Deep Sea Drilling Project Initial Reports Volume 40 · been recorded from the lower Miocene...

16. NEOGENE PLANKTONIC FORAMINIFERS FROM DSDP LEG 40SITES 360 AND 362 IN THE SOUTHEASTERN ATLANTIC

D. Graham Jenkins, Department of Geology, University College of Wales, Aberystwyth, Wales

ABSTRACT

From the documentation of the Neogene planktonic foraminiferspecies from 126 samples of DSDP Leg 40 Sites 360 and 362 in thesoutheastern Atlantic, a comparison is made of the two sets offaunas within the framework of the established Austral bio-stratigraphic zonal scheme. A species diversity difference existsbetween the two sites with a greater species number at Site 362 dueto the migration southwards of exotic species which did not reachSite 360. A strong affinity exists between the faunas of Sites 360 and362 and those of southeastern Australia and New Zealand, probablydue to their similar latitudinal positions and to the circum-Antarcticcurrent connection.

INTRODUCTION

For the convenience of this Neogene report on theplanktonic foraminifer faunas of Sites 360 and 362 inthe southeastern Atlantic (Figure 1), the base of theMiocene is taken at the initial appearance ofGloborotalia kugleri Bolli and the upper Mioceneboundary at the initial appearance of Globorotaliamargaritae Bolli and Bermudez.

Both sites yielded excellent faunas, and species fromthe southern Site 360 (lat 3O°51'S, long 18°O5'E) havebeen recorded from the lower Miocene Globigerinawoodi connecta Zone through the lower Pliocene Globo-rotalia puncticulata Zone (Table 1). Similarly, speciesfrom the more northern Site 362 (lat 19°45'S; long10°32'E) have been recorded from selected samplesfrom the lower Miocene Globoquadrina dehiscens Zonethrough to the upper Pleistocene to Recent Globo-rotalia truncatulinoides Zone (Table 2). Thus it ispossible to make a direct comparison of the faunas ofthe two sites for the whole of the Miocene and basalPliocene, and use this information to elucidate theoceanic conditions in the southeastern Atlantic at thistime. A complication is that solution effects at bothsites have effectively reduced species diversity in someindividual samples.

Significant faunal differences existed between the twosites throughout the Miocene, mainly because of thehigher species diversity at the more northern Site 362;only a few species existed at Site 360, apparentlyrestricted to the relatively cooler southern waters (forexample, Globorotalia zealandica Hornibrook in thelower Miocene Globigerinoides trilobus trilobus Zone).Even so, the fauna from Site 362 was never entirelytropical in the Neogene, not only because of the lack ofcertain species (e.g., Globorotalia fohsi robusta Bolli,Pulleniatina obliquiloculata [Parker and Jones], Globi-gerinoides ßstulosus [Schubert], etc.) but also more

30° W 0" 30° E

Figure 1. DSDP Leg 40 Sites 360 and 362.

significantly because of the paucity of certain tropicalspecies even when present (e.g., Globigerinatella insuetaCushman and Stainforth, Sphaeroidinella dehiscens[Parker and Jones], and Globoquadrina tripartita[Koch]). Also, the dominant keeled Globorotalia in themiddle-upper Miocene was the cooler water Globo-rotalia miozea Finlay and thereafter in the Pliocene-Pleistocene, keeled Globorotalia are generally absentexcept for small Globorotalia menardii (d'Orbigny)which was restricted to only the lower part of thePliocene Globorotalia puncticulata Zone. This inter-pretation of a progressive cooling is supported by thelack of known tropical species such as Globorotalia

723

D. G. JENKINS

TABLE 1Planktonic Foraminiferal Neogene Range Chart: Site 360

σ

LEG 40 3SITE 360 „ | .2 2

° n 3 — n u o

§ I I -I 3 o g | J -JS j •=σ•- " o £ T? 2 ° σ ° c ._ » 'ü 3 "α> J <2 £,

i δ , i 111! 11! i] ! l i U H 1111'. 11 j * t i l l if I": 11 H 111S 8 z «j •! 5 o •! o .2 o S i I β o o o .2 1 α .5 .2 .2 .2 1 5 , ] £ .2 ° g o ._= | „ •! .2 .2 .2 .2 o .2 .2

J 5 O > "8 •z S "8 E •S . | £ .£ .£ .5 .£ .£ .£ "ö .£ .5 £ "ö ^ p .E £ .S ^ .£ Tj ~ i ~ £ .E "B "σ "ö £ 15 .£ £ p

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ^ 0 0 0 : 0 : 0 : 0 0 0 0 0 0 0 0 0 0 0

79,5 - 89 1 1 30-32 _(__

cc X89 - 98,5 2 1 87-89 J_ _ J J T=:

ç^ ; ; ; ; ;_ ; ]98,5 - 108 3 3 88-90

__*L_:___: ;______,: : T _ _ T _ _ _ _ _ _ _ _ T _ I _ _ _ _ _ _ _ I : rtrrf:: :ΛI108 - 117,5 4 3 89-91 jc

çç .ZZZZIJ!"" "Z I"~ * T TT~117,5 - 127 5 3 107-109

CC R|c '

