to 4 km/sec, and this layer is generally in excess of 1 kilometer thick. Much of the roughtopography of the basin, including the ridges proper, isdeveloped in this material, which was interpreted as
volcanic by Murauchi et al.
The sedimentary cover in the Philippine Sea is normallyless than 100 meters thick; exceptions to this are foundon the western side of the Iwo Jima Ridge, and locallyin the western side of the Parece Vela Ridge, as well as
in close proximity to the Philippines. This lack ofsedimentary cover left most of the Philippine Sea hazardous for the drilling techniques available.
Two theoretical approaches could be taken to theorigin of the Philippine Sea. On the one hand, it may
have been a part of the Pacific Ocean cut off from therest by the development of the island arc system, in the
Eocene or earlier. In this case, the floor of the Philippine Sea must be of Mesozoic or greater age, and atime gap at the trenches, between the age of the Pacificfloor to the east and the older Philippine Sea floor to
the west, should be a clue to the amount of crustswallowed in the trench.
The alternative view is that the floor of the Philippine
Sea developed independently of the Pacific, either byaccretion at some now vanished ridge, or by someother process, perhaps by the oceanization of a former
continental area as proposed by Belousov (1969) for
the Sea of Japan. In this case, the floor of the Philippine Sea could be younger, perhaps much younger,
than that of the adjacent parts of the Pacific.

293140° E

145°E

20° N

15°N

Figure 1. Bathymetric contour map at Sites 53 and 54.

In any case, the Philippine Sea clearly had a history
somewhat different from that of the adjacent Pacific,
as expressed in (1) the 3.0 to 4.0 km/sec layer thickly
and widely developed in it, and (2) the rough topography, largely associated with this layer.
Intimately associated with this problem is the origin
and history of the intervening island arcs; further, therelationship which ancient geosynclines and the associated sedimentary basins bear to modern island arc settings. Drilling in the Philippine Sea was, therefore, an
important program.
The Challenger bathymetric and magnetic profile at
Site 53 is given as Figure 3.
Objectives

The specific objectives of drilling in the Philippine Sea
were to determine the age of the crust, and stratigraphyof the sediment and the history revealed thereby.

294

Strategy

The general lack of sediment, but existence of somesedimentary belts more than 100 meters thick, had beenbrought out by the Lamont-Doherty seismic reflection
profiles from the area (Ewing et al, 1968). The earlier
work was supplemented by a site survey carried out by
D. E. Karig on the Argo, and transmitted to the scientists
by voice and facsimile (Figure 4). The basin between the
Mariana and Iwo Jima Ridges was found to be mainlybare of sediment, but a notable apron of sediments
against the flanks of basements highs, the basin floors
and the underlying stratification show more relief thanis typical of true abyssal plains and sites of turbidity
current sedimentation.
Bottom soundings around Site 53 are given as Figure 5.
OPERATIONS

The beacon was dropped at Site 53 at 1100 hours on
July 13. The hole was spudded at 1930 hours and carried to 99 meters in order to bury the bottom hole

141°E

143° E

142° E

19°N

18°N

—

Figure 2. Bathymetric contour map at Site 53.
assembly. Drilling was soft despite the reflective natureof the acoustic profiles. Four cores were taken in a
Miocene volcanic ash sequence, before hard drilling was
encountered in the last four cores to a total depth ininterbedded flows, pyroclastics and baked limestones at
201 meters subbottom, at which depth the bit ceased
to penetrate further. Liners collapsed in Cores 1 and 3.
The open hole was then logged (electric logs, gamma
ray log, neutron log, caliper log, and acoustic velocitylog).
Tools were retrieved to mudline and Hole 53.1 was
drilled for 3 cores, in the upper section. Tools wereagain brought to mudline for an additional core (Hole53.2).
The light diamond bit was retrieved essentially intact, asurprise in view of the slow drilling rate on the deepest
core.

subbottom depth. Cores from all three holes are described together because in composite they allow recognition of five general lithologic units, as follows:rnit

Lithology

Estimated Thickness

A

Yellow brown clay
and zeolitic clay

13 meters

B

Brown to graysilty radiolarianooze with volcanic glass
Gray to graybrown volcanicash
Red to brown
chalk ooze andnannoplankton
chalk ooze, apparently interlayered
with lithified
limestone
Volcanic rocks
interbedded withlimestone

8 meters

C

D

The site was abandoned at 1730 hours on July 16.
NATURE OF THE SEDIMENTS

E
Twelve cores were recovered at this site in three holes(53.0,53.1, and 53.2) between mudline and 200 meters

approximately
153 meters
approximately
21 meters

unknown

295

TAU

GAMMA

1500

38000

37900
PHILIPPINE SEA
37800
2000
37700

37600

2500

13 JULY 1969
J
00

i

l
l
02

37500
' P*
04

06

08

10

12

14

16

HRS

Figure 3. Challenger bathymetric and magnetic profile at Site 53.

Unit A extends from mudline to a depth of about 13
meters (Core 1, 53.1; upper 130 centimeters of Core 1,53.2). It consists of dark yellow-brown zeolitic clay containing abundant clay minerals, zeolites, and limonitic
grains, and generally lesser amounts of quartz, feldspar,and volcanic glass. Zeolites tend to become less abundant toward the base of the unit, while the amount of
volcanic glass tends to increase.
Unit B, which is transitional in color and composition
between units A and C, lies between 13 and 21 meterssubbottom depth (lower 8 meters of Core 1, 53.2).
The sediment is brown to gray-brown silty radiolarianooze with abundant clay minerals, well-preserved radiolarian tests, and volcanic glass, rare to abundant sponge
spicules, and variable amounts of quartz, Plagioclase
and mica. Nannofossils and zeolites are occasionallypresent in very small amounts. Within this unit are
scattered pebbles of pumice and several layers of sandy
volcanic ash with up to 75 per cent clear glass shards.
Unit C is gray to gray-brown volcanic ash, in layers thatare decimeters thick, and lies between 21 and 174 meters below mudline (Cores 2 and 3, 53.1; Cores 1 to 4,53.0), although this interval was not continuously cored.
Most of this ash is firm and coherent, and some layers
in the upper part appear to be moderately lithified. The
ash is predominantly in the sand and silt size range, but

296

there are scattered layers of clayey and pebbly ash.
Grain size in general appears to decrease downward in
the unit; pumice pebbles are common near the top,
less abundant lower. Compositionally, volcanic glass
dominates, clay minerals, quartz, Plagioclase, amphiboles, and opaque minerals are common, and calcareous
nannofossils and Radiolaria are usually rare to absent.
Nannofossils are most common in the upper part of
the unit (Cores 2 and 3, 53.1) where in places they
form up to 25 per cent of some calcareous ash layers.
Radiolaria are likewise most common near the top of
the unit and decrease downward.
The glass in the volcanic ash of Unit C is chiefly colorless, unaltered vesicular glass, commonly in the form ofelongate shards with tubular vesicles. Measurements of
the refractive index of glass in the catcher sample ofCore 1, 53.0 (depth of 92 meters) have n = 1.520, indicating an andesitic composition (62 per cent SiO2,
d = 2.80). In addition to this colorless glass, smaller
amounts of pale brown, unaltered glass and varying
amounts of apparently altered and devitrified glass arealso present. The latter consists of sand to silt size
grains of fine-grained, very weakly birefringent material
that appears to be a mixture of clay minerals, microcrystalline quartz, and opaque iron oxides. The proportion of altered glass seems to increase downward in
Unit C, and most of the grains in the basal part appear

18°02'N141°10'E

2400

18°04'N141°20'E FATHOMS
2400

120'

2500

2600

2700

2800
ARGO PROFILE (COMPILED FROM RADIO FAX AND RADIOGRAM.)
UPPER TRANSPARENT .05 SEC 20 FM 120'OPAQUE "TURBIDITES" .23 SEC 92 FM 550'
LOWER TRANSPARENT .32 SEC 128 FM 780'
"TURBIDITES"

