Deep Sea Drilling Project Initial Reports Volume 54 · and Globorotalia ungulata. G. scitula,...

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

10°N

9 N

SIQUEIROS FRACTURE ZONE

PT-4 SITES(419 423. 426429)

105°W 104°W

Figure 1. Location of Leg 54 sites.

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

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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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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-

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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


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


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


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

Berggren, W. A., 1973. The Pliocene time-scale: calibration ofplanktonic foraminiferal and calcareous nannoplanktonzones. Nature, v. 243, p. 391-397.

Blow, W. H., 1969. Late Middle Eocene to Recent planctonicforaminiferal biostratigraphy. Proceedings of the First In-ternational Conference on Planctons and Microfossils:Geneva, 1967, p. 199-421.

Bolli, H. M., 1970. The foraminifera of Sites 23-31, Leg 4. InBader R. G., Gerard R. D., et al., Initial Reports of theDeep Sea Drilling Project, v. 4: Washington (U. S. Govern-ment Printing Office), p. 577-643.

Bolli, H. M., and Premoli Silva, I., 1973. Oligocene to Recentplanktonic foraminifera and stratigraphy of Leg 15 Sites inthe Caribbean Sea. In Edgar T. N., Saunders J. B., et al.,Initial Reports of the Deep Sea Drilling Project, v. 15: Wash-ington (U. S. Government Printing Office), p. 475-497.

Bukry, D., Dinkelman, M. G., and Kaneps, A. G., 1973. Bio-stratigraphy of the equatorial East Pacific Rise. In van AndelTj. H., Heath, G. R., et al., Initial Reports of the DeepSea Drilling Project, v. 16: Washington (U. S. GovernmentPrinting Office), p. 915-936.

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Hays, J. D., Cook H. E., et al., 1972. Initial Reports of theDeep Sea Drilling Project, v. 9: Washington (U. S. Govern-ment Printing Office).

Jenkins, D. G., and Orr, W. N., 1972. Planktonic foraminiferalbiostratigraphy of the eastern equatorial Pacific, Leg 9. InHays J. D., Cook H. E., et al., Initial Reports of the DeepSea Drilling Project, v. 9: Washington (U. S. GovernmentPrinting Office), p. 1059-1193.

Kaneps, A. G., 1973. Cenozoic planktonic foraminifera fromthe eastern equatorial Pacific Ocean. In van Andel Tj. H.,Heath G. R., et al., Initial Reports of the Deep Sea DrillingProject, v. 16: Washington (U. S. Government PrintingOffice), p. 713-746.

Kennett, J. P., 1973. Middle and Late Cenozoic planktonic for-aminiferal biostratigraphy of the Southwest Pacific, DSDPLeg 21. In Burns, R. E., Andrews, J. E., et al., Initial Re-ports of the Deep Sea Drilling Project, v. 21: Washington(U. S. Government Printing Office), p. 575-639.

Krasheninnikov, V. A., 1976. Importance of oceanic depositsfor working out a stratigraphic scale of Mesozoic and Ceno-zoic (Indian Ocean). Questions of Micropaleontology, No.19, p. 124-227 (in Russian).

, 1978a. Importance of oceanic deposits for workingout a stratigraphic scale of Mesozoic and Cenozoic (Pacificand Atlantic Oceans). Ibid., No. 21, p. 42-161 (in Russian).

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: Washington (U. S.Government Printing Office), p. 319-322.

., 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


PLATE 1

521

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.

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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.

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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.

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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.

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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.

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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.

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Deep Sea Drilling Project Initial Reports Volume 54 · and Globorotalia ungulata. G. scitula,...

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Transcript of Deep Sea Drilling Project Initial Reports Volume 54 · and Globorotalia ungulata. G. scitula,...