127,5 - 136,5 6 3 88-90

çç Z ZZZZZZZZZZZZZZZZZZIZ_ ZZ^ IYLZ136,5 - 146 7 3 109-111

cc ; zzzz_zz_ z _z zrili_; ;i_146 - 155,5 8 3 108-110

155,5 - 165 9 3 86-88

çç ;zzzzz:zr zz^zzzzzzzz:;_; :ZZZZZZIIZ : :t_; ; i i_165 - 174,5 10 3 106-108

ZZç<EZZZZZZZZZ~ ZZZ~ZZZZZZZZZZZIZZZZZI IZZ ZZ174,5 - 184 11 3 59-60

cç_; IZZ ~~ ZZZZZZZZ" ZZZZ |t J I | T" _184 - 193,5 12 3 84-86

çç z z"_zzzzzizzt t |TTΠTI ~ ~193,5 - 203 13 3 88-90

cc " I" I I 1" TTt~T~f " T ~203 - 212,5 14 3 87-89 X I J

212,5 - 222 15 1 81-83 X X ^ X _

CC _ ^

222 - 231,5 16 2 61-63

~ZKZ\ z: zzzzz~ : T _ I , i x_ I _.,it IJI"z_i231,5 - 241 17 1 123-125

:z:zz:::_:; tx z x_: :ZZZZZZZ_XT^: ;_; ML241 - 250,5 18 1 127-129

CC

260 - 269,5 19 4 107-109 T XZ

Ec~t~":zzzzzzx zzzzzzzzz~z:;_; zizzzxt. z h ; t XTT279 - 288,5 20 1 102-104 I :f]

zzzzxz: zzzjzxi-zrzzzz:zE:z: tzizzzzz; t:: TX \\ I ~298 - 307,5 21 3 82-84

cc I ;317 - 326,5 ~22 5~" 61-63 " X T c "

cc ' j " '_[ Z"ZZZZ XZITTi\b(, ZZZZZZZZZZ336 - 345,5 23 3 93-95 | c

ZZZZ 1IIZIZX Z ~ZZZ II__ZZZZZZZZZZZZZZZZZZZ355 - 364,5 24 2 12-14

zzz: ixzxzx til Tzzz xzzzzzzzzztzzzzzzzzzzzzz

374 - 383,5 25 1 86-88_—I 1— — I 1

- O l — -– -JZ393 -402,5 26 _ J _ 136-139 TLf |cfI 1 I cc I I I I I I I I I 1 1 j I I 1 I I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1

724

NEOGENE PLANKTONIC FORAMINIFERS

TABLE 1 - Continuedo

bo

rotα

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per

iphe

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/mα

yeri

tra

ns.

1

o

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1

bul

ina

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o

-

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oro

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m

enar

dii

0

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ige

rin

a ty

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0

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iger

ino

ides

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liquu

s

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1

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iger

ino

ides

sa

ccu

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ige

rin

ella

ae

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late

ral i

s

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11

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ia

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111

1

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a bi

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11

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ü

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icat

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ia

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eros

aO

c

c

c

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c

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leni

atin

a pr

imal

is

£

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bf

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otal

i a

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rm is

O

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otal

ia

cras

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1

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|

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bo

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oro

talia

p

un

ctic

ula

ta

ü

obig

erin

a fa

lcon

ensi

s

O

11

AUSTRAL-NEW ZEALAND

PLANKTONIC

FORAMINIFERAL ZONES

(Jenkins 1966, 1967, 1975)

Globorotalia puncticulata

Globorotalia conomiozea

Globorotalia miotumida

Globorotalia mayeri mayeri

Orbulina suturalis

Praeorbulina glomerosa curva

Globigerinoides trilobus trilobus

Globigerina woodi connecta

Globoquσdrina dehiscens

TROPICAL

PLANKTONIC

FORAMINIFERAL ZONES

(Boll! 1957, 1966, 1973)

Globorotalia margaritae

Neogloboquadrina duterrrei

Globorotalia acostaensis

Globorotalia menardii

Globorotalia mayeri

Globigerinoides ruber

Globorotalia fohsi robusta

Globorotalia fohsi lobata

Globorotalia fohsi fohsi

Globorotalia fohsiperlpheroronda

Praeorbulina glomerosa

Globigerinatella insueta

Globigerinita stainforthito

Globigerinita dissimitis

Globigerinoides primordiusGloborotalia kualeri

Globiaerina ciperoensis cipero.