Figure 4. Sketch of Argo profile at Site 53.
to be of this type, as seen in Core 4, 53.0. Core 4, 53.0,
also records a color change from the predominantly
gray colors above to shades of red, brown and green; inaddition, it has thinner bedding, on the centimeter
rather than the decimeter scale.
Unit D is poorly defined at this site due to a lack ofrecovery. It appears to consist of interlayered soft chalkooze, slightly lithified brown marl, friable white limestone, and hard red limestone, possible with thin interlayers of lithified volcanic tuff. These types of materials
were recovered sporadically, mainly as core catcher andcenter bit samples, between 174 and 195 meters below
mudline (core catcher sample of Core 4, center bit
sample between Cores 4 and 5, catcher sample of Core5, Core 6; all from Hole 53.0).
At the top of Unit D (catcher sample, Core 4, 53.0)
the sediment is unlithified but firm, reddish brown nannoplankton chalk ooze consisting of approximately
equal amounts of clay minerals, nannofossils, and smallanhedral calcite grains. Lower in the unit (Core 5 and6, 53.0) the proportion of recognizable nannofossils decreases to 5 per cent or less, while anhedral calcite grains become the dominant constituent. Thisanhedral calcite is very fine-grained (Chapter 38), mostof it being in the 2 to 5 micron size range, with occasional larger crystals up to 15 microns across. Nannofossils, particularly discoasters, commonly show peripheral overgrowths of secondary calcite and other formsof alteration (Chapter 38). The possibility exists thatwhat appeared in the cores as soft chalk ooze may havebeen produced during coring through disintegration of
the lithified marls and oozes described below.
Lithified carbonates are first present in small amounts
as angular fragments in the catcher samples for Cores 4
and 5, and in the center bit sample between Cores 4 and5. They become more abundant in Cores 5 and 6, andthree main types are present:(1) Small pieces of friable white limestone that areabout 30 per cent nannofossils, 60 per cent fine-grainedanhedral calcite.
(2) Rounded pieces, up to 10 centimeters across, of
punky brown nannoplankton marl that is heavily burrowed and slightly cemented. Clay minerals form about
half of this material, and nannofossils and anhedral calcite are present in approximately equal amounts.
(3) Hard pale red to brown to yellowish-brown
limestone with veins of white sparry calcite (see Chapter 38). Most of this limestone is a breccia, with angularand irregular clasts of limestone cemented by finegrained pinkish limestone; in some cases the clasts are
partially or completely rimmed by white sparry calcite,with the remainder of inter-clast space filled by pinkish
limestone. Some veins are entirely sparry calcite-filled,
others are composite and have alternating bands ofsparry calcite and fine-grained pinkish limestone, thelatter representing internal resedimentation of carbonate ooze. Both the breccias and veins appear to havebeen generated by fracturing of lithified limestone,
followed by precipitation of sparry calcite and infiltration of carbonate sediment into open spaces. In thin297

141° E

/0/5

SITE 53/•3 w

6918° N

Figure 5. Bottom soundings in area of Site 53.
section the limestone consists of a matrix of fine anhedral calcite and argillaceous matter in which are embedded scattered aggregates of sparry calcite that areprobably highly altered microfossils. Also present are
scattered grains of feldspar, chlorite, devitrified volcanic glass, and reddish brown iron oxides that occur
as discrete aggregations and as coatings around othergrains, particularly remnants of fossils. The internallyresedimented pinkish limestone is likewise very finegrained, but is very even grained and lacks remains of
microfossils or other types of grains. Both types oflimestone appear to have been thoroughly re crystallized.
The only significant continuous recovery from Unit D
is in Core 6, 53.0. This contains about 150 centimetersof: (1) hard, pale red limestone like that describedabove, and (2) alternating friable limestone and unlithified chalk ooze, which may be in part or wholly a "drilling breccia".
In addition to the carbonate rocks and sediments in
Unit D, the center bit sample between Cores 4 and 5
contained small pieces of varicolored lithified tuff, but298

these may be cavings from Unit C above. The catcher
sample for Core 5 contained larger chunks, up to 3 centimeters across, of hard, dark brown lithified tuff thatappears more likely to be a part of Unit D, perhaps asthin interlayers.
Unit E, encountered in Cores 7 and 8 of Hole 53.0 at
subbottom depths between 196 and 200 meters, isalso poorly defined, but seems to consist of interbedded
dark volcanic rocks and pale red to brown limestone.
A variety of volcanic rocks are present. Some seem tobe altered amygdaloidal flow rocks of basaltic or andesitic composition. These have a variolitic texture withspherulite-like masses of acicular Plagioclase laths andreddish-brown iron oxide aggregations in a fine-grained
and highly altered matrix of weakly birefringent clay
minerals, iron oxides and possibly chlorophaeite or achloritic (?) material. Other volcanic rocks are clearlyfragmental tuffs and tuff breccias. Refractive index
measurements of unaltered glass in one of these tuffs(from the catcher sample, Core 7) gave n = 1.56 to
1.57, indicating an andesitic composition. R. I. measurements of Plagioclase in the same tuff gave values of
1.565 (labradorite) and 1.55 (andesine). The originalTABLE 1
Summary of Coring at Site 53

Core No.

53.0-153.0-253.0-353.0-453.0-553.0-653.0-753.0-853.1-1
53.1-2
53.1-353.2-1

Interval Cored(below mudline)

Recovery

(ft)

(m)

(ft)

(m)

326-341

99.4-103.9
103.9-113.1

15

4.6

5

1.5

136.6-141.1

5

1.5

633-638638-641164.9-174.0
192.9-194.5
194.5-195.4

6
1

1.8
0.3

3

641-646646-658

195.4-196.9
196.9-200.6

30-30
71-101
175-205
41-71

0.0-9.1
21.6-30.8
53.3-62.5
12.5-21.6

2
30
28

0.9
0.9
0.6
9.6
8.5

25
30

7.6
9.1

341-371448-463541-571

Water depth: 4629.3 meters (15,188 feet)character of other specimens is indeterminate pending
more detail study; among these is a highly altered,chloritic "greenstone".
Limestones in Unit E are similar to those in Unit D.
They are chiefly light brown to pale red, fine-grained,
hard, and appear to be recrystallized. They containnumerous veins of sparry calcite, as well as small aggregations of sparry calcite that resemble highly alteredmicrofossils (Chapter 38). Some veins are composite,
containing zeolites (harmotome) and other minerals aswell as sparry calcite (Chapter 38). Like Unit D, mostof these limestones are breccias consisting of angularlimestone clasts cemented in places by fine-grained
limestone, in other places by sparry calcite composite.
Relations between limestones and volcanic rocks areillustrated by a number of specimens from Cores 7 and8. The limestone breccias mentioned above also contain a few large clasts of altered volcanic rock; in addition some specimens have limestone clasts that in turn
contain angular clasts of altered volcanic rock (i.e. afragment of a breccia within a breccia). In some specimens thin layers of limestone are sandwiched between
volcanic layers; in one instance of this kind the top ofa limestone layer is irregularly eroded by a tuff breccia.
One specimen has a limestone-filled vein within volcanic rock, and this vein can be traced to its probablesource in an interlay er ed limestone band. In anotherspecimen, limestone is cut by a sparry calcite vein that
contains an angular chunk of altered volcanic rock.

Interpretation of Units D and E: The intimate association of limestone and volcanic rocks in Unit E seems
best interpreted as the result of alternating episodes ofsubmarine volcanism and volcanic quiescence, with carbonate sediments accumulating, probably as nannoplankton chalk ooze, during the latter intervals. Suchcarbonate layers would tend to be disrupted, locallyintruded and eroded, and perhaps lithified and recrystallized during igneous activity subsequent to their deposition.
Less clear is the origin of the oozes and limestones with
abundant anhedral calcite in Unit D. These first appear
at 174 meters below mudline, some 22 meters above
the first volcanic rock encountered. Two origins seem
possible for the fine-grained, anhedral calcite in thesematerials: (1) inorganic precipitation, to which a small
amount of nannoplankton were added by normal depositional processes, or (2) recrystallization of an original nannoplankton chalk ooze, either due to low temperature diagenetic reactions or to thermal metamorphism associated with igneous activity. Evidence favoring the latter alternative is more fully discussed in
Chapter 38. And it should be noted at this point thatsince thermal metamorphism appears likely here, thepossibility exists that dikes or localized sills may intrude Unit D in areas immediately adjacent to Site 53,
or that the basaltic rocks of Unit E may have been ashallow intrusive body (rather than a flow on the sea
floor) that thermally metamorphosed early Oligocene
chalk oozes.
PHYSICAL PROPERTIES

These cores were slightly disturbed during coring operations, therefore, the physical property measurements
do not accurately represent in situ conditions.
Natural Gamma Radiation
Holes 53.0, 53.1, and 53.2

