Hine, A.C., Feary, D.A., and Malone, M.J. (Eds.) Proceedings of the Ocean Drilling Program, Scientific Results Volume 182 4. EOCENE–OLIGOCENE PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY OF SITES 1126, 1130, 1132, AND 1134, ODP LEG 182, GREAT AUSTRALIAN BIGHT 1 Qianyu Li, 2 Brian McGowran, 2 and Noel P. James 3 ABSTRACT Planktonic foraminiferal results indicate that Paleogene sediments recovered at Sites 1126, 1130, 1132, and 1134 in the Great Australian Bight are of middle Eocene–late Oligocene age, in intervals equivalent to (sub)tropical Zones P12–P22. The southern temperate assemblage hosted several subtropical species in the middle–late Eocene and late Oligocene as immigrants probably transported by a warm-water system similar to the present-day Leeuwin Current. The four major hiatuses recognized or inferred fall (1) between Zones P12–13 and P15 in the middle Eocene, (2) within Zone P15, (3) between Zones P16 and P18 across the Eocene/Oligocene boundary, and (4) between Zones P19 and P20 and Subzone P21b in the mid-Oligocene. These unconformities represent region-wide events across the southern Australian margin, corresponding to global sequence boundaries Part-1 (39.1 Ma), Pr1 + Pr2 (37.1–36.0 Ma), Pr4/Ru1 (33.7 Ma), and Ru4/Ch1 (28.5 Ma), respec- tively. Unconformities at Site 1130 had a longer duration as lower Oli- gocene ooze with Zone P18–P19 species overlying a middle Eocene sandy limestone of Zone P12 age and the whole Oligocene were con- densed to only half as thick as the coeval sediments from up- and downslope, indicating stronger erosion at this upper slope locality dur- ing the late Eocene. The biostratigraphic results confirm previous stud- ies of the neritic record, reporting that carbonate deposition began in 1 Li, Q., McGowran, B., and James, N.P., 2003. Eocene–Oligocene planktonic forminiferal biostratigraphy of Sites 1126, 1130, 1132, and 1134, ODP Leg 182, Great Australian Bight. In Hine, A.C., Feary, D.A., and Malone, M.J. (Eds.), Proc. ODP, Sci. Results, 182, 1–28 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/ publications/182_SR/VOLUME/ CHAPTERS/006.PDF>. [Cited YYYY- MM-DD] 22 Department of Geology and Geophysics, The University of Adelaide, Adelaide SA 5005, Australia. Correspondence author: [email protected]33 Department of Geological Sciences, Queen’s University, Kingston ON K7L 3N6, Canada. Initial receipt: 2 April 2001 Acceptance: 30 September 2002 Web publication: 3 February 2003 Ms 182SR-006
Transcript
Hine, A.C., Feary, D.A., and Malone, M.J. (Eds.)Proceedings of the Ocean Drilling Program, Scientific Results Volume 182
4. EOCENE–OLIGOCENE PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY OF SITES 1126, 1130, 1132, AND 1134, ODP LEG 182, GREAT AUSTRALIAN BIGHT1
Qianyu Li,2 Brian McGowran,2 and Noel P. James3
ABSTRACT
Planktonic foraminiferal results indicate that Paleogene sedimentsrecovered at Sites 1126, 1130, 1132, and 1134 in the Great AustralianBight are of middle Eocene–late Oligocene age, in intervals equivalentto (sub)tropical Zones P12–P22. The southern temperate assemblagehosted several subtropical species in the middle–late Eocene and lateOligocene as immigrants probably transported by a warm-water systemsimilar to the present-day Leeuwin Current. The four major hiatusesrecognized or inferred fall (1) between Zones P12–13 and P15 in themiddle Eocene, (2) within Zone P15, (3) between Zones P16 and P18across the Eocene/Oligocene boundary, and (4) between Zones P19 andP20 and Subzone P21b in the mid-Oligocene. These unconformitiesrepresent region-wide events across the southern Australian margin,corresponding to global sequence boundaries Part-1 (39.1 Ma), Pr1 +Pr2 (37.1–36.0 Ma), Pr4/Ru1 (33.7 Ma), and Ru4/Ch1 (28.5 Ma), respec-tively. Unconformities at Site 1130 had a longer duration as lower Oli-gocene ooze with Zone P18–P19 species overlying a middle Eocenesandy limestone of Zone P12 age and the whole Oligocene were con-densed to only half as thick as the coeval sediments from up- anddownslope, indicating stronger erosion at this upper slope locality dur-ing the late Eocene. The biostratigraphic results confirm previous stud-ies of the neritic record, reporting that carbonate deposition began in
1Li, Q., McGowran, B., and James, N.P., 2003. Eocene–Oligocene planktonic forminiferal biostratigraphy of Sites 1126, 1130, 1132, and 1134, ODP Leg 182, Great Australian Bight. In Hine, A.C., Feary, D.A., and Malone, M.J. (Eds.), Proc. ODP, Sci. Results, 182, 1–28 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/182_SR/VOLUME/CHAPTERS/006.PDF>. [Cited YYYY-MM-DD]22Department of Geology and Geophysics, The University of Adelaide, Adelaide SA 5005, Australia. Correspondence author: [email protected] of Geological Sciences, Queen’s University, Kingston ON K7L 3N6, Canada.
