Ocean Drilling Program Scientific Results Volume 135 J., Parson, L., Allan, J., et al., 1994 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 135 13. CALCAREOUS

Hawkins, J., Parson, L., Allan, J., et al., 1994Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 135

13. CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY OF SITES 834-839, LAU BASIN1

Michael J. Styzen2

ABSTRACT

Calcareous nannofossils were examined from six sites drilled within the Lau Basin during Ocean Drilling Program Leg 135.These sites lie in a transect roughly west to east across the basin from the Lau Ridge remnant arc to near the active spreadingcenter. The main objective of the biostratigraphic studies was to date the base of the sedimentary section, immediately overlyingbasement at each site. Material from all these sites yielded calcareous nannofossils. Site 834, which is closest to the Lau Ridge,yielded floras from Holocene to possible late Miocene age. Site 836, furthest from the remnant arc, produced nannofossils ofmiddle Pleistocene age at the base of the sedimentary section. Reworked material was noted from all sites but caused correlationproblems only at Site 835.

One new taxon, Discoaster ono, is described from Pliocene sediments.

INTRODUCTION

Six sites were drilled in the Lau Basin during Ocean DrillingProgram (ODP) Leg 135 (Fig. 1). These sites were located in a roughlywest to east transect across the basin to provide sample material fromthe Lau Ridge remnant arc to near the active axial ridge. The sites areall located in north-trending, partially filled, fault-bounded sub-basins.Sites 834 and 835 lie in sub-basins between 100 and 200 km east ofthe axis of the Lau Ridge. Sites 836,837,838, and 839 lie in sub-basinscloser to the modern backarc spreading system. The purpose of thispart of Leg 135 was to provide information on the history and develop-ment of the Lau backarc basin and, by comparison with similar basins,to provide insights into backarc development in general.

Paleontologic studies were conducted mainly to provide dates for theigneous material at the base of the sedimentary sequence at each site.

CALCAREOUS NANNOFOSSILBIOSTRATIGRAPHY AND GEOCHRONOLOGY

The biostratigraphic scheme used in this study is that of Bukry(1973,1975) and Okada and Bukry (1980). The geochronology (Fig.2) follows mainly that presented in Berggren et al. (1985). Some ofthe dates have been modified after Gartner (1990). Additional datumhorizons that may have some value as correlation points have beenadded. Most of the datums listed in Table 1 are in general use andrequire no explanation. Some, however, are based on operationalconcepts described below.

In this study, Pseudoemiliania lacunosa and Emiliania ovata areconsidered as distinct species. Perch-Nielsen (1985) regards E. ovataas a junior synonym off! lacunosa. Considered phylogenetically, thisis probably the case as within the range of P. lacunosa every interme-diate between the two certainly exists. Nannofossil workers in the oilindustry of North America generally distinguish two morphotypes,especially near the top of their range. In the Gulf of Mexico, the moredelicate circular forms (Plate 1, Figs. 10-11) here called P. lacunosahave a slightly younger extinction than the more robust oval forms(Plate 1, Figs. 8-9), here called E. ovata. This appears also to be thecase in Holes 834A and 836A, therefore the two distinct species areretained here.

Hawkins, J., Parson, L., Allan, J., et al., 1994. Proc. ODP, Sci. Results, 135: CollegeStation, TX (Ocean Drilling Program).

2 Shell Offshore Inc., P.O. Box 61933, New Orleans, LA 70161, U.S.A.

Gartner (1991) encouraged the documentation of the extinction ofScyphosphaera pulcherrima. That extinction, as noted in this study,is slightly above the one of Helicosphaera sellii.

Gephyrocapsa oceanica, as used in this study, refers to thosespecimens that have a maximum diameter larger than 3 µm and possessa low-angle bridge with respect to the short axis (Plate 2, Fig. 9).Gephyrocapsa caribbeanica, as used in this study, refers to those spec-imens larger than 3 µm that have a very high-angle bridge with respectto the short axis (Plate 2, Fig. 10). With this species concept, the initialoccurrence of each of these taxa appear to correspond very well to thoseused by Bukry in the zonal scheme mentioned above. Gartner (1990)and Shyu and Muller (1991) use a datum based on G. oceanica s.L,with a slightly different species concept for that species as describedhere; however, the initial occurrence datums for both appear to besimilar in age. The extinction event falls approximately at the top ofthe Olduvai paleomagnetic event, which approximates the Pliocene/Pleistocene boundary. Using the biostratigraphic framework describedabove, the CN13/CN14 boundary would also approximate that age.

METHODS

Smear slides were prepared for each sample. A small amount ofraw material was placed in a small vial with enough distilled water toproduce a thin slurry. After thorough mixing with a Vortex Genie, asmall drop of the slurry was immediately placed on a clean slide usinga disposable glass capillary tube. The slurry was then spread evenlyusing the side of the capillary tube. The material on the slide wasimmediately dried on a hot plate. A cover glass was then attachedusing Piccolyte as a mounting medium. This method of slide prepa-ration provided a uniform layer of material across the entire slide.

Relative abundances were estimated based on counts recorded ona single traverse consisting of 132 fields of view at 980×, each fieldhas a diameter of 220 µm. Examination of an average slide with a richflora using this technique takes about 45 min. The following abun-dance categories were assigned:

R = rare (1-5 specimens per traverse),S = rare to frequent (6—15 specimens per traverse),F = frequent (16-35 specimens per traverse),M = frequent to common (36-75 specimens per traverse),C = common (76-150 specimens per traverse),L = common to abundant (151-300 specimens per traverse),A = abundant (301-600 specimens per traverse),V = very abundant (601-1000 specimens per traverse),W = very very abundant (1001-2000 specimens per traverse), andX = extra abundant (over 2000 specimens per traverse).

191

MJ. STYZEN

15°S

19'

21'

23C

25C

179°W 177° 175° 173C

Figure 1. Regional setting for Sites 834 through 839 with the locations of other Leg 135 sites and the major geologic features of the TongaTrench and Lau Basin system. Z = Zephyr Shoal; islands include T = Tongatapu, E = 'Eua, V = Vava'u, A = 'Ata, U = Upolu, andNF = Niuafo'ou. The locations of the Central Lau (CLSC) and Eastern Lau (ELSC) spreading centers, Valu Fa Ridge (VF), and MangatoluTriple Junction (MTJ) are shown. The location of DSDP Site 203 is shown as an open box. Contour intervals are in kilometers. (From Parson,Hawkins, Allan, et al., 1992.)

192

CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY

UJ

<

-

-

1 -

;

-•

2 -

:

:--

:3 -

i:-

4 -

RIT

Y

|<

| P

OL

1

•

•r

-

•1

|8

CH

I

iocCD

-

J

<

<

AT

SU

2

O

R

-

I 0

M

L .

ILB

E

(9C

c

Lu

I

UJ

8Oi -coLU

α

IU

IOC

EP

L

- i

UJ

DQ

2

LU

LU

<

—

RLY

<LU

Calcareous Nannoplankton

UJ22ON

C M 5

CN14

CN13

CN12

CN11

CN10

UJ

oSCO

b

a

b

a

d

c

a

b

a

c

LOCATIONOF

BIOSTRATK3RAPHICEVENTS

IE. huxleyi 0.275

L P. lacunosa .465*

^ E. ovafa

— ] f H. sβ/*V1.2r

L C. madntyrβi 1.45

|V G. ocβanica 1.68

|̂ G. caribbeanica 1.74

^ 0. brouwen 1.9

— L D. pentaradiatus 2.29*

^ D. surculuε 2.4

^ D. tema/β 2.6

J~K Sphenolithus attβs3.45*

. ^ ft. psθudoumbilica 3.50. asymmetricus Acme

L A primusA. tricomiculatis

UJσ<

-

-

-

-

1 -

-

--

2 -

-•

-

-

3 -

-

4 -

Figure 2. Chronostratigraphic framework adopted for this study. Source of agesof calcareous nannofossil biohorizons are from Berggren et al. (1985), exceptthose marked with an asterisk (*) are from Gartner (1990).

