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19. PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY OF PLIOCENE AND
QUATERNARYDEPOSITS OF THE EAST PACIFIC RISE AND THE GALAPAGOS
SPREADING CENTER
DEEP SEA DRILLING PROJECT LEG 54
V. A. Krasheninnikov, Geological Institute of the USSR Academy
of Sciences, Moscow, USSR
ABSTRACT
During Leg 54 drilling was carried out in two regions: the
Galapa-gos Spreading Center (GSC) (Sites 424 and 425), and on the
westernslope of the East Pacific Rise (EPR) (Sites 419 through 423,
and 426through 429) in the equatorial part of the Pacific Ocean. In
the firstregion, the basalts are overlain by Quaternary
foraminifer-nannofos-sil planktonic oozes and hydrothermal clays
with tropical assem-blages of planktonic foraminifers rich in
number of specimens, butsomewhat poor in specific composition. The
absence of the Globoro-talia crassaformis group and some other
species prevents subdivisionof the Globorotalia truncatulinoides
Zone into five subzonal units.On the EPR, the basalts are overlain
by foraminifer-nannofossil,nannofossil, and siliceous calcareous
oozes, with planktonic fora-minifers strongly affected by selective
dissolution. At Sites 419 and420 the section begins with late
Pliocene (the Globorotalia tosaensisZone). To the east, nearer the
axial part of the ridge, the basaltsare overlain by sediments of
Quaternary age. The morphologydistribution, frequency of
occurrence, stability to selective dissolu-tion, and paleoclimatic
significance of selected species of plank-tonic foraminifers are
discussed.
INTRODUCTION
In the eastern equatorial part of the Pacific Ocean(Figure 1),
18 holes were drilled at 11 sites during Leg54. The sites are
associated with two regions of the Paci-fic Ocean—the western slope
of the East Pacific Rise(EPR) (Sites 419-423, 426-429) and the
southern slopeof the Galapagos Spreading Center (GSC) (Sites 424
and425). No sediments were recovered at Site 426. In theseregions
the basalts of the oceanic basement are coveredby young upper
Cenozoic sediments, up to 150-meter-thick nannofossil,
foraminifer-nannofossil and nanno-fossil-radiolarian oozes,
sometimes argillaceous, withthin interbeds of clays in the upper
part of the section;at the GSC, they are supplemented by green
hydrother-mal clays with iron-manganese fragments. Site data
arepresented in Table 1; planktonic foraminiferal assem-blages were
investigated from 221 samples of sedimentsfrom cores obtained at
these sites.
The first information on the stratigraphy and char-acter of
planktonic foraminifers of the upper Ceno-zoic of the eastern
Pacific was obtained on Legs 9 and16 of the Deep Sea Drilling
Project (Hays, Cook, et al.,1972; van Andel, Heath, et al., 1973;
Jenkins and Orr,1972; Kaneps, 1973; Bukry et al., 1973).
Directlysoutheast of Sites 424 and 425, Sites 156 and 157
weredrilled on the Carnegie ridge. Here, upper Miocene,Pliocene,
and Quaternary sediments were penetratedabove the basalts. The
sediments had planktonic fora-minifers of moderate to good
preservation, but relative-ly low species diversity and no index
species. More
diverse are planktonic foraminifers in upper Cenozoicdeposits to
the north of the GSC—in the Panama Basinand the surrounding ridges
of Coiba, Cocos, and on theeastern slope of the EPR (Sites 83, 84,
155, and 158). Onthe latter's western slope the nearest Site 82 was
drilledat a considerable distance southwest of the drilling sitesof
Leg 54; this hole penetrated upper Miocene, Plio-cene, and
Quaternary sediments with various well-pre-served planktonic
foraminifers. Jenkins and Orr (1972)and Kaneps (1973) point out the
absence or scarcity ofsuch species as Globorotalia tosaensis and G.
truncatu-linoides. Therefore, the upper Pliocene sediments
aresingled out as the Globigerinoides fistulosus or the
Glo-borotalia limbata zones respectively. Quaternary sedi-ments
were assigned to the Pulleniatina obliquiloculataZone. Planktonic
foraminiferal assemblages of the up-per Cenozoic are characterized
by these authors as typi-cally equatorial. In some interbeds,
however, Globoro-talia inflata was recognized, testifying to
cooling andclimatic fluctuations.
LATE CENOZOIC STRATIGRAPHY ATLEG 54 SITES
The stratigraphic subdivision of upper Cenozoic de-posits is
considered separately for the GSC and the EPRsites.
Galapagos Spreading Center
In this region, Sites 424 and 425 were drilled at mod-erate
ocean depths (2685 to 2850 m), much higher thanthe carbonate
compensation depth. Therefore, the
509
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10°N
9 N
SIQUEIROS FRACTURE ZONE
PT-4 SITES(419 423. 426429)
105°W 104°W
Figure 1. Location of Leg 54 sites.
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PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
TABLE 1Data on Sites of Leg 54
Holes
419419A420420A421
422423424424A424B424C425427428428A429429A
Latitude (N)
08°55.96'08°55.47'09° 00.10'09° 00.50'09°01.41'09° 10.59'09°
08.81'00° 35.63'00°35.33'00° 35.82'00° 35.93'01° 23.68'08°
06.79'09°02.77'09° 02.77'09° 02.01'09°02.01'
Longitude (W)
105°41.17'105°41.22'106° 06.77'106° 06.32'106°03.68'105°
16.27'105° 06.57'86°07.82'86°07.81'86°07.82'86° 07.82'86°
04.22'
104°36.35'105°26.14'105°26.14'106°46.35'106°45.87'
Water Depth(m)
32743274338133823339324731612685270827052699285038343295328634063426
Thickness ofSediments
(m)
3546
1156395
4542363432
26.779
1466663
3131
planktonic foraminiferal assemblages are well preservedand give
us a fairly comprehensive picture of the natureof the tropical
microfauna. The sediments are of Quat-ernary age only.
Site 424Four holes were drilled at this site (Holes 424,
424A,
424B, and 424C), the sections of which supplement eachother. The
basalts are overlain by grayish, yellowish,and greenish
foraminiferal-nannofossil and siliceous(radiolarians, diatoms,
sponge spicules) nannofossiloozes. In the upper part, they
alternate with hydro-thermal deposits—green clays, and some
iron-man-ganese material. The sediment thickness is up to
36meters.
The assemblage of planktonic foraminifers in thelower part of
the section consists of numerous Neoglo-boquadrina dutertrei,
Globorotalia menardii, Globiger-inoides ruber, G. trilobus and
common Orbulina univer-sa, Globigerina bulloides, Globorotalia
tumida. Suchspecies as Sphaeroidinella dehiscens, Pulleniatina
obli-quiloculata, Globorotaloides hexagonus, Globigerin-oides
conglobatus, G. sacculifer, G. elongatus, Globi-gerinella
siphonifera, Hastigerina pelagica, Globigerinarubescens, G. calida
praecalida, Globigerinita uvula, G.glutinata, Globorotalia tumida
flexuosa, G. ungulata,G. cultrata, G. obesa, G. cavernula, G.
scitula, and G.hirsuta occupy a subordinate position. Single
specimensof Globorotalia truncatulinoides (Samples 424-4-4,49-51
cm, 424-4-5, 31-33 cm, and 424B-4-3, 70-72 cm)occur sporadically.