AGE

L

U

M

L

U

PLIOCENE

MIOCENE

OLIGOCENE

725

D. G. JENKINS

TABLE 2Planktonic Foraminiferal Neogene Range Chart: Site 362

LEG 40SITE 362

DE

PT

H

BE

LOW

SE

A

FL

OO

R

IN

ME

TER

S

36 - 45,5

45,5- 55

55 - 64,5

64,5- 74

74 - 83,5

83,5- 93

93 - 102,5

102,5-112

112 -121,5

121,5-131

131 -140,5

140,5-150

150 -159,5

159,5-169

178,5-188

197,5-207

216,5-226

235,5-245

254,5-264

273,5-283

292,5-302

311,5-321

330,5-340

349,5-359

368,5-378

387,5-397

406,5-415

425,5-435

444,5-454

463,5-173

482,5-492

501,5-511

520,5-530

549 -558,5

577,5-587

596,5 -606

615,5 -625

644 -653,5

672,5 -682

701 -710,5

729,5 -739

758 -767,5

786,5- 796

796 -805,5

Su

1

2

3

4

5

6

7

8

9

10

11

12 1

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

O

5

3

3

3

3

3

3

3

1

3

4

4

4

3

3

3

3

3

3

3

3

3

3

3

3

3

4

5

3

3

2

1

3

3

1

1 i 1 i Io o o o i

58-60

CC

CC

58-60

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58-60

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58-60

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58-60

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58-60

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58-60

CC

58-60

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58-60

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58-60

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CC cf cf

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726


TABLE 2 - Continued

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rota

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tu

mid

σ

1

AUSTRAL-NEW ZEALAND

PLANKTONIC

FORAMINIFERAL ZONES

(Jenkins 1966, 1967, 1975)

Globorotσl ia truncatul inoides

G loborotal ia puncticulata

Globorotσl ia conomiozeo


Orbulina suturalis



Globigerino woodi

Globigerina euσpertura

TROPICAL

PLANKTONIC

FORAMINIFERAL ZONES

(Bolli 1957, 1966, 1973)

Globorotalia truncotulinoides

Globorotalia trunc. cf. tosoensis

Globorotalia miocenica

Globorotalia marga • itae

Globorotalia dutertrei

Globorotalia acostaensis

Globorotalia menardü

Globorotalia moyert -

Globorotalia fohsi robusta

Globorotalia fohji lobato

Globorotalia fohsi fohsi

Globorotalia fohsi peripheroronda

Globigerinatella insueto

Globigerinita stoinfortKi

Globigerinia dissimilis

Globigerinoides primordius

Globorotolia kugleri

Globigerina ciperoemis cip.

AGE

PLEISTOCENE

P

u

M

L

U

M

I

U

EISTOCENE

?PER PLIOCENE

PLIOCENE

MIOCENE

OLIGOCENE

727

D. G. JENKINS

exilis Blow, G. miocenica Palmer, and G. multi-camerata Cushman and Jarvis from the lower to middlePliocene.

An important part of the fauna at both sites was thecontinued presence of Globigerina bulloides d'Orbignyand Globigerina quinqueloba Natland which are bothrestricted to transitional and cooler waters in thepresent day oceans (Be and Toderlund, 1971).

Further in this report the faunas are brieflycompared with the Neogene faunas of New Zealand,Australia, and those recorded on DSDP Leg 29 southof these two countries; the zones established there havebeen used on Leg 40 (Table 3). The forecast that theCenozoic zonal scheme established in the Australianand New Zealand region would be applicable to otherregions of the Southern Hemisphere (Jenkins, 1973)appears to be supported by the results from Leg 40.

COMPARISON OF FAUNASFROM SITES 360 AND 362

Lower Miocene

Diversity: Species diversity at Site 360 is 18 in theGlobigerina woodi connecta Zone and 22 in the Globi-gehnoides trilobus trilobus Zone as compared with 14 inthe Globigerina woodi woodi Zone and 28 in the Globi-gerinoides trilobus trilobus Zone at Site 362.

Faunas: Globorotalia zealandica Hornibrook,present only at Site 360, is possibly the only speciesfound which was restricted to the cooler Austral waters,previously recorded from southeastern Australia(Jenkins, 1960), New Zealand (Jenkins, 1971), and atSites 279 and 281 DSDP Leg 29 south of New Zealandand Australia (Jenkins, 1975).

TABLE 3Planktonic Foraminiferal Zones Showing Zonal Boundary Markers

PLANKTONIC FORAMINIFERAL ZONES

(Jenkins, 1960, 1966, 1967, 1975)

BOUNDARY MARKERS

I = IniHαl appearance, E = Extinction

PLEISTOCENE

PLIOCENE

MIOCENE

9 .0

OLIGOCENE

Globorotalia truncatulinoides

Globorotalia inflata

Globorotalia puncticulata

Globorotalia conomiozea

Globorotalia miotumida


M Orbulina suturalis



Globigerina woodi connecta

Globigerina woodi woodi

Globoquadrina dehiscens

Globigerina euapertura

G. truncatulinoides

G. inflata

G. puncticulata

G. conomiozea

G. mayeri mayeri

G. mayeri mayeri

Orbulina suturalis

P. glomerosa curva

G. trilobus trilobus

G. woodi connecta

G. woodi woodi

G. dehiscens

G. angiporoides

728


Globorotalia kugleri Bolli is restricted to the Globi-gerina woodi connecta Zone at Site 360, but has a longerrange, from the Globigerina woodi woodi Zone into thelower part of the Globigerinoides trilobus trilobus Zoneat Site 362. Globigerinita dissimilis (Cushman andBermudez) became extinct in the Globigerinoidestrilobus trilobus Zone at both sites at a similar level tothat at DSDP Leg 29 Site 279 south of New Zealand,but all these are stratigraphically later than itsextinction in the Globigerina woodi connecta Zone inNew Zealand (Jenkins, 1971).

The following species are present in the Neogeneonly at Site 362 and could be regarded as warmer waterindicators: Cassigerinella chipolensis (Cushman andPonton), Globoquadrina altispira (Cushman and Jarvis),Globigerinoides ruber (d'Orbigny), Globigerinatellainsueta Cushman and Stainforth, and Globigerinoidesmitra Todd. However, the low numbers of specimens ofthese species plus the earlier extinction of Globi-gerinatella insueta in the Globigerinoides trilobustrilobus Zone (compared with its middle Mioceneextinction after the initial appearance of Orbulinasuturalis Bronnimann in Trinidad [Bolli, 1957]) areindications of deteriorating conditions, possiblycooling, which affected Site 362.

The brief appearances of Globigerinatella insueta andGlobigerinoides mitra in the upper part of theGlobigerinoides trilobus trilobus Zone at Site 362 arelinked to Site 360 by the similarly short rangingGlobigerina eamesi Blow which survived a little longerat Site 360 into the Praeorbulina glomerosa curva Zone.

Globoquadrina dehiscens (Chapman, Parr, andCollins) made a much earlier appearance in the Globo-quadrina dehiscens Zone at Site 360 as compared withits appearance in the Globigerina woodi woodi Zone atSite 362. This diachronous spread northwards ofGloboquadrina dehiscens has already been noted in NewZealand and Trinidad (Jenkins, 1973).

In constrast to the New Zealand region, Globorotaliapseudocontinuosa Jenkins became extinct earlier at thetwo sites in the Globigerinoides trilobus trilobus Zone asopposed to its extinction in the middle MioceneOrbulina suturalis Zone.

Biostratigraphic markers: Important markersinclude the initial appearances of Globigerinoidestrilobus trilobus (Reuss), Globorotalia praescitula Blow,and Globorotalia miozea Finlay in the Globigerinoidestrilobus trilobus Zone; the extinction of Globoquadrinatripartita (Koch) also occurs in this zone.

Middle Miocene

Diversity: Species diversity in the three zones at Site360 is 16 in the Praeorbulina glomerosa curva Zone, 24in the Orbulina suturalis Zone, and 28 in theGloborotalia mayeri mayeri Zone, as compared with 18,16, and 26 in these zones at Site 362. The lower diversityin the more northern site in the upper two zones isunexpected, but it may be partly explained in that theOrbulina suturalis Zone appears to be much thinner atSite 362, with a possibility of a hiatus.

Faunas: Warmer water species occur at Site 362which are not present at the more southern Site 360,

and these include Hastigerinella bermudezi Bolli,Globorotalia peripheroacuta Banner and Blow, and G.fohsi lobata Bermudez. Site 360 was south of thesouthern limit of keeled G. fohsi lineage taxa (Jenkins,1965) with only brief incursions of a few keeledspecimens at Site 362.

Globorotalia peripheroronda Banner and Blowappeared earlier in the more northern Site 362 in theGlobigerinoides trilobus trilobus Zone, at a similarstratigraphic level to that recorded in Trinidad (Bolli,1957). By contrast it appeared later in the middleMiocene Praeorbulina glomerosa curva Zone at Site 360,at the same stratigraphic level as in New Zealand(Jenkins, 1967).

Transition populations exist between Globorotaliaperipheroronda and Globorotalia mayeri Cushman andEllisor in the upper Orbulina suturalis Zone and lowerpart of the Globorotalia mayeri Zone. A similartransition has been recorded in southeast Australia andNew Zealand (Jenkins, 1960, 1971), but this transitionwas not detected in the faunas of Site 362.

The comparatively late appearance of Globi-gerinoides obliquus in the lower part of the Globorotaliamiotumida Zone at Site 362 and in the upper part of theGloborotalia mayeri mayeri Zone in Site 360 and ofGlobigerinoides sacculifer only in the Globorotaliamiotumida Zone at Site 362 suggests a possible warmingat this interval with a greater temperature increase atSite 362. This is apparently contradicted by the initialappearance of Globorotalia pachyderma (Ehrenberg) atboth sites in the upper Miocene Globorotalia miotumidaZone, but could be explained by mixing of two watermasses.

Biostratigraphic markers: Of importance are theinitial appearances of taxa of the Orbulina lineage atSite 362 and those of the Globorotalia mayeri lineage atSite 360.

Upper MioceneDiversity: Species diversity in the two sites is not

greatly different with 27 in the Globorotalia miotumidaZone and 32 in the Globorotalia conomiozea Zone atSite 360 compared with 29 and 28 at Site 362. The slightdiversity reduction in the higher zone at Site 362 isunexplained.

Faunas: There is an overlap in the ranges of Globo-rotalia obesa Bolli and Globigerinella aequilateralisCushman at Site 360 in the Globorotalia miotumidaZone which was not recorded at Site 362. Globo-quadrina dehiscens became extinct much earlier at Site360 in the lower part of the Globorotalia miotumidaZone as compared with its extinction in the lower partof Globorotalia conomiozea Zone at Site 362. This isconsistent with the view that Globoquadrina dehiscensbecame extinct earlier in the higher latitudes in theSouthern Hemisphere. Globigerinoides obliquus madeits initial appearance in the uppermost part of theGloborotalia mayeri Zone at Site 360, but only in theupper lower part of the Globorotalia miotumida Zone atSite 362. Globigerinoides sacculifer (Brady) made its lateinitial appearance at both sites in the lower part of theGloborotalia miotumida Zone and Globigerina apertura

729

D. G. JENKINS

Cushman occurred only in the upper part of the Globo-rotalia miotumida Zone at both sites. Globorotaliamargaritae is recorded from the upper part of theGloborotalia conomiozea Zone ranging into the lowerpart of the Globorotalia puncticulata Zone at Site 360but is only recorded in one sample in the Globorotaliapuncticulata Zone at Site 362.

Biostratigraphic markers: The initial appearance ofGloborotalia acostaensis is recorded at both sites in thelower part of the Globorotalia miotumida Zone; theinitial appearance of sinistrally coiled Pulleniatinaprimalis Banner and Blow is recorded in the middle partof the Globorotalia conomiozea Zone at Site 360; andthe initial appearance of Globorotalia crassaformis(Galloway and Wissler) occurs at both sites in theGloborotalia conomiozea Zone.

Pliocene-PleistoceneFaunas: Pulleniatina primalis has a short range in the

upper part of the Globorotalia puncticulata Zone at Site362 but without its descendant species in the Pliocene,whereas at Site 360 it ranged from the upper part of theGloborotalia conomiozea Zone into the lower part of theGloborotalia puncticulata Zone.

One of the significant series of events in the Pliocenewas the extinction of the larger keeled Globorotalia atSite 362, namely G. miozea, G. miotumida Jenkins, andG. menardii (d'Orbigny). Progressive extinctions of taxaoccurred, with both Globigerinoides obliquus Bolli andG. sacculifer (Brady) becoming extinct in the lower partof the Globorotalia inflata Zone at Site 362.

The Pleistocene species in Core 1 of Site 362 isconsistent with the Recent transition fauna recorded byBe and Toderlund (1971).

Biostratigraphic markers: Orbulina bilobata(d'Orbigny) became extinct in the lower part of theGloborotalia puncticulata Zone at both sites and isconsistent with the extinction level recorded by Parker(1967) in the Indo-Pacific. A marked horizon ofextinction occurred in the lower part of the Globorotaliainßata Zone at Site 362 with the extinctions of Globo-rotalia hirsuta (d'Orbigny), G. puncticulata (Deshays),Globigerina apertura .Cushman. Globigerinellaaequilateralis Cushman, Globorotaloides hexagona(Natland), Globigerinoides sacculifer (Brady), andGloboquadrina altispira (Cushman and Jarvis). Such alevel could be explained either by a radical change inthe fauna or a hiatus.

SYSTEM ATICS

Selected species are illustrated to show the interrelationship of thecooler Austral and the warmer water tropical forms. Comments arelimited to a few observations on some important taxa:

Globigerina woodi connecta Jenkins(Plate 1, Figures 1-5)

The subspecies is illustrated to show its morphological affinitywith Globigerina woodi Jenkins (pi. 1, fig. 6, 7) and withGlobigerinoides trilobus (Reuss) (pi. 1, fig. 8, 9) which is regarded asits direct descendant (Jenkins, 1964). Not only is there close similarityof the general test shape of Globigerina woodi connecta andGlobigerinoides trilobus, but it is also true for the wall structure ofboth taxa (pi. 1, fig. 5, 8); specimens of Globigerinoides trilobus weretaken from a stratigraphically low position in the Globigerinoidestrilobus trilobus Zone.

Globorotalia conomiozea Kennett(Plate 2, Figures 15-17)

The illustrated specimens are thick-walled varieties and con-sequently appear slightly different from the holotype; these areprobably deeper water ecophenotypes similar to forms already notedfor other keeled Globorotalia including G. truncatulinoides.

Globorotalia miotumida Jenkins(Plate 2, Figures 6-8)

The type population from southeastern Australia were relativelythin walled (Jenkins, 1960) and since then observations have beenmade linking the species to Globorotalia miozea conoidea Walters(Jenkins, 1971). Specimens (Plate 2, Figures 6-8) have been chosento illustrate the intermediate morphology and should be comparedwith the illustrations of G. miozea conoidea (Plate 2, Figures 12-14).