The results were tabulated on an IBM PS/2 using the Bugin dataentry system.

SUMMARY OF CALCAREOUSNANNOFOSSIL BIOSTRATIGRAPHY

Site 834

Site 834 is located in the western Lau Basin about 100 km east ofthe Lau Ridge in a small north-trending sub-basin (Fig. 1). The sedi-mentary sequence at this site consists of 112.5 m of clayey nannofos-sil oozes, turbiditic foraminiferal sands, and oozes and clayey nanno-fossil mixed sediments. Below 112.5 mbsf, numerous thick basaltflows are interlay ered with thin clay stone tuffs. The sedimentarysequence was divided into three sedimentary units but these units bearlittle relation to the nannofossil biostratigraphy. Most of the sedi-mentary section present at this site was sampled in Hole 834A. Theoldest sediment recovered in this hole is probably early Pliocene orslightly older.

A distribution chart of the calcareous nannofossils recovered fromHole 834A is given in Table 2. Emiliαniα huxleyi was present in onlythe top sample examined, at 2.8 mbsf (Sample 135-834A-1H-1,130-131 cm). Reworking is not evident in this sample. The next datumobserved is the highest occurrence of Pseudoemiliαniα lαcunosα at 9.5mbsf (Sample 135-834A-2H-2, 40-41 cm). This taxon is rare at thisdepth, but the sample bears a well-preserved and abundant nannofossilflora with no evidence of reworking; therefore, the specimens observedwere thought to be in place. This sample also yielded the only speci-mens of Helicosphαerα inversα noted in this hole. The highest ob-served Emiliαniα ovαtα does not occur until the next sample at 22.9mbsf (Sample 135-834A-3H-4, 134-135 cm). Both E. ovαtα and P.lαcunosα are very abundant in this sample. As discussed above, thesetwo species are usually lumped under P. lαcunosα. The distribution andabundance pattern observed here, however, is identical to that observedin the Gulf of Mexico where the two taxa are usually distinguished, atleast informally, at their extinction. If the separation observed hererepresents a widespread occurrence of the temporal separation of theextinction of these two morphotypes, there may be some implicationsas to the relationship of zonal boundaries in the two widely usednannofossil zonations. The tops of Zone NN19 (Martini, 1971) andSubzone CN14a (Okada and Bukry, 1980) are generally representedas being equivalent in age as in Perch-Nielsen (1985). The top of ZoneNN19 is defined as the top of P. lαcunosα with no specified morpho-type. The top of the Gephyrocαpsα oceαnicα Subzone (= CN14a) asdefined by Bukry (1973) is the extinction of E. ovαtα. The fossildistribution as seen here may indicate that the top of Zone NN19 isindeed slightly younger than that of Subzone CN14a.

Table 1. Calcareous nannofossil biohorizons, ages, and depths at Sites 834 through 839.

HOLOHOHOLOHOHOHOLOLOHOHOHOHOHOHOHO

Biohorizons

Helicosphαerα inversαEmiliαniα huxleyiPseudoemiliαniα lαcunosαEmiliαniα ovαtαHelicosphαerα inversαScyphosphαerα pulcherrimαHelicosphαerα selliiCαlcidiscus mαcintyreiGephyrocαpsα oceαnicαGephyrocαpsα cαribbeαnicαDiscoαster brouweriDiscoαster pentαrαdiαtusDiscoαster surculusDiscoαster tαmαlisSphenolithus neoαbiesSphenolithus αbiesReticulofenestrα pseudoumbilicα

Age(Ma)

0.2750.465

1.271.451.681.741.92.29

Hole834A

9.52.89.5

22.92.8

33.226.633.228.533.235.335.340.540.568.074.277.3

Hole835A

0.35

66.5

73.773.7

Hole836A

0.6610.715.3

?20.2

Hole837A

2.9

2.92.92.9

41.752.4

63.1470.180.0

Hole838A

3.589.2

13.213.29.2

29.632.568.153.5

91.791.7

Hole838B

230.4

Hole839A

4.51.49.29.29.2

58.486.8

138.2109.2186.2

Hole839B

256.4

Note: HO = highest occurrence, and LO = lowest occurrence.

193

MJ. STYZEN

Table 2. Distribution chart of calcareous nannofossils. Hole 834A.

Age

Holocene-Pleistocene

Ple

isto

cene

Pli

ocen

e

Zone

CN15

CN14b

CN14a

CN13b

CN12c

CN12a

CN11

Core, section,interval (cm)

135-834A-

1H-2, 13-131

2H-2, 40-41

3H-4, 134-1353H-CC4H-2, 42-43

4H-5, 60-65

4H-6, 120-1245H-2, 125-126

5H-3, 144-1455H-CC6H-3, 10-117H-5, 73-748H-2, 1008H-3, 408H-6, 135-1369H-10, 10

9H-3, 19-20lOH-1,5011H-3, 10812H-1, 10016H-1, 111-112

Cal

cidi

scus

le

ptop

orus

Cer

atol

ithu

s cr

ista

tus

Em

ilia

nia

huxl

eyi

Gep

hyro

caps

a ca

ribb

eani

ca

Gep

hyro

caps

a oce

anka

C R X M L

L S M X

C F MA R F MF C M

A R R

AA S

A FL SA FLCFFL

CLAV RC

Hel

icos

phae

ra h

yali

na

Hel

icos

phae

ra

kam

ptne

ri

Hel

icos

phae

ra p

avim

entu

m

Pon

tosp

haer

a ja

poni

ca

Pon

tosp

haer

a sp

p.

C M F S S

C L M S F

F C R FF V S MR F S R

F A S

F A MM A R F

V FR L S RR L R R

F

RFFCFCs s

Rha

bdos

phae

ra c

lavi

ger

Rha

bdos

phae

ra

styl

ifer

Scap

holi

thus

fos

sili

s

Syra

cosp

haer

a sp

p.

Tho

raco

spha

era

saxe

a fr

.

L A L L M

L S C L F

F A F LL W F VF M R A

M V R A

C X F VC X R V

L W F VR V R AF L R W

RM F R RRR SF R R

SL R F

S SR

Tho

raco

spha

era

saxe

a

Um

bili

cosp

haer

a sp

p.

Cyc

loli

thel

la a

nnul

a

Gep

hyro

caps

a sp

p. (

smal

l)

Cer

atol

ithu

s te

lesm

us

S V F L

F L F X R

S L S XW F XC R X

S A F X

S V C X RW X S

S V F XR A M X

V L X RR A

R F F XS S AS R AF F W

S M WL L X

S F L XR S M L

F S V

Hay

ast

er p

erpl

exus

Hel

icos

phae

ra i

nver

sa

Pon

tosp

haer

a in

dooc

eani

ca

Pse

udoe

mil

iani

a la

cuno

sa

Scyp

hosp

haer

a fr

agm

ent

M R M R R

C V RF W RR M

S W F

M A SX R

S WW RX RLW RA RCC

C RL RS R

RR

Ool

itho

tus

frag

ilis

Em

ilia

nia

ovat

a

Hol

odis

coli

thus

spp

.

Tho

raco

spha

era

spp.

fr.

Cal

cidi

scus

mac

inty

rei

gr.

F

L V F F RL W CC M

C W L

L W LF X F

L X FW SX FACRMF

FF W FS

R

Cer

atol

ithu

s ru

gosu

s

Dis

coas

ter

5-ra

y gr

.

Dis

coas

ter

6-ra

y gr

.

Dis

coas

ter

frag

men

ts g

r.

Dis

coas

ter

pent

arad

iatu

s gr

.