Natural gamma radiation emitted from the MioceneOligocene (?) brown clays, siliceous oozes, and ash retrieved at Site 53 (0 to 197 meters), ranged from 100
to 900 counts/7.6 cm core segment/1.25 minutes. The
differing lithologies of the Miocene red zeolite clay,
radiolarian silt, volcanic ash and chalk oozes had typical counts of 500 counts/7.6-cm core segment/1.25
minutes. The highest count of 900 was emitted from
Miocene volcanic sand in Core 53.0/1. The lowest emissions, averaging about 200, were from the Oligocene
limestones and volcanic rocks recovered in Cores 53.0/6,
7, and 8 at depths within 195 to 197 meters. The
general good condition of the cores indicated that theseradiation counts were probably representative of in situ
conditions with a few exceptions. See the well log
taken at this site (Appendix IV).
299

It was interesting to note that the radiation did not increase with depth as the porosity decreased in theupper 100 meters. This suggests at least two possibilities. First, the siliceous oozes and brown clays may
have emitted higher radiation per weight of solid material, but the total radiation was reduced by high porosities so that it was equivalent to the radiation emitted from the volcanic ash and ooze which had lower
porosities. Secondly, it may also be possible that thesource was in the interstitial water as the relative percentage change of its volume was much less than therelative percentage change of the matrix minerals.
Porosity, Wet-Bulk Density, and Water Content
Holes 53.0, 53.1, and 53.2

Miocene-Oligocene (?) brown clay, siliceous ooze, ash,and hard tuff cored at Site 53 had porosities, wetbulk densities, and water contents ranging from 10 to85 per cent, 1.20 to 2.28 g/cc, and 20 to 73 per cent,respectively, averaging about 67 per cent, 1.49 g/cc,
and 45 per cent. Porosities decreased from 80 per centto about 60 per cent with increasing depth from 0 to
100 meters. As the sediment was cored without plastic
liners below this depth, GRAPE porosities could not bemeasured. The 10 per cent minimum porosity occurredin lithified volcanic tuff at depths of 197 meters. Of
course, the wet-bulk densities irregularly increased withincreasing depth being directly similar to sound velocity
averages. These variations were in part related to increasing particle size with depth.
The lithologic variations at Site 53 were reflected bytheir porosities and wet-bulk densities. The Miocene"red" zeolite clay (Unit A: 0 to 13 meters) had distinctly higher porosities (68 to 84 per cent) and lower
wet-bulk densities (1.24 to 1.44 g/cc) than the otherlithologic units.
Miocene ashey radiolarian ooze with silty clay andradiolarian clayey silt with ash forms Unit B (13 to 21
meters). The silty clay had higher porosities of 79 percent (1.25 g/cc) wet-bulk density and the radiolarian
clayey silt had intermediate porosities of 68 per cent(1.42 g/cc). The ashey radiolarian ooze had porosities
of about 65 per cent (1.50 g/cc), with many porosity
highs depending on the ash content and coring disturbance.
Unit C (21 to 174 meters) was a Miocene-Oligocene
volcanic ash with porosities ranging from 40 to 78 percent with an average of 63 per cent, a wet-bulk densityof 1.52 g/cc between 21 and 110 meters being typical.
The wide range of values is attributed to pebbles in thesediment in addition to drilling deformation. Below
110 meters the GRAPE measurements were not taken
in Unit C. But water content measurements decreased
from 50 per cent at 102 meters to 42 per cent at 138
and 166 meters.

300

Unit D was Oligocene (?) chalk ooze which contained
limestone cobbles (artificial?) and volcanic tuff fragments, which had porosities as lbw as 10 per cent measured by the GRAPE, (2.3 g/cc) wet-bulk density where
the cobbles were present in the ooze. These are not true
minimum porosities as the rocks occur in a matrix of
calcareous ooze and the GRAPE measurement averages
the porosity of all constituents.
A neutron well log was taken at this site, but as porosity measurements were made only down to 110 meters
the log could not be calibrated below this depth. The
neutron log was in API units of radiation and thus
without proper log analysis absolute porosities of these
deeper sediments could not be calculated with confidence.
Sound Velocity
Holes 53.0, 53.1, and 53.2
Miocene unlithified clays, siliceous ooze, and ashes
cored at Site 53 had sound velocities ranging from 1.50
to 2.23 km/sec, which averaged 1.65 km/sec. Sound
traveled through Miocene-Oligocene (?) limestone andtuff at a rate of 3.19 to 4.27 km/sec with an average of
3.62 km/sec. Sound velocity core averages increased
from 1.55 to 1.95 km/sec from 0 to 90 meters. Velocity
variations with depth were directly similar to the wetbulk density depth variations, but higher velocities werea function of the coarser grain size distribution, lowporosity, and increased the rigidity of the sediment.
The differing lithologies at the site appeared to havesemicharacteristic sound velocity ranges or averages.
Unit A, a Miocene brown zeolite clay (0 to 13 meters),
had low velocities of 1.52 to 1.60 km/sec. Sound velocities through Unit B of radiolarian silt and ooze were1.54 to 1.65 km/sec. Unit C, a Miocene volcanic ash(21 to 174 meters), had a wide velocity range of 1.50
to 2.23 km/sec with core averages from 1.57 to 1.93
km/sec.
Sound traveled through the lithified Oligocene (?) brown
limestone (with white sparry calcite veins) in Unit D at
3.19 km/sec (53.0/6/1; 175 to 195 meters) and at 3.40
km/sec in the black tuff (7.5-centimeter fragment;
53.0/7/1). Sound velocities were 3.95 and 4.07 km/sec
in the red limestone and green brecciated limestone,
respectively, of a 13-centimeter core segment from
53.0-8-CC in Unit E (200 meters). A 2.5-centimetercore segment of black tuff from 53.0-8-CC (200 meters)
had a velocity of 3.25 km/sec.
The sound velocity well logs were good but were taken
below areas of coring in which sound velocities were
measured and thus were not directly comparable to thelaboratory values. However, well log sound velocities
compare well to the overlying ash (Unit C) velocity of
1.5 to 2.2 km/sec. The well log velocities decreased
from 2.2 to 1.5 km/sec at the bottom of the hole,averaging about 2.0 km/sec. The highest well log velocities, however, were about 2.9 km/sec.
Heat Conductivity
Holes 53.0, 53.1, and 53.2
Heat conductivity of unconsolidated Miocene-Oligocene(?) clays, radiolarian silt, and ashes cored at Site 53(0 to 200 meters) ranged from 2.0 to 2.7 X 10"3 cafC' 1
cm"1 sec"1 averaging 2.26 X I0" 3 . Conductivity variations
were inversely similar to porosity and questionably
similar to the penetrometer averages plotted against
depth. A systematic variation did not seem to exist
between the lithologies.
Penetrometer
Holes 53.0, 53.1, and 53.2
Penetrometer readings at Site 53 ranged from nil tocomplete penetration to the core liner. Miocene redclay and radiolarian silt from 0 to 21 meters has average penetrometer values of 90 and 110 X I0"1 millimeters. These values irregularly decrease with depth andat 200 meters they average 10 X I0"1 millimeters in
Miocene-Oligocene (?) ash.
CONCLUSIONSThe sediment apron west of the West Mariana Ridge isa sequence of Miocene volcanic ashes, mainly pumice
ash of andesitic composition, with an admixture of themost solution-resistant nannofossils (discoasters).
Restriction of thick sediments to one side of the Iwo
Jima Ridge suggests that this feature was the source of
the ash, and was volcanically active mainly during the
Miocene.
The sediments are underlain by basaltic flows and pyroclastics with interbedded altered limestones, of Oligocene or Lower Miocene age. Velocity measurements onthese rocks in the laboratory confirm the view that thisrepresents the 3 to 4 km/sec layer of the refraction profiles in the Philippine Sea.
This (?) basement seems to correspond to the EoceneOligocene Alutom Formation, and the Lower Miocene
Umatac Formation of Guam. These are the oldest rocks

exposed on Guam, and are volcanic-sedimentary complexes some thousands of feet thick, with no base exposed. The Guam section was formed at shallower
depths to judge from fossils in interbedded limestones.
The similarity of the sequence to that on Guam and thewide distribution of the 3 to 4 km/sec layer in thePhilippine Sea, suggest that this volcanism was not a
localized phenomena of the island arc, but was regionally widespread.
Still unsolved is the question whether the ultramafic
basement presumably present beneath these volcanic
complexes is ancient Pacific sea floor, or whether it
also dates from Eocene-Oligocene time. If it is young,then the question arises as to its site and manner of
emplacement.
Preservation of the early Miocene fossils, and the abundance of anhedral authigenic calcite in the early Miocene
beds, suggests peculiar diagenetic conditions, perhaps
a lingering touch of hydrothermal activity.
REFERENCES
Belousov, V. V., 1969. Interrelations between the earth's
crust and upper mantle. In The earth's crust andupper mantle, yarn. Geophys. Union, Monograph 13,698.
Ewing, J., Ewing, M., Aitken, T. and Ludwig, W. J.,
1968. North Pacific sediment layers measured byseismic profiling. In The crust and upper mantle of
the Pacific area. Trans. Am. Geophys. Union. (12),147.
Hess, H. H., 1946. Bathymetry and geologic structureof the western North Pacific, Geol. Soc. Am., Bull,
57,(12), pt. 2, 1201.
Karig, D. E. (in press), Structural History of the Mariana Island Arc System. Bull. Geol. Soc. Am.
Marauchi, S., Den, N., Asano, S., Hotta, H., Yoshii, T.,
Asanuma, T., Hagiwara, K., Ichikawa, K., Sato, T.,
Ludwig, W., Ewing, J., Edgar, T., and Houtz, R.,
1968, Crustal Structure of the Philippine Sea, /.
Geophys. Res., 73, 10, 3143.
Menard, H. W., 1964. Marine Geology of the Pacific.
New York (McGraw-Hill Book Company), 271 p.
Tracey, J. I. Jr., (etal.) 1964. General Geology of Guam,
U.S. Geol. Surv., Prof Paper 403-A, 104 p.