Globorotalia mayeri mayeri Cushman and Ellisor(Plate 1, Figures 20-22)

Specimens have been chosen from the lowermost sample in theGloborotalia mayeri mayeri Zone to illustrate the close morphologicalaffinity of the subspecies with its immediate ancestor G. periphero-ronda (e.g., recurved sutures).

Globorotalia panda Jenkins(Plate 2, Figures 3-5)

At both sites G. panda is recorded sporadically in the middleMiocene to lower Pliocene (Tables 1, 2). A remarkable case ofhomeomorphy exists between G. panda and Globorotalia margaritaeBolli (Plate 3, Figures 13-15).

Wall structure: (1) The pustular wall ornamentation of Globi-gerinella aequilateralis is illustrated in Plate 3, Figure 7. (2) There is astrong similarity between the wall structures of Globigerinoidesobliquus (Plate 3, Figures 1, 3) and G. sacculifer (Plate 3, Figure 5);small holes exist along the ridges of the hexagons surrounding thepores in both species. (3) The thickening of the wall ornamentationand lip nearly obscures all pores in Globorotaliapachyderma (Plate 1,Figure 13).

CONCLUSIONSFaunas: Neogene planktonic foraminifers from Sites

360 and 362 are similar to the faunas described fromsoutheastern Australia and New Zealand (Jenkins,1960, 1966, 1967) where the dominant Austral faunaswere occasionally invaded by exotic species migratingfrom the northern waters. There is a gradual extinctionof various species in the Pliocene, consistent withestablished evidence of a deterioration in climatetowards the Pleistocene. The lack of some species andscarcity of other tropical stratigraphic markers makes itdifficult to apply some of the tropical zones, but anattempt at correlating the Austral cooler water zoneswith the tropical zones of Bolli (1957 et seq.) has beenundertaken (Tables 1, 2).

Although there are marked contrasts in the faunasfrom the two sites it is nevertheless difficult to detectnorth-south pulsations. What can be detected arepossible warm water invasions followed by cooling atSite 362 causing premature extinctions not seen inknown warm water regions. For example, such anexplanation could apply to the brief appearance ofGlobigerinella insueta and Globigerinoides mitra in theupper part of the Globigerinoides trilobus trilobus Zone.Similarly Sphaeroidinella dehiscens appeared briefly inthe lower Pliocene Globorotalia puncticulata Zone, butthe differences between the two sites are best illustratedby plotting the range of selected taxa at the two sites(Figure 2). This demonstrates the possible interaction

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INTERNATIONALUNITS

NEOGENE PALEOGEOGRAPHIC DISTRIBUTION OF SELECTED SPECIES

ONLY AT SITE360 (Lat. 3051'S)

BOTH360 and 362 ONLY AT SITE 362 (Lat. 19 45'S)

PLEISTOCENE

PLIOCENE

MIOCENE

CD

dCD

CD CD

CDICDI

OCEANICCURRENTS

TRANSITION FAUNAS DUE TO THE

j SUB-TROPICAL FAUNAS DUE TOT I WARMING OF WEST WIND DRIFT

IBENGEULACURRENT

Figure 2. General ranges of selected species to illustrate the possible faunal influences during the Neogene at Sites 360 and362: the Benguela current becoming progressively colder towards the Upper Neogene.

of the transition and subtropical fauna due to theeffects of the cold Benguela current and the warmerwest-wind-drift (see Sverdrup et al, 1942).

The difference in the oceanic regime as comparedwith the Pacific New Zealand region is exemplified bythe changing species diversity in the Neogene. Whereasthe maximum species number was recorded in themiddle Miocene Praeorbulina glomerosa curva Zone inNew Zealand, there was a relative low at both Sites 360and 362 in this zone. However, the maximum numberof species in the Pliocene Globorotalia puncticulataZone at Sites 360 and 362 was reflected in theNew Zealand lower Pliocene species number(Jenkins, 1968).

Zones: The zones established in Australia and NewZealand (Jenkins, 1960, 1966, 1967) and later extendedto the Southern Ocean on DSDP Leg 29 (Jenkins, 1975)are applicable to Leg 40 Sites 360 and 362 where thesame zonal markers were utilized (Table 3). The onlydifficulty experienced in zonal identification was theapparent lack of two zones:

1) The lower Miocene Globigerina woodi woodi Zoneat Site 360 possibly exists in the unsampled sequencebetween core Samples 26-1, 136-139 cm and 26, CC.Alternatively, the zone may be missing because of ahiatus.

2) The Globigerina woodi connecta Zone was notrecognized in the lower Miocene of Site 362 because of

the poor development of the zonal species. It isconcluded that this zone is probably equivalent to theupper part of the Globigerina woodi woodi Zone at Site362 (Table 3).