R R R R RR

S

FR

RR

R SF FR FR R

RF

FS F

SR

F F

Note: R = 1-5, S = 6-15, F = 16-35, M = 36-75, C = 76-150, L = 151-300, A = 301-600, V = 601-1000, W = 1001-2000, X = 2001+, B = taxa absent, gr. = grainy, fr. = fragment.

Sample 135-834A-3H-4, 134-135 cm, also has some rare, re-worked specimens of poorly preserved Pliocene discoasters, spheno-liths and small Reticulofenestra.

The highest observed occurrence of Helicosphaera sellii is at 26.6mbsf (Sample 135-834A-3H-CC). This sample also shows signs ofminor Pliocene reworking. Sample 135-834A-4H-2, 42-43 cm (28.5mbsf), contains the lowest observed occurrence of Gephyrocapsaoceanica. This datum is the top of Subzone CN13b, which approxi-mates the Pliocene/Pleistocene boundary. The actual level of this datumis probably between this sample and the next sample examined becausethe flora here does not include Calcidiscus macintyrei, which has itsextinction slightly later than this datum (Fig. 1). At 33.2 mbsf (Sample135-834A-4H-5, 60-65 cm), the highest observed occurrence of C.macintyrei and the lowest observed occurrence of Gephyrocapsacaribbeanica (top of Subzone CN13a) are noted. The highest occur-rence in this hole of Scyphosphaera pulcherrima was also observed inthis sample; however as it occurs above H. sellii in other holes includedin this study, this occurrence is probably below its point of extinction.A sample from 35.3 mbsf (135-834A-4H-6,120-124 cm) yielded thehighest observed specimens of Discoaster brouweri and D. pentara-diatus. The true extinctions of these two species define the top and baseof Subzone CN12d, respectively. It is assumed that sediment depositedduring that subzone lies between this level and the level of the sampleexamined immediately above at 33.2 mbsf. The single Reticulofenestrapseudoumbilica noted for this sample was assumed to be reworked. Asample at 38.9 mbsf (135-834A-5H-2,125-126 cm) contains a similarflora, but also includes single, poorly preserved, grainy specimens ofDiscoaster surculus and D. tamalis. These specimens are probablyreworked. Sample 135-834A-5H-3, 144 cm (40.5 mbsf) has a well-preserved and abundant flora, including common to abundant D.surculus and frequent D. tamalis. The presence of D. tamalis indicatesdeposition in Subzone CN12a. Subzone CN12b, which is defined onthe presence of D. surculus without D. tamalis, if it is indeed presentin this hole, would have to occupy a very short section between 38.9and 40.5 mbsf. It is possible that Subzone CN12b is missing at this site.The remaining datums present in this hole are the highest observedSphenolithus neoabies at 68.0 mbsf (Sample 135-834A-8H-3,40 cm),the highest observed Sphenolithus abies at 74 mbsf (Sample 135-

834A-9H-1, 10 cm), and the highest observed Reticulofenestra pseudo-umbilica at 77.3 mbsf (Sample 135-834A-9H-3, 19-20 cm). Samplesexamined from this sequence contain no obvious reworking. Thehighest occurrence of R. pseudoumbilica defines the top of ZoneCN11. The remaining continuous sedimentary section to the first basaltappears to have been deposited in this zone. Amaurolithus delicatus,present in two samples in this section, may indicate an age as old asZone CN10. Rui Amaurolithus tricorniculatus, the zonal marker indi-cating the top of that zone, was not observed in this hole.

Cycloperfolithus carlae, which previously has been reported onlyfrom Miocene sediments (Perch-Nielsen, 1985), is present consis-tently below 40.5 mbsf.

A sample from sediment interbedded with basalt at 133 mbsf(Sample 135-834A-16X-1, 111-112 cm) contains a moderately pre-served, low-diversity flora with taxa characteristic of Zone CN11.

Hole 834B yielded a sample of sediment interbedded with basaltat 312 mbsf (Sample 135-834B-37R-2, 106-107 cm) that appears tobe the oldest material recovered in the Lau Basin sites. The flora inthis sample is abundant but unfortunately is poorly preserved. Thedominant taxa in this flora are Dictyococcites productus, Spheno-lithus moriformis, and Dictyococcites perplexa. An extensive searchof slides prepared shipboard failed to relocate a single specimen ofTriquetrorhabdulus rugosus that was identified for the Initial Reports(Parson, Hawkins, Allan, et al., 1992). It was on the basis of thepresence of that taxon that this sample was assigned a late Mioceneage in that volume. The flora present contains relatively abundantDictyococcites and Reticulofenestra and lacks small Gephyrocapsa.Although it is devoid of any other important marker species, this florais typical of Miocene assemblages. Discoaster deflandrei and Cycli-cargolithus floridanus, identified from this sample, are probably re-worked. Table 3 is a distribution chart for this sample.

Site 835

Site 835 is located in the west central Lau Basin, approximately200 km east of the remnant arc of the Lau Ridge, and about 80 kmwest of the Central Lau Spreading Center (Figure 1). The sedimentarysequence recovered at this site consists of 155 m of clayey nannofossil

194


Table 2 (continued).

R R RR RR

LCAFL F

M FX LV CA LA R F S

11

R F

M L R S

F C S FR S L R

S A RM R

R C S SS

S RR R

RR

FR SR FS S R

a l l

S L S F CR V L F S

L W V V RS C A A RS A V V RR F L C

L CMM

F FR SR FS

F RF

F C L

F M C FS M A CS L A V RR A L V

F L M

11!Si a S

R RR R R S

S RR

R F RR R

R

S RCA S

R MF

δ δ ù δ S

R R

S L FM R

F F L RM S SF S FS R

R S S RR M F S

S RR M F R

F LF AF R

S RR R RR S R

SRR

R S SS RS R R RS R

ti? Q

FS R

R RS C R

R LC AR A

VL F

R RRS SF S

II

R L

Table 3. Distribution chart of calcareous nannofossils, Hole 834B.

Age

late Miocene ?

ZoneCore, section,interval (cm)

135-834B-

37R-2, 106-107

5

epto

p,se

n?

cidi

Cal

C

...

naci

nivi

<li

Cal

S

husf

l.C

y,

R

1

33

01

Die

A

ctu

sis

pro

iu

%

tyoi

Die

W

-ray

g:

δ

R

're,

δ

R

ICO

!

S

?

ill/

ir

Q

Ret

)

C

'.ra

st)

a

-s

lR

3

com

p

-5

SpA

V

mis

mor

ijen

oS

ph

A

'O.π

Syn

R

:osp

Um

M

β

1α

thel

,

R

Note: Key as in Table 2.

oozes, mud clast conglomerates, turbiditic foraminiferal sands, andclayey nannofossil mixed sediments. These sediments are often inter-bedded with epiclastic and volcanic silt layers, especially below 130mbsf. The sedimentary sequence was divided into two lithologicunits, but these units have no relation to nannofossil biostratigraphy.

Sediments recovered from Hole 835A generally contain well-preserved and abundant calcareous nannofossils, but extensive re-working throughout the section severely limits the biostratigraphicdeterminations possible. Table 4 is a distribution chart for Hole 835 A.

A sample at 0.35 mbsf (135-835A-1H-1, 35-37 cm) yielded anabundant and well-preserved flora, including E. huxleyi. This indi-cates deposition during Subzone CN15. This sample has no sign ofreworking. Samples examined from the section between Samples135-835A-2H-4, 37-38 cm (15.4 mbsf), and 135-835A-8H-5, 120-121 cm (73.7 mbsf), contain floras that indicate deposition in ZoneCN14. All the samples in this interval contain reworked Pliocenefloras. A section including parts of Cores 135-835A-7H and -8Hyielded samples with no apparent in-place Pleistocene taxa at all. Thismay be interpreted a rafted block or a thick turbidite unit sampled inthose cores. For a more extensive discussion and interpretation ofreworking at this site see Roth well et al. (this volume). The highestobserved S. pulcherrima at 66.5 mbsf (Sample 135-835A-7H-7, 55cm) is probably meaningless as it is in a sample with no positivelyidentified in-place flora. With a single exception, the rest of thesamples examined to basement contain floras from Zone CN12 or

younger. A sample collected from a mud clast at 124.5 mbsf (135-835A-14H-1, 100 cm) yielded a flora with S. abies, S. neoabies, andR. pseudoumbilica. This shows that material at least as old as ZoneCN11 is available in the vicinity. No other age determinations werepossible at this site.

Site 836

Site 836 is located about 220 km west of the Lau Ridge and about48 km east of the Eastern Lau Spreading Center. This site is locatedclosest to the active spreading center, and consequently the short (23m) sedimentary sequence overlies the youngest crustal material en-countered. The sedimentary sequence comprises a single unit consist-ing of clayey nannofossil ooze with vitric silt, and clayey vitric mixedsediments. Volcaniclastic material increases down section. Calcare-ous nannofossils are present, abundant, and generally well-preservedthroughout the section. The oldest sediment recovered at this site isearly Pleistocene in age.

Table 5 is a distribution chart of calcareous nannofossils observedin Hole 836A. A sample at 0.66 mbsf (135-836A-1H-1, 66-67 cm)contains an assemblage that includes E. huxleyi. This indicates thatHolocene sediment (Zone CN15) is present at this depth. Two samplesexamined between this Holocene material and the next datum containneither E. huxleyi nor E. ovata; that section, therefore, is assigned toSubzone CN14b. The highest observed occurrence of P. lacunosa wasat 10.7 mbsf (Sample 135-836A-2H-CC). The highest observed oc-currence of E. ovata was at 15.3 mbsf (Sample 135-836A-3H-4,10-11 cm). This stratigraphic relationship of these two taxa is similarto that observed in Hole 834A. The remaining possible datum fromthis hole is the highest observed H. sellii. Only a single specimen ofthis taxon was identified from Sample 135-836A-3H-CC (20.2 mbsf),but this sample also contains Pliocene reworked material so thisdatum is questionable. In any case, no in-place flora older than Sub-zone CN14A was identified at this site.

Site 837

Site 837 is located in the central Lau Basin about 160 km east ofthe Lau Ridge remnant arc and approximately 69 km west of the axial

195

MJ. STYZEN

Table 4. Distribution chart of calcareous nannofossils, Hole 835A.

Age


<u

so.2E

c ^

" o

a. £

c

i

Me

<u

0

CU

Zone

CN15

CN14

CN12

CN12

CN11

CN12


135-835A-

1H-1,35-37

2H-4, 37-383H-7, 18-194H-5, 52-535H-7, 10-116H-3, 306H-4, 606H-5, 306H-6, 606H-6, 906H-6, 1207H-1, 307H-2, 407H-3, 707H-4, 907H-5, 60

7H-6, 907H-7, 558H-2, 548H-2, 1008H-2, 120-121

8H-2, 1448H-2, 1458H-3, 588H-5, 120

9H-5, 70-7110H-5,41-4211H-5, 88-8912H-3, 72-7313H-4, 125-126

14H-1, 100-101

14H-7, 3115H-5, 140-14116H-4, 129-13018X-1, 1-2

top

oru

sle

p:i

dis

cus

L

MCLRC

cLLLAAALCC

LLLCM

LLCL

CALLC

C

LMC

c

ista

tus

• ;

ito

lith

us

Cen

S

RRS

R

R

SS

sR

R

R

R

S

R

F

R

'esm

us

a

R

R

R

men

ts

2

'oa

ster

f

δ

R

WMX

A

RL

FSC

MC

wAC

ccF

CMVV

cA

WAVW

•yi

"2

lia

nia

hi

1X

|

a

hyr

oca

pG

ep

M

FRRR

F

AS

S

s

MFFM

ocea

nic

ah

yroc

ap

Gep

C

MFSCMLR

ACR

S

MFFF

hya

lin

aco

sph

ae

Hel

l

C

RFMLSFMFMSFF

FR

RR

CMMF

SFR

R

ka

mpt

ner

i

1C

MSCRCMLLAALLCCC

LCLLF

LLML

LALCF

F

ARS

caK

|

g3-c

|

M

R

S

R

(spp

.

.3

•>

disc

olit

1R

R

R

R

RRR

R

nd

ooce

an

ic

53

tosp

hae

)P

on

R

apo

nic

a

?'

tosp

hae)

Pon

S

RR

ipp.

tosp

hae)

Pon

R

RR

FFR

RSS

RR

SRRS

FRSF

SS

ss

ss

a la

cun

osa

S

idoe

mil

i

R

VCVRLLXWX

wV

wwVV

V

wX

wA

V

wLw

AW

wwA

A

WV

cV

i cl

avi

ger

h

bdos

pha

Rha

L

RFSRCSLAFMMACC

cFFF

S

cccA

FLFFF

S

SR

F

i st

ylif

erbd

osph

aR

ha

L

MFSRMFLAVVCAALA

VVVLF

AACA

AWLLC

M

V

R

::

Sea

,

C

RFFFRR

SS

sF

FRR

SFRS

CΛ

F

RR

R

frag

men

t

R

F

RRFRR

FRR

S

RRF

SRSF

SRFRR

R

S

dd

s

TO

|

1

Syre

L

FMC

sV

cLAVAAALCL

ALAAC

C

ccL

LAALM

F

AMFF

a sa

xea

>

raco

sph

Tho

C

s

ss

RR

R

S

rag

ith

otu

s f

Ool

R

FS

MFFS

cMMMFSS

MF

SF

FFFM

FFFRF

A

SRS

ra s

pp

.

g.

Um

,

L

C

SALALLVAALLA

AAVFF

LACL

LVAAC

V

V

sF

loli

thel

hC

yc

M

MRF

FFMSRFMS

SR

SRALF

FFF

CΛ

ssFFF

A

FFSM

spp.

(sm

all

1

Gep

W

wwXVXXXXXXXXXX

XXXX

wXXXX

XXXX

wA

X

wVA

rift zone of the Eastern Lau Spreading center (Fig. 1). The sedimen-tary sequence recovered at this site consists of 84 m of clayey nanno-fossil oozes and volcaniclastic turbidites. The sequence is subdividedinto two lithologic units that have no relationship to biostratigraphicsubdivisions. The oldest sediment recovered at this site is late Plio-cene in age. Calcareous nannofossils are generally abundant and wellpreserved, but both preservation and abundance decrease downhole.Reworking of Pliocene taxa in Pleistocene turbidites is present butnot to the extent of the reworking at Site 835.

Table 6 is a distribution chart of calcareous nannofossils recoveredin Hole 837A. The flora from a sample from 2.9 mbsf (Sample135-837A-1H-2, 104-105 cm) contains P. lacunosa, E. ovata, andHelicosphaera inversa. This sample is assigned to Subzone CN14a.The next two datums encountered in this hole also lie within SubzoneCN14a. They are the highest observed S. pulcherrima at 41.7 mbsf(Sample 135-837A-5H-4, 123-124 cm) and the highest observed H.sellii at 52.4 mbsf (Sample 135-837A-6H-5, 38-39 cm). The singlespecimen of//, sellii identified from Sample 135-837A-1H-CC wasconsidered reworked as rich floras immediately below do not containindividuals of that taxon. The extinction of C. macintyrei, which alsofalls in Subzone CN14A, is not picked in this hole as rare individualsoccur sporadically throughout the upper part of this hole associatedwith rare reworked discoasters. C. macintyrei does not occur consis-tently in this hole until within the Pliocene section. The lowest observedoccurrence of G. oceanica is at 63.14 mbsf (Sample 135-837A-7H-6,14-15 cm). That of G. caribbeanica is in Sample 135-837A-8H-4,109-110 cm (70.1 mbsf). The section with floras containing G. carib-beanica but not G. oceanica represents deposition in Subzone CN13b.Rare D. brouweri occur in reworked floras throughout the section, butthe abundance of that taxon greatly increases in Sample 135-837A-9H-

4, 99-100 cm (80 mbsf). The datum based on the highest occurrenceof D. brouweri (top Subzone CN12a) is placed at this depth.

Site 838

Site 838 is located in the central Lau basin about 87 km west ofthe Central Lau Spreading Center and approximately 125 km east ofthe axis of the Lau Ridge remnant arc (Fig. 1). The sedimentarysequence penetrated at this site is 103.2 m thick. Sediments weredivided into three lithologic units. Unit I, which includes sedimentsto 23.4 mbsf, consists of clayey nannofossil oozes and thin interbed-ded volcaniclastic turbidites. Recovery was good in this unit, and thelithology was conducive to nannofossil preservation. Floras recov-ered from Unit I are abundant and well preserved. Unit II is anupward-fining sequence with coarse volcaniclastic gravels at its baseand vitric silts with interbedded clayey nannofossil oozes at the top.This unit extends from the base of Unit I to 98.7 mbsf. The upper partof this unit yielded good nannofossil floras. Most lithologies in thelower part of this unit, however, are too coarse to be conducive to theaccumulation and preservation of calcareous nannofossils so thefloras recovered from them tend to be spotty, concentrated in what-ever thin, fine-grained layers are present. Unit III (98.7-259.2 mbsf)had spotty, very poor recovery. Sediments from this unit, whichinclude pumiceous volcanic gravel, volcanic conglomerate, vitricsandstone, and vitric clayey siltstone, sometimes yielded excellent,well-preserved floras; however, the record is very discontinuous.Given the lithology and the poor recovery, one should consider anybiostratigraphic determinations below Core 135-838A-7H to be spotinformation rather than part of a recognizable sequence. The oldestsediments encountered at this site are late Pliocene in age.

L96



6 1

Q Q

C F F F AR R R

M S R A

SC

c sFMSS

R

LRRLRLL

R A

R

FFF SS R SS RS SSS R S

R MM CM F M AF F F R CR S S M

C C F R L

F R S LR R S R CF F F R LS C

1 8

δ δ

W C R R AF R R R L

W M F V

MCVww

R VR V

WM WF VF W

V C SC MC M R RC S RL RM SR

C R R RF

A M F RL R SC F F R

A A F R V

V R RM F RA M M F

a- Hj Se Q

LS FL R R R

FSF

R S SR F F

F FF S F

F FR R FR R RS S

RAFFR S

SF

S

RRS SR

R

R

F R SFL R S RA R R SC S R

A S F R S

C R S RAA R RAS R

R R RR

F RR RS RR RR R RFS RS RF

FR

F SS SS

F L

F RFF RF

RR

S R

R R

R S

F W R

δ co

R R

S M

R SF R R

L

R R R

S R

R R

R R

Table 7 is a distribution chart of calcareous nannofossils recoveredfrom Hole 838A. Floras in samples at 3.58 mbsf (135-838A-1H-3,58-59 cm) and 9.2 mbsf (135-838A-2H-4, 98-99 cm) contain E.huxleyi and H. inversa; these samples are assigned to Zone CN15.Sample 135-838A-2H-CC (13.2 mbsf) yielded a flora that includedextra abundant E. ovata and P. lacunosa; this is the highest observedoccurrence of each of these species. The same sample included thelowest observed occurrence of H. inversa, which was common toabundant. Material in this sample was deposited in the late part ofSubzone CN14a. The next datum encountered is the highest observedoccurrence of S. pulcherrima in Sample 135-838A-4H-5, 93-94 cm(29.6 mbsf). The highest observed H. sellii is at 32 mbsf (Sample135-838A-5H-1, 35-36 cm). The single, poorly preserved C. macin-tyrei in this sample appeared to be reworked. Both of these datumsfall within Subzone CN14a. The lowest observed specimens of G.oceanica and G. caribbeanica occur in samples from Core 135-838A-7H, immediately overlying a section of coarse-grained sedimentbarren of nannofossils. This sample does not contain C. macintyrei,which should be present in the basal part of Zone CN14. The materialrecovered from Core 135-838A-8H, below the barren section, con-tains C. macintyrei but not G. oceanica, G. caribbeanica, or D.brouweri. This indicates deposition in Subzone CN13a. This series ofassemblages indicates that nannofossils from the lowest part of ZoneCN14 and all of Subzone CN13b were not recovered in this hole. Thehighest observed occurrences of D. brouweri and D. pentaradiatusare in Sample 135-838A-11H-2, 102-103 cm (91.7 mbsf). The as-semblage in this sample indicates deposition in Subzone CN12c.Sparse floras in samples from the remainder of Hole 838A have nospecies, indicating deposition earlier than Subzone CN12c.

Table 8 is a distribution chart of nannofossils recovered in samplesfrom Hole 83 8B. Recovery was generally poor from Hole 83 8B. Allof the samples examined are from short sections or core-catcher sam-ples. Floras are, however, generally quite well preserved and range fromsparse to fair in abundance. Sample 135-838B-9R-CC (220.6 mbsf)yielded a rather sparse, poorly preserved flora including grainy, poorlypreserved D. surculus, which may indicate deposition as old as Sub-zone CN12b. The first sample yielding a really definitive flora, how-ever, is Sample 135-838B-11R-1, 20-21 cm (230.4 mbsf). This floraincludes Discoaster tamalis, which indicate deposition as old as Sub-zone CN12a. Rare Sphenolithus spp., which are present in this samplebut not in any lower samples, are thought to be reworked. The remain-ing samples examined in this hole to Sample 135-838B-13R-CCcontain similar floras, which indicate deposition in this same subzone.

Site 839

Site 839 is in the central Lau Basin about 70 km west of the EasternLau Spreading Center and approximately 225 km east of the LauRidge remnant arc (Fig. 1). Sediments collected at this site consist ofclayey nannofossil ooze, turbiditic glassy sands and silts, pumiceousvolcaniclastic gravels, and rare pyroclastic air-fall ashes. The sedi-mentary sequence is divided into three lithologic subunits that haveno relation to biostratigraphic subdivisions. The oldest sedimentencountered at this site is late Pliocene in age. The ages reported forthis site, especially the position of the Pliocene/Pleistocene boundaryin the present study, represent the only major departure from thebiostratigraphic determinations as reported in the Leg 135 Initial Re-ports volume (Parson, Hawkins, Allan, et al., 1992).