301

HOLE 53.0. 53.1 8.53.2

AGE
LITHOLOGIC DESCRIPTIONSERIES-SUBSERIES

CLAY and ZEOLITE CLAY, dark yellow brown
ASHEY RAOIOLARIAN OOZE, gray brown to brown, with less commonly
RADIOLARIAN CLAY and CLAY; small pumice fragments and a thin ash
layer occur in lower part of core

LATE MIOCENE

ASH, yellow brown, l i g h t gray, dark grayish brown, sand and s i l tsize, well sorted; few thin beds of CLAY with RADIOLARIA present
in central part of core

LATE MIOCENE

ASH, dark grayish brown, dark gray, olive gray, and black, s i l tsize; contains numerous pebbles of pumice and l i t h i f i e d ash inupper part

LATE and MIDDLEMIOCENE

ASH, medium dark gray, s i l t size, sediment quite firm with
scattered pebbles of l i t h i f i e d ash

MIDDLE MIOCENE

40

100

ASH,

medium dark gray, with pebbles of l i t h i f i e d ash

EARLY MIDDLEMIOCENE and
LATE MIOCENE

ASH,

dark gray - black, with pebbles of l i t h i f i e d ash

EARLY MIDDLEMIOCENE*

120

ASH, brown, red, green, and black, well bedded and laminated,
deformed by slumping? in places; Core Catcher contained cemented
EARLY OLIGOCENE
and recrystallized dark reddish brown NANNOPLANKTON MARL OOZE
to EARLY MIOCENE
5 Core Catcher sample only of l i g h t brown CHALK, medium brown NANNOPLANKTON MARL OOZE, dark brown, hard ASH, hard pale red LIMESTONE
6 Gray brown, red gray hard LIMESTONE and softer brown - red brown
CHALK
7Hard greenish gray VOLCANIC ROCK, with CHALK, LIMESTONE and BASALT
1n Core Catcher^Fragments of CHALK, BASALT, "GREENSTONE," LIMESTONE, NANNOPLANKTON EARLY OLIGOCENE
MARL OOZE, and VOLCANIC BRECCIA
to EARLY MIOCENE

Figure 6. Summary oflithology in Holes 53.0, 53.1 and 53.2.

302

HOLE: 53.0.53.1,53.2
DEPTH
IN
HOLE

NATURAL GAMMA
RADIATION

WET-BULKDENSITY

COUNTS/7.6cm/1.25miπ

g/cc
5000

1.4

1.8

% wt
2.2

SOUND
VELOCITY

WATER CONTENTANDPOROSITY

20

40

% vol
60

80

THERMALPENETROMETERCONDUCTIVITY

km/sec
100

1.6

1.8

cal/(°C cm sec)
2.0

2.2

2.0

3.0

4.0 0

c p

100

200

300

53.2

53.1

40-

53.1

53.0

120 -

160 -

180-

53.0

3.19 to 3.40 km/sec

200 3.25 to 4.24 km/sec*O = LABORATORY- ATMOSPHERIC BACKGROUND COUNT.

Figure 7. Summary of physical properties in Holes 53.0, 53.1 and 53.2.

303

S2

=r•

UJ

*
-1

1

•2

kugle

"fi I"

u*" * II > *DEPTH

99-4-103.9 m

>. 0

TU

LITHOLOGIC DESCRIPTION δ*
σ
CO

cö
,0

IC

9 67 24 54
37 44 19

*

&

a
5

*
*

*

-4
c

-6

O

-7

CO

*

(NJ

CO

3

-8

*
*" "*** "«**Λ
*,** * %
*

-9

3- in
IU

v * **** *

-II
-Id

-13

A
LLJ

2;
LU
O
O

3

-14

***"*** * * **»* * *
» * «*»%, * *

t—1

15

111

ASH
Medium dark gray (N4 - N5)
Glass (mostly clear) D-A
Clay R ( i n a few places i n sect. 3-A)
FeldsparMonodinic pyroxene
Apati teChlorite
Opaque minerals
Mica
R
Volcanic rock fragments
Vesicular glass
Palagoni te
Nanno
Sponge spcl
Gray to dark gray (2.5Y N5/0 to N4/0),
l i g h t gray (2.5Y N7/0) and medium darkgray (N5/0), yery dark gray (2.5Y N3.5/0)
with mottles l i g h t gray (N6/0)

-16

O

O

t—t

3E

-17
-

-18

4

Sediment f i r m and cohesive; contains
scattered pebbles of l i t h i f i e d ash
Part of section 3 well layered,part mottled - see X-ray photograph

•

•

-19

b. -20
•

21
22

7: 23

5

24
25

8: 26
; 27
-28
•

6

29

cc

* *

Figure 8. Summary oflithology in Hole 53.0 Core 1.
304

HOLE •°

|%ciα

O <or

O

PAL

<*D O
<X N

SS

LEG
CORE

^—*—1

LIT!

U
(J)

Z

SECTIO

LU

:

CD

4

SME

—^

UJ

LU

MPL

LU
GD

50

3 76 210 64 36 49

1 69 302
5CORE: 53.0-1
DEPTH
NATURAL GAMMA
IN
RADIATION
CORE

WET-BULKDENSITY

COUNTS/7.6cm/1.25min

WATER CONTENTANDPOROSITY

g/cc
5000

1.4

1.8

i wt
2.2

20

40

SOUND
VELOCITY

THERMAL PENETROMETERCONDUCTIVITY
X10' 3cal/(°C cm sec)

% vol
€0

80

100

1.6

1.8

2.0

2.2

2.0

3.0

4.0

X10' 1 mm

0

100

200

300

\ I I I I I I I I [ I1-•O = LABORATORY-ATMOSPHERIC BACKGROUND COUNT.

Figure 9. Summary of physical properties in Hole 53.0 Core 1.

305

er

UJ

LU
CD

δ
3

<
u

LU

if)

CD

O
NI E ^ _

o

LU

SU-

M-CO

—J

<

LEG
CORE

HOLE

53.0

DEPTH

103.9-113.1 m

1LITHOLOGIC DESCRIPTION

CO

Q. (O

to

s

I

2

i

ASH
Medium dark gray (N5/0)
Glass D
Clay C
Nanno R
Others (same as core 1) R

3
4
5

Pebble size fragments of l i t h i f i e d
ash also occur

-6
al
et

:-β

-9

-12

4 : "13
-14

5:

6i20
4-21
;-22
:

7 -23
-24
-25
-26
27
28
29

cc

** *

Figure 10. Summary oflithology in Hole 53.0 Core 2.
306

74 26

CORE: 53.0-2
DEPTH
NATURAL GAMMA
IN
RADIATION
CORE

WET-BULKDENSITY

WATER CONTENTANDPOROSITY

COUNTS/7.6cm/1.25π

i wt
5000

1.4

1.8

2.2

20

SOUND
VELOCITY,60

X10" 3cal/(°C cm sec)

km/sec% vol40

THERMAL PENETROMETERCONDUCTIVITY

80

100

1.6

1.8

2.0

2.2

2.0

3.0

4.0

X10"1 mm
0

100

200

300

i I i i i i I r

1-

2 —

4-

5-

o
o

7-

1

I

I

I

I

I

I

I

I

I

I

r

i

i

I

I

I

I

I

I

i

i

i

i

i

I

I

I

I

I I

*O - LABORATORY-ATMOSPHERIC BACKGROUND COUNT.

