32. STRATIGRAPHY AND PLANKTONIC FORAMINIFERS OF NEOGENE AND QUATERNARYSEDIMENTS OF SITE 396, LEG 46 OF DSDP

V. A. Krasheninnikov, Geological Institute of the USSR Academy of Sciences, Moscow, USSR

INTRODUCTION

Site 396 is located on the eastern flank of theMid-Atlantic Ridge, in the tropical area of the AtlanticOcean. The drilling by Glomar Challenger in this regionwas started on Leg 45. Hole 396 (22°58.88'N, 43°30.95'W;4450 m water depth) penetrated 125 meters of middleMiocene-Quaternary nannofossil foraminiferal oozes and 96meters of basalts. The drilling was continued on Leg 46,with two additional holes drilled slightly to the north(22°59.14'N, 43°30.90'W, 4459 m water depth). Hole396A penetrated the sedimentary cover, but only two coresof Quaternary sediments (within the 0 to 19-meter interval)were taken. Hole 396B penetrated 150.5 meters ofnannofossil foraminiferal ooze and 256 meters of basalts;three cores of lower Pliocene sediments were taken (122.0to 150.5 m sub-bottom).

The stratigraphic subdivision of Miocene, Pliocene, andQuaternary sediments by means of planktonic foraminifersin Hole 396 was given in the Initial Reports of the DSDP,Leg 45 (Krasheninnikov, 1978). This article summarizesvery briefly all the stratigraphic data obtained for Holes396, 396A, and 396B; the general idea about the mainfeatures of microfauna, the character of sediments, and acomparison with the Pliocene-Quaternary section of Site395 on the west flank of the Mid-Atlantic Ridge are given aswell.

ZONAL STRATIGRAPHY OF NEOGENE ANDQUATERNARY SEDIMENTS OF SITE 396

The Site 396 site chapter (this volume) indicates thepresence of thin intercalations of sediments interbeddedwith basalts. Thus, notable pieces occur in the top of thesparsely phyric unit (Cores 396B-5 and 396B-6), sometimesmixed with palagonite to form the breccia. A piece ofsediment (3 cm thick) separates basalts in Core 396B-13.The sediments are represented by well-lithified nannofossiloozes with rare preserved foraminifer outlines. In thebasaltic sands of Core 396B-30 (377 to 382 m sub-bottom),foraminifers have been found and sampled for a shore-basedanalysis.

This study focuses on the foraminifers from Core396B-30 that we had at our disposal. The assemblageconsists of well-preserved tests of Globigerinoidesconglobatus, G. ruber, G. sacculifer, Orbulina universa,Sphaeroidinella dehiscens, Globorotalia crassaformis, G.tumida, and Globigerina bulloides that are typical forsediments of Pliocene-Quaternary time. The age of thisforaminiferal assemblage is younger, as compared with thatof the basal layers of the sedimentary cover in Hole 396(middle Miocene). Taking into account the biostratigraphic

data and excellent preservation of foraminifers, it isreasonable to assume uphole contamination.

Basalts are covered by a pile of biogenic oozes; theirthickness in Holes 396 and 396B is 125 and 151 meters,respectively. The character of the basalt/sediment contactcould be carefully examined in Hole 396. Sediments abovethe basalts are not metamorphosed, and the contact can beconsidered normal, i.e., depositional. The character of thebasalt/sediment boundary in Hole 396B is unknown,because the sediments near the contact were not preservedin the process of drilling; in any case, the nearest sedimentsdo not display traces of any thermal metamorphism.

The sedimentary pile can be subdivided into twolithological units. The lower one (8 m thick in Hole 396 and13 m thick in Hole 396B) is composed of yellow andbrownish clayey nannofossil oozes and calcareous clays.The upper unit (117 m thick in Hole 396 and 138 m thick inHole 396B) consists of grayish, yellowish, and palebrownish nannofossil and nannofossil foraminiferal oozes.This unit represents an alternation of normal pelagicbiogenic oozes and calcareous turbidites with redepositedand well-sorted fossils. Abundant planktonic foraminiferswithin the sedimentary pile allow distinction of subdivisionsof the middle Miocene, Pliocene, and Quaternary.

Middle MioceneSediments of this age correspond to the Globorotalia

fohsifohsi Zone with the index-species, G. peripheroronda,G. peripheroacuta, G. siakensis, Orbulina suturalis,Globigerinoides trilobus, Globigerina bollii, G. druryi,Globoquadrina dehiscens, and G. altispira. Amongspecimens of Sphaeroidinellopsis, only the species Sph.seminulina has been determined. The absence of Sph.subdehiscens prevents assignment of the sediments to thenext (younger) Sphaeroidinellopsis subdehiscens-Globigerina druryi Zone. Thickness is not over 4 to 4.5meters (from Samples 396-14-5, 144-146 cm to 396-14-3,99-101 cm).

Upper Miocene-Lower Pliocene

Upper layers of brownish calcareous clays and clayeynannofossil oozes include poor assemblages of planktonicforaminifers, i.e., Sphaeroidinellopsis subdehiscens, Sph.seminulina, Globigerinoides conglobatus, G. ruber, G.sacculifer, Globigerina nepenthes, Globoquadrinadehiscens, G. altispira, Globorotalia menardii, and G.dutertrei. They can be assigned to the uppermost Miocene(the Globorotalia margaritae margaritae Zone) and thelower Pliocene (the Globorotalia margaritae evoluta Zone)from Samples 396-14-2, 90-92 cm to 396-13-6, 146-148cm.

409

V. A. KRASHENINNIKOV

Consequently, the two above-mentioned stratigraphicsubdivisions in Hole 396 are separated by a gap; the upperpart of the middle Miocene (the Sphaeroidinellopsissubdehiscens-Globigerina druryi and Globigerinanepenthes-Globorotalia siakensis zones) and almost theentire upper Miocene (the Globorotalia continuosa,Globorotalia merotumida, Globorotalia plesiotumida, andpart of the Globorotalia margaritae margaritae zones) aremissing.

In Hole 396B, there is an 8-meter interval withoutrecovery between basalts and nannofossil foraminiferaloozes of the lower Pliocene (the Globorotalia margaritaeevoluta Zone). Evidently, this uncored interval correspondsto the middle Miocene and undifferentiated upperMiocene-lower Pliocene sediments of Hole 396.

The sequence of Pliocene and Quaternary sediments ofSite 396 is continuous, so all zonal and subzonal units canbe singled out.

Pliocene

Rich assemblages of planktonic foraminifera allow thesezones to be recognized easily:

1) The Globorotalia margaritae evoluta Zone includesthe index-species G. tumida, G. margaritae margaritae, G.pseudomiocenica, G. menardii, G. dutertrei, G.crassaformis crassaformis, G. crassaformis ronda,Sphaeroidinella dehiscens, Sphaeroidinellopsis seminulina,Sph. subdehiscens, Globigerina nepenthes, Globoquadrinaalti ra, G. dehiscens, Globigerinoides conglobatus, G.ruber, G. sacculifer, and G. obliquus extremus. Thisinterval ranges from Samples 396-13-5, 109-111 cm to396-11-6, 89-91 cm; and 396B-3-1, 134-136 cm to396B-2-1, 108-110 cm.

2) The Globorotalia miocenica Zone includes theindex-species G. exilis, G. pertenuis, G. pseudomiocenica,G. dutertrei, G. crassaformis crassaformis, G.crassaformis ronda, G. crassaformis oceanica, Candeinanitida, Pulleniatina obliquiloculata, Sphaeroidinelladehiscens, Globigerinoides conglobatus, and G. ruber, G.sacculifer. Very rare specimens of Globorotaliamulticamerata and Globigerinoides trilobus fistulosus havebeen found in the lower part of this zone. This intervalranges from Samples 396-11-4, 134-136 cm to 396-8-2,73-75 cm.

3) The Globorotalia tosaensis Zone, includes theindex-species G. dutertrei, G. hirsuta, G. crassaformiscrassaformis, G. crassaformis viola, G. crassaformisronda, Orbulina universa, Sphaeroidinella dehiscens,Candeina nitida, Globigerinoides conglobatus, G. ruber,G. sacculifer, Globigerinella siphonifera, andGlobigerinita uvula. This interval ranges from Samples396-7-6, 74-76 cm to 396-5-3, 125-127 cm.

Quaternary

The normal succession of stratigraphic subdivisionstestifies to a gradual transition of the Pliocene sediments(the Globorotalia tosaensis Zone) to the Quaternary ones(the Globorotalia crassaformis viola Subzone). Poorrecovery at the Pliocene/Quaternary boundary did notpermit fixing this boundary exactly.

Quaternary sediments correspond to the Globorotaliatruncatulinoides Zone which is characterized by abundantplanktonic foraminifers: Globorotalia truncatulinoides, G.crassaformis s.l., G. menardii, G. dutertrei, G. ungulata,G. tumida, Candeina nitida, Globigerinoides conglobatus,G. sacculifer, G. ruber, Pulleniatina obliquiloculata,Sphaeroidinella dehiscens, Globigerina rubescens (white),G. bulloides, and Globorotaloides variabilis.

The Globorotalia truncatulinoides Zone is subdividedinto three subzones:

1) The Globorotalia crassaformis viola Subzone which isdetermined by the coexistence of subspecies G. tosaensisandG. truncatulinoides. This subzone ranges from Samples396-3-3, 86-88 cm to 396-2-5, 139-141 cm.

2) The Globorotalia crassaformis hessi Subzone with thegiven subspecies developed; Gl. crassaformis viola ispractically absent, except for very rare specimens in thebasal layers of this subzone. This subzone spans Samples396-2-4, 83-85 cm to 396-1-2, 121-123 cm.

3) The Globigerina calida calida Subzone with rarespecimens of G. aff. calida calida accompanied by pinkGlobigerina rubescens and Globigerinoides ruber, togetherwith Globorotalia tumida flexuosa. This subzone isobservable in Samples 396A-1-1, 139-141 cm; 396A-1-1,129-130 cm; and 396-1-1, 139-141 cm.

The youngest Quaternary sediments (the Globigerinabermudezi and the Globorotalia fimbriata subzones) havenot been discovered in Site 396.

PECULIARITIES OF FORAMINIFERDISTRIBUTION IN THE CENOZOIC SEDIMENTS

OF SITE 396

Two types of foraminiferal associations have beenestablished in the Cenozoic sediments of Site 396. The firsttype can be qualified as the natural assemblages(paleocoenoses) of planktonic foraminifers, generallyreflecting their composition in the upper layer of the watercolumns of the appropriate time. These assemblagesconsist of the species of Globorotalia, Globi-gerina Globigerinoides, Orbulina, Globigerinita,Globorotaloides, Sphaeroidinella, Sphaeroidinellopsis,Globigerinella, Candeina, and Pulleniatina typical of theNeogene and Quaternary sediments of the tropical andsubtropical areas. Based on the given assemblages, zonaland subzonal subdivisions of the Cenozoic stratigraphicscale have been recognized: the Globorotalia fohsi fohsiZone (middle Miocene); the Globorotalia margaritaeevoluta, Globorotalia miocenica, and Globorotaliatosaensis zones (Pliocene); and the Globorotaliatruncatulinoides Zone with Globorotalia crassaformisviola, Globorotalia crassaformis hessi, and Globigerinacalida calida subzones (Quaternary).

The middle Miocene is represented by the Globorotaliafohsi fohsi Zone only. Therefore, the evolutionary lineageof the Globorotalia fohsi group cannot be traced here.Nevertheless, the presence in some samples of G.peripheroronda, G. peripheroacuta, and G. fohsi fohsiindirectly testifies to this lineage.

In some regions of the Atlantic Ocean, Globorotaliatosaensis is lacking (or very rare) in upper Pliocene

410

FORAMINIFERS OF NEOGENE.AND QUATERNARY SEDIMENTS

sediments. This species is common for the area of Site 396,allowing observation of the G. tosaensis-G.truncatulinoides lineage and precise determination of thePliocene/Quaternary boundary. It is an example of theirregular distribution of planktonic foraminifers whichshould be taken into consideration in the process ofstratigraphic investigations and application of zonal names.All subspecies of Globorotalia crassaformis (crassaformis,ronda, oceanica, viola, and hessi) are very well developedin the Pliocene-Quaternary sediments of Site 396. Thelineage of the Globorotalia crassaformis group is clearlyobserved here, and enables subzones within the Quaternarysediments to be singled out.

The distribution of planktonic foraminifers in theCenozoic sediments of Site 396 is shown in Table 1.

The sediments with the above-mentioned paleocoenosesof planktonic foraminifers can be treated as normal pelagicdeep-water biogenic oozes.

Planktonic foraminiferal assemblages of the second typeare of the heterogenic character. They include a number offoraminifers redeposited from more ancient deposits andalso display a well-pronounced sorting of tests according totheir size. Sometimes these assemblages consist ofenormous quantities of minute and juvenile tests ofGlobigerina, Globigerinita, and Globigerinoides that createdifficulties for age determination; in other cases, theassemblages, formed by big tests of Orbulina,Globigerinoides, Sphaeroidinella, Globorotalia, andPulleniatina, resemble foraminiferal sands. It is quiteevident that sediments with such assemblages of planktonicforaminifers can be treated as calcareous biogenic turbiditesoriginated in connection with turbidity currents down theeastern slope of the Mid-Atlantic Ridge.

Sediments with heterogenic assemblages of planktonicforaminifers were met in all subdivisions of the Plioceneand Quaternary: the Globorotalia margaritae evoluta Zone(in Samples 396-13-3, 66-68 cm and 396B-2-1, 108-110cm); the Globorotalia miocenica Zone (Samples 396-10-5,108-110 cm; 396-10-3, 120-122 cm; 396-9-4, 64-66 cm;and 396-9-2, 8-10 cm); the Globorotalia tosaensis Zone(Samples 396-7-2, 96-99 cm; 396-6-6, 86-88 cm; 396-6-4,105-107 cm; 396-6-2, 82-84 cm; 396-5-5, 74-76 cm;396-5-3, 125-127 cm; and 396-5-1, 116-118 cm); the

Globorotalia crassaformis viola Subzone (Samples396-3-3, 86-88 cm; 396-3-1, 87-89 cm; and 396-2-5,139-141 cm); the Globorotalia crassaformis hessi Subzone(Samples 396-2-1, 123-125 cm and 396-2-4, 83-85 cm);and the Globigerina calida calida Subzone (Samples396A-1-1, 139-141 cm and 396-1-1, 129-130 cm).

Consequently, bottom turbidity currents were acting inthe course of the entire Pliocene-Quaternary time, but werenot constant. The latter accounts for the alternation ofcalcareous turbidites with normal pelagic biogenic oozes.Obviously, the most active turbidity currents were in theupper Pliocene time (the Globorotalia tosaensis Zone) andin the lower Quaternary time (the Globorotalia crassaformisviola Subzone).

It should be noted that it is rather difficult to estimate thescope of redeposited material because stratigraphic rangesof many foraminiferal species correspond to the wholePliocene-Quaternary interval. The state of preservationcannot help in this case; undoubtedly, reworked species ofplanktonic foraminifers (species of Sphaeroidinellopsis,Globigerina nepenthes, Globorotalia miocenica, G. exilis,G. multicamerata, G. pertenuis, etc.) are characterized bythe same excellent preservation as the species found in situ.

Certainly, wide development of heterogenic assemblagesof planktonic foraminifers prevents an exact determinationof the position of stratigraphic boundaries.

Analogous calcareous turbidites alternating with normalpelagic oozes are widely developed at Site 395 on thewestern flank of the Mid-Atlantic Ridge (Figure 1). Thethickness of Pliocene-Quaternary sediments in Sites 395 and396 is rather significant: 84 and 115 meters, respectively. Acomparatively high rate of sedimentation of calcareousmaterial is connected, evidently, with a pronounced input ofreworked organic remains.

REFERENCES

Krasheninnikov, V. A., 1978. Stratigraphy of Neogene andQuaternary sediments by means of planktonic foraminifers nearthe crest of the Mid-Atlantic ridge, Sites 395 and 396, Leg 45of DSDP. In Melson, W. G., Rabinowitz, P. D., et al.,InitialReports of the Deep Sea Drilling Project, v. 45: Washington(U.S. Government Printing Office).

411

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TABLE 1Distribution of Planktonic Foraminifers in the Cenozoic Sediments of Site 396, Leg 46

_ _^ . • . j •

\ Species ,a S l a

\ Siii il !iil , iilililii .Hütilitl.Hiii! üjiUli\ f i l l „ •§ § 11«11111 l l .w l? I I {H« l i ! !Mii l i t ! i ièS£i§1ii .gi l i ! i !•! i l

\ i < s i i i f i < s ^ i i i π i i i i i i i i i i i i i i i i t i i i i & i i t i i i i i H | i i i i i i t i s & i i i t iSample \ 0 < o Q . a , o » v > ' « α i f c o f c f c f c Q , ö , n , f c • < 3 . s ; . i : . _ » α t j t j ü s j ü £ ; S Q ^ i • Q S o c α c C Q - •. • . u o o w k C . Q . o g o ^ i α o . s . c . c . c c S i . g . g

Age (Interval in cm)\ - _ - _ _ _ O O O O ü O ü ü U O O O <J ü üi U U ü O O ü' <O U O δ D d ü ü ü θ ' c i δ u ü ü ü a ü C ) t ó l 3 O ? δ ö θ • O M M ( j ^ δ δG. cali- 396-1-1, 139-141 - - - - - R - - - R R R R - R C R C - - R - R R F F - C - F - - F F F - C - - - - R - - - - R - F -da ca-lida

1-2, 121-123 - - - - - R - - - - R - - - - - - - R C R R R R R R - - - F - - R - R - C - - C - F - - F F - - C - - - - R - - - C - R C R

| | 1-4, 145-147 - - - - - R C R - - - - - - - C C R R - C R - - - - C - - R - R - C - - F - A - - C F - - F - - - - - - - - R R - R R

J | , B 1-5,69-71 R R C _ _ ^ ^ F R R C - R - C R F R C - C C F R - R R R R C R

| S 1 1 2-1,123-125 R R R - C R R - R R A R - R ~ C F - F F C C R - R R -

1 i \ 2-2, 121-123 _ _ _ _ _ _ _ _ _ _ _ - - - _ _ _ _ _ R _ _ _ R _ _ _ R R C - _ _ _ - - - - - R _ C - - R R - - R - - - - - - - - - - - R -

2-4, 83-85 - - - - - R - - - C R - - - - - - - F C R R R C C R - C R A - - R - C - F - - A - A - - A A - - . A - - - - C - - - F C C A C

, ^ 2-5, 139-141 _ _ _ _ _ R _ _ _ C C - - - - - - F R R C - C . C - C - R F - - R - R - R - - F - F - - F A - - F - - - - - - - - R R R F F

| | 2-6,76-78 _ _ _ _ _ _ _ i r p - - - - - - - C R - R R C - C C - R F - - R - R - C - - A - F - - F F - - F - - - - R - - - C R - R R

" | 3-1, 87-89 _ _ - - - R _ _ _ R - - - _ - - _ _ R _ _ - _ R _ _ R _ R C _ _ - - - _ R - - R - R - - C C - - C - - - - - - - - - - R - R

~5- 3-3, 86-88 ^ _ _ _ _ _ _ _ _ _ _ R _ _ _ _ _ _ _ R _ _ _ _ R _ _ R _ _ R _ _ A - A - A - - R - R - - R R - - R - - - - - - - - R - R A C

5-3, 125-127 - - - - - R - - - R R - - - - - - - R R - R - C - R R - R - - - A - C - F - - C - R - - C C - - . C - - - - - - - - R - - A F

6-4, 105-107 - - - - - - - - - R - - - - - - - - R R - R - R - - R - R - _ _ A - C - C - - R - R - - R C - - - - - - - - - - - R R - A C

^ .g 6-6, 86-88 _ _ - - - R _ _ _ R _ _ _ _ _ _ _ _ _ R _ _ _ R _ _ R _ R _ _ _ A - C - C - - R - R - - R R - - R - - - - - - - - - - R A R

S | 7-2, 96-98 - _ _ _ _ _ _ _ _ C C - - - - - - - F C - C R C C C C - C - - - A - F - F - - F - F - - C C - - C - - . - - R - - - R R - A R

3 S 7-4,64-66 - - - - - - - - - F F - - - - - - - C R - R - C C R C - C - _ _ R _ R _ R - _ C - I ' - - F F - - F - - - - C - - ~ C R R R -

7-5,40-42 _ _ _ _ - R _ _ _ C C - - - - - - - R C R R - F R R C - R - _ _ R _ R _ R _ _ F - A - - A F - - F R - - - R - - - C R - C -

7-6, 74-76 _ _ _ _ _ _ _ _ _ R R _ _ _ _ _ _ _ R _ _ _ _ R. _ R _ _ C - _ _ R _ _ _ _ _ _ c - R - - R C - - R - - - - - - - - R - - R R

8-2, 73-75 _ _ _ _ _ R _ _ _ R _ _ _ _ R _ F F C R - R - F R F R - - - _ _ R _ _ - - - _ F - A - - F A - - A - - - - R - - - F R R C R

8-4,74-76 _ _ _ _ _ C - - - R - - - - C R R F C R - - - F - C - - - - _ _ - - - _ - _ _ F - F - - F F - - C - - - - R - - - R - R R -

^ S 8-6,119-121 _ _ _ _ - _ _ _ _ _ R _ _ _ C R R F - - - - - C R C - - - - _ _ R _ _ _ _ - _ C - C - - C F - - C - - - - - - - - R - - R -

= | § 9-4,64-66 _ _ _ _ _ _ _ _ _ R _ _ _ _ R _ _ R _ _ _ _ _ R _ R _ _ _ _ _ _ A - - - - - - C - R - - R R - - - - - - - - - - - - - - F R

| 3 1 10-5, 108-110 _ - - _ - R - - _ - R R _ R _ _ _ _ _ R _ _ _ _ _ _ _ _ A - - - - - - R - R - - R R - _ R - - - - R - - - R - - A C

11-2, 113-115 - - - - - - - - R R C R R R R R R - - - - - - R - - - - - - R R R - - R R - - R - - - - - - - - R R - R -

11-4, 134-136 - - - - - - - - - R R - - F C C R R C R - R - C - - - - - - - - R - - - - - - F R C - - C F - - R - - - - R - - - C R R R R

11-6, 89-91 - _ - - - R _ _ - R - - R R C R - _ R R - - - F - R - - - - - - R - - - - - - C - C - - R C - - C - - - - - - - - R - - R R

| 12-3, 110-112 - - - - - R - - - C R - R R C R - - C R R R - C R R - - - - - - R C - - - - - C - F R R F F - - F - - C C R C C - R R R R R

| 12-5,74-76 _ _ _ _ _ _ _ _ R _ R R _ R R _ _ C R - - - R - R - - - - - - R C - - - - - F - F C C F F - - C - - R C - C C - C - R C R

1 | 13-3,66-68 _ _ _ _ - _ _ _ _ _ R _ R _ R _ _ _ R _ _ . R _ R _ _ _ _ _ _ _ _ A R - - - - - R - R R - R R - - R - - - R - R R R R - - A R

| | 13-5,109-111 R R - C R R R R C R F C - C - F C C R F - A - A F F F A A C C R C C R F R C R -

S 396B-2-1, 108-110 - - - - - - - - - R - - R - - - _ _ R _ - - _ R R _ _ _ _ _ - - A R - - - - - R - R - R - R - - R - - - - - R R - R - - F RO

2 396B-2-1, 132-133 - - - - - - - _ _ - - _ - - _ _ _ _ R _ _ R _ R _ _ _ _ _ - - - F F - - - - - R - R R - R R - - R - - R - - R R - R - - F -U 396B-3-1, 134-136 _ - _ _ - - - - - R - - R - _ _ _ _ R _ _ _ _ R _ _ _ _ _ _ - - R R - - - - - C - R R R R R - - R - - - R R R - - R - - C -

Pliocene- 396-13-6, 146-148 _ - - - R R - R R R _ _ - - ^ - _ _ R R - _ _ _ _ _ _ _ _ _ - - R R - - - - - C - C C C C C - - C - - - R - C R R - - - R R

? Upper 14-0, 34-36 - - _ _ _ R _ R R R R - - R _ _ _ _ C R - - - - R R - - - - - - R R - - - - - F - - C C C C - - F - - - C - C R R - - - R -

Miocene , 4 2 9 Q 9 2 _ _ _ _ _ R _ R C - R - - - - - - - C R - - - - - - - - - - - - R F - - - - - C - R C C - - - - C - - C C R F F R - - - R -_ 1 o - 1 4 " 3 ' 9 9 " 1 0 1 C R C C C R F - - - - - - - - - - - - - - - - - - - - - - - C F - - - - - - C F - - - - - - - C R R R A A R F - - - - - - -

•§ § _,-§ 14-5, 144-146 C - R C R - F - - - - - - - - - - - - - - - - - - - - - - - C C - - - - - - C F - - - - - - - C C - R R F F - F - - - - - -ë^ . = a " I I | | | 1 I | | I INote: A = abundant, F = frequent, C = common, R = rare.

FORAMINIFERS OF NEOGENE AND QUATERNARY SEDIMENTS

Site 395(4484 m)

QcQhQv_

N 2 t

15m

Qc

Qh

Qv

Site 396(4450 m)

30 m\

N2t

\\

\69 m \

\\ N2'

\ \

\ \\

\\

- 84 m

^ \ N2me

•24 m

•33 m

•61 m~-r~<~-η

4

5

6

•95 m

•115m•120 m•125 m

Figure 1. Stratigraphic correlation of the Cenozoic sediments of Sites 395 and 396, Leg

45 and Leg 46. Lithologic symbols: 1 = nannofossil oozes, 2 = foraminiferal oozes,

3 = nannofossil foraminiferal oozes, 4 = clayey nannofossil and nannofossil foramini-

feral oozes, 5 = calcareous clays with nannofossils and foraminifers, 6 = basalts.

Stratigraphic symbols: Quarternary: Qc = the Globigerina calida calida Subzone;

Qh = the Globorotalia crassaformis hessi Subzone; Qv = the Globorotalia crassaformis

viola Subzone; Pliocene: N2 t = the Globorotalia tosaensis Zone; N2 m = the Globoro-

talia miocenica Zone; N2 me = the Globorotalia margaritae evoluta Zone; N2 - Nj =

undifferentiated basal Pliocene and the uppermost Miocene. Nj ? Upper Miocene?

Nj f = Middle Miocene, the Globorotalia fohsi fohsi Zone.

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