2. site 44
TRANSCRIPT
2. SITE 44
The Shipboard Scientific Party1
MAIN RESULTS
Penetrated two thirds of sedimentary cover-carbonateooze with chert beds or lenses; recovered cores throughLower Oligocene, Upper Eocene, and most of MiddleEocene; established age and character of acoustic re-flector as a Mid-Eocene chert.
BACKGROUND
Site 44 was chosen to contribute to the knowledge ofthe Mid-Pacific Mountains and thereby to the generalhistory of the mid-Pacific area. These mountains are ofvolcanic material ranging in age from at least as old asMiddle Cretaceous to Recent (Hamilton, 1956; Menard,1964). Some mountains are peaked seamounts, othersare flat-topped guyots. The Horizon feature, commonlycalled a guyot, is really neither, being a narrow ridgetrending NE-SW for a distance of 170 miles with a flat-tish top that is 10 to 20 miles wide in the area drilled;it has sharply defined shoulders at depths of 1850 to2050 meters (Figures 1,2). Gentle hills along the ridgeaxis rise to depths of about 1400 meters in the regionof Site 44. Bottom soundings in area of Site 44 aregiven in Figure 4. Dredging near the southwestern endyielded Eocene limestones, partly silicified and phos-phatized, and recovered olivine basalt from depths ofabout 1800 meters (Hamilton, 1956). A dredge haul by
1B. 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 Com-pany ;V. Krasheninnikov, Academy of Sciences of theU.S.S.R.;A. P. Lisitzin, Academy of Sciences of the U.S.S.R.; A. C.Pimm, Scripps Institution of Oceanography.
Newman (personal communication) recovered Eocenelimestone and chert from the northern shoulder.
A site survey by the Argo is discussed in Chapter 19.It showed the presence of a sedimentary cap, thickestunder the hills along the axis of the ridge (up to 100meters thick). A prominent reflector lies at a maximumdepth of about 60 meters and outcrops locally alongthe northern edge where it forms a small terrace. Evi-dence from dredging tentatively suggested that this isan Eocene chert bed. The sedimentary cap is underlainby an acoustically distinct, opaque mass largely devoidof coherent reflections with seismic velocities of 3 to3.5 km/sec; this was interpreted by Shor as either vol-canics or limestone. This material seems to crop out inplaces along the northern'edge of the ridge, and formsin such places a terrace below that of the sedimentaryreflector.
The magnetic survey (Figures 2,3) revealed a prominentpattern of anomalies, roughly parallel to the topography,with major lows corresponding to the flanks of theridge.
Bottom photographs showed rippled sand on the crest,and a rocky bottom with patches of sand along thenorthern edge.
Objectives
The specific objectives, in order of importance, were(1) to sample the oldest sediments and the underlyingmaterial (presumably basalt), in order to determine theage of the mountain and the date of its initial sub-mergence; and (2) to sample the sedimentary sequence,in order to shed some light on the history of submer-gence, and to provide biostratigraphic and sedimen-tologic data.
Only a limited amount of time was judged allowablefor this second priority site.
Strategy
Two drill sites were considered: the crest of the featureor its extreme northern shoulder.
A hole in the crest would provide suitable soft sedimentfor spudding in, and would allow sampling of the upperpart of the sedimentary section. The risk in such a holewas posed by the reflector, interpreted as Eocene chert,which might prove to be impenetrable.
17
Figure 1. Argo profile at Site 44.
The northern shoulder appeared to offer areas notunderlain by this chert, but seemingly underlain by themassive opaque material below the sedimentary cap-material which might be either Cretaceous reef lime-stone (by comparison with some of the guyots) orbasalt (more likely, to judge from the dredging). Therisk here lay in not being able to spud in. The hardrocky appearance of the bottom photographs was notencouraging.
Therefore, the first alternative—a crest location—waschosen. With only two massively set diamond bits onboard, a lightly set diamond bit was run. And it wasdecided to make this a one-hole site barring unusualgeological discoveries, even if the reflector might proveimpenetrable.
OPERATIONS
Site 44 was occupied at 2245 hours June 13. The holewas drilled to 40 meters, and mainly cored beyond this
to a total depth of 76 meters (Table 1). Chert encoun-tered at 62 meters damaged the bit, and that encoun-tered at 76 meters proved impenetrable. On starting outof the hole, the bottom assembly parted at the top ofthe sixth drill collar, bending the pin. Failure may haveresulted either from insufficient torque in making upthe string, or from stresses induced by encounteringchert at such shallow depth below the sea floor. Thesediment recovered was so water-saturated that thecore sections were largely left unsplit.