197

MJ. STYZEN


Age


e_ g

CN15

CN14

CN12

CN12

CN12


135-835A-

1H-1,35-37

2H-4, 37-383H-7, 18-194H-5, 52-535H-7, 10-116H-3, 306H-4, 606H-5, 306H-6, 606H-6, 906H-6, 1207H-1.307H-2, 407H-3, 707H-4, 907H-5, 60

7H-6, 907H-7, 558H-2, 548H-2, 1008H-2, 120

8H-2, 1448H-2, 1458H-3, 588H-5, 120

9H-5, 7010H-5, 4111H-5, 8812H-3, 7213H-4, 125

14H-1, 100

14H-7, 3115H-5, 14016H-4, 12918X-1, 1

•ë J

L W R F C

R M M

ft =§ s

ü Q

R S

S S



AgeCore, section,interval (cm) •= a. ts. Λ

i. * ^

a, a, a. asJ §• I: I: Sat to to to to

^> a, s3 § -

K S O ö o

I I I 18 i I i l • S•

8 -§as &

PleistoceneCN15

135-836A-

1H-1, 66-67 C A F F R X F A F M L S F F C W L R S W F L F V S

CN14b2H-6, 302H-6, 1202H-CC

R C RL S RA R

M X A FL X F FM X L S

A RLC

M MF FC F

A C S VL M R AA C R S V

C M C A SR M M A F

F L V F

X R SX R R FX R R F

ML R R

3H-4, 10-113H-CC4H-CC6X-CC7X-CC

A SS V F C

L M SF V R FR F

R RS C F

M Mc s

M FLM FACF S AC L FL

R F S M RR L C A S

R A SR S R

RF FSS F

S L R LF M A R AM S A AC S A R A

R S


Table 9 is a distribution chart for Hole 839A. The shallowestsample examined from this site was one at 1.4 mbsf (Sample 135-839A-1H-1, 139-140 cm); this sample contained E. huxleyi and wasassigned to Zone CN15. Sample 135-839A-1H-CC (4.5 mbsf) con-tained a rich flora that did not include E. huxleyi, P. lacunosa, or E.ovata. On this basis, the sample was assigned to Subzone CN14b. Thesample did include the highest observed occurrence of H. inversa.The highest observed occurrence off! lacunosa and E. ovata plus thelowest observed occurrence of//, inversa was in Sample 135-839A-

2H-4,120-121 cm (9.2 mbsf). This sample was assigned to SubzoneCN14a. Two more datums from within that same subzone, the highestobserved occurrences of S. pulcherrima and H. sellii, occur at 58.4mbsf (Sample 135-839A-7H-5, 44-45 cm) and 86.8 mbsf (Sample135-839A-10H-5, 31-32 cm), respectively. Some minor reworkingof Pliocene taxa also occurred in this part of the sequence. The lowestobserved G. oceanica at this site occurred in the core-catcher samplefrom Core 135-839A-12X (109.2 mbsf), which overlies a section ofpoor recovery extending to Core 135-839A-15X. The flora in this

198


sample also did not include C. macintyrei, which would probably bepresent in sediments from near the initial occurrence of G. oceanica.The datum associated with this lowest occurrence, the top of ZoneCN13, which approximates the Pliocene/Pleistocene boundary, couldlie anywhere in this interval. Below Core 135-839A-12X recoverywas very poor; therefore, as in the lower part of the section at Site838, age assignments below this point must be regarded as spotdeterminations. Sample 135-839A-15X-CC (138.2 mbsf) yielded aflora including C. macintyrei and G. caribbeanica. This sample wasassigned to Subzone CN13b. The flora in Sample 135-839A-20X-CC(186.2 mbsf) is the lowest sample containing G. caribbeanica. Florasrecovered from below this point contain no further determinate nanno-fossils and were assigned to Subzone CN13b.

Table 10 is a chart of nannofossil taxa encountered in Sample135-839B-17R-CC. This sample, which is from a thin lamina of sedi-ment between basalt flows at 256.4 mbsf, contains a flora that includesrare D. brouweri. This sample is probably from Subzone CN12d.

SUMMARY AND CONCLUSIONS

Sediments recovered at the Lau Basin sites drilled during Leg 135generally yielded well-preserved nannofossil floras. The main interestin biostratigraphic studies at these sites was to provide dates for thedeposition of sediments immediately above basalts penetrated at fiveof the six sites. As expected, the age of these sediments increases awayfrom the Central Lau Spreading Center and toward the Lau Ridge rem-nant arc. Age determinations for these basal sediments is unchangedfrom those presented in Parson, Hawkins, Allan, et al. (1992).

The sequence of nannofossil biostratigraphic events is as presentedin Table 1. Of particular interest among these events are the extinctionpoints of E.ovata, P. lacunosa, H. inversa, and S. pulcherrima. Extinc-tion points, although generally considered less reliable datums thaninitial evolutionary occurrences, are of vital importance to paleontolo-gists in the oil industry who work almost exclusively with drill cuttingsrather than cores. The highest observed specimens E. ovata in Holes834A and 836A occur above the highest observed specimens of P.lacunosa. This is similar to the pattern of extinctions for these taxa inthe Gulf of Mexico, where I am usually employed. Although thesespecies are generally lumped for sound biological reasons, perhaps aseparation of the two is warranted for operational purposes. Theextinction of H. inversa in Hole 838A falls above the base of ZoneCN15; if this situation is widespread, it could possibly provide a usefuldatum for subdivision of that zone. In this study, the ranges of H.inversa and E. ovata sometimes overlap. This overlap was not reportedby Shyu and Muller (1991). This may imply that the initial occurrenceof//, inversa is within the very top part of Subzone CN14a but that theoverlap of ranges may be small enough to require fortuitous samplingto pick it up. Gartner (1991) encouraged documentation of the extinc-tion of S. pulcherrima. In three of the six sites, this datum falls withinSubzone CN14a above the highest observed H. sellii.

Systematic Paleontology

Kingdom PLANTAEDivision CHRYSOPHYTA

Class COCCOLITHOPHYCEAE Rothmaler, 1951Order DISCOASTERACEAE Tan, 1927Family DISCOASTERACEAE Tan, 1927

Genus DISCOASTER Tan, 1927Discoaster ono n. sp.(Plate l,Figs. 1-4)

Description. Asterolith minute (1.5-4 µm) and symmetric with five bluntlypointed rays with the free length one half or less than the diameter of the centralarea. The central area is usually unornamented, but a slight knob is sometimespresent. Between crossed nicols, the asterolith shows birefringence similar tothat of Discoaster pentaradiatus.

Remarks. Discoaster ono is distinguished from D. pentaradiatus by itsmuch smaller size and shorter bluntly pointed, nonbifurcated rays.

Holotype. The specimen illustrated in Plate 1, Figures 1-2, is designatedas the holotype. This specimen, from Sample 135-834A-8H-2, 100 cm, dis-plays typical development of rays and central area.

Paratype. The specimen illustrated in Plate 1, Figures 3-4, is a designatedparatype. This specimen, from Sample 135-838B-13R-CC, shows atypicallywell-developed rays and central area ornament.

Type level, late Pliocene, Zone CN12.Type locality. Lau Basin Holes 834A and 838B. Similar specimens are

present in Pliocene sediments in the Gulf of Mexico (MJ. Styzen, unpubl. data).Epithet. For many years, this species has had the designation "Discoaster

6" in the Shell Offshore Inc. nannofossil dictionary. It was suggested in thepost-cruise meeting that the designation be retained but in a local language.The word "ono" is "six" in both Tongan and Fijian.

Discoaster sp. A(Plate l,Fig. 5)

Remarks. This medium-sized (5-10 µm) discoaster possesses six non-tapering rays of moderate length that terminate bluntly or with a slight notch.The central area is small and unornamented. The asterolith appears to be flatwithout the umbrella-shaped curvature seen in D. brouweri.

ACKNOWLEDGMENTS

I would like to thank Shell Offshore Inc. for supporting thisresearch. Many individuals helped my participation in this project.Each knows what he or she contributed. They are Mary Berthonnaud,Anne Hill, Ralph Kerr, Brenda Melder, Ed Picou, and all the past andpresent members of the Shell Offshore Paleo staff. Thanks to all of you.I would also like to thank my reviewers Tony D'Agostino, JohannaResig, and Steve Root for making this a better paper. Special thanksalso to my mentors Lauralee Reugger and Peter Webb. Finally, thanksto my family, Renee, Andrea, and Valerie, for patience in my absence.

REFERENCES*

Berggren, W.A., Kent, D.V., and Van Couvering, J.A., 1985. The Neogene:Part 2. Neogene geochronology and chronostratigraphy. In Snelling, NJ.(Ed.), The Chronology of the Geological Record. Geol. Soc. LondonMem., 10:211-260.

Bukry, D., 1973. Low-latitude coccolith biostratigraphic zonation. In Edgar,N.T., Saunders, J.B., et al., Init. Repts. DSDP, 15: Washington (U.S. Govt.Printing Office), 685-703.