The intervals representing this lowerpart of the section were from
Sample 424-4-1, 31-33 cmto Sample 424-4-6, 49-51 cm; from Sample
424A-3-1, 49-51 cm to Sample 424A-3-3, 60-62 cm; and from
Sample424B-4-1, 90-92 cm to Sample 424B-4-4, 60-62 cm.
Higher up the section in calcareous oozes, the samespecies of
planktonic foraminifers occur, but with pinkGlobigerina rubescens,
Globigerinoides ruber, andsingle Globigerina calida calida; the
species Globoro-
talia truncatulinoides was not identified. Somespecimens of
Globorotaloides hexagonus occur at thevery top of the section
(Sample 424B-1-1, 40-42 cm).This upper part is from Sample 424-3-2,
30-32 cm toSample 424-3-6, 50-52 cm; from Sample 424A-2-1,49-51 cm
to Sample 424A-2-2, 39-41 cm; and fromSample 424B-1-1, 40-42 cm to
Sample 424B-3-5,110-112 cm.
Site 425The basalts are overlain by grayish and greenish
fora-
minifer-nannofossil oozes, 79 meters thick. The middlepart of
this member abounds in foraminifer-nannofossiloozes with a high
content (up to 30%) of siliceous skele-tons (radiolarians, diatoms,
and sponge spicules).
In the interval from Sample 425-3-1, 49-51 cm toSample 425-6-2,
49-51 cm, planktonic foraminifers arerepresented by numerous
Globorotalia menardii, G.tumida, Neogloboquadrina dutertrei,
Globigerinoidesruber, G. trilobus, sometimes supplemented with
simi-larly abundant Orbulina universa, Globigerina rubes-cens,
Pulleniatina obliquiloculata. Globorotaloides hex-agonus,
Globigerinoides conglobatus, G. sacculifer,and Globorotalia
ungulata. G. scitula, Globigerina bul-loides, Globigerinella
siphonifera, and Sphaeroidinelladehiscens are constantly present,
although in a minornumber of specimens. Globorotalia cavernula, G.
hir-suta, Hastigerina pelagica, and Globigerina calida prae-calida
are sporadic. Single specimens of Globorotaliatruncatulinoides
occur in two specimens only: Samples425-3-3, 49-51 cm and 425-5-3,
49-51 cm; scarce, smallspecimens of Globorotalia tosaensis occur in
Samples425-4-3, 49-51 cm and 425-5-4, 49-51 cm. In Samples425-3-4,
49-51 cm and 425-3-5, 49-51 cm, Globorotaliainflata and Globigerina
bulloides are common; thistestifies to a decrease of temperature of
surface waters.The presence of Globorotalia crassaformis oceanica
andG. crassaformis crassaformis in Sample 425-4-2, 49-51cm seems
likely to be related to some deterioration ofclimatic conditions.
The lowest beds of the memberunder question are characterized by
scarce Globigerin-oides fistulosus (Samples 425-6-1, 49-51 cm and
425-6-2,49-51 cm). These layers appear to be assignable to thebasal
part of the Quaternary.
Most of these species also occur in the upper part ofthe section
(interval from Sample 425-1-1, 40-42 cm toSample 425-2-5, 49-51
cm). Globorotalia truncatulin-oides, G. tosaensis, G. crassaformis,
G. inflata, andGlobigerinoides fistulosus are exceptions. Here
numer-ous pink Globigerinoides ruber and Globigerina rubes-cens
appear combined with scarce Globigerina calidacalida. Specimens of
Globorotaloides hexagonus andGloborotalia tumida flexuosa occur in
the uppermostSample 425-1-1, 40-42 cm.
East Pacific RiseOn the western slope of the EPR, Sites 419
through
423 and 426 through 429 were drilled in considerablewater
depths—3161 to 3834 meters. At all the sitesplanktonic foraminifers
are more or less affected byselective dissolution. At Sites 419 and
420 the sections
511
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V.A. KRASHENINNIKOV
begin with upper Pliocene sediments; at other sites thebasalts
are overlain by Quaternary oozes.
Site 419
The basalts are overlain by a member of the palegray, gray,
gray-greenish, and gray-yellowish foramini-fer-nannofossil oozes
with interbeds of radiolarian-nan-noplanktonic oozes in the middle
of the section andbrown calcareous clays at the top; thickness is
46meters.
At the base of the section (Sample 419-5-4, 39-41cm), the
assemblage of planktonic foraminifers includesscarce Globorotalia
tumida, G. menardii, Pulleniatinaobliquiloculata, Globorotaloides
hexagonus, Sphaer-oidinella dehiscens, Globigerinoides ruber, G.
trilobus,G. conglobatus, G. sacculifer, and G. obliquus ex-tremus.
The presence of G. obliquus extremus enablesus to attribute the
sediments to the uppermost part ofthe Pliocene, which is confirmed
by the presence ofdiscoasters. Tests of foraminifers show clear
traces ofselective dissolution, fragments of Globorotalia
keelsbeing numerous.
In the interval from Sample 419-3-2, 39-41 cm toSample 419-5-3,
38-40 cm, planktonic foraminifers arepoor in number of specimens:
Globorotalia tumida, G.menardii, Globigerinoides ruber, G.
sacculifer, andPulleniatina obliquiloculata. Neogloboquadrina
duter-trei, Globigerinoides trilobus, G. conglobatus,
Globi-gerinita glutinata, Globorotaloides hexagonus, Globo-rotalia
ungulata, G. hirsuta, Orbulina universa, Sphae-roidinella
dehiscens, Globigerinella siphonifera, Globi-gerina bulloides, and
G. rubescens are very scarce.Noteworthy are traces of dissolution
reflected in theabundance of Globorotalia keels. These deposits are
ofQuaternary age.
Higher in the section, these species are accompaniedby
Globorotalia fimbriata, G. tumida flexuosa, Globi-gerina calida
calida, pink G. rubescens, and Globi-gerinoides ruber. Sediments
with such an assemblage ofplanktonic foraminifers belong to the
upper Quater-nary. There are traces of dissolution, and
numerouskeels of Globorotalia. This upper interval is from Sam-ple
419-2-2, 29-31 cm to Sample 419-3-1, 40-42 cm, andfrom Sample
419A-1-1, 39-41 cm to Sample 419A-2-1,35-37 cm. The species
Globorotaloides hexagonus oc-curs in the uppermost section (Sample
419A-1-1, 39-41cm).
Site 420
In this hole, the drill penetrated a thick pile of sedi-ments,
120 meters above the basalts. Foraminifer-nan-nofossil oozes
(nannofossil 45-70%, and foraminifers5-25%) of pale gray, greenish,
or yellowish colorprevail among the sediments. As the nannofossil
con-tent increases up to 75-85 per cent, or that of
siliceousmicroorganisms (radiolarians, diatoms, silicoflagel-lates)
increases up to 40-50 per cent, or that of diatomsincreases up to
50-80 per cent, these sediments pass intonannofossil, siliceous
nannofossil, and diatom oozes,
respectively. In the uppermost part of the section, theseoozes
alternate with brown calcareous clays.
Planktonic foraminifers are not very numerous andare heavily
affected by selective dissolution. Onlythickened keels and
intercameral sutures remain pre-served from Globorotalia tests.
This group of planktonserves as the basis for subdivision of the
deposits intothe upper Pliocene (the Globorotalia tosaensis
Zone)and Quaternary (the Globorotalia truncatulinoidesZone). The
lower and upper parts are distinguished inQuaternary sediments.
The upper Pliocene (the Globorotalia tosaensis Zone)is
established by means of Globorotalia pseudomiocen-ica, G.
pertenuis, and Globigerinoides obliquus ex-tremus, despite the
absence of the index species. Thesespecies are accompanied by
Neogloboquadrina duter-trei, Globorotaloides hexagonus,
Globorotalia tumida,G. menardii, G. cultrata, G. scitula,
Globigerinoidesruber, G. sacculifer, G. trilobus, G. conglobatus,
Or-bulina universa, Pulleniatina obliquiloculata, Sphaer-oidinella
dehiscens, and Globigerinella siphonifera.This interval is from
Sample 420-11-2, 50-52 cm toSample 420-13-5, 39-41 cm. The
Pliocene/Quaternaryboundary is established conditionally to be
below thefirst sample in which Globorotalia truncatulinoides
wasidentified (Sample 420-10-6, 40-42 cm). However, thelast
specimens of Pliocene Globorotalia pseudomioceni-ca and
Globigerinoides obliquus extremus were recog-nized in Sample
420-12-3, 40-42 cm. Thus, unquestion-able Pliocene and
unquestionable Quaternary sedimentsare divided by an interval (from
Sample 420-11-2, 50-52cm to Sample 420-12-2, 40-42 cm, thickness
about 12m) with transitional Pliocene-Quaternary
planktonicforaminifers. The age of this interval of sediments
re-mains obscure.
Lower Quaternary deposits are characterized byGloborotalia
menardii, G. tumida tumida, Globigerin-oides trilobus, G. ruber, G.
sacculifer, Orbulina uni-versa, and Neogloboquadrina dutertrei that
are accom-panied by scarce or even single Pulleniatina
obliquilo-culata, Globorotaloides hexagonus, Sphaeroidinella
de-hiscens, Globorotalia cultrata, G. tumida flexuosa, G.ungulata,
G. hirsuta, G. scitula, Globigerinoides con-globatus,
Globigerinella siphonifera, Turborotalita io-ta, Globigerina
bulloides, G. rubescens, G. calida prae-calida, Globigerinita
uvula, and G. glutinata. As has al-ready been mentioned, single
specimens of Globorotaliatruncatulinoides occur in one sample only
(Sample420-10-6, 40-42 cm). In Samples 420-9-3, 39-41 cm
and420-10-3, 40-42 cm, single specimens of Candeina nitidawere
identified. This lower Quaternary interval is fromSample 420-4-2,
39-41 cm to Sample 420-10-6, 40-42 cm.
In the upper part of the Quaternary, a similar assem-blage of
planktonic foraminifers is developed. New ele-ments of microfauna
include Globorotalia fimbriata,Globigerina calida calida, pink G.
rubescens, andGlobigerinoides ruber. In Sample 420-4-1, 39-41
cm,single specimens of Globorotalia truncatulinoides oc-cur; the
species Globorotaloides hexagonus was ob-served in the uppermost
section studied (Sample420A-1-1, 59-61 cm). The upper Quaternary
interval isfrom Sample 420-1-1, 33-35 cm to Sample 420-4-1,
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PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
39-41 cm; and from Sample 420A-1-1, 59-61 cm toSample 420A-1-4,
40-42 cm.
Site 421A mudline core in this hole is composed of foramini-
fer-nannofossil and nannofossil oozes with interbeds ofbrown
calcareous clay. The sediments belong to the up-per Quaternary and
are characterized by pink Globige-rina rubescens and
Globigerinoides ruber, as well asGloborotalia fimbriata and
Globigerina calida calida.Other species of planktonic foraminifers
present areNeogloboquadrina dutertrei, Pulleniatina
obliqui-loculata, Sphaeroidinella dehiscens, Globorotaliamenardii,
G. tumida tumida, G. tumida flexuosa, G.ungulata, Globorotaloides
hexagonus, Orbulina uni-versa, Globigerinoides trilobus, G. ruber
(white), G.sacculifer, G. conglobatus, G. tenellus,
Globigerinellasiphonifera, and Globigerina bulloides. The
speciesGloborotaloides hexagonus is recognized in the upper-most
sample (Sample 421-1-1, 40-42 cm). Poor preser-vation of the tests
indicates the influence of selectivedissolution; there are numerous
fragments of Globoro-talia keels.
An additional 85 meters of sediments was washed inthis hole
during drilling down to the contact withbasalts. At the very
contact zone, a section of some cen-timeters of calcareous oozes
was taken, but was not ex-amined by us.
Site 422Quaternary sediments, about 45 meters thick, are
represented by greenish gray, gray, and pale gray
fora-minifer-nannofossil and nannofossil oozes with scarceinterbeds
of siliceous nannofossil oozes in the middlepart of the section and
brown calcareous clays in its toppart. The sediments rest on
basalts, but recovery waspoor at the contact zone. Planktonic
foraminifersfacilitate a subdivision of Quaternary deposits into
twoparts.
Predominant in the lower part of Quarternary depos-its from
Sample 422-3-3, 39-41 cm to Sample 422-5-6,39-41 cm are
Globorotalia menardii, G. cultrata, G. tu-mida tumida,
Neogloboquadrina dutertrei, Globigeri-noides ruber, and G.
trilobus; sometimes they are sup-plemented by Pulleniatina
obliquiloculata, Globigeri-noides sacculifer, Orbulina universa,
and Globorotal-oides hexagonus. The rest of foraminiferal species
arein minor amounts: Globorotalia ungulata, G. hirsuta,G scitula,
G. obesa, Sphaeroidinella dehiscens. Globig-erinoides conglobatus,
Globigerinella siphonifera, Has-tigerina pelagica, Globigerinita
uvula, G. glutinata,Globigerina bulloides, G. rubescens, and G.
calidapraecalida. In Sample 422-5-3, 39-41 cm there are
scarceGloborotalia crassaformis oceanica.
In the upper part of the section from Sample 422-1-1,39-41 cm to
Sample 422-3-2, 39-41 cm, these species ofplanktonic foraminifers
(except for Globorotalia crassa-formis) are accompanied by
Globorotalia fimbriata andpink Globigerina rubescens and
Globigerinoides ruber.
Calcareous oozes of Hole 422 contain no Globorotal-ia
truncatulinoides; Globorotaloides hexagonus was
identified in the uppermost sample of sediments (Sam-ple
422-1-1, 39-41 cm).
Site 423In this hole, the basalts are overlain by 42 meters
of
Quaternary foraminifer-nannofossil and nannofossiloozes,
interbedded wtih brown calcareous clays at thetop. Planktonic
foraminifers are not numerous, fre-quently poorly or moderately
preserved because ofselective dissolution. Fragments of
Globorotalia keelsare abundant.
Quaternary deposits of the lower part of the section(from Sample
423-4-2, 40-42 cm to Sample 423-5-4,40-42 cm) are characterized by
Globorotalia tumidatumida, G. tumida flexuosa, G. menardii, G.
scitula,Neogloboquadrina dutertrei, Globorotaloides hexagon-us,
Pulleniatina obliquiloculata, Sphaeroidinella dehis-cens, Orbulina
universa, Globigerinoides trilobus, G.ruber, G. sacculifer, G.
conglobatus, Globigerina bul-loides, and G. rubescens. Single
specimens of Candeinanitida occur in Sample 423-4-4, 40-42 cm.
In the upper part of the Quaternary (from Sample423-1-1, 40-42
cm to Sample 423-3-5, 40-42 cm), asimilar assemblage of planktonic
foraminifers (exceptfor Candeina nitida) is developed. Along with
thesespecies, pink Globigerina rubescens and Globigerin-oides ruber
were identified here, as well as Globorotaliafimbriata, G.
ungulata, G. cultrata, G. cavernula, G.subscitula, and Hastigerina
siphonifera. Specimens ofGloborotaloides hexagonus have been known
from theuppermost sample of our material (Sample 423-1-1,40-42
cm).
As at Hole 422, no Globorotalia truncatulinoides andGlobigerina
calida calida occur among Quaternaryplanktonic foraminifers.
Site 427This hole, in the deepest trough of the Siqueiros
frac-
ture zone, penetrated the thickest pile of Quaternarysediments
(146 m) drilled on Leg 54. These sedimentsare represented by
alternations of clayey foraminifer-nannofossil,
radiolarian-nannofossil, and diatom-nan-nofossil oozes; in the
upper part of the section there areinterbeds of brown calcareous
clays. Planktonic fora-minifers were selectively dissolved as a
consequence ofthe considerable depth of the ocean (3834 m),
ap-proaching the CCD. In the interval from Sample 427-6-1,59-61 cm
to Sample 427-8-6, 59-61 cm, a poor forami-niferal assemblage
includes Globorotalia menardii, G.tumida tumida, G. ungulata, G.
scitula, Pulleniatinaobliquiloculata, Globorotaloides hexagonus,
Sphaer-oidinella dehiscens, Neogloboquadrina dutertrei,
Glo-bigerinoides trilobus, G. ruber, G. sacculifer, G.
con-globatus, Orbulina universa, Globigerinella siphonifera,and
Globigerina bulloides.
In the interval from Sample 427-1-1, 3-5 cm to Sam-ple 427-2-3,
6-8 cm, the forementioned species ofplanktonic foraminifers are
accompanied by pink Glo-bigerina rubescens and Globigerinoides
ruber. The posi-tion of the boundary between these two intervals
ofsediments with a somewhat different microfauna re-
513
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V.A. KRASHENINNIKOV
mains obscure, because in the interval between Cores 2and 6 the
coring was not continuous, and we did not re-ceive samples of
sediments from Cores 3 and 4.
Abundant fragments of keels of Globorotalia tumidaand
Globorotalia menardii with etched surfaces wereobserved in all
samples.
Site 428Here, 66 meters of Quaternary gray and greenish,
clayey foraminifer-nannofossil and siliceous (radio-larians,
diatoms, silicoflagellates, and sponge spicules)nannofossil oozes
with two interbeds of brown,calcareous clays at the top of the
section overlie basalts.
The sediments are rather poor in planktonic fora-minifers
(5-25%), although their species composition isrelatively diverse:
Neogloboquadrina dutertrei, Globo-rotalia menardii, G. tumida
tumida, G. ungulata, G.scitula, G. hirsuta, Sphaeroidinella
dehiscens, Orbulinauniversa, Pulleniatina obliquiloculata,
Globorotaloideshexagonus, Hastigerinapelagica, Globigerinella
siphon-ifera, Globigerinita uvula, G. glutinata,
Globigerinaquinqueloba, G. bulloides, G. rubescens,
Globigeri-noides ruber, G. trilobus, G. sacculifer, G.
conglobatus,G. elongatus, and G. tenellus. They are
representativeof the entire section of Quaternary sediments, and
inSample 428-1-1, 119-121 cm alone a pink Globigerinarubescens is
found to accompany them.
In basal layers of this section, scarce specimens
ofGlobigerinoides fistulosus occur (Samples 428-4-6, 99-101 cm and
428-5-2, 99-101 cm). They obviously tes-tify to the early
Quaternary age of the sediments. Thisage is confirmed by rare
occurrences of Pterocaniumprismatium, a radiolarian species
peculiar to the up-per Pliocene but passing into the base of
Quaternarysediments (Goll, this volume).
Site 429During drilling at this site, the Quaternary
sediments
(31m thick) were washed down to the contact with thebasaltic
basement. Only one mudline core was sampled:nannofossil oozes with
fairly minor planktonic foramin-ifers—Sphaeroidinella dehiscens,
Neogloboquadrinadutertrei, Globigerinoides ruber, G. trilobus, G.
sac-culifer, Globorotalia menardii, G. tumida tumida, G.tumida
flexuosa, G. scitula, G. ungulata, Pulleniatinaobliquiloculata,
Globorotaloides hexagonus, Orbulinauniversa, Globigerinella
siphonifera, Globigerina bul-loides, and G. rubescens.
The correlation of Pliocene and Quaternary sedi-ments of the EPR
and the GSC is shown in Figures 2and 3, respectively.
ZONAL STRATIGRAPHY OF PLIOCENE ANDQUATERNARY DEPOSITS
The zonal stratigraphy of the Pliocene and Quater-nary by means
of planktonic foraminifers has advancedconsiderably in recent
years. Several zonal schemes havebeen suggested for subdivision of
sediments of this age(Blow, 1969; Bolli, 1970, Bolli and Premoli
Silva, 1973;Berggren, 1973; Rögl and Bolli, 1973; Kennett,
1973;Lamb and Beard, 1972; Rögl, 1974; Saito et al.,
1975, etc.) I believe that the three-membered subdivi-sion of
the Pliocene is the most expedient and bestgrounded: the
Globorotalia margaritae evoluta Zone (orthe Sphaeroidinella
dehiscens-Globoquadrina altispiraZone), the Globorotalia miocenica
Zone, and theGloborotalia tosaensis Zone.
Biostratigraphic subdivision of Quaternary sedimentsformed
during a rather short geological period (1.8m.y.) runs into
considerable difficulties. They should beregarded as the
Globorotalia truncatulinoides s.l. Zone.Blow (1969) subdivided
Quaternary sediments into twozones (it would be more correct to
regard them as sub-zones): Globorotalia truncatulinoides s. str.
and Globi-gerina calida calida-Sphaeroidinella dehiscens
excavata.The analysis of deep-sea drilling data shows that
thesezones (or subzones) have been established in many sec-tions of
the Indian (Krasheninnikov, 1976), Atlantic,and Pacific oceans
(Krasheninnikov, 1978a). The subdi-vision of Quaternary sediments
(the Globorotalia trun-catulinoides Zone) in the Cariaco Basin of
the Carib-bean Sea is much more detailed with five subzones:
Glo-borotalia crassaformis viola, Globorotalia crassaformishessi,
Globigerina calida calida, Globigerina bermudezi,and Globorotalia
fimbriata (Bolli and Premoli Silva,1973; Rögl and Bolli, 1973).
These subzones have sincebeen established for the Mid-Atlantic
Ridge (Sites 395and 396, Legs 45 and 46; Krasheninnikov, 1978b,
c),near the western coast of Africa (Sites 366, 367, 368,and 369,
Leg 41; Pflaumann and Krasheninnikov,1978), and in the Timor Trough
of the Indian Ocean(Site 262, Leg 41; Rögl, 1974). Such a wide
geographicalextension of these subzones witnesses to their
chrono-stratigraphic character.
However, a reliable establishment of subzones ofQuaternary
sediments is only possible when rich assem-blages of planktonic
foraminifers are available. The im-poverishment of the latter
because of unfavorableecological factors, selective dissolution
caused by sub-siding toward or through the foraminiferal lysocline,
orin diagenetic transformations in sediment, can
makebiostratigraphy difficult. Such impoverished
planktonicforaminiferal assemblages characterize the upper
Plio-cene and Quaternary sediments in the regions of the Leg54
sites.
Upper Pliocene deposits occur on the western slopeof the EPR
(Sites 419 and 420). The age of sediments isbased on single
specimens of Globigerinoides obliquusextremus, Globorotalia
pertenuis, and scarce Globor-otalia pseudomiocenica. It should be
admitted thatscarce specimens of these species apparently persisted
tothe late Pliocene. I assign the sediments concerned tothe
Globorotalia tosaensis Zone, although the indexspecies itself is
missing. An older Pliocene assignment(the Globorotalia miocenica
Zone) is hardly probable,because Globorotalia miocenica, G.
multicamerata, andrepresentatives of Globoquadrina and
Sphaeroidinel-lopsis are lacking. The tropical assemblage of
plankton-ic foraminifers includes Globorotalia tumida, G.
men-ardii, G. scitula, Sphaeroidinella dehiscens,
Pulleniatinaobliquiloculata, Orbulina universa,
Globorotaloideshexagonus, Globigerinoides ruber, G. conglobatus,
G.
514
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PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
Site 4293406 m
Site 4203381 m
Site 4213339 m
Site 4193274 m
Site 4273434 m
4
8 . 1 ~1 1 '
Figure 2. Stratigraphic correlation of the late Pliocene and
Quaternary sediments of the East Pacific Rise. Lithologicsymbols: 1
- foraminifer-nannofossil ooze (sometimes marly); 2 = nannofossil
ooze; 3 = siliceous nannofossilooze; 4 = calcareous siliceous ooze;
5 — brown calcareous clay; 6 = green hydrothermal clay; 7 =
iron-manganesefragments; 8 = basalts; 9 = washed-down or
not-recovered intervals. Stratigraphic symbols: N.21 =
f/zeGloboro-talia tosaensis Zone, upper Pliocene; N.22 = The
Globorotalia truncatulinoides Subzone s.str., Quaternary; N.23= the
Globigerina calida calida-Sphaeroidinella dehiscens excavata
Subzone, Quaternary.
sacculifer, G. trilobus, Neogloboquadrina dutertrei,and
Globigerinella siphonifera. All of these persist inthe Quaternary
sediments. There are no species peculiarto subtropical and higher
latitudes such as Globorotaliacrassaformis, G. inflata, Hastigerina
pelagica, Globig-erinita glutinata, Globigerina bulloides, G.
calida, andG. quinqueloba.
The species compositional diversity of Quaternaryplanktonic
foraminifers appears to have been at the ex-pense of a few
specimens of subtropical and temperatespecies. This seems to be
related to a general deteriora-tion of climatic conditions in
Quaternary time and epis-odic penetration of colder water masses
into the equa-torial area. It should be borne in mind however, that
wehad rather limited upper Pliocene materials from Leg54.
At the GSC (0°-2°N), planktonic foraminifers werenot affected by
selective dissolution; they are represent-ed by an equatorial
assemblage: predominant Globor-otalia tumida tumida, G. tumida
flexuosa, G. menardii,G. cultrata, Globigerinoides ruber, G.
sacculifer, G.conglobatus, Pulleniatina obliquiloculata,
Sphaeroid-
inella dehiscens, and Neogloboquadrina dutertrei; fre-quent
Globigerinoides trilobus, Globigerinella siphon-ifera, Hastigerina
pelagica, Orbulina universa, Globo-rotaloides hexagonus,
Globorotalia ungulata, G.scitula, G. hirsuta, Globigerina
bulloides, G. rubescens,and G. calida praecalida; single and
sporadic Globo-rotalia truncatulinoides, G. inflata, G.
crassaformisoceanica, Globigerinita glutinata, G. uvula, and
Glo-bigerina quinqueloba. Planktonic foraminifers enableus to
subdivide the Quaternary deposits of Sites 424 and425 into two
divisions: the lower division with theforementioned assemblage of
species associated withsingle Globorotalia tosaensis, as well as
single Globig-erinoides fistulosus at the base of the section, and
an up-per division where this assemblage is accompanied
byGlobigerina calida calida, pink G. rubescens, and
Glo-bigerinoides ruber.
On the western slope of the EPR (8°- 9°N), plank-tonic
foraminifers unexpectedly display extensive selec-tive dissolution.
In smear slides of sediments, the for-aminiferal content is rather
significant (10% - 25%,rarely 30% - 50%). However, after the
washing proc-
515
-
V.A. KRASHENINNIKOV
Site 4252782 m
Site 4242685 m
41-1-*
• K
Figure 3. Stratigraphic correlation of the Quaternary sed-iments
of the Galapagos Spreading Center. Lithologicand stratigraphic
symbols are the same as for Figure 2.
ess, this amount is rather small — some hundreds ofspecimens,
often only some tens of specimens. They areaccompanied by mass
accumulations of keel fragmentsbelonging to Globorotalia. This is
because semi-dissolved, fragile, thin walls of foraminiferal
testschange into powder (micarb) after washing, but thick-ened
keels remain preserved. Such corroded specimensof Globorotalia
tumida and G. menardii with etchedsurfaces are shown in Plate 4,
Figure 12, and Plate 6,Figure 5. It should be noted, however, that
along withcorroded tests, scarce well-preserved specimens
occur;this is hardly explicable.
On the whole, the Quaternary deposits of the EPRare
characterized by resistant species — Globorotaliatumida, G.
menardii, G. scitula, G. hirsuta, Sphaeroid-inella dehiscens,
Pulleniatina obliquiloculata, Neoglo-boquadrina dutertrei, and
Globorotaloides hexagonus.Specimens of other species are not
numerous — Globi-gerinoides ruber, G. sacculifer, G. conglobatus,
G. elon-gatus, G. tenellus, G. trilobus, Orbulina universa,
Glo-bigerinella siphonifera, Hastigerina pelagica, Globoro-talia
cultrata, G. ungulata, Globigerina bulloides, G.rubescens and G.
calida praecalida. Very scarce are Glo-borotalia truncatulinoides,
G. cavernula, G. subscitula,G. crassaformis crassaformis, G.
crassaformis oceanica,Candeina nitida, Globigerinita glutinata, G.
uvula, andGlobigerina quinqueloba.
The Quaternary deposits of this region can be sub-divided into
the same two divisions as in the GSC: thelower division with the
forementioned species of plank-tonic foraminifers, and the upper
division, where theyare accompanied by Globorotalia fimbriata,
Globiger-ina calida calida, and pink G. rubescens, and
Globigeri-noides ruber.
Thus, at EPR sites drilled on Leg 54, upper Plioceneand
Quaternary deposits are characterized by impover-ished assemblages
of planktonic foraminifers. Absenceor extremely rare occurrence of
Globorotalia tosaensisand G. truncatulinoides makes definition of
the Plio-cene/Quaternary boundary difficult. The Quaternary
issubdivided into two divisions, the lower of which is like-ly to
correspond to the Globorotalia truncatulinoidess.str. Zone
(Subzone) and the upper to the Globigerinacalida
calida-Sphaeroidinella dehiscens excavata Zone(Subzone) after
Blow's terminology. An exact determin-ation of the boundary between
these zones (subzones) isdifficult owing to rare occurrence of
specimens of Glob-igerina calida calida and absence of Hastigerina
(Bol-liella) adamsi. Even more noteworthy is that this bound-ary
occupies a fixed position relative to the radiolarianzonal scale
(Goll, this volume). It is consistently withinthe Amphirhopalum
ypsilon Zone, between one thirdand halfway from its top (Sites 419,
420, 422, 423, 425,427, and 428). Where only younger sediments of
theCollosphaera tuberosa radiolarian Zone were penetra-ted, the
Globigerina calida calida-Sphaeroidinella de-hiscens excavata Zone
alone could be identified bymeans of foraminifers (Site 421). Where
the sedimentsof the lower Amphirhopalum ypsilon radiolarian
Zoneoccur near the sediment surface, only the
Globorotaliatruncatulinoides s.str. Subzone can be established
usingforaminifers (Site 429).
The Globorotalia truncatulinoides s.str. Subzone ofBlow (1969)
corresponds to the Globorotalia crassafor-mis viola and
Globorotalia crassaformis hessi subzonesof Bolli and Premoli Silva
(1973). The recognition of thetwo latter subzones in the region of
Leg 54 studies is im-possible, as these subspecies of G.
crassaformis are en-tirely missing.
The Globigerina calida calida-Sphaeroidinella dehis-cens
excavata Subzone of Blow (1969) can be correlatedto the Globigerina
calida calida, Globigerina bermu-dezi, Globorotalia fimbriata
subzones of Bolli andPremoli Silva (1973). The boundary of the
Globigerinacalida calida and Globigerina bermudezi subzones
isrecognized according to disappearance of Globorotaliatumida
flexuosa and Globorotaloides hexagonus, andthe boundary of the
Globigerina bermudezi and Globor-otalia fimbriata subzones by
appearance of Globoro-talia fimbriata in the base of the latter.
All three indexspecies occur in the Leg 54 sediments, but
distinguishingthe Globigerina calida calida, Globigerina
bermudezi,and Globorotalia fimbriata subzones does not
appearfeasible. The fact is that Globorotalia fimbriata, G. tu-mida
flexuosa, and Globorotaloides hexagonus occurtogether, the latter
two species having been recognizedin the uppermost samples (30-40
cm below the sedimentsurface). One might therefore presume that our
data onthe stratigraphic ranges of Globorotalia fimbriata, G.tumida
flexuosa, and Globorotaloides hexagonus re-quire revision. I
believe, however, that the unusual jointoccurrence of these three
index species is a consequenceof extreme mechanical disturbance of
a normal succes-sion of weakly consolidated sediments in the
process ofdrilling; the thin sedimentary cover above the
basalts
516
-
PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
did not favor the stabilization of the column of
drillingpipes.
Comparison of stratigraphic data obtained fromLegs 54, 16, and 9
in the eastern equatorial area of thePacific Ocean shows their
great similarity.
Kaneps (1973) points out the absence of Globorotaliatosaensis
and G. truncatulinoides in upper Pliocene andQuaternary eastern
equatorial Pacific sediments. There-fore, he defined upper Pliocene
sediments on the basisof the Globorotalia limbata Zone, and
Quaternarysediments on the basis of the Pulleniatina
obliquiloc-ulata Zone. He recognized the
Pliocene/Quaternaryboundary through disappearance of
Globigerinoidesobliquus and Globorotalia limbata, a synonym of
thelatter being G. pseudomiocenica. South of CarnegieRidge (Site
157, oceanic depth 1591 m), planktonicforaminifers have moderate to
good preservation, buttheir species diversity is low and some index
species aremissing. On Coiba Ridge (Site 155), where the depth
islarger (2752 m), planktonic foraminifers show obvioustraces of
dissolution; their impoverished assemblage in-cludes mostly
resistant species.
Jenkins and Orr (1972) also speak of the extremescarcity or
absence of Globorotalia tosaensis and G.truncatulinoides. They
consider that upper Pliocene sed-iments belong to the
Globigerinoides fistulosus Zone,with the Pliocene/Quaternary
boundary determined bythe disappearance of this species; Quaternary
depositscorrespond to the Pulleniatina obliquiloculata Zone. Inthe
Panama Basin (Site 84) and on the western slope ofthe EPR (Site
83), some interbeds of Quaternary depos-its contain Globorotalia
inflata, this testifying to climat-ic cooling.
The absence of Globorotalia truncatulinoides, G. to-saensis, and
the G. crassaformis group in PlioceneQuaternary deposits of the GSC
appears to be related tothe equatorial position of the region; on
the westernslope of the EPR (9 °N) it is more probably the result
ofselective dissolution. In any case, at the same latitude inthe
Caribbean Sea (10-11 °N) and in the Timor Troughof the Indian Ocean
(11 °S) the first two species are fre-quent, and the Globorotalia
crassaformis group is suc-cessfully used for the subzonal division
of lower Quater-nary sediments. Each zone is recognized through an
as-semblage of planktonic foraminifers, the compositionof which
undergoes variations depending upon climaticbelts, local ecological
conditions, and other reasons.Therefore, I believe that absence of
one or anotherspecies should not serve as the basis for creation of
newzonal units. Stratigraphic studies in the World Oceannecessitate
unification of zonal scales, as well as zonalnames. I consider it
entirely permissible to use theGloborotalia tosaensis and
Globorotalia truncatuli-noides zones in the zonal scale of Pliocene
Quaternarydeposits of the eastern equatorial part of the
PacificOcean.
SYSTEMATIC PALEONTOLOGY
This section contains brief remarks on some selected species
ofplanktonic foraminifers concerning their morphological
peculiarities,stratigraphic and paleoclimatic importance, frequency
of occurrence,degree of preservation, etc.
Genus GLOBIGERINOIDES Cushman, 1927Globigerinoides elongatus
(
-
V.A. KRASHENINNIKOV
Genus GLOBIGERINITA Brönnimann, 1951
Globigerinita glutinata (Egger)(Plate 2, Figures 5-10)
This temperate to cool-water species is a scarce component
ofplanktonic foraminiferal assemblages in Quaternary deposits of
theeastern equatorial part of the Pacific Ocean. The character of
convexbulla and the number of apertures are variable (Figures 6, 7,
8, and10). For comparison, we observe that the boreal Globigerinita
uvula(Ehrenberg) is generally found as single specimens.
Genus CANDEINA d'Orbigny, 1839
Candeina nitida
-
PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
Globorotalia tumida tumida (Brady)(Plate 4, Figures 12-15)
This is a widely distributed species in upper Pliocene and
Quater-nary sediments of the region of Leg 54 studies. Many of the
tests arestrongly corroded. Abundant accumulations of thickened
keelsbelonging to G. tumida tumida (and G. tumida flexuosa too)
testify tomultiplicity of this species.
Globorotalia crassaformis oceanica Cushman and Bermudez(Plate 5,
Figures 1-4)
This variety is characterized by a robust test with
inflatedchambers, rounded peripheral margin, small but distinct
umbilicus,and almost subrectangular equatorial outline. Single
specimens werefound in lower Quaternary deposits (the Globorotalia
trun-catulinoides Subzone s. str.) of the East Pacific Rise (Site
422) andGalapagos Spreading Center (Site 425).
Globorotalia truncatulinoides (d'Orbigny)(Plate 5, Figures
5-8)
This is an extremely scarce species of planktonic foraminifers
fromQuaternary deposits of the East Pacific Rise (Site 420) and
GalapagosSpreading Center (Holes 424, 424B, 425).
Globorotalia fimbriata (Brady)(Plate 5, Figures 9-12)
Typical specimens of this species with a thin (Figure 11) four-
orfive- chambered test and peculiar "spinose" keel are frequent in
upperQuaternary sediments (the Globigerina calida
calida-Sphaeroidinelladehiscens excavata Subzone) of the East
Pacific Rise (Sites 420, 421,422, and 423). The stratigraphic
distribution of this species is confinedto the Holocene (Rögl and
Bolli, 1973). In the materials of Leg 54 thisspecies is recognized
in sediments that make up the upper half to two-thirds of the
thickness of the forementioned subzone; this phenome-non is likely
to be related to disturbance and contamination ofsediments by
drilling.
Globorotalia pertenius Beard(Plate 5, Figures 13, 14)
Scarce specimens of this species with a multichambered test,
nar-row chambers and thickened spiral suture were found in the
upperPliocene of the East Pacific Rise (Site 420). This species
appears tohave stopped its existence in the Globorotalia tosaensis
Zone, but notin underlying deposits as was previously thought. The
recorded speci-mens differ somewhat from typical representatives of
G. pertenuis. Inany case, they belong to the G. pertenuis - G.
multicamerata group.
Globorotalia menardii (Parker, Jones and Brady)(Plate 6, Figures
1-7)
A standard species of planktonic foraminifers from upper
Plio-cene and Quaternary deposits in the region of Leg 54 studies,
it occursin almost all samples of sediments; the numbers of
specimens is some-times large. The latter are frequently affected
by selective dissolution,and corroded (Figure 5).
Globorotalia pseudomiocenica Bolli and Bermudez(Plate 6, Figures
8-10)
Not many specimens of this species have been recognized in
upperPliocene deposits (the Globorotalia tosaensis Zone) of the
East PacificRise (Site 420). The species appears to have stopped
its existence in thePliocene top. It is characterized by a slightly
lobulate outline, slightlyconvex spiral side, and much more convex
ventral side. Some authorsconsider it as a synonym to G. limbata
(Fornasini). Not being con-cerned with the problems of taxonomy, we
will state only that "G.limbata" does not pass beyond the
Pliocene/Quaternary boundary.
Globorotalia cavernula Be(Plate 6, Figures 14-16)
A small test has slightly lobulate outline, flat spiral, and
high um-bonal side; the peripheral margin is non-keeled, relatively
acute, withdistinctly deep umbilicus. This boreal species was
established as singlespecimens in Quaternary sediments of the East
Pacific Rise (Site 423)and the Galapagos Spreading Center (Sites
424 and 425).
Globorotalia ungulata Bermudez(Plate 6, Figures 11-13)
Typical specimens of this species have an elongated test (Figure
11)with a high umbonal side (Figure 13); less frequently the
outline of thetest is oval (Figure 12). The keel is well
pronounced. The species hasbeen observed throughout the pile of
Quaternary deposits of the EastPacific Rise and the Galapagos
Spreading Center, although thenumber of specimens is small.
Globorotalia hirsuta (d'Orbigny)(Plate 7, Figures 1-3)
A subrectangular test with four chambers in the last whorl
ischaracterized by an acute peripheral margin with a thin distinct
carina(Figure 3). In Quaternary deposits of the East Pacific Rise
thespecimens of this species are sporadic, whereas in
synchronoussediments of the Galapagos Spreading Center they are
more common.
Globorotalia scitula (Brady)(Plate 7, Figures 4-6)
This species is invariably recognized in planktonic
foraminiferalassemblages from upper Pliocene and Quaternary
deposits of theregion under study. As a rule, the tests are well
preserved.
Globorotalia subscitula Conato(Plate 7, Figures 7-12)
Not many specimens of the given species were found in the
basallayers of Quaternary deposits of the East Pacific Rise (Sites
419 and420). According to the data presented by Blow (1969), G.
subscitula ispeculiar to tropical and temperate areas, disappearing
in the top of thePliocene. The specimens concerned are attributed
somewhat conven-tionally to G. subscitula.
Globorotalia cultrata (d'Orbigny)(Plate 7, Figures 13-19)
A flattened, almost equally biconvex test is characterized by
agradual increase of whorls, a thin wall, and relatively thin keel.
Thespecies is common to Quaternary deposits of the region of Leg
54studies. The tests are frequently affected by selective
dissolution.
ACKNOWLEDGMENTS
The author thanks Yu. I. Dmitriev (petrologist of Leg 54,Moscow)
for making available the material for
investigation.Scanning-electron photomicrographs were made at the
Geo-logical Institute of the USSR Academy of Sciences, Moscow,by N.
D. Serebrennikova and A. I. Nikitin, to whom the au-thor expresses
his sincere gratitude.
REFERENCES
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ofplanktonic foraminiferal and calcareous nannoplanktonzones.
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Blow, W. H., 1969. Late Middle Eocene to Recent
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1967, p. 199-421.
Bolli, H. M., 1970. The foraminifera of Sites 23-31, Leg 4.
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Bolli, H. M., and Premoli Silva, I., 1973. Oligocene to
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Bukry, D., Dinkelman, M. G., and Kaneps, A. G., 1973.
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Jenkins, D. G., and Orr, W. N., 1972. Planktonic
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Kaneps, A. G., 1973. Cenozoic planktonic foraminifera fromthe
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Kennett, J. P., 1973. Middle and Late Cenozoic planktonic
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the Deep Sea Drilling Project, v. 21: Washington(U. S. Government
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Krasheninnikov, V. A., 1976. Importance of oceanic depositsfor
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, 1978a. Importance of oceanic deposits for workingout a
stratigraphic scale of Mesozoic and Cenozoic (Pacificand Atlantic
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1978b. Stratigraphy by means of planktonic fora-minifers, of
Neogene and Quaternary sediments near thecrest of the Mid-Atlantic
ridge, DSDP Sites 395 and 396. InMelson, W. G., Rabinowitz, P. D.,
et al., Initial Reports ofthe Deep Sea Drilling Project, v. 45:
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., 1978c. Stratigraphy and planktonic foraminifers ofNeogene and
Quaternary sediments of Site 396, Leg 46 of
DSDP. In Dmitriev, L., Heirtzler J., et al., Initial Reportsof
the Deep Sea Drilling Project, v. 46: Washington (U. S.Government
Printing Office), p. 409-414.
Lamb, J. L., and Beard, if. H., 1972. Late Neogene
planktonicforaminifers in the Caribbean, Gulf of Mexico, and
Italianstratotypes. The University of Kansas Paleontological
Con-tributions, Article 57 (Protozoa, art. 8), p. 1-103.
Pflaumann U., and Krasheninnikov, V. A., 1978.
Quaternarystratigraphy and planktonic foraminifera of the
EasternAtlantic, Deep Sea Drilling Project, Leg 41. In Lancelot,Y.,
Seibold, E., et al., Initial Reports of the Deep Sea Drill-ing
Project, Supplement to v. 41: Washington (U. S. Gov-ernment
Printing Office), p. 883-912.
Rögl, F., 1974. The evolution of the Globorotalia
truncatulin-oides and Globorotalia crassaformis group in the
Plioceneand Pleistocene of the Timor trough, DSDP Leg 27, Site262.
In Veevers J. J., Heirtzler, J. R., et al., Initial Reportsof the
Deep Sea Drilling Project, v. 27: Washington (U. S.Government
Printing Office), p. 743-767.
Rögl, F., and Bolli, H. M., 1973. Holocene to
Pleistoceneplanktonic foraminifera of Leg 15, Site 147 (Cariaco
Basin[Trench], Caribbean Sea) and their climatic interpretation.In
Edgar, N. T., Saunders, J. B., et al., Initial Reports of theDeep
Sea Drilling Project, v. 15: Washington (U. S. Govern-ment Printing
Office), p. 553-615.
Saito, T., Burckle L. H., and Hays, J. D., 1975. Late Mioceneto
Pleistocene biostratigraphy of equatorial Pacific sedi-ments. In
Saito, T. and Burckle, L. H. (Eds.), Late Neo-gene Epoch
Boundaries: MicropaL, Spec. Publ. 1: New York(Micropaleontology
Press), p. 226-244.
van Andel, Tj. H., Heath, G. R., et al., 1973. Initial Reportsof
the Deep Sea Drilling Project, v. 16: Washington (U. S.Government
Printing Office).
PLATE 1
Figures 1-3 Globigerinoides elongatus (d'Orbigny).
Sample420-3-2, 39-41 cm, Quaternary, N23. ×96.
Figures 4-6 Globigerinoides ruber (d'Orbigny). Sample 420A-1-3,
40-42 cm, Quaternary, N23. ×96.
Figures 7-9 Globigerinoidessacculifer (Brady). Sample
425-3-3,49-51 cm, Quaternary, N22. ×96.
Figures 10, 11 Globigerinoides obliquus obliquus Bolli.
Sample420-12-5, 40-42 cm, upper Pliocene, N21. ×77.
Figures 12, 13 Globigerinoides fistulosus (Schubert). Sample
425-6-2, 49-51, Quaternary, N22. ×96.
Figures 14-16 Globigerinoides conglobatus (Brady). Sample
422-3-4, 29-31 cm, Quaternary, N22. ×96.
Figures 17-19 Globigerinoides trilobus (Reuss). Sample
422-3-2,39-41 cm, Quaternary, N22. ×96.
520
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PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
PLATE 1
521
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PLATE 2
Figure 1 Globigerinoides tenellus Parker. Sample 424B-1-1, 40-42
cm, Quaternary, N23. ×116.
Figures 2, 3 Globigerinoides (?) sp. Sample 424-3-5, 85-87
cm,Quaternary, N23. ×73.
Figure 4 Orbulina universa d'Orbigny. Sample 420-1-2,49-50 cm,
Quaternary, N23. ×97.
Figures 5-10 Globigerinita glutinata (Egger). 5-7: Sample
425-1-1, 40-42 cm, Quaternary, N23. ×IOO. 8-10:Sample 424-4-6,
49-51 cm, Quaternary, N22.×97.
Figures 11,12 Candeina nitida cTOrbigny. Sample 423-4-4,
40-42cm, Quaternary, N22. ×116.
Figures 13-15 Globigerinella siphonifera (d'Orbigny).
Sample424-4-2, 80-82 cm, Quaternary, N22. ×97.
Figures 16, 17 Hastigerina pelagica (d'Orbigny). Sample
423-2-2,40-42 cm, Quaternary, N23. ×73.
Figures 18-21 Globigerina bulloides d'Orbigny. Sample
425-3-4,49-51 cm, Quaternary, N22. ×97.
522
V.A. KRASHENINNIKOV
-
PLATE 2
523
PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
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V.A. KRASHENINNIKOV
PLATE 3
Figures 1-7 Globigerina calida calida Parker. 1-4.
Sample425-2-4, 49-51 cm, Quaternary, N23. ×123. 5,7.Sample 423-2-2,
40-42 cm, Quaternary, N23.×123. 6. Sample 419-3-1, 40-42 cm,
Quaternary,N23. ×142.
Figure 8 Globigerina (?) quinqueloba Natland. Sample424A-3-3,
60-62 cm, Quaternary, N22. ×71.
Figures 9-11 Globigerina rubescens Hofker. Sample 423-2-2,40-42
cm, Quaternary, N23. ×95.
Figures 12-14 Sphaeroidinella dehiscens excavata Banner andBlow.
Sample 420-1-3, 49-51 cm, Quaternary,N23. ×47.
Figures 15-18 Globorotaloides hexagonus (Natland).
Sample421-1-1, 40-42 cm, Quaternary, N23. ×105.
524
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PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
PLATE 3
525
-
PLATE 4
Figures 1-3 Neogloboquadrina dutertrei (cTOrbigny).
Sample428-2-2, 109-111 cm, Quaternary, N22. ×114.
Figures 4-7 Globorotalia inflata (cTOrbigny). Sample
425-3-5,49-50 cm, Quaternary, N22. ×95.
Figures 8-10 Pulleniatina obliquiloculata (Parker and
Jones).Sample 425-3-3, 49-51 cm, Quaternary, N22.×95.
Figure 11 Globorotalia tumida flexuosa (Koch). Sample421-1-5,
40-42 cm, Quaternary, N23. ×71.
Figures 12-15 Globorotalia tumida tumida (Brady). 12.
Sample420-2-4, 89-91 cm, Quaternary, N23. ×114. 13-15. Sample
425-3-6, 49-51 cm, Quaternary, N22.×95.
V.A. KRASHENINNIKOV
526
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PLATE 4
527
PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
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V.A. KRASHENINNIKOV
PLATE 5
Figures 1-4 Globorotalia crassaformis oceanica Cushman
andBermudez. Sample 425-4-2, 49-51 cm, Quater-nary, N22. ×123.
Figures 5-8 Globorotalia truncatulinoides (d'Orbigny). 5,
6.Sample 425-5-3, 49-51 cm, Quaternary, N22.×95. 7-8. Sample
424B-4-3, 70-72 cm, Quater-nary, N22. (7. ×95; 8. ×71).
Figures 9-12 Globorotalia fimbriata (Brady). Sample
423-1-3,50-52 cm, Quaternary, N23. (9. ×123; 10-12.×95).
Figures 13, 14 Globorotalia pertenuis Beard. Sample
420-12-4,40-42 cm, upper Pliocene, N21. ×71.
528
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PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
PLATE 5
529
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V.A. KRASHENINNIKOV
PLATE 6
Figures 1-7 Globorotalia menardii (Parker, Jones and Brady).1-4.
Sample 422-1-2, 39-41 cm, Quaternary, N23.×95. 5. Sample 420-6-2,
34-36 cm, Quaternary,
N22. ×95. 6-7. Sample 434B-3-5, 110 cm, Quater-nary, N23. (6.
×75; 7. ×95).
Figures 8-10 Globorotalia pseudomiocenica Bolli and Ber-mudez.
Sample 420-13-1, 40-42 cm, late Pliocene,N21. ×95.
Figures 11-13 Globorotalia ungulata Bermudez. Sample
423-3-2,40-42 cm, Quaternary, N23. ×95.
Figures 14-16 Globorotalia cavemula Be . Sample 424-4-2,
80-82cm, Quatnerary, N22. ×95.
530
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PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
PLATE 6
531
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V.A. KRASHENINNIKOV
PLATE 7
Figures 1-3 Globorotalia hirsuta (d'Orbigny). Sample
425-3-6,49-51 cm, Quaternary, N22. ×116.
Figures 4-6 Globorotalia scitula (Brady). Sample 425-5-2,49-51
cm, Quaternary, N22. ×97.
Figures 7-12 Globorotalia subscitula Conato. 7-9.
Sample420-10-5, 40-42 cm, Quaternary, N22. ×97. 10-12. Sample
419-5-2, 40-42 cm, Quaternary, N22.×116.
Figures 13-19 Globorotalia cultrata (d'Orbigny). 13.
Sample419-4-3, 39-41 cm, Quaternary, N22. ×97. 14-16.Sample
422-3-1, 39-41 cm, Quaternary, N23.×73. 17-19. Sample 425-5-1,
49-51 cm, Quater-nary, N22. ×97.
532
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PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY
PLATE 7
533