Figure 11. Summary of physical properties in Hole 53.0 Core 2.

307

en

er
LU
αo
ID

UJ

UJ
CD

<x

—J
<

Lu

CO

O

UJ
CL
>-

o

1—

y.

LU
CO

N

<

3

o

I—

Zj

LU
_l

LEG

HOLE

0

CORE 3

DEPTH

136.6^141.1 m

or

LITHOLOGIC DESCRIPTION

2

ASH
Dark gray (5Y 4/1) to black (5Y 2/1)
Glass A-D
Clay C
Nanno R
Others (same as core 1) R

c

el
-4

Contains pebbles of l i t h i f i e d ash

UJ

-6

o

DDLE

2-

• f

-8
-9

>-

--I0

UJ
4-> CU
C •M
CU C
<J CU

-σ
x

4:
-14

16

5- M7
18
19
20

;-22
7-23
24

8:

cc

*
*

*

Figure 12. Summary oflithology in Hole 53.0 Core 3.

308

CO O

65 34 41

ö8

CORE: 53.0-3
DEPTH
NATURAL GAMMA
IN
RADIATION
CORE

WET-BULKDENSITY

COUNTS/7.6cm/1.25min

WATER CONTENTANDPOROSITY

g/cc
5000

1.4

1.8

%wt
2.2

20

40

SOUND
VELOCITY80

X10J
cal/t°C cm seel

km/sec%vol60

THERMAL PENETROMETERCONDUCTIVITY

100

1.6

1.8

2.0

T I I I I I I I I r T I I

2.2

2.0

3.0

4.0

0

100

200

300

I I

1-

2-

4-

7-

I

I

I

I

I

I

I I I I I I I

I I I I I I

I

I I I

I I

I I I I I I*O = LABORATORY-ATMOSPHERIC BACKGROUND COUNT.

Figure 13. Summary of physical properties in Hole 53.0 Core 3.

309

LEG
|
§

y
LU

<

|

^

Sg N j ^ g
I

CORE
C

δ

s

^

r^^>

<

Z
5
o
o

o

I

R

E

44

""

Q
DEPTH

164.9-174.0m

E P T H5 i t L1TH0L0G1C DESCRIPTIONI λ I
rv,,"*-;| *| J•-|
ΛVV J *:*.?•/*'-*•-2 1 'V. VΛ}:*I '•'"';{-"«,i-3 ' Λ^IV; *:V• ' ;

ë
ö
2
Σ

Q

HOLE

: 4

° P a q u e s -I

—-5
•

X%f—4

See

H'CV"Y"Λdescription°"80 c m " b e d s 5 to 10 cm thick•-6
O_......

80-150 cm - beds 2 t o 3 mm t h i c k2s e c t i o n

•-β E

<:
LU

- .Q

3: •'o —

-

-

~

—

:•n

12

3

;•i4
—;•I5—

:-i6

5

;»4

-•I8

:•i9

6- 2Ö —
j-21:-22 C
7:•23J
;-24
: "25
Q--26
ö
~

NANN0 MARL OOZE
reddish brown (5YR 3/2)
Partially cemented and recrystallized

Dark:•27 C:

Nanno A\J

Clay A--28:-t~29|~i—

HHI->I-3 "*"^

CC

S8S85 *

C a l c i t e and/or Dolomite A
Chert, cosmic p a r t i c l e s , r
l i m o n i t e , opaques
Also contains sand s i z e limestone*grainsFigure 14. Summary oflithology in Hole 53.0 Core 4.
310

ggggg

ASH
0 10 90 43
Brownish black (5YR2/1), grayish
11 49 40red (10R 4/2), dark greenish gray4 25 71(5GY 4/1) to greenish black (5GY 2/1)
Glass (altered) A
Clay C-A
1 9 90Feldspar] r .

||^'***•™*»o

2 11 87 41 0

CORE: 53.0-4
DEPTH
NATURAL GAMMA
IN
RADIATION
CORE

WET-BULKDENSITY

COUNTS/7.6cm/1.25min

WATER CONTENTANDPOROSITY

g/cc
5000

1.4

1.8

%wt
2.2

20

40

SOUND
VELOCITY80

X10"Jcal/(°C cm sec)

km/sec%vol60

THERMAL PENETROMETERCONDUCTIVITY

100

1.6

1.8

2.0

2.2

2.0

3.0

4.0

Xi<r' mm

0

100

200

300

i I I I i I I

1-

2-

5-

J

I

I

I I

*O = LABORATORY-ATMOSPHERIC BACKGROUND COUNT.

Figure 15. Summary of physical properties in Hole 53.0 Core 4.

311

i r

-J
<
%

v/

|

|

z

w

LU

UJ
Z

^
g

g

N £^g

è
g
o

LEG
CORE
CORE s5— — —HOLE «M
DDEPTHE P T H 192.9-194.5™
«»'•«»
— — —

^ ^
o gi

i..

5 < | LITHOLOGIC DESCRIPTION

-– i

j:; i
—-5 —
-6

2
u

2

3vio—

LU
O
o

• -||

LÜ

; -12

!

:•w

i
Qi
<C

.IC
_

^
LU

3

,:-=

o

I||

j

' ^

;.i6
5"

s

:•i8

o
:
_i

-

"I9

j-21
'-22 C
7 -Core Catcher sample only

O

CHALK
l . L i g h t brown (7.5YR 6 / 4 )' 1 "23

-'2 4
T7
-'"
'. ?f.
8: * b--27 Cl
'.
^
"-23
1-29
—'—'
CC

•;—;—— -JT—
. *.". * *Probably recrystallized nanno
chalk ooze comprisingNon-skeletal C a l c i t e E
Clay C
Nanno R
2. L i t h i f i e d rocks of following
types:' s ° f t » medium brown nanno marlooze
b. hard, dark brown l i t h i f i e d ashc. hard, pale red limestone;
appears t o be r e c r y s t a l l i z e d ,contains veins of white sparrycalciteFigure 16. Summary oflithology in Hole 53.0 Core 5.

312

|

11 #

gggfg

NO PHYSICAL PROPERTIES FOR HOLE 53.0 CORE 5

313

MPL

UJ
LU
_J
<

LU

CD

i

o
CO

O
N E

UJ
CO

+1
2
7

+4
-6

-9

3--

<

LEG β

CORE

HOLE
DEPTH

O
31

α.

UTH0L06IC DESCRIPTION/Nodules" of gray brown, red gray
(5YR 5 / 1 ) , and white f r i a b l e
LIMESTONE i n a matrix of s o f t ,brown t o red brown (5YR 5/4) CHALK(authigenic c a l c i t e D)
The "nodular" s t r u c t u r e may be a
drilling artifact

-14

O
-M

O
O
CS

O
>-

-15

5:
.-17

-20
--2I
|-22

r--23
24

cc

Soft, l i g h t reddish brown (5YR 6/4)
CHALK OOZE and crushed, white,friable LIMESTONE

Figure 18. Summary of lithology in Hole 53.0 Core 6.
314

o
CO

a

Two types of sediment:
1. Rounded pebbles of s o f t , l i g h t
brown (7.5YR 6/2) to brown(7.5YR 5/2), s l i g h t l y l i t h i f i e d
NANNO MARL OOZE
Hard, r e c r y s t a l l i z e d , pale red(2.5YR 6/2) LIMESTONE withsparry c a l c i t e veins

: •i:

LU

194.5-195.4 m

to

-12
4

53.0

20 66

CORE: 53.0-6
DEPTH
NATURAL GAMMA
IN
RADIATION
CORE

WET-BULKDENSITY

COUNTS/7.6cm/1.25min

WATER CONTENTANDPOROSITY

g/cc
5000

1.4

i

iwt

1.8

i

i

i

2.2

20

i

i i

i

SOUND
VELOCITY

60

i

i i

80

i

i i

X10"J
cal/<°C cm sec)

km/sec%vol40

THERMAL PENETROMETERCONDUCTIVITY

100

i

1.6

i

1.8

2.0

2.2

2.0

3.0

4.0

X10'' mm

0

100

200

300

r

BROWN LIMESTONEWITH WHITE VEINS
3.19 km/sec*O = LABORATORY-ATMOSPHERIC BACKGROUND COUNT.

Figure 19. Summary of physical properties in Hole 53.0 Core 6.

315

er
CO
LU
<
O
CO

2=
O

P
C_3

Q.

δ
3
°
_i

<
if)

α; co

LEG

HOLE

S3

CORE i

DEPTH

195.4-196.9 m°

LITHOLOGY DESCRIPTION"I
2
3

Hard, greenish gray (10GY 5/2)
volcanic rock containing alteredvolcanic glass and feldspar; t u f f
or flow rock?