The Orbulina suturalis Zone recorded in Cores 20 and21 at Site 360 was only identified in one sample (35-3,58-60 cm) at Site 362. This thinning could be explainedby differences in the rates of sedimentation at the twosites, but because Praeorbulina glomerosa glomerosa(Blow), P. glomerosa circularis (Blow), and P.glomerosa circularis (Blow) were not recorded at 362, itis possible that the lower part of the Orbulina suturalisZone is missing because of a hiatus.

ACKNOWLEDGMENTS1 wish to thank Professor H.M. Bolli for the opportunity of

examining the faunas from Sites 360 and 362 and forarranging research facilities at Zurich where the SEM photo-graphs were taken by Mr. H. Franz. Preliminary work on thesamples was undertaken at the University of Canterbury,Christchurch, New Zealand, and later at the UniversityCollege of Wales, Aberystwyth.

REFERENCESBe, A.W.H. and Toderlund, D.S., 1971. Distribution and

ecology of living planktonic foraminifera in surface waterof the Atlantic and Pacific Oceans: Micropaleontology ofoceans: (Eds.), Funnell, B.M. and Riedel, W.R.,(Cambridge Univ. Press), p. 105-149.

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D. G. JENKINS

Bolli, H.M., 1957. Planktonic foraminifera from theOligocene-Miocene Cipero and Lengua formations ofTrinidad B.W.I.: Bull. U.S. Nat. Mus., v. 215, p. 97-123.

Jenkins, D.G., 1960. Planktonic foraminifera from the LakesEntrance oil shaft, Victoria, Australia: Micro-paleontology, v. 6., p. 345-371.

, 1964. A new planktonic foraminiferal subspeciesfrom the Australasian lower Miocene: Micropaleontology,v. 10, p. 72.

, 1 9 6 5 . Planktonic foraminifera and Tertiaryintercontinental correlation: Micropaleontology, v. 11,p. 265-277.

, 1966. Planktonic foraminiferal zones and new taxafrom the Danian to Lower Miocene of New Zealand: NewZealand J. Geol. Geophys., v. 8, p. 1088-1125.

, 1967. Planktonic foraminiferal zones and new taxafrom the Lower Miocene to Pleistocene of New Zealand:New Zealand J. Geol. Geophys. v. 10, p. 1064-1078.

, 1968. Variation in the numbers of species andsubspecies of planktonic foraminifera as an indicator ofNew Zealand Cenozoic paleotemperatures: Paleogeog.,Palaeoclimat., Paleoecol., v. 5., p. 309-313.

, 1971. Cenozoic planktonic foraminifera of NewZealand: New Zealand Geol. Surv. Paleontol., Bull. 42,p. 1-278.

, 1973. The present status and future progress in thestudy of Cenozoic planktonic foraminifera: Rev. Espan.Micropaleontologia, v. 5., p. 133-146.

1975. Cenozoic planktonic foraminiferal bio-stratigraphy of the southwestern Pacific and Tasman Sea,DSDP Leg 29. In Kennett, J.P., Houtz, R.E., et al., InitialReports of the Deep Sea Drilling Project, Volume 29:Washington (U.S. Government Printing Office) p. 449-467.

Parker, F.L., 1967. Late Tertiary biostratigraphy (planktonicforaminifera) of tropical Indo-Pacific deep-sea cores: Am.Paleontol., Bull., v. 52, p. 115-208.

Sverdrup, H.W., Johnson, M.W., and Fleming, R.H., 1942.The oceans, their physics, chemistry and general biology:New York (Prentice Hall), p. 1-1060.

PLATES

Each figure is of a different specimen, unlessotherwise stated. The specimens illustrated on Plates 1-3 are deposited in the Museum of Natural History,Basel, Switzerland, under the numbers C 33321-33369.

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D. G. JENKINS

PLATE 1

Figures 1-5 Globigerina woodi connecta Jenkins; Sample 360-25-1, 80-88 cm; lower Miocene, Globorotalia woodiconnecta Zone.

1. Side view, ×IOO; C 33321.2. Umbilical view, ×IOO; C 33322.3. Spiral view, ×IOO; C 33323.4. Side view, ×IOO; C 33324.5. Wall structure of Figure 4, X1000.

Figures 6, 7 Globigerina woodi Jenkins; Sample 362-36, CC;lower Miocene, Globigerinoides trilobus trilobusZone.

6. Umbilical view, ×IOO; C 33325.7. Wall structure of Figure 6, ×IOOO.

Figures 8, 9 Globigerinoides trilobus (Reuss); Sample 362-37,CC; lower Miocene, Globigerinoides trilobustrilobus Zone.8. Umbilical view, ×IOO; C 33326.9. Wall structure of 8, ×IOOO.

Figures 10-13 Globorotalia pachyderma (Ehrenberg); Sample362-20, CC; upper Miocene, Globorotalia cono-miozea Zone.10. Side view, ×IOO; C 33327.11. Spiral view, ×IOO; C 33328.12. Umbilical view, ×IOO; C 33329.13. Wall structure of 12, ×500.

Figures 14-16 Globorotalia pseudocontinuosa Jenkins; Sample360-25-1, 86-88 cm; lower Miocene, Globigerinawoodi connecta Zone.14. Side view, ×IOO; C 33330.15. Spiral view, ×IOO; C 33331.16. Umbilical view, ×IOO; C 33332.

Figures 17-19 Globorotalia zealandica Hornibrook; Sample 360-23-3, 93-95 cm; lower Miocene Globigerinoidestrilobus trilobus Zone.17. Side view, ×IOO C 33333.18. Umbilical view, ×IOO C 33334.19. Spiral view, ×IOO C 33335.

Figures 20-22 Globorotalia mayeri Cushman and Ellisor; Sample362-34, CC; middle Miocene, Globorotalia mayerimayeri Zone.20. Side view, × 100; C 33336.21. Umbilical view, ×IOO; C 33337.22. Spiral view, ×IOO; C 33338.

Figures 23, 24 Globorotalia semivera (Hornibrook); Sample 360-24, CC; lower Miocene, Globigerinoides trilobustrilobus Zone.23. Side view, × 100; C 33339.24. Umbilical view, ×IOO; C 33340.

734


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PLATE2Figures 1,2 Globorotalia puncticulata (Deshays); Sample 362-

13, CC; lower Pliocene, Globorotalia puncticulataZone.

1. Side view, ×IOO; C 33341.2. Umbilical view, X 100; C 33342.

Figures 3-5 Globorotalia panda Jenkins; Sample 360-17, CC;middle Miocene, Globorotalia mayeri mayeriZone.

3. Side view, × 100; C 33343.4. Umbilical view, ×IOO; C 33344.5. Spiral view, ×IOO; C 33345.

Figures 6-8 Globorotalia miotumida Jenkins; Sample 360-16,CC; middle Miocene, Globorotalia mayeri mayeriZone.

6. Side view, X 100; C 33346.7. Umbilical view, ×IOO; C 33347.8. Spiral view, ×IOO; C 33348.

Figures 9-11 Globorotalia miozea miozea Finlay; Sample 362-36, CC; lower Miocene, Globorotalia trilobustrilobus Zone.9. Side view, ×IOO; C 33349.

10. Umbilical view, ×IOO; C 33350.11. Spiral view, ×IOO; C 33351.

Figures 12-14 Globorotalia miozea conoidea Walters; Sample362-27, CC; upper Miocene, Globorotaliamiotumida Zone.12. Side view, ×IOO; C 33352.13. Umbilical view, ×IOO; C 33353.14. Spiral view, × 100; C 33354.

Figures 15-17 Globorotalia conomiozea Kennett; Sample 360-7,CC; upper Miocene, Globorotalia conomiozeaZone.15. Side view, ×IOO; C 33355.16. Umbilical view, ×IOO; C 33356.17. Spiral view, X100; C 33357.

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PLATE 2

737

D. G. JENKINS

PLATE 3Figures 1-3 Globigerinoides obliquus Bolli; Sample 262-18, CC;

upper Miocene, Globorotalia conomiozea Zone.1. Detail of aperture and wall structure of Figure

2, X250.2. Umbilical view, ×IOO; C 33358.3. Wall structure of Figure 2, ×IOOO.

Figures 4, 5 Globigerinoides sacculifer (Brady); Sample 362-13,CC; lower Pliocene, Globorotalia puncticulataZone.

4. Umbilical view, ×IOO; C 33359.5. Wall structure, ×500.

Figures 6,7 Globigerinella aequilateralis Cushman; Sample360-1, CC; lower Pliocene, Globorotaliapuncticulata Zone.

6. Side view, × 100; C 33360.7. Wall structure of Figure 6, ×750.

Figure 8 Globorotalia menardii (d'Orbigny); Sample 362-18,CC; upper Miocene, Globorotalia conomiozeaZone.Umbilical view, ×40; C 33361.

Figures 9-11 Globorotalia fohsi lobata Bolli; Sample 362-33, CC;middle Miocene, Globorotalia mayeri mayeriZone.

9. Side view, ×IOO; C 33362.10. Umbilical view, ×IOO; C 33363.11. Spiral view, ×IOO; C 33364.

Figure 12 Globigerinatella insueta Cushman and Stainforth;Sample 362-37, CC; lower Miocene, Globi-gerinoides trilobus trilobus Zone.Spiral view of juvenile, ×IOO; C 33365.

Figures 13-15 Globorotalia margaritae Bolli; Sample 362-14, CC;lower Pliocene, Globorotalia puncticulata Zone.13. Umbilical view, ×IOO; C 33366.14. Side view, ×IOO; C 33367.15. Spiral view, ×IOO; C 33368.

Figure 16 Hastigerinella bermudezi Bolli; Sample 362-35,CC; middle Miocene, Praeorbulina glomerosacurva Zone.Spiral view, ×IOO; C 33369.

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PLATE 3

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Deep Sea Drilling Project Initial Reports Volume 40 · been recorded from the lower Miocene...

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