The site was abandoned at 0100 hours on June 15.
NATURE OF THE SEDIMENTS
The 24 meters of sediment recovered at this site con-sist of yellowish-white nannoplankton-foraminiferalchalk ooze and small amounts of chert. At the time ofrecovery the sediment varied from a water-rich slurry topasty, incoherent material; consequently, none of the
18
TAU
1000
1500
2000
2500
16 18 20HRS
\ -
GAMMAS
34500
34400
Figure 2. Bathymetric and magnetic profile at Site 44.
19
169°W
19°30'N
19°20'N
19°10'N
DEPTH CONTOURS,FATHOMS
MAGNETIC COUNTOURSGAMMAS
'ACOUSTIC PROFILES,SCAN III
X DRILL SITE 44
Figure 3. Challenger bathymetric and magnetic contour map at Site 44.
20
169°
19°
•S T-. c*
19° N
169°W
Figure 4. Bottom soundings in area of Site 44.
21
TABLE 1
Summary of Coring at Site 44
Core No.
44.0-1
44.0-2
44.0-3
44.0-4
44.0-5
Interval Cored(Below Mudline)
(ft)
131-161
161-191
191-206
217-245
245-248
(m)
39.9-49.1
49.1-58.2
58.2-62.8
66.1-74.7
74.7-75.6
Recovery
(ft)
17
30
15
28
3
(m)
5.2
9.1
4.6
8.5
0.9
Water depth: 1478.3 meters (4850 feet)
core sections were split open, and the sections weresampled only at the ends.
The chalk ooze at this site is very uniform (Chapter 38).Nannofossils (coccoliths, discoasters and Thoracos-phaera) compose 80 per cent to 90 per cent ofthis sediment, and foraminifera, chiefly planktonics,constitute most of the remainder. Small amounts ofanhedral carbonate crystals, in the 5 to 20 micron sizerange, occur throughout the sediment recovered, but itis uncertain whether this material is of authigenic originor represents broken fragments of molluscan or for-aminiferal shells.
The only other lithology noted is chert which is usuallybrown, fine-grained and vitreous. Chert first appears assmall angular fragments in Core 1 at a depth of 41meters below mudline; this may represent penetrationof a thin chert stringer or a small nodule. Below thispoint most samples contain small amounts of chertwhich could likewise represent thin stringers, or alter-natively, might be cavings from uphole.
The main chert body encountered occurs at 63 metersbelow mudline, at the base of Core 3, where severalangular fragments of brown chert were recovered in thecore catcher. These fragments have thin white crusts ofhard, partially silicified limestone on one side. Theyresemble pieces of the nodular cherts seen in theBritish and other chalks. Within the outer crusts aretests of foraminifera that have been replaced by micro-crystalline or chalcedonic quartz, but the test outlinesremain distinct and sharply bounded against the sur-rounding fine-grained matrix of microcrystalline quartzand calcite (Chapter 38). This crust grades into themain body of the chert which is very fine-grained,uniform microcrystalline quartz containing only scat-tered and very faint outlines of silicified foraminifera.
Similar chert fragments were recovered from the corecatcher of Core 5, at a subbottom depth of 76 meters.These may be from another chert body, or they mayrepresent cavings from the body at 63 meters.
The chert recovered at this site appears to be of second-ary origin, formed through local replacement of chalkooze. Noteworthy is the fact that no siliceous micro-fossils were noted either in the cherts themselves or inthe associated chalk oozes. Possibly their total obliter-ation by diagenetic solution supplied the silica for thechert bodies.
PHYSICAL PROPERTIES
Methods used in the physical property determinations,the effects of coring disturbance, and a general discus-sion are given in the Appendix.
During drilling operations at Site 44 the sediments weredisturbed and thus all physical property measurementsmay not represent in situ values.
Natural Gamma Radiation
Twenty-eight meters of Eocene-Oligocene white foram-iniferal-nannoplankton chalk ooze were cored within40 to 76 meters beneath the sediment surface fromHole 44.0. Emissions of natural gamma radiation variedfrom 0 to 250 counts per 7.6-centimeters (3 inches)core segment during a 1.25 minute scanning period,with an average of 100. Such a low gamma count istypical for nannoplankton chalk ooze which containsvery little clay, zeolite, or other radionuclide-bearingsubstances. There is no significant variation in radia-tion with depth in this hole (see hole and core plots).
Porosity, Wet-Bulk and Water Content
Porosities of the Eocene-Oligocene white foraminiferalnannoplankton chalk ooze recovered within 40 to 76meters in Hole 44.0 spanned from 48 to 90 per centwith a typical value of about 58 per cent. Wet-bulkdensities ranged from 1.23 to 1.87 g/cc with a mode ofabout 1.76 g/cc. These values do not exhibit a sys-tematic variation with depth (see hole and core plots).The maximum porosity and minimum wet-bulk densityvalues probably represent artifically disturbed sediment.Individual samples were not taken, thus water contentwas not measured.
Sound Velocity
Sediment sound velocities through 23 meters of Eocenewhite nannoplankton ooze recovered at a depth of 49to 75 meters from Hole 44.0 ranged from 1.46 to 1.61km/sec with a norm of 1.57 km/sec. No systematicvariation with depth is apparent and the statisticalpopulation is too small to make correlations with otherphysical properties with a high degree of confidence.
22
However, core averages of sound velocity and wet-bulkdensity have an apparent indirect variation (see holeand core plots). See porosity section for a discussionof this relationship.
````````````````````````
As the cores were too soft to split, no penetrometermeasurements were made.
Thermal Conductivity
Heat conductivity values in the Eocene white forami-niferal-nannoplankton ooze from 50 to 75 meters atHole 44.0 were 3.62 and 3.61 × I0"3 cal^C"1 cm'1 sec'1.
CONCLUSIONS
The sediments on this mountain are, as expected,mainly foraminiferal-nannoplankton oozes. While theNeogene was penetrated without recovery of samples,a good sequence of cores was obtained through theLower Oligocene, the Upper Eocene, and most of the
Middle Eocene. The sediment is so soft and watery thatit was badly disturbed inside the core barrel.
Traces of brown chert were encountered in the Oligo-cene and Upper Eocene, and more massive vitreousbrown layers in the Middle Eocene; the latter may beconfidently identified with the prominent acousticreflecting horizon shown on the profiles, and termin-ated the drilling here.
No new light was shed on the sediments below thisreflector, nor on the composition of the underlying,"opaque" material. It seems likely that Eocene sedi-ments here rest on basalt.
REFERENCES
Hamilton, E. L., 1956. Sunken islands of the mid-Pacific mountains. Geol. Soc. Amer. Mem. 64, 97 p.
Menard, H. W., 1964. Marine geology of the Pacific.New York (McGraw-Hill).
23
HOLE 44.0
100
LITHOLOGIC DESCRIPTION
NANNOPLANKTON CHALK OOZE, very pale orange, with rare angular, darkchert fragments
NANNOPLANKTON CHALK OOZE, white
NANNOPLANKTON CHALK OOZE, white, with common chert fragments
NANNOPLANKTON CHALK OOZE, white
NANNOPLANKTON CHALK OOZE and CHERT, Core Catcher sample only
AGE
SERIES-SUBSERIES
EARLY OLIGOCENE
LATE EOCENE
MIDDLE EOCENE
MIDDLE EOCENE
Figure 5. Summary oflithology in Hole 44.0.
24
HOLE: 44.0
DEPTH NATURAL GAMMA WET-BULK WATER CONTENT SOUND THERMAL PENETROMETERIN RADIATION DENSITY AND VELOCITY CONDUCTIVITY
HOLE POROSITY
COUNTS/7.6cm/1.25n
8 0 -
vm-3 vm-1X10 Λ I U mm
9/cc % wt % vol km/sec cal/(°C cm seel c p
5000 1.4 1.8 2.2 20 40 60 80 100 1.6 1.8 2.0 2.2 2.0 3.0 4.0 0 100 200 300
i i r I I I T
*O = LABORATORY- ATMOSPHERIC BACKGROUND COUNT.
Figure 6. Summary of physical properties in Hole 44.0.