4
5

-6

-9

o
o

-I2

4J -I3
-14
o

-15

4J
UJ

o
CD

5:

o
>-

6::20

Core Catcher sample contained:
1. Soft, coherent, dark brown tobrown (10YR 4/3 - 5/3) CHALK
Authigenic calcite C
Clay minerals C
Poorly preserved nanno R
2. Hard, dark gray, amygdaloidal tovesicular, highly altered BASALT
or ANDESITE, containing veins ofwhite sparry calcite. Abundantrosettes of brown, prismatic,
secondary Plagioclase (andesineor labradòrite) in fine grained
matrix.
Thin layers of light brown
LIMESTONE occur interbeddedwith volcanic rocks

-24

-25
J-26
27
28
29

cc

**

Figure 20. Summary oflithology in Hole 53.0 Core 7.
316

50 23 27

12

CORE: 53.0-7
DEPTH
NATURAL GAMMA
IN
RADIATION
CORE

WET-BULKDENSITY

WATER CONTENTANDPOROSITY

COUNTS/7.6cm/1.25min

a *0

iwt
S00O

1.4

1.8

2.2

20

40

SOUND
VELOCITY

km/sec

%vol
βO

80

THERMAL PENETROMETERCONDUCTIVITY

100

1.6

1.8

2.0

2.2

X10" 3cal/(°C cm sec)

X10"1 mm

2.0

100

200

300

I

I

I

10

4.0 0

2-

4-

5-

7-

*O = LABORATORY-ATMOSPHERIC BACKGROUND COUNT.

Figure 21. Summary of physical properties in Hole 53.0 Core 7.

317

3
0_

LU
_J
<

LU

HOLE 53.0

CORE 8D E P T H 196.9-200.6 m

<

o
CO

SE

LEG

U0

o

o

-r-

UJ

t a s

LITH0L06IC DESCRIPTION c3+I
2

Loose rocks recovered from barrel
and Core Catcher as follows:
1. CHALK - soft brown to dark gray
(10YR 5/3 - 4/2)
2. BASALT or ANDESITE - dark gray,altered, amygdaloidal
3. ("GREENSTONE") - c h l o r i t i c ,highly altered basaltic
or andesitic flow rock or t u f f
4. NANNO MARL OOZE - l i g h t brown,
soft, with burrow mottles
5. LIMESTONE - hard, pale red(2.5YR 6/2) to pinkish white(5YR 8/2), recrystallized andcut by numerous sparry calcite
veins. In some pieces thisrock is interlayered withvolcanic rocks
6. VOLCANIC BRECCIA - angularfragments of altered volcanic
rock in tuffaceous matrix

-4
-5
-6

-9
:

3 -io
-12

o

4- -13
<

-14
-I!
-16

o
CD
O

0:
:

>-

:•i9

20

\-n
24

8:

cc

*
*

*

Figure 22. Summary oflithology in Hole 53.0 Core 8.

318

CORE: 53.0 8
DEPTH
NATURAL GAMMA
IN
RADIATION
CORE

WET-BULKDENSITY

COUNTS/7.6cm/1.25min

g/cc
5000

1.4

1.8

% wt
2.2

SOUND
VELOCITY

WATER CONTENTANDPOROSITY

20

40

80

X10, 3cal/(°C cm sec)

km/sec% vol60

THERMAL PENETROMETERCONDUCTIVITY

100

1.6

1.8

2.0

T~~l F T i i i

2.2

2.0

3.0

4.0

0

100

200

300

T I

2-

4.07 to 4.27 km/sec
13 cm SEGMENT: RED
LIMESTONE AND GREEN BRECCIA
3 . 2 5 km/sec
2 . 5 cm BLACK TUFFj

I i i i•O = LABORATORY-ATMOSPHERIC BACKGROUND COUNT.

Figure 23. Summary of physical properties in Hole 53.0 Core 8.
319

LEG
CORE

HOLE •«•D E P T H 99A103.9 m

FORAMINIFER A
None.

NANNOPLANKTON

RADIOLARIA

Middle Miocene assemblages

Radiolaria are very rare incomposed of Cyoloaoooolithina this core. No age diagnostic
leptoporusj C. neogaπmation,
Disaoaster> aulakost D.
brouwevi s. 1., D. deflanchcei3
D. exilis3 D. per>βZcams, D.
sp. aff. D. vaviábilis, andRetiaulofenestra•pseudoum-

biliaa are present throughout
the core. At the top of thecore Discoaster kugleri ispresent and indicates correlation with the Disooastev
kuglevi Zone.

Figure 24. Summary

320

of biostratigraphy in Hole 53.0 Core 1.

species were seen.

LEG
CORE

HOLE •"
DEPTH 10391131 m

FORAMINIFERA
None.

NANNOPLANKTON

RADIOLARIAThis core was extruded onto

Radiolaria are wery rare in

the deck of the Challenger

this core. No age diagnostic

explosively.

species were seen.

Four random

samples were gathered andexamined to supplement the
paleontologic information
available from the corecatcher sample.

Assemblages

from all samples are assigned
to the lower middle Miocene
Sphenolithus heteromorphus.
Species present include
Cyβloooacolithina neogammation3 Disaoaster brσuweri s.
1., D. chállengeri, D.
deflandrei, D. exilis, D.
variabiliSj Heliaopontosspaera kamptneri, andSphenolithus heteromorphus.

Figure 25. Summary of biostratigraphy in Hole 53.0 Core 2.
321

LEG
CORE

HOLE

53.0

DEPTH

136.6-141.1 m

FORAMINIFERANANNOPLANKTON

Rare but diverse planktonic

The assemblages appear to be The center bit sample

Foraminifera found in themixed and may be either

between cores 2 and 3

center bit sample between

lower or middle Miocene.

contains species of thecores 2 and 3 determine theSpecies present include

lower UDDer Miocene

age of sediments as the

CyaloβoQaolithina leptopovust

Ommatar>tus antepenultimus

Globorotalia menar>dii Zone,

C. neogammation, isaoaster

Zone. The core itself

upper Middle Miocene

aulákosy D. brouwevi s . l . j

contains too few specimens(Tortonian stage).

D. deflandrei,

to make an accurate age

The assemblage includes

exilisy Relioopontosphaer>adetermination.

Globorotalia menardii, G.

hxmptner>i [large], and2/3:

lenguaensis> G. may evi,

Sphenolithus heteromorphus.

timuβy 0. hughesi, Cannartus

D. druggii3

CENTER BIT

Ormatavtus antepenul-

Sphaeroidinellopsis

latiaonusj Lithopeva baoca.

gvimsdalei, S. rutsohi,

Stiahoaorys pevegr>ina, andOrbulina universa, Globi-

S. delmontense.

gerina nepenthes, G. bulloidesy G. bulboβa> Globigerinoides boll•ii> G.

adriatica.

G. altiapevtva>a, Biovbulina
bilobata> Globoquadrina
larmeui, G. altispiraG.

dehisβenβ, Globorotaloidés
variabiliβ.

Figure 26. Summary of biostratigraphy in Hole 53.0 Core 3.
322

RADIOLARIA

LEG
CORE

HOLE
°
i649i74 m
DEPTH°

FORAMINIFERA
None.

NANNOPLANKTON

RADIOLARIA

Three samples from the coreRadiolaria are too rare in

itself proved to be barren.

this core to permit an

Nannoplankton assemblages

accurate age determination,

are present in the top andPreservation is poor.

core-catcher samples.
Species present include
Cycloooceolithina neogammatiorij Disaoaβter brouweris.l., D. challengeri s.l.,D. deflandrei, Eelioopontosphaera kamptner>i, Sphenolithus heter omorηphus, andTviquetrorhabdulus sp. cf.
T. oarinatus.

These assem-

blages are considered to belower Miocene.

Figure 27. Summary of biostratigraphy in Hole 53.0 Core 4.
323

LEG βCORE 5HOLE

D E P T H 1K9.194.5m

FORAMINIFERA
None.

•"

NANNOPLANKTON

RADIOLARIA

The identifiable species inRadiolaria are rare in this

this core include only

core. Species present at

Coccolithus petagious3 Cyato-

the bottom suggest a latecoooolithina neogammation3

Miocene age.

and Disooastev deflandvei.

BOTTOM: Ommatartus hughesi,

Even these are irregular in

Stiahoaorys delmontense.

form owing to overgrowths ofcalcite. Since these species
are the most resistant todeterioration and also themost abundant forms in thelower Oligocene to lower
Miocene interval, this range
must be assumed in theabsence of any otherevidence.

Figure 28. Summary of biostratigraphy in Hole 53.0 Core 5.

324

LEG
CORE

HOLE «*
DEPTH

FORAMINIFERA
None.

NANNOPLANKTON
Only Cyoloaoβoolithina

RADIOLARIANo Radiolaria.

neogammation and Disβoaβter
deflandrei are identifiablein this core.

On thisbasis the core is consideredlower Oligocene to lower
Miocene.

Figure 29.

Summary of biostratigraphy in Hole 53.0 Core 6.

325

LEG
CORE

HOLE
DEPTH

FORAMINIFERA
None.

°
195.4-196.9 m

NANNOPLANKTON
Only Cyclococcolithina
neogammation is identified
from this core. The core istentatively considered lower
Oligocene to lower Miocene.

Figure 30. Summary of biostratigraphy in Hole 53.0 Core 7.
326

RADIOLARIANo Radio!aria.

LEG βCORE

0HOLE
DEPTH i969-2°°6m

FORAMINIFERA
None.

NANNOPLANKTON
Cooaolithus eopetagioust

RADIOLARIANo Radio!aria,

Cyctococcotithina neogammat•ion, and D•isooaster>
deflandrei are present in apoor state of preservation.
The core is considered lower
Oligocene to lower Miocene.

Figure 31. Summary of biostratigraphy in Hole 53.0 Core 8.

327

CORE
SECTION— Ocm

Plate 1. Photographs of Hole 53.0 Cores 1,3 and 4.
328

CORE
SECTION• Ocm

Plate 2

. Photographs of Hole 53.0 Cores 6, 7 and 8.

329

HOLE 53.0
CORE 4
SECTION 1

ucm

SS
1.

ASH: Brownish blackfrom 0-70 cm these beds moderate-strongly
deformed by slumping?
Composition: Glass (altered) 65%
Opaque minerals 20%
Clay
15%

2.

ASH: Grayish red
Composition: Glass (altered) 50-60%
Opaque minerals
and altered
Plagioclase
15-30%
Clay
10%

3.

ASH: Dark greenish gray to greenish black
Composition: Glass (altered) 50%
Opaque minerals
and altered
Plagioclase
40%
Clay
10%

f i".»r-* •«*

25

- ***

50

* * * *,*"=" * .*

• .*'

'*

r *'

A l l ash is of s a n d - s i l t - c l a y size. From
80-140 cm beds t h i n l y laminated (2-3 mm t h i c k ) .
From 0-80 cm beds are t h i c k e r (5-10 cm).

100

125

Figure 32. Summary oflithology in Hole 53.0 Core 4 Section 1.
330

er

LÜ

LU
CD
LU

O

HOLE

CORE i

DEPTH <«.im

53.1

<

LU
CD

LEG

O
(J)

r-

<X. N E

CO

_i

Q.

LITHOLOGIC DESCRIPTION

ëCO

37 63 67
-1

2
3

5

27 73 73

-6

-8
-9

3--io

4:
-14
— "15
:•i6

SILTY CLAY and ZEOLITIC SILTY CLAY
Dark yellow brown (1OYR 3/4)
Clay A-D
Zeolite A (at top and bottom of core)C-R ( i n central part)
Glass R (fresh and altered)
Feldspar]Limonite
R-C
Hematite J

45 54 63

Contains scattered lumps of more
coherent brown clay throughout

35 64

65
64

5-

--I7
:•i8

6

":20
:

38 61 63

2I

; 22

r--23
•24
••25

8:

cc
Figure 33. Summary oflithology in Hole 53.1 Core 1.

332

24 76 63

CORE: 53.1-1
DEPTH
NATURAL GAMMA
IN
RADIATION
CORE
µ
M

to

COUNTS/7.6cm/1.25min
0

g/cc
5000

i

i

r

,

•

WATER CONTENTANDPOROSITYWET-BULKDENSITY

1.4

1.8

%wt
2.2

20

40

SOUND
VELOCITY

%vol
60

80

THERMAL PENETROMETERCONDUCTIVITY

km/sec
100

1.6

1.8

2.0

cal/(°C cm sec)
2.2

2.0

3.0

4.0 0

100

200

CP
300

1-

5-

7-

•J•

,

J

I t

I

*O = LABORATORY-ATMOSPHERIC BACKGROUND COUNT.

Figure 34. Summary of physical properties in Hole 53.1 Core 1.

333

LEG
CORE

HOLE 631
DEPTH

FORAMINIFERA
None.

NANNOPLANKTON
No nannoplankton are present
in samples from this core.

Figure 35. Summary of biostratigraphy in Hole 53.1 Core 1.
334

RADIOLARIANo Radiolaria,

SECTION—Ocm'late 3. Photographs of Hole 53.1 Core 1.
335

er

UJ
0_

UJ
_i
<

<

O

N

u
<S)

EC

SECT

AGE

UJ

δ
3
o

<
CO

LEG β

HOLE

CORE *D E P T H 21.6-30.8 m

53.1

si LITHOLOGIC DESCRIPTION M
QI

CO O

CO

Very watery - sections 1 and 2 notopened

a *

3" •

ASH
Yellow brown (10YR 4/4)
Glass (mostly clear, some brown) A
Clay C-A
ZeoliteFeldsparLimonite
Hemati te
Opaques
Rad R
Spcl R
Foram R
Non-skeletal carb R

51 38 11

ASH and CLAY with RAD
UJzInterbedded

4:
-14

UJ

o

5:

:-i9

6-

7:-;

Ash: l i g h t gray, well sorted
Glass A
Plagioclase
Zeolite R
Hornblende
Foram R
Rad R
Opaques?Shell.R
LimoniteRock fragments.
Clay: dark brown
Clay A Zeolite C Hemati te
Limonite
Opaques
Feldspar.
Sections 4-6
ASH
Dark grayish brown (10YR 4/2)
All sections contain siliceous
fossils - in t o t a l A, rads predominantSection 6 also contains Nanno C
Section 4 has coarse ash beds up to
5 cm thickcontain small pieces of weathered
pumiceDj

cc
Figure 36. Summary oflithology in Hole 53.1 Core 2.

336

13 65 22 51

74 18 51

14 69 17 48

12 67 21 44

CORE: 53.1-2
DEPTH
IN
CORE

NATURAL GAMMA
RADIATION

WET-BULKDENSITY

COUNTS/7.6cm/1.25min

g/cc
5000

I

I

1.4

, wt

1.8
\

I

WATER CONTENTANDPOROSITY

2.2 20 40
I I I I I

SOUND
VELOCITY

THERMALPENETROMETERCONDUCTIVITY

km/sec

% vol
100

I.β

1.8
I

I

2.0
I

2.2

X10'3
cal/(°C cm sec)

X10'1 mm2.0

100 200

3.0

4.0 0

CP
300

I T

o
o
iNi
•O = LABORATORY-ATMOSPHERIC

I

I

I

I

i

BACKGROUND COUNT.

Figure 37. Summary of physical properties in Hole 53.1 Core 2.

337

LEG
CORE

HOLE

"•i

DEPTH

21 308FORAMINIFERA
None.

*

NANNOPLANKTON

RADIOLARIA

Three samples from this coreThis core contains species

proved to be barren.

indicating the lower upper

Other

samples contained assemblages

Miocene Ommatartus

composed only of small

antepenultimus Zone.

discoasters which have aRadiolaria are abundant andcentral pore instead of awell preserved throughout

central knob

the core.

solution.

owing toQuestionably

identified in these samples

TOP:

Ommatavtus antepenul-

timus 0. hughesij Cannartus

are Disooaster brouweri s. 1 ., latieonuSj C. (?) petter>ssoni,
D. challengeri, D. exilis, D.

Stiahooor ys delmontense, S.

quintatus, and D. variabilis. peregr>ina, Lithopera baooa.
One sample contained, inand L. neoteva.

addi tion, Cyolooooaolithina

BOTTOM:

leptoporus, Discoasterltimus3 0. hughesij Cannartus

pentaradiatus, Heliaoponto-

latioonus, Stiahoβorys

sphaera kamptner>i, anddelmontense3 and Lithopera

Reticulofemstva pseudoum-baooa.

bilica. The presence of D.
pentaradiatus and ?D.
quintatus suggests an upper
Miocene assignment.

Figure 38. Summary of biostratigraphy in Hole 53.1 Core 2.