, 1975. Coccolith and silicoflagellate stratigraphy, northwestern PacificOcean, Deep Sea Drilling Project Leg 32. In Larson, R.L., Moberly, R., et al.,Init. Repts. DSDP, 32: Washington (U.S. Govt. Printing Office), 677-701.

Gartner, S., 1990. Neogene calcareous nannofossil biostratigraphy, Leg 116(Central Indian Ocean). In Cochran, I.R., Stow, D.A.V., et al., Proc. ODP,Sci. Results, 116: College Station, TX (Ocean Drilling Program), 165-187.

, 1991. A note on Gephyrocapsa caribbeanica and amphora-shapedScyphosphaera. INANewsl, 13:103-104.

Martini, E., 1971. Standard Tertiary and Quaternary calcareous nannoplanktonzonation. In Farinacci, A. (Ed.), Proc. 2nd Int. Conf. Planktonic Microfos-sils Roma: Rome (Ed. Tecnosci.), 2:739-785.

Okada, H., and Bukry, D., 1980. Supplementary modification and introductionof code numbers to the low-latitude coccolith biostratigraphic zonation(Bukry, 1973; 1975). Mar. Micropaleontol, 5:321-325.

Parson, L., Hawkins, J., Allan, J., et al., 1992. Proc. ODP, Init. Repts., 135:College Station, TX (Ocean Drilling Program).

Perch-Nielsen, K., 1985. Cenozoic calcareous nannofossils. In Bolli, H.M.,Saunders, J.B., and Perch-Nielsen, K. (Eds.), Plankton Stratigraphy:Cambridge (Cambridge Univ. Press), 427-554.

Shyu, J.-P, and Muller, CM., 1991. Calcareous nannofossil biostratigraphyof the Celebes and Sulu seas. In Silver, E.A., Rangin, C, von Breymann,M.T., et al., Proc. ODP, Sci. Results, 124: College Station, TX (OceanDrilling Program), 133-158.

* Abbreviations for names of organizations and publication titles in ODP reference listsfollow the style given in Chemical Abstracts Service Source Index (published byAmerican Chemical Society).

Date of initial receipt: 25 June 1992Date of acceptance: 8 December 1992Ms 135SR-113

199


f , ^"C S 5 3 ^ S ^ -* *c3 S ^ ^ ^ <>> •£ t ,

1 1 1 | I 1 I I g l . l l J e l l I 1 t á 1 d ė •a 4 •= 3 1 1 1 I 1 I I 1 I I I 1 1 I H . a á g I 1

l l l l i t l l l l j t M 3 1 1 1 1 1 l l l l i l u l l 3 i f S I fcttlB ^ f c f c f c t l f c f c l f c S i tCorrection j | j | J | | | | | | { I f J J | t l f I S j l l 1 I 1 t I I 1 I 1 1 1 1 { { 1 I J J J i 1 J J ] J H I

b ' ' ^ o a : S 5 o ^ u o u o u a ; a : a : 3 ; a : α : : a : c g ^ g ^ ^ c g g o u q * S è Q u Q Q £ £ U Q Q Q C I ^ O Q Q C ? C I Q • Ü QI 3 3 - 8 3 7 A -

1H-2 , 1 0 4 - 1 0 5 C X A V C A X C F R R M M F R S S R R F L R C L S V F C X1 H - C C R X A W F C A L F C M F S S S R C F V M C X R R R S2H-5, 132-133 X F L W M A W L R R L M R C X M C F V F F X R S R

u 3H-5, 133-134 X R A W S A V L R F F M S R M X C F F V F F X R R§ 4H-6, 111-112 A F L L S S L F S M F F F S F A F S R C F S X R R2 CN14a 5H-4, 123-124 L M C C R F L F R SF F RS F L F R M S S W R R R R R R R•g 5H-CC L M C L R MM S F R F R R S F L F F F C F R X R R RS 6H-5,38-39 V F C L C L S S L F R V F R F S X R R

6H-5, 127-128 W M V V F X L F S A F F S R C W L F F A M F X R R R RR7H-3,60-61 W M A A S A A F S A V F R R W R S S R L M C X S R R R R R7H-6, 14-15 V S A A R R L C R S F S F S F A F C S A F S X R R

CN13b 8H-4, 109-110 C M C R F F S R R R R R LS F R R W R R__jl

§ CN13a 8H-5, 147-148 C C L S C M R R R F F M R R A M S A S F X S J* F_ _R I* R R

S PNIOH 9H-4,99-100 W F A R S C V R R R R W C S C F R X L F SM CL SLiNizα 9H-CC M M S R R S S R R R M R R F W R R R S R



1

c°

r e™ ill II III ti n i l ! iilii lilii III till.!!.! Ililill.ill llll

A g e z • o n e i n t e r v a l ( c m ) j p m t 3 : 3 : a : i £ g g £ £ • g j £ p a o O ü ^ i £ £ u o u i a : i C £ £ £ u g g Q J j u Q 3 : m o u g £ g g ^ i g135-838A-

Holocene- QN ) 5 1H-3 ,58-59 S L X M M F C S R M M F A S M C L R F X

2H-4 ,98 -99 R A X F F S L F M C F A S F L W M M X R S R

CN 14a 2H-CC - X C F L L F S L V L W L L A X A S X R L S F R X A X F S F . S R R R3H-6 ,38 -39 R R C L A F S M A C L S M L W A F X F C R R X W F

£ 4 H - 5 , 9 3 - 9 4 C A S C A F R C A F A R M L W C F X S M R V A F R« 4H-CC L V C A R M A F L R S V L S X R F W S W F§ 5H-1 ,35 -36 C L F M L F S M A F V R C L W L X R M W F V S R R R3 5H-CC C L S C A R S M W F A R M L A L C X S M W V R R R*" 6H-6, 111-112 M C R L S L L C C A A F X C R V V S R S

7H-2 ,77 -78 R R R R R R S R S S7H-6 ,66 -67 *8H•5, 136-137 M F A S M V F V R C C V L F X S F W W S F S S

r N J . , 9H-5, 19-20 R R R R R<_IN 13a ] O H - 1 , 2 3 - 2 4 *

10H-2,49:50 *

11H-2, 102-103 L C F C S F C L F W A R V V R R A L R L S F S M S S S11H-3,26-27 R R S S R RC S R R C R R R

c 14X-1,31-32 R R R R8 CN 12c 15X-CC R R S F S SF R R F R= 16X-1,55-56 R R R R R R S R L S S F R S R R F° " 1 6 X - C C R R R F R SS R F

17X-CC R


Table 8. Distribution list of calcareous nannofossil, Hole 848B.