25
erLLJCD
COLu
CL
UJ
LEG 6
CORE i
H O L E 44.0
D E P T H 39.9-49.1 m
LU < Zo o
O LITHOLOGIC DESCRIPTION CO CO a
LUO
O
> -
- I
-2
-3
-4
5
-6
-8
-9
• I I
-I2
4 J 1 3
-I4
—: -15
: • i 6
5:-i7: i8
6 " :20
;-22
7-23
24
cc
Core not s p l i t as sediment very watery
Angular dark chert fragments - rare
NANNO CHALK OOZEVery pale orange (10YR 8/2)Nanno DForam C
59 37 94
94
56
59
39
36
93
91
Figure 7. Summary oflithology in Hole 44.0 Core 1.
26
CORE: 44.0-1
DEPTH NATURAL GAMMA WET-BULK WATER CONTENT SOUND THERMAL PENETROMETERIN RADIATION DENSITY AND VELOCITY CONDUCTIVITY
CORE POROSITY
COUNTS/7,6cm/1.25min % wt % vol
×10•
km/sec cal/(°C en
5000 1.4 1.8 2.2 20 40 60 80 100 1.6 1.8 2.0 2.2 2.0 3.0 4.0 0 100 200 300
2 -
i i i i i i r i i i I i i r i i i I r i i i i I i i
•O = LABORATORY- ATMOSPHERIC BACKGROUND COUNT.
Figure 8. Summary of physical properties in Hole 44.0 Core 1.
27
erLUCD
Lu
ON
LJ_ l<uCO
δo
LUU0
UJ
<CO
§ 1α: to
LEGCORE *
HOLEDEPTH
44.0
49.1 58.2 m
LITHOLOGIC DESCRIPTION CO CJ>o cc
o
1
803
-2
h' 3
-4
5
J-6
3 : •ic
4 : 1 3
-14
5:16
-17
: • i 8
6" :20
;•22
7-23
-24
-25
-26
-27
28
29
cc
Core not split as sediment very watery
NANNO CHALK OOZEWhite (2.5YR 8/2)Nanno DForam RPellets of non-skeletal c a l c i t e RChert fragments R (Section 2)
Trace of glauconite
63 36
61 38
59 40
58 41
60 39
63 37
94
95
91
89
92
9197
Figure 9. Summary oflithology in Hole 44.0 Core 2.
28
CORE: 44.0-2
DEPTH NATURAL GAMMA WET-BULK WATER CONTENT SOUND THERMAL PENETROMETERIN RADIATION DENSITY AND VELOCITY CONDUCTIVITY
CORE POROSITY
COUNTS/7.6cm/1.25min I wt % volX10° X10''mrr
cal/(°C cm sec)
5000 1.4 1.8 2.2 20 40 60 80 100 1.6 1.8 2.0 2.2 2.0 3.0 4.0 0 100 200 300
2-
i i i i i I I I I I I I i I i I I i I I | I r i I I I I l l
I I 1 I I
*O = LABORATORY-ATMOSPHERIC BACKGROUND COUNT.
Figure 10. Summary of physical properties in Hole 44.0 Core 2.
29
erUJGD
LU
LU
0_
<
LEGCORE
44.0HOLED E P T H 58.2-62.8 m
LU <
O r-N E
3oLUCO LITHOLOGIC DESCRIPTION c^ CO
oo
-6
2-i-8
-9
- - I0
II
12
13
14
5-
20
--2I
22
7-21
24
CC
Core not s p l i t as sediment very watery;strongly deformed by d r i l l ing .
Few dark grains of Mn/fe oxide and chertat top of Section 1
NANNO CHALK OOZEWhite (2.5YR 8/2)Nanno DForam RPellets of non-skeletal ca l c i t e R
Several small dark chert fragments
Core CatcherPieces of brown chert, vitreouswith hard limestone crust; chertf inely crystall ine quartz; mosaic;no siliceous microfossils; tracesof foram
65 34
73 27
59 40
54 38
22 45 33
97
94
96
84
85
Figure 11. Summary oflithology Hole 44.0 Core 3.
30
CORE: 44.0-3DEPTH NATURAL GAMMA WET-BULK WATER CONTENT SOUND THERMAL PENETROMETER
IN RADIATION DENSITY AND VELOCITY CONDUCTIVITYCORE POROSITY
µ COUNTS/7.6cm/1.25min g/cc % wt % vol
M <n o 5000 1,4 1.8 2.Z 20 40 60 80 100
X10J X10"cal/l°C cm seel
2.0 2.2 20 3.0 4.0 0 100 200 300
2 -
5 -
i i i r i i I r i i
*O - LABORATORY-ATMOSPHERIC BACKGROUND COUNT.
Figure 12. Summary of physical properties in Hole 44.0 Core 3.
31
enLUαo
LU
Q-
LU
LEGCORE 4
HOLE 44.0
DEPTH βe.1-74.7 m
AGE
LU
LU
OLU
LU
as:
UJINO
Z
1ilI i
•Q + *CO
CO 0505 K
O O
-&+*N 05Oft;
<j
OCO
1-
2-
0
4:
5:
6:•
7-
-
cx>
1 l•
l 1
-
-1
-2
-3
-4
cD
-6
- 7
-8
-9
I Λ
-IU
-II
-19
-13
-14
-15
-16
-17
-18
-19
-20
-21
-22
-23
-24
25
26
27
28
29
o
SECT
I11
2
3
4
5
6
cc
OGY
LITH
OL
" " *
', \ \ *
" * *' ' 'T <
* *
, , ,
* * ' , *
* ' '
' ' *
* *
w n "
* * * ' '
, ' , " ,
, ' , ' ,
' * '
(
1—
PA
LEO
SM
EA
R
*
*
*
*
*
*
LITHOLOGIC DESCRIPTIONCore not
NANNOWhiteNannoForam
s p l i t as sediment very watery
CHALK OOZE(2.5YR 8/2)DC
Pellets (both calcareous and
AL . 1 1
ShellChert
non-calcareous) R
RR
%Sα
nd
4
2
3
1
13
7
CO
57
56
61
61
52
57
>-o
39
42
36
38
35
36
o s3
91
95
95
94
93
96
o
Figure 13. Summary oflithology in Hole 44.0 Core 4.
32
CORE: 44.0-4
DEPTH NATURAL GAMMAIN RADIATION
CORE
WET-BULK WATER CONTENT SOUND THERMAL PENETROMETERDENSITY AND VELOCITY CONDUCTIVITY
POROSITY
COUNTS/7.6cm/1.25min g/cc % wt % vol km/sec cal/(°C cm sec)CP
1.8 2.2 20 40 60 80 100 1.6 1.8 2.0 2.2 2.0 3.0 4.0 0 100 200 300
i i i i i i i i i i i i n i i i i i i i i iI
*O = LABORATORY-ATMOSPHERIC BACKGROUND COUNT.
Figure 14. Summary of physical properties in Hole 44.0 Core 4.
33
Lu
SE
LU_ l<OCO
erLUOG
CO
> -
COLU
2 CO
LEGCORE
HOLEDEPTH
44.0
74.7-75.6 m
LITHOLOGIC DESCRIPTION
O Os
Ott;
-2
-3
-4
5
-6
-9
y -
4 :
5:
-12
•-13
-14
-15
1-19
--20
I -21: -22
-23
24
cc
Core CatcherNANNO CHALK OOZE and CHERTChert - angular pieces up to 6 cmacross; banded; occasionally withchalky crust; contain few foram -probably si 1 i c i f i ed limestone
97
Figure 15. Summary oflithology in Hole 44.0 Core 5.
34
LEGCORE '
44.0HOLEDEPTH 399491
FORAMINIFERA
Assemblages of foraminifers
throughout the core are
rather similar and belong to
the Globigerina ampliapertura
Zone (the lower part of
Oligocene).
They include numerous
Globigerina ampliapertura, G.
selliii G. pseudovenezuelana,
G. praebulloides3 G. offiaina-
lisy G. angustiurribilicata> G.
tripartita, G. tapuriensis,
G. ouachitaensis> Globorotalia
postaretacea3 Cassigerinella
ahipolensis, Pseudohastigerina
barbadoensis, Chiloguembelina
aubensis together with rare
Globigerina aiperoensis and
G. gortanii.
NANNOPLANKTON
lannofossil assemblages
throughout the core are
similar and represent the
ower Oligocene lower
Sphenolithus predistentus
Zone. The spines of S.
predistentus are very long
and abundant in this core and
appear as long rods when
broken from their base.
RADIOLARIA
None.
Figure 16. Summary of biostratigraphy in Hole 44.0 Core 1.
35
LEGCORE
HOLE " °DEPTH 491582
FORAMINIFERAPlanktonic Foraminifera
indicate the Upper Eocene age
of sediments (the Globigevina
oorpulenta Zone).
Throughout the core are
developed Globigerina
oorpulenta, G. pseudo-
venesuelana, Globigerapsis
tropiaalis, Hantkenina
suprasuturalis3 Cribro-
hantkenina inflata,
Pseudohastigerina miara.
The lower part of the core
(sections 6 - 4) with
Globigerapsis semi-involuta
and G. index belongs to the
G. semi-involuta Subzone; the
upper part (sections 3-1)
with Globorotalia cervo-
azulensis, Globigerina
gortanii and rare G.
ampliapertura and G.
offiainalis - to the
Globorotalia aerro-
azulensis Subzone.
NANNOPLANKTONAssemblages of the upper
Eocene Discoaster
barbadiensis Zone are present
throughout the core. The
surficial character of the
discoasters is obscured by
excess calcification. Rare
specimens of middle Eocene
species such as Chiasmolithus
grandis and Thoraaosphaera
prolata occur in the lower
part of the core.
RADIOLARIANone.
Figure 17. Summary of bio stratigraphy in Hole 44.0 Core 2.
36
LEGCORE
HOLE ""DEPTH 2628
FORAMINIFERA
Planktonic foraminifers
determine the age of sediments
as the upper part of the
Middle Eocene.
Sections 1 - 4 belong to the
Trunoorotaloides Zone and are
characterized by T. rohri,
Aaarinina rugosoaouleata.
Hantkenina longispina,
Pseudohastigerina miora,
Globigerina praebulloides, G.
inaretaoeat G. turβmenioa, G.
azerbaidjaniaa^ G.
pseudovenezuelana, Globi-
gevinita howei, Globorotalia
aentvalis and rare G.
spinulosa and G. venzi.
Sections 5 - 6 with
Globorotalia armenioa, G.
aentralis, G. spinulosa3 G.
renzi, Hantkenina alabamensis,
Trunaorotaloides topilensis,
T. rohri, Globiger>apsis
kugleri correspond to the
Orbulinoides beckmanni Zone.
NANNOPLANKTON
Only upper middle Eocene
assemblages of the
Retioulofenestra umbilica
Zone are present. Heavily
calcified Disaoaster
barbadiensis and D. tani
nodifera dominate the
discoasters; D. tani tani is
rare and small.
RADIOLARIA
None.
Figure 18. Summary of bio stratigraphy in Hole 44.0 Core 3.
37
LEGCORE
HOLE «°D E P T H 66.174.5
FORAMINIFERA
Throughout the core chalk
oozes contain abundant
foraminifers of the
Orbulinoides beckmanni Zone
(upper Middle Eocene), 0.
beokmanni, Hantkenina
alabamensis, Glogorotalia
oentralis, G. armenioa, G.
venzi, G. spinulosa3 G.
golivariana, Globigerinatheea
barrij Globigerapsis index.
G. kuglevi, Trunaorotaloides
topilensisj T. Tohri3
Globigerina pseudoeaaena
aompacta> G. fz>ontoscij
Globiger>inita eahinata, and
infrequent Globorotalia
tehneri and Aβarinina
votundimarginata near the
base of the core.
NANNOPLANKTON
Upper middle Eocene
assemblages of the
Retioulofenestva vmbilioa
Zone are present throughout
the core. Species present
include Chiasmolithus gx>andis
and Thoraeosphaer>a pvolata.
RADIOLARIA
None.
Figure 19. Summary of biostratigraphy in Hole 44.0 Core 4.
38
LEGCORE
HOLE ««D E P T H 74.7-75.6 m
FORAMINIFERA NANNOPLANKTON RADIOLARIA
Core 5 comtains mixture of
abundant Pliocene - Lower
Pleistocene Foraminifer with
rare specimens of
Ovbulinoides beakmanni,
Hantkenina alabamensis,
Globorotalia aentr>alis,
Globigevapsis kuglevi,
Trunaor>otálo•ides topilensis
(the Orbulinoides beakmanni
Zone of Middle Eocene), as a
result of contamination of
microfossils in the process
of drilling.
Upper middle Eocene
assemblages of the
Retioulofenestra wnbiliaa
Zone are present in both top
and core-catcher samples.
Species present include
Bramletteius serraouloides,
Thor>acosphaer>a prolata, and
Triquetrorhabdulus inoevsus.
None.
Figure 20. Summary ofbio stratigraphy in Hole 44.0 Core 5.
39