338

Ommatartus antepenu-

SECTION
—Ocm

3

150
Plate 4. Photographs of Hole 53.1 Core 2.
339

LEG
CORE

er

LU
CD

<x

O
N ECI

LITf-I0L0GY

LU

CD

<J~>

SEC

LU

M N0I1

LU
_l
<=t
<J>

«%*

0

^—

o

*

<

LITHOLOGIC DESCRIPTION
Section watery - not s p l i t :pebbles visible in X-rayenu

1
1 »**""*-t*J

-2

10!

<§ 2-

- 7

-8

2

* * * * *»* **=*?«****."**-II* >*.*»»'' *öl ,* ii I, * #*" .»* *

*

Σ
LU

O

1IDDL

UJ

3
4-R

o
CO

B
-S

-14

Q.

-Ib

o•

-16

"a 5:
is

-17

- -18

|
CO

.

# *

4

» ! * * * *> ** I m » * - **** ** 1***7

i

- 28
-29

IV »*/*' ***Gray (5Y 5/1) with mottles andstreaks of black
Dark gray (5Y 4/1) and dark olive
gray (5Y 3/2)
Light red (2.5YR 6/6) pumice layer
Gray (5Y 5/1) with layers of l i g h t
gray (5Y 7/1), very dark gray(5Yand^ v 1 3/1)
\J f I J
U l I U black\J 1 U W i\
See X-ray photograph

5 «* * * * ** "* f * * *
*«* *

*

M
* II * n «* " * H * *» * • * , « !

*

*

6

cc

' »** * * "**Figure 39. Summary oflithology in Hole 53.1 Core 3.
340

34 51

12
1 i—
15

n

42

0

11 70 19 50

4

14 68 18 37

3

6 74 20 40

0

ASH
Dark grayish brown (2.5YR 4/2) andmottled dark gray (5Y 4/1) andgray (5Y 5/1) with thin (1-3 cm)
black ash beds

- 25

27

&

abundant

ASH with PEBBLES
Brown and dark grayish brown(10YR 4/3 and 4/2)
Ash similar to section 1
Pebbles, mostly round, 5-25 mm
diameter, two varieties:
black pumice,dark grayish brown l i t h i f i e d ashwith common black specks ofmagneti te

21

8: 26

61

CSJ

wx. c |INαππO M 1 OWcr pαr‰ OT S c C l l On 0**# *•* * « ** * * * * * // -

b. 20

f- 23
- 24

27

σ

k

*

- 19

22

c7

^" „ * > *

-12

:ENE
1—1

*

• - r»/i.

*o**/*"*'"" V"*^*\"»' **3- IU_^_ >- o|Very dark grayish brown (10YR 3/2)
Glass A Rad C-A
Nanno R-C
Clay C
Spcl C
Feldspar, Pyroxene, Mica, Opaques A

I M

-9

TU

ASH

-4

-6

53-3-62.5 m

*

- 1

EL

DEPTH

-*—.
or

Lu

=

HOLE •"

CORE: 53.1-3
DEPTH
NATURAL GAMMA
IN
RADIATION
CORE

M

µ
u
M

WET-BULKDENSITY

9/cc

COUNTS/7.6cm/1.25min

SOUND
VELOCITY

WATER CONTENTANDPOROSITY
% vol

% wt

THERMAL PENETROMETERCONDUCTIVITY

km/seccal/(°C cm sec)

#

0

rr

5000

i

1.8

2.2

20

40

60

80

100

1.8

1.1

2.0

2.2

2.0

3.0

4.0

0

100

200

CP
300

r

<f

4-

I

I

I

I

I

I

1 I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

*O = LABORATORY-ATMOSPHERIC BACKGROUND COUNT.

Figure 40. Summary of physical properties in Hole 53.1 Core 3.

341

LEG βCORE 3

HOLE

53.1

DEPTH

53.3-62.5 m

FORAMINIFERA
None.

NANNOPLANKTON

RADIOLARIA

Assemblages of long-ranging

Among rare Radiolaria at the

species in this core

top of this core isindicate a middle or upper

Ommatavtus antepenultimus

Miocene correlation.

suggesting the presence ofSpeciespresent include Cyaloβoβao-

the upper Miocene Zone named

lithina leptopovus, Disaoastev for that species.

Abundant

bvouwevi, D. challengevi, D.

Radiolaria in the middle ofexilis, D. vaviabilis, andthe core belong to the middle

Tviquetvovhabdulus rugosus.

Miocene Cannavtus (?)
petterssoni Zone.

Radiolaria

are again rare at the bottomof the core.
TOP:

Ommatavtus antepenulti-mus, Stichooovys delmontense,and Lithopera neoteva.
MIDDLE:

Cannavtus latioonus,

Stichooovys delmontense>
Cyvtooapsella oovnuta,
Lithopeva neoteva3 and L.
baooa.
BOTTOM:

Stichocovys delmon-

tense and Lithopeva neoteva.

Figure 41. Summary of biostratigraphy in Hole 53.1 Core 3.

342

SECTION— 0 cm2

Plate 5. Photographs of Hole 53.1 Core 3.
343

er

LU

LU
CD

UJ

O
N

<

u

CO

^

α_
>-

i I
CO

<

LEG
CORE 1

HOLE
DEPTH

CO

LITHOLOGIC DESCRIPTION
36 64 65

-1
-2
-3
-4

-6

2- -T
-9

-I2

4:
-I4

o
o

-15

SILTY CLAY
Mostly dark yellow brown (10YR 3/4)
with pale brown (10YR 6/3) to brown(10YR 4/3)
Clay D Z e o l i t e R Glass R(103-126 cm) clay with glass
ASHEY RAD OOZE w i t h CLAY
Dark gray brown (10YR 4/2)
Rad A
Glass A
Clay A
Hemati teA
Nanno R
Limonite
Feldspar .
Spcl R

68 26 51

RAD CLAYEY SILT
Gray brown (10YR 5/2) t o brown(10YR 5/3)
Clay ARad A
Diatom, Sponge, Nanno, Zeolite R
ASHEY RAD OOZE
Gray brown (10YR 5/2) to brown(10YR 5/3)
Rad A
Glass A
Spcl R
Clay C
Feldspar, Opaques, Mica, Pyroxene R

26 57 18 43

26 58 16 47

5:
Very dark grayish brown (10YR 3/2)

:•i9

6 -20
;•22

66

Very dark grayish brown (10YR 3/2)
contains small pumice fragments•24

16 67 17 48

Dark grayish brown (1OYR 4/2) withbrown and black mottles
Gray (10YR 6/1) ash layer

cc
Figure 42. Summary oflithology in Hole 53.2 Core 1.

344

CORE: 53.2-1
DEPTH
NATURAL GAMMA
IN
RADIATION
CORE

WET-BULKDENSITY

SOUND
VELOCITY

WATER CONTENTANDPOROSITY

THERMAL PENETROMETERCONDUCTIVITY
X10 J

COUNTS/7.6cm/1.25min

km/sec

5000

I

1.4

1.8

2.2

20

40

100

60

1.6

i i I i i i i i i r iI

1.8

X10"' mmcal/(°C cm sec)

2.0

2.2

2.0

3.0

4.0

0

100

200

300

r

9 A

o
o

1-

o

I

I

I

l< I

I

I

I

I

I

I

I

I

I

I

L> l

I

I

I

I

I

I

I

I

I

I

I

• 0 = LABORATORY-ATMOSPHERIC BACKGROUND COUNT.

Figure 43. Summary of physical properties in Hole 53.2 Core 1.
345

LEG
CORE

HOLE
DEPTH «**•*»>
53.2

FORAMINIFERA
None.

NANNOPLANKTON

RADIOLARIA

Assemblages composed only ofThis core contains radiolar-

discoasters with dissolved

ian species indicating thecenters are present

lower upper Miocene Ommatar-

sporadically in this core.

tus penultimus Zone.

Questionably identified

TOP:

species include DisaoastermuSj 0. hughesi, StiohocorysOπmatartus antepenulti-

brouweri s.1 ., D. ahalleng- delmontense} S. peregrina3
erij D. quintatus, and D.

Cannartus latioσnus, Acro-variábilis. An upper Miocene

botrys tritubuSj Lithopera

correlation is indicated bybaooa, Cyrtooapsella βor>nuta3

this assemblage.

C. Q<xponioa.
BOTTOM:

Stichoeovys delmon-

tense, Ommataz>tus hughesi, 0.
antepenultirms, Cannartus
laticonus, C. (?) pettevssonij Stióhooovys peregrina3
Lithopera baooa.

Figure 44. Summary346

of biostratigraphy in Hole 53.2 Core 1.

SECTION

1•Oc

Plate 6. Photographs of Hole 53.2 Core 1.
347