•?

l l Ö,1 I J11 i è * * I a f 111 1 • l ! 11 11 i J i 11 * i I 11 * I i s 11 a 1111 i 1fun liiii niti Hiii ttui nisi mil 11in mil inn it

Correction, l l l l j . | f f l | t | j S f 1 1 1 1 1 l l ! l . l t i ! ! l | i | | l i 8 3 2 J 1 H 1 1 f 1 J | 1 g |A g e z , o n e m i e r v a n c m j ^ Q Q Q ^ a ; ^ i g ^ g ^ • ^ o a o Q Q Q Q 5 ; g o Q c ^ G ü Q Q Q a ; g ^ g ü ü Q Q C H Q Q c o Q C l ^ < o a c o a ; g q

1 3 5 - 8 3 8 B -

P M O K 9H-CC C F F R M C F A V F F M R C F S S M F R F R S R F Vc P 10H-CC R R R R R R R R R R

g 11H-1,20-21 C C V L S W C V F L F M C S S M X L M M R S F R S R R S R R R R8 11H-CC C R R C W C V C A R L C C M S R R R M X A C F S F R S R F F R R R S S RS r N I 1 - 12X-1,7-8 M M A L A M L S C F C F S R M W L F R S F R S R S R R R‰ L.iNi/a 12X-CC C S M V C F A L L R M F M C R R R F X C C F F S S R R R R R R R R R

13X1,33-34 R R M S R F F R S F R R R A R R R13X-CC C F R L W L F A V A S L M A C F R S C X A L F R C R F R F F R R S F R R S R R C R R



1._ I s a .a a w .ε s

I l l s 1 1 1 1 . 1 . 1 1 a i d . i è i • | t a l a I 1 1 1 I I É I'S I f l s i M - ^ • S i •§ 1I δ s 1 1 s s s s ^ g i i § ^ ε s 1 I J § g 2 g • ^ i a | 5 | | I | I 1 | | | ? | s s | s l e t 1

1111 .a i i it 111• i I i t l i l i i i i fc t l i i i l i i l i 11111 i i 111 IIICore,Sect,on, | | | | I | J || | | l l | t t l g | l I l l l l J i t l l l l l i S 1 1 1 1 1 f. i 1 | ! 1 1 3 |

Age Z° "

e i"terval(cm) ^ ^ S ^ g g g β ^ ^ g g c § c ^ ^ g g l ö S S S g g ^ ^ ^ i S l ^ l a Q S Q Q Q Q ^ c ^ ^ g g 0 δ I

135-839A-

H o l o c e n e - C N 1 5 1 H - 1 , 1 3 9 - 1 4 0 A S S F X W F V F F R F L W A R W C R X M XP l e i s t o c e n e

C N 1 4 b 1 H - C C C F S F X M V F A S C C W A R X M M X C X R F C R R R R R2 H - 4 , 1 2 0 - 1 2 1 C S S X M C F A R M L A L R V F M V F X F M S S R L4H-5, 10-11 A R C A C L M R S C M A A R V F F A F W R R S W V C6H-3,7-8 C R R M F L F M M M L S R L S S L R X C F L L F R R S

g 7H-3,45^16 M S M S C F F F F C R R C R S L S X F L L F SR8 7H-5,44-45 F R S C F C R F R M M A S R C R S L S X F R R L C S R R R S R R R R

PN Ma 8H-1, 136-137 C R S M F C R S F F L S M R F C R X M S R A L R R R R R R.- U S I « 9H-1, 144-145 R R R R R R R R R C R R S^ 10H-5,31-32 L S F C M A S F F L W S F A F F V S X L R R A W R S

11H-3, 104-105 A S R F A M A F F M L V L S W M M V R X L R R R W W L R R11H-6,40-41 C S F L F L R R F F L F R M S F L F X C R A A R S R11HCC S S S F S R S S R S R S R A S M F12H-CC L S F M S A S F C V F V R F V S X L R F W W F R R15H-CC C S F S A F R R F R A M R C R F A F X F W V F R R R

r w n h 17X-CC M F R L S S M R M R C S X S A L S R RIJNIJD i8x-CC M R R F R M R R R F R V S LL

g 20X-CC M R F R C S R R R F S R F W F L L R S RI 21X-CC SR F R R R R R V M M S°- r N M , 22X-CC F R R F S S R R R F W R C L R R R

u u 23X-CC F F S S R R R R W V L M24X-CC *

Note: Key as Table 2.

MJ. STYZEN

Table 10. Distribution chart of calcareous nannofossils, Hole 839B.

Pliocene

Zone

CN12d


135-839B-

17R-CC

I IIJ 8 8 1g . SJ .SJ .13

O -3 "3 "3

á S 5 S"3 "3 "3 o

A L M S R

v ° o β β

8 •S i i i

R W F S F

2 ft β

•~ - C -SS

ε s• s

O a, a.5 -Ia- o-

S R A M L S R R F R F M R X



12

15a 15b 15cPlate 1. All specimens are magnified 2800×. 1-2. Discoaster ono n. sp. holotype, Sample 135-834A-8H-3, 40 cm. 3, 4. Dis-coaster ono n. sp. paratype, Sample 135-838B-13R-CC. 5. Discoaster sp. A, Sample 135-838B-13R-CC. 6, 7. Scyphosphaerapulcherrima Deflandre, Sample 135-838B-13R-CC. 8,9. Emiliania ovata Bukry, Sample 135-836A-3H-4,60 cm. 10-11. Pseudo-emiliania lacunosa (Kamptner) Gartner, Sample 135-836A-3H-4, 60 cm. 12. Cyclolithella annula (Cohen) Boudreaux and Hay,Sample 135-835A-6H-4, 60 cm. 13-14. Scyphosphaera galeana Kamptner, Sample 135-836A-3H-CC. 15. Helicosphaera pava-mentum Okada and Mclntyre; (15a) phase contrast; (15b) view parallel to crossed nicols; (15c) view 45° to crossed nicols; Sample135-838A-1H-3, 58-59 cm.

203

MJ. STYZEN

13a 13b 13c 14a 14b

Plate 2. All specimens are magnified 2800×. 1-2. Helicosphaera inversa Gartner, Sample 135-836A-2H-6, 30 cm. 3. Coccolithuspataecus Gartner, Sample 135-838A-11H-3, 26-27 cm. 4. Coccolithus pataecus Gartner, Sample 135-837A-7H-3, 60 cm. 5-6. Coc-colithus pelagicus (Wallich) Schiller, Sample 135-838B-13R-CC. 7. Cycloperfolithus carlae Lehotayova and Priewalder, Sample 135-834A-8H-3,40 cm. 8. Cycloperfolithus carlae Lehotayova and Priewalder, Sample 135-834A-9H-1, 10 cm. 9. Gephyrocapsa oceanicaKamptner, Sample 135-836A-2H-6, 30 cm. 10. Gephyrocapsa caribbeanica Boudreaux and Hay, Sample 135-836A-2H-6, 30 cm.11-12. Oolithotus fragilis (Lohman) Martini and Muller, Sample 135-836A-3H-CC. 13. Pontosphaera indooceanica epek; (13a) phasecontrast; (13b) view parallel to crossed nicols; (13c) view 45° to crossed nicols; Sample 135-836A-2H-6, 30 cm. 14. Pontosphaeraindooceanica Cepek; (14a) phase contrast; (14b) view parallel to crossed nicols; Sample 135-836A-2H-6, 30 cm.

204


10a 10b 11a 11b 11c

Plate 3. All specimens are magnified 2800×. 1-2. Pontosphaera japonica (Takayama) Nishida, Sample 135-835A-1H-1, 35-37 cm.3-4. Holodiscolithus sp., Sample 135-837A-5H-4, 123-124 cm. 5-6. Ceratolithus telesmus Norris, Sample 135-837A-7H-3, 60 cm.7. Sphenolithus neoabies Bukry and Bramlette; (7a) parallel to crossed nicols; (7b) 45° to crossed nicols; Sample 135-834A-9H-1, 10 cm.8. Sphenolithus abies Deflandre; (8a) parallel to crossed nicols; (8b) 45° to crossed nicols; Sample 135-834A-9H-1, 10 cm. 9. Spheno-lithus abies Deflandre; (9a) parallel to crossed nicols; (9b) view 45° to crossed nicols; Sample 135-834A-9H-1, 10 cm. 10. Sphenolithuscompactus Backman; (10a) parallel to crossed nicols; (10b) view 45° to crossed nicols; Sample 135-834A-16X-1, 111-112 cm.11. Sphenolithus moriformus (Brönnimann and Stradner) Bramlette and Wilcoxon; (lla) phase contrast; (lib) parallel to crossed nicols;(lie) view 45° to crossed nicols; Sample 135-834A-16X-1, 111-112 cm.

Documents

Ocean Drilling Program Scientific Results Volume 135 J., Parson, L., Allan, J., et al., 1994 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 135 13. CALCAREOUS