Initial receipt: 2 April 2001Acceptance: 30 September 2002Web publication: 3 February 2003Ms 182SR-006
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 2
the middle Eocene probably as a response to global warming and mar-ginal subsidence because of the accelerated seafloor spreading betweenAustralia and Antarctica at ~43 Ma.
INTRODUCTION
During Ocean Drilling Program (ODP) Leg 182, Paleogene sedimentswere recovered at Sites 1126, 1128, 1130, 1132, and 1134 in waterdepths between 218 m (Site 1132) and 3875 m (Site 1128) from thewestern Great Australian Bight (Fig. F1). The siliciclastic sequence ofpre–late Eocene age, at which most holes terminated, is poorly fossilif-erous and could be fluvial to deltaic in origin. The overlying middleEocene limestones grade upward to wackestones and calcareous oozesof younger ages (Feary, Hine, Malone, et al., 2000). Core recovery is low,<30% on average, as a result of cherts. Fossil assemblages of planktonicforaminifers and nannoplankton are moderately preserved, providingevidence for age determination and correlation.
Early work on the Cenozoic biostratigraphy of the Great AustralianBight Basin and other basins along the southern Australian margin fo-cused mostly on macrofossils. Glaessner (1951, 1953) pioneered the de-cisive shift to microfossils by describing three foraminiferal zones.Crespin (1956) and Ludbrook (1958a, 1958b, 1961) analyzed biofacies,including foraminifers, in samples from outcropping and drill hole sec-tions in the onshore Eucla Basin north of the Great Australian Bight.McGowran and Lindsay (1969) reported planktonic foraminiferal as-semblages of middle Eocene age, and McGowran et al. (1971) first at-tempted the correlation of local assemblages to tropical zonations.Based on sidewall cores, McGowran (1991) identified key events in theupper Eocene–lowermost Oligocene section from Jerboa-1 within thedrilling area of Leg 182. These and subsequent studies distinguish a suc-cession of planktonic foraminifer events for subdivision and correlationof the local neritic strata on which the temporal patterns of the strati-graphic record of southern Australia can be evaluated (McGowran,1989; McGowran et al., 1992, 1997a).
We have examined all Paleogene core catchers from Sites 1126, 1130,1132, and 1134 plus some additional samples from relevant core inter-vals. Our purpose is to document planktonic foraminiferal distributionin the middle Eocene–late Oligocene, to compare the assemblage com-position between different settings, to identify hiatuses and their signif-icance in the development of Cenozoic cool-water carbonate platform,and to extract biofacies information on environmental changes beforeand after the full opening of the Tasman Gateway, an event triggeringcircum-Antarctic deepwater circulation and global cooling in the latestEocene–early Oligocene (Kennett, 1977; Kennett and Stott, 1990).
METHODS
A total of 141 samples from Sites 1126, 1130, 1132, and 1134 wereused in this study. Core catcher samples were washed, dried, and exam-ined on board and reexamined after the cruise. Thin sections of theEocene limestone were made by N.P. James, collaborating a study onthe first major transgression in the region. Material from the deepwaterSite 1128 was not used because it has been distorted by dissolution.
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F1. Map showing southern Austra-lia, location of Cenozoic basins, Leg 182 sites, and Jerboa-1, p. 17.
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Species identification was made by reference mainly to Blow (1979)and Bolli et al. (1985). Key species for biostratigraphy are discussed andillustrated. The timescale and zonal scheme of Berggren et al. (1995)were correlated with relevant datum levels of species found widely insouthern Australia (Fig. F2). We used the calibrated first occurrence (FO)and last occurrence (LO) datums of many species given in Berggren etal. (1995) and updated by the Shipboard Scientific Parties of Leg 181(Carter, McCave, Richter, Carter, et al., 1999; table T3 in Shipboard Sci-entific Party, 2000a) and Leg 182 (Feary, Hine, Malone, et al., 2000; ta-ble T3 in Shipboard Scientific Party, 2000b).
PLANKTONIC FORAMINIFERAL DATUMS AND ZONES
Figure F2 summarizes the integrated Paleogene geochronostratigra-phy, emphasizing standard planktonic foraminiferal zones and datumlevels from the (sub)tropics. The P-zonation of Berggren et al. (1995)has been correlated with the southern mid-latitude zones identified byJenkins (1966, 1971, 1993) and important datum levels found in south-ern Australia (McGowran, 1986, 1991; McGowran et al., 1997a). To-gether with those used in defining the P-zones, many calculateddatums provide the basic framework for the regional biostratigraphy.Local biozonations are not applied in this study for the same reason asstated in McGowran (1986; p. 250) that “it is easier to shuffle the inven-tory of biostratigraphic events than to redefine zones and subzoneseach time there is a new discovery, a correction, or a modest step for-ward in our understanding” (of the distribution of species). Apart fromthese datum levels, major components of the planktonic foraminiferalassemblages also provide evidence for changes in age and environment.Species associations help determine if datums are in situ or displaced.Biostratigraphic results from previous studies of neritic sediments aresummarized below.
Eocene
The Paleocene–early Eocene marine record in southern Australia issparse, and the Kings Park section near Perth and the coastal PebblePoint section to the southwest of Melbourne are the only two outcropswith good planktonic and benthic foraminifers of that age (McGowran,1964, 1965). In contrast, middle–late Eocene carbonates rich in plank-tonic foraminifers are more widespread along the coast of southernAustralia (Quilty, 1969, 1981; McGowran, 1979, 1990, 1991, 1992). Theplanktonic foraminiferal assemblages have these characteristics.
1. Prominent in the Eocene assemblage are Globigerinatheka index,Acarinina primitiva, Acarinina bullbrooki, Acarinina collactea, Tur-borotalia spp., Subbotina linaperta, and Chiloguembelina cubensis.
2. Most (sub)tropical species, especially those zonal markers listedin Fig. F2, are absent. Morozovella is rare and present mostly inZone P10 or older intervals. Hantkenina is sporadic in Zones P15–lower P16.
3. The middle Eocene sediments can be subdivided on the follow-ing evidence. Planorotalites australiformis last appears withinZone P11. Assemblages with A. bullbrooki, Acarinina densa, and G.
index indicate Zone P12. A. primitiva last appears within Zone
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P14 equivalents, whereas the LOs of A. collactea and A. aculeataare in the middle Eocene part of Zone P15. The microperforatePraetenuitella insolita and related species are present in ZonesP15–P16.
4. The late Eocene assemblage characterizes Zones upper P15–lowerP16, mainly including G. index, S. linaperta, S. angiporoides, Tur-borotalia increbescens, Turborotalia pseudoampliapertura, Catapsy-drax spp., and Globorotaloides spp. Zone P16 can be recognizedonly if Turborotalia cunialensis is present.
5. Pseudohastingerina spp. from the region appear to have their LOin the late Eocene, similar to their record elsewhere from south-ern mid to high latitudes (Jenkins and Srinivasan, 1986; Stottand Kennett, 1990; Nocchi et al., 1991).
Oligocene
The Oligocene planktonic foraminifers comprise chiefly cool-temperate species, and only during the late Oligocene did some sub-tropical forms occur. Globorotaloides and Tenuitella are most abundant,accompanied, respectively, by frequent Chiloguembelina in the early Oli-gocene and Globigerina in the late Oligocene.
1. Typical Subbotina brevis is present across the Eocene/Oligoceneboundary. Zone P18 is difficult to recognize without Pseudohasti-gerina micra, but S. brevis can be used as a proxy because its LOdatum falls close to the upper part of Zone P18 equivalents ac-cording to Jenkins (1985, 1993). Guembelitria triseriata is firstpresent in the Zone P18 interval.
2. Subbotina angiporoides is common in the lower Oligocene up tothe vicinity of the Zone P19/P20 boundary. It is accompanied inZone P19 and replaced above Zone P19 by Subbotina labia-crassata, a species ranging into the upper Oligocene, close to theZone P21/P22 boundary (Stott and Kennett, 1990; Huber, 1991;Berggren, 1992).
3. Typical Paragloborotalia opima is sporadic and restricted mainlyto two intervals, Zone P19–P20 and Subzone P21b.
4. The southern Australian record of C. cubensis is consistent withBerggren et al. (1995), so its LO can be used to mark the SubzoneP21a/P21b boundary and the upper/lower Oligocene boundary.Leckie et al. (1993), however, reported rare C. cubensis presentthroughout the upper Oligocene in tropical–subtropical sections(see comments in Berggren et al., 1995).
5. Four- and five-chambered Globigerina (Globigerina ouachitaensis,Globigerina officinalis, G. praebulloides, and G. ciperoensis) arecommon in the upper Oligocene. On the influx of G. angulisutur-alis, Lindsay (1985) proposed a G. angulisuturalis Zone for sedi-ments equivalent to Zone upper P21b–lower P22.
6. As well as P. opima and G. angulisuturalis, other warm-water spe-cies also invaded southern Australia during the late Oligocene–earliest Miocene. They include Globoquadrina tripartita, Globo-quadrina dehiscens s.l., Dentoglobigerina globulosa, Globigerinoidesprimordius, and Paragloborotalia kugleri.
7. Sporadic Turborotalia euapertura range throughout the Oli-gocene, and its LO has been used for defining the Oligocene/Miocene boundary in high latitudes (Berggren, 1992). In thesouthern Australian–New Zealand region, T. euapertura often
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 5
ranges into the lowermost Miocene (Jenkins, 1985, 1993; Li andMcGowran, 2000).
BIOSTRATIGRAPHY OF LEG 182 HOLES
Holes 1126B and 1126D
Planktonic foraminifers indicate that the Oligocene section at Site1126 extends from 205.85 to 329.89 meters below seafloor (mbsf) be-tween Samples 182-1126B-26X-CC, 15–18 cm, and 20R-CC, 20–22 cm,and the Eocene from 338.87 to 396.63 mbsf between Samples 21R-CC,18–19 cm, and 27R-CC, 0–2 cm (Fig. F3).
Typical late Oligocene assemblages are present between 205.85 and254.82 mbsf in Holes 1126B and 1126D. Sample 182-1126B-26X-CC,15–18 cm (205.85 mbsf), contains well-preserved specimens of, amongothers, G. primodius, Globoquadrina praedehiscens, and G. tripartita. Theyare accompanied downcore to 254.82 mbsf (Sample 182-1126B-32X-CC, 26–28 cm) by Globigerina ciperoensis (rare), G. angulisuturalis (rare),S. labiacrassata, and T. euapertura, a typical Zone P21–P22 association. P.opima, a species confined to Zones P20–P21, is also present in this sam-ple. Therefore, the Zone P21/P22 boundary falls in Core 182-1126B-31Xat ~250 mbsf where there was no core recovery.
Between 254.82 and 329.89 mbsf, poor recovery hampers a properdating of this interval, which is believed to encompass the upper/lowerOligocene boundary and Zones P19–P21 sediment. However, a fairlywell preserved assemblage in Sample 182-1126D-16R-CC, 38–39 cm(290.98 mbsf), contains abundant C. cubensis and tenuitellids (includ-ing Tenuitella munda and Tenuitellinata juvenilis), frequent Globorota-loides suteri, Catapsydrax unicavus, and Paragloborotalia nana, as well asrare T. euapertura and S. ex gr. angiporoides. It indicates an early Oli-gocene age, probably within Zones P19–P20, in the absence of typicallyolder or younger species.
Typical S. angiporoides dominates the coarser fraction of Sample 182-1126D-20R-CC, 20–22 cm (329.89 mbsf), whereas C. cubensis, Tenuitellagemma, and T. munda are abundant in the fine fraction. As the last twotaxa are often present together in the lowermost Oligocene (Li et al.,1992), we assign this assemblage to Zone P18, even though the zonalmarker P. micra is absent. It has become apparent that P. micra did notrange through the Eocene/Oligocene boundary in either southern Aus-tralia (Lindsay, 1985; McGowran, 1991; Li et al., 2000) or sub-Antarctica(Jenkins and Srinivasan, 1986; Stott and Kennett, 1990; Nocchi et al.,1991).
An unconformity is inferred to be present at the Oligocene/Eoceneboundary, as the underlying sediments in Sample 182-1126D-21R-CC,18–19 cm (338.87 mbsf), contain Globigerinatheka luterbacheri, G. index,P. insolita, S. linaperta, and other middle–late Eocene species. Earlierstudies indicated that G. luterbacheri as an immigrant from the subtrop-ics is mainly confined to a short interval between Zones P15 and lowerP16 in high southern latitudes (Nocchi et al., 1991) and so is P. insolitaas a southern provincial dweller at a similar time period (Li et al., 1992).Zone P15 extends farther down to Sample 182-1126D-25R-CC, 15–17cm (380.38 mbsf), in the presence of Turborotalia cerroazulensis s.l., Acar-inina aculeata, and A. collactea but without A. primitiva. The upper/mid-dle Eocene boundary is tentatively placed in Core 182-1126D-23Rwithin Zone P15 (as per Berggren et al., 1995), approximating the LO of
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these small Acarinina species as suggested for the Australian–NewZealand region (Jenkins, 1996; McGowran et al., 1997a).
Zone P14 is probably missing from Hole 1126D, as an assemblagetypical of Zones P12–13 characterized by A. primitiva, A. bullbrooki, andA. cf. densa was found in the lowermost two samples with planktonicforaminifers (Samples 182-1126D-26R-CC, 23–25 cm, and 27R-CC, 0–2cm [390.38–396.63 mbsf]). An interval of Zone P12 or older in the mid-dle Eocene is indicated by an association of these species with manylong-ranging Eocene forms such as C. cubensis, G. index, P. micra, and S.linaperta. The underlying sand sequence contains no foraminifers;therefore, its age cannot be determined. An Eocene age is inferred on itsferruginous feature similar to those from onshore localities and by itsposition in the seismic Sequence 7 (Feary, Hine, Malone, et al., 2000).
Holes 1130A and 1130C
The stratigraphic succession at Site 1130 is truncated by large uncon-formities in the Miocene, Oligocene, and Eocene. An upper Mioceneooze unconformably overlies the Oligocene chalk/chert section, itselfdivided by unconformities and overlying the middle Eocene sandylimestone (Fig. F4). The ooze is present between 323.34 and 328.57mbsf in Samples 182-1130C-3R-CC, 16–19 cm, and 35X-5, 87–92 cm (Liet al., this volume).
Immediately downcore at 328.89 mbsf (Sample 182-1130A-35X-CC,27–30 cm) is a dark gray porcellanite containing poorly preservedplanktonic foraminifers. The assemblage is dominated by small-sizedspecies, including Globigerina praebulloides, G. officinalis, G. ciperoensis,Globorotaloides spp., and Tenuitella spp. Others are minor or rare, mainlyT. euapertura, T. venezuelana, P. nana, Globoquadrina cf. globulosa, andGlobigerinita spp. The assemblage indicates Zone P22 because P. opima, aZone P21 species, is absent from this sample but is present in samplesfrom below. The three core catcher samples between 337.73 and 351.37mbsf (Samples 182-1130C-5R-CC, 3–4 cm; 6R-CC, 10 cm; and 182-1130A-38X-CC, 27–30 cm) all contain P. opima, plus other Oligocenespecies listed above, representing Subzone P21b.
The presence of lower Oligocene sediment is indicated by an assem-blage with C. cubensis and S. cf. angiporoides in Sample 182-1130C-7R-CC, 6–8 cm (356.96 mbsf). Typical P. opima was not found in this sam-ple, but specimens of P. nana–P. opima bioseries show transitional fea-tures between these two species, as illustrated by Bolli et al. (1985) assubspecies of Globorotalia opima. According to these authors, transi-tional forms between the small four-chambered P. nana and larger five-chambered P. opima are commonly present before and during the estab-lishment of P. opima as a species in upper Zones P19–P21. Conse-quently, the assemblage from 356.96 mbsf is considered to representZone upper P19–P20 but not older because typical S. angiporoides (ZonesP19 and older) is absent.
Thin sections from the underlying sandy limestone in Cores 182-1130C-8R through 10R show rare and poorly preserved neritic benthicspecies. Among the scattered planktonic specimens are A. primitiva, G.index, and S. linaperta (especially in Sample 182-1130C-8R-1, 99 cm), in-dicating Zone P12 or older in the middle Eocene.
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tura
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O. u
nive
rsa
Glo
boro
talia
ple
siot
umid
a
late
Olig
ocen
em
iddl
eE
ocen
e
R
R
P
C
P R R
C
CP P
P
Neo
glob
oqua
drin
a pa
chyd
erm
aG
lobo
rota
lia s
citu
la
P
late
Mio
cene
Pla
noro
talit
es s
pp.
Glo
boro
talo
des
sute
ri
Sub
botin
a an
gipo
roid
es
Chi
logu
embe
lina
cube
nsis
Pse
udoh
astig
erin
a m
icra
Ten
uite
lla s
pp.
S
ubbo
tina
linap
erta
Glo
bige
rinat
heka
inde
x
Tur
boro
talia
incr
ebes
cens
Tur
boro
talia
ven
ezue
lana
Tur
boro
talia
eua
pert
ura
Glo
botu
rbor
otal
ita la
biac
rass
ata
Glo
bige
rinoi
des
prim
ordi
us
Glo
boqu
adrin
a tr
ipar
tita
+ G
. sel
lii
Par
aglo
boro
talia
kug
leri
s.l.
Pra
eten
uite
lla in
solit
a
Glo
bige
rina
bullo
ides
s.l.
Aca
rinin
a pr
imiti
va
Han
tken
ina
prim
itiva
Par
aglo
boro
talia
opi
ma
Glo
bige
rinat
heka
lute
rbac
heri
Cat
apsy
drax
uni
cavu
s
P
Glo
bige
rina
angu
lisut
ural
isG
lobi
gerin
a ci
pero
ensi
s
Glo
boqu
adrin
a de
hisc
ens
Tur
boro
talia
cer
roaz
ulen
sis
Glo
boqu
adrin
a gl
obul
osa
Par
aglo
boro
talia
nan
a
Glo
bige
rinita
spp
.
Cas
sige
rinel
la w
inni
ana
Cat
apsy
drax
dis
sim
ilis
Gue
mbe
litria
tris
eria
ta
Par
aglo
boro
talia
sem
iver
a
Pra
eten
uite
lla p
raeg
emm
a
Ten
uite
llina
ta s
pp.
Tru
ncor
otal
oide
s sp
p.T
urbo
rota
lia a
mpl
iape
rtur
a
2R
3R
4R
5R
6R
7R
8R
9R
10R
T.D.395.2 mbsf
34X
35X
36X
37X
38X
39X
40X
41XT.D.
380.4 mbsf
?
cf.
?
P
RRC
R
R
CR
CR
cf.
C
C
Rcf.
R
C
RR
C
C
CC P
cf.R
cf.
R
P
R
P
PR
?
cf.
C
C
C
R
R
P
RR
cf.
P
P
R
R
Glo
bige
rina
quin
quel
oba
Glo
bige
rinel
la o
besa
P
PCR P cf.
N17
P22
P21b
P20/P19
P12
early
Olig
o.
320
340
360
380
400
Hole1130A
Hole1130C
cf.
Dep
th (
mbs
f)
Zone Age
F4. Distribution of planktonic for-aminifers, Holes 1130A and 1130C, p. 20.
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 7
Hole 1132C
Hole 1132C was drilled at a water depth of 218.5 m with very lowcore recovery (6.1%). Planktonic foraminifers are rare and poorly pre-served in core catcher samples from this shallow-water hole. Truncatedby three unconformities, the Eocene–Oligocene sequence is present be-tween 450.94 and 555.93 mbsf in Samples 182-1132C-24R-CC, 14–17cm, through 35R-CC, 83–85 cm (Fig. F5). The upper Oligocene ZonesP21b–P22 equivalent is indicated by an assemblage dominated by C.unicavus, Globigerina praebulloides, G. ciperoensis, Globorotaloides suteri,and Tenuitella spp., with rare S. labiacrassata, P. nana, and T. euaperturafound in Samples 182-1132C-24R-CC, 14–17 cm, through 27R-CC, 17–20 cm (478.17 mbsf). The absence of key species such as P. opima madeseparation of these zones impossible.
Farther downhole, Sample 182-1132C-28R-CC, 20–21 cm (487.9mbsf), contains frequent S. angiporoides and G. tripartita but without C.cubensis. Such an association appears to be mainly associated with ZoneP19 of the lower Oligocene (cf. Leckie et al., 1993) (Fig. F6). Togetherwith those long-ranging species listed above, both S. angiporoides and C.cubensis were found in Samples 182-1132C-29R-CC, 24–26 cm (497.64mbsf), and 30R-CC, 17–19 cm (507.27 mbsf), indicating Zones P18–P19.All this suggests that the mid-Oligocene Zones P20–P21a are missingand the existence of a hiatus of at least 1 m.y. between 28.5 and 30.3Ma on the timescale of Berggren et al. (1995). The absence of suchwarm-water species as T. ampliapertura and G. angulisuturalis that char-acterize Zones P18–P19 cannot be a result of a cooler water regime be-cause they are present farther east in the Gambier Basin where warm-water influence was much weaker (Li et al., 2000).
No specimens could be freely disaggregated from the sandy lime-stone in the lower part of Hole 1132C. In most thin sections of Samples182-1132C-31R-1, 11 cm, through 35R-1, 80 cm, there are typicalEocene species G. index, A. collactea, and A. primitiva, as well as manysmall globigerinid forms, indicating Zones P14–lower P15 or older inthe middle Eocene. Many specimens referable to Planorotalites cf., P.australiformis, and Truncorotaloides cf. T. topilensis were found from thebase of the limestone in Samples 182-1132C-34R-2, 27 cm, to 35R-1, 80cm, implying Zone lower P12 and older. These results point to the pos-sibility that the entire upper Eocene (Zones upper P15–P17) is missingfrom Hole 1132C, and the upper middle Eocene is incomplete, as theZone P12 assemblage similar to those in other holes has not been posi-tively identified (Fig. F5).
Hole 1134A
The Eocene–Oligocene planktonic foraminiferal succession in Hole1134A is similar to that recorded in Holes 1126B and 1126D (see “Holes1126B and 1126D,” p. 5) in both species composition and their strati-graphic distribution (Fig. F6). The Oligocene assemblage was foundfrom 238.64 to 304.51 mbsf in Samples 182-1134A-27X-CC, 34–37 cm,through 34X-CC, 31–34 cm. Sample 182-1163C-27X-CC, 34–37 cm,consists of Globigerina ciperoensis, G. angulisuturalis, G. praedehiscens, andother long-ranging species but not P. opima, suggesting Zone P22. Thepresence of P. opima in Sample 182-1134A-29X-CC, 18–21 cm (253.08mbsf), above the LO of C. cubensis, denotes Subzone P21b. The relation-ship between the upper and lower Oligocene sediments appears to beunconformable, as Sample 182-1134A-30X-CC, 22–25 cm, at 262.72
PP
PR
C
RP
late
Olig
ocen
em
iddl
eE
ocen
ee. Mio
.
Aca
rinin
a bu
llbro
oki
Pla
noro
talit
es s
pp.
R
Glo
boro
talo
des
sute
ri
Sub
botin
a an
gipo
roid
es
Chi
logu
embe
lina
cube
nsis
Pse
udoh
astig
erin
a m
icra
Ten
uite
lla s
pp.
Sub
botin
a lin
aper
ta
Glo
bige
rinat
heka
inde
x
Tur
boro
talia
incr
ebes
cens
Tur
boro
talia
pse
udoa
mpl
iape
rtur
a
Tur
boro
talia
eua
pert
ura
Glo
botu
rbor
otal
ita la
biac
rass
ata
Glo
bige
rinoi
des
prim
ordi
us
Glo
boqu
adrin
a tr
ipar
tita
+ G
. sel
lii
Par
aglo
boro
talia
kug
leri
s.l.
Pra
eten
uite
lla in
solit
a
Glo
bige
rina
bullo
ides
s.l.
Aca
rinin
a ac
ulea
ta
Aca
rinin
a co
llact
ea
Aca
rinin
a pr
imiti
va
Han
tken
ina
prim
itiva
Par
aglo
boro
talia
opi
ma
Glo
bige
rinat
heka
lute
rbac
heri
Cat
apsy
drax
uni
cavu
s
R P C CP
Glo
bige
rina
angu
lisut
ural
is
Glo
bige
rina
cipe
roen
sis
Glo
boqu
adrin
a pr
aede
hisc
ens
Tur
boro
talia
cer
roaz
ulen
sis
Glo
boqu
adrin
a de
hisc
ens
P
Par
aglo
boro
talia
nan
a
R
Aca
rinin
a de
nsa
Glo
bige
rinita
spp
.
Cas
sige
rinel
la w
inni
ana
Cat
apsy
drax
dis
sim
ilis
Gue
mbe
litria
tris
eria
ta
Par
aglo
boro
talia
pse
udom
ayer
i
Pra
eten
uite
lla p
raeg
emm
a
Ten
uite
llina
ta s
pp.
RRRPRR
P
CRCRC
C
CC
CC
C
RRR
?
PR
P
R
RPPRP
P
PRP
C
R
RRR
Tru
ncor
otal
oide
s sp
p.
PP
440
460
480
500
520
540
560
580
600
? ?
P
?
C
RR
P
C
P
Tur
boro
talia
am
plia
pert
ura
P
R
P
P
C R PC C
CCR
PC
R
R
R
CC
R
early
Olig
o.
P
RR P
cf.
cf.
P14
P12-older
P19/
P18
P22/
P21b
T.D. 603.2 mbsf
?cf.
?
R
Dep
th (
mbs
f)
Hole 1132C Zone Age
Rare
Barren
23R
24R
25R
26R
27R
28R
29R
30R
31R
32R
33R
34R
35R
36R
37R
38R
39R
F5. Distribution of planktonic for-aminifers, Hole 1132C, p. 21.
P
T.D. 397.1 mbsf
260
300
340
27X
28X
29X
30X
31X
32X
33X
34X
35X
36X
37X
38X
39X
40X
41X
42X
43X
P22
P16/
P15
P21b
Aca
rinin
a bu
llbro
oki
Par
aglo
boro
talia
sem
iver
a
P
Glo
boro
talo
des
sute
ri
Sub
botin
a an
gipo
roid
es
Chi
logu
embe
lina
cube
nsis
Pse
udoh
astig
erin
a m
icra
Ten
uite
lla s
pp.
Sub
botin
a lin
aper
ta
Glo
bige
rinat
heka
inde
x
Tur
boro
talia
incr
ebes
cens
Tur
boro
talia
pse
udoa
mpl
iape
rtur
a
Tur
boro
talia
eua
pert
ura
Glo
botu
rbor
otal
ita la
biac
rass
ata
Glo
boqu
adrin
a tr
ipar
tita
Par
aglo
boro
talia
kug
leri
s.l.
Pra
eten
uite
lla in
solit
a
Glo
bige
rina
bullo
ides
s.l.
Aca
rinin
a ac
ulea
ta
Aca
rinin
a co
llact
ea
Aca
rinin
a pr
imiti
va
Han
tken
ina
prim
itiva
Par
aglo
boro
talia
opi
ma
Glo
bige
rinat
heka
lute
rbac
heri
Cat
apsy
drax
uni
cavu
s
P
C
P
Glo
bige
rina
angu
lisut
ural
is
Glo
bige
rina
cipe
roen
sis
Glo
boqu
adrin
a pr
aede
hisc
ens
Tur
boro
talia
cer
roaz
ulen
sis
Glo
boqu
adrin
a de
hisc
ens
R
Par
aglo
boro
talia
nan
a
P
Aca
rinin
a de
nsa
26X
R
P
R
R
R
R
RR
P
PR
C
C
C
RC
C
CR
P
P
C
R
CR
P
P
P
R
R
R
R
R
C
C
C
R
CR
R
RR
P
P
P
P
P
P
C
CR
P
P
C
RP
P
PP
P
R
RR
P
P
R
R
C
C
C
C
CP
P
P
R
P
R
P
P
P
Rare
PP
R
RP
PR
R
P12
Cas
sige
rinel
la w
inni
ana
Cat
apsy
drax
dis
sim
ilis
P
P
P
P
R
P
P
P
RP
Glo
bige
rinita
spp
.
R
R P cf.
R
Gue
mbe
litria
tris
eria
ta
P
Par
aglo
boro
talia
pse
udom
ayer
i
Pra
eten
uite
lla p
raeg
emm
a
Ten
uite
llina
ta ju
veni
lis
R
R
P
P
P
P
P
R
P
P
P
P
P
R
R
R
R
P R P R R PRR cf.P P R
cf.
P240
280
320
360
380
R
PP
Tur
boro
talia
am
plia
pert
ura
P
P19/
P18
P
No sample
?
Hole1132A
Dep
th (
mbs
f)
Zone Age
late
Olig
o.m
iddl
eE
ocen
ee. Mio
.ea
rlyO
ligoc
ene
late
Eoc
ene
F6. Distribution of planktonic for-aminifers, Hole 1134A, p. 22.
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 8
mbsf contains not only C. cubensis but also Turborotalia ampliapertura, aspecies present only in Zone P19 of the lower Oligocene and rangingdown to upper Eocene Zone P16. This also accords with the absence ofG. angulisuturalis and P. opima, two species characteristic of Zone P20and younger assemblages. Therefore, Zone P20 and Subzone P21a of theupper lower Oligocene are likely missing, assuming they are not con-densed into the nonrecovered Core 182-1134A-29X.
Zones P15–P16 planktonic foraminifers are present between 310.93and 361.91 mbsf in Samples 182-1134A-35X-CC, 0–2 cm, to 40X-CC,31–34 cm. Species including G. index, P. micra, C. cubensis, and S. lina-perta are accompanied, in the upper part, by T. increbescens, P. insolita,and in the lower part, by A. aculeata and A. collactea. The LO of A. collac-tea in Sample 182-1134A-39X-CC, 31–34 cm (351.64 mbsf), marks themiddle/upper Eocene boundary.
Foraminifers are rare in Sample 182-1134A-41X-CC, 20–22 cm (368.4mbsf), from the underlying sandy limestone, and they are dominatedby benthic forms. Zone P12 or older planktonic species such as A. prim-itiva and A. bullbrooki are present together with a few G. index and G.linaperta. The limestone is yellowish and poorly consolidated withabundant limonite and some kaolinite, suggesting probable weather-ing. The hiatus between the limestone and the overlying calcareousooze of Zone P15–P16 in Hole 1134A, as at Hole 1126D, could havelasted at least for 2 m.y. No samples were available from the bottom ofHole 1134A, but the siliciclastic section is believed to be similar to Hole1126D in containing no diagnostic foraminifers.
Correlation between Holes
Figure F7 summarizes the planktonic foraminiferal results for theEocene–Oligocene sections studied. The following generalizations canbe made.
1. Planktonic foraminiferal assemblages change from warm tem-perate with subtropical immigrants in the Eocene to cool tem-perate in the early Oligocene and warm temperate in the lateOligocene.
2. Biostratigraphy is better constrained in the middle–upperEocene and upper Oligocene than in the lower Oligocene wherefewer species datums were found. Stratigraphic packages are sim-ilar between sites, as are the ages of sediments.
3. The oldest planktonic foraminiferal assemblage, indicatinglower Zone P12 or older, is present at 545–555 mbsf in Hole1132C from a water depth of 218.5 m but not at sites from inter-mediate water depths. An early–middle Eocene depocenter is,therefore, inferred to have existed in what is now close to theshelf edge, although its altitudinal position could have been al-tered especially by the late Neogene basin inversion widely re-corded in south Australia.
4. Carbonate deposition became widespread (over all sites studied)in P12 equivalents (Bartonian Stage, later middle Eocene). A hi-atus of >1-m.y. duration may separate sediments of Zone P12from Zones P14/P15 equivalents, and another is inferred withinZone P15 close to the middle/late Eocene boundary.
5. The Eocene–Oligocene sections at these four sites are all trun-cated by unconformities also at the Eocene/Oligocene boundary
1130A/C(-488 m)
1132C(-218 m)
400
30R
31R
32R
33R
34R
35R
36R
37R
G. index, A. collactea
Planorotalites,Truncorotaloides
early
Olig
ocen
e
G. indexH. primitivaT. cunialensis
A. primitivaA. bullbrooki
A. collactea
1126D(-784 m)
21R
22R
23R
24R
25R
26R
27R
28R
340
360
380
400
420
Depth(mbsf)
35X
36X
37X
38X
39X
40X
3R
4R
5R
6R
7R
8R
9R
10R
320
340
380
G. indexA. primitiva
P. opima
G. plesiotumida
late
Mio
.la
teO
ligo.
mid
dle
Eoc
ene
late
Eoc
ene
P15
P13/
P12
P16/
P15
P12or
older
P12/
13
A. primitiva, A. bullbrooki
260
280
300
320
340
P. micraG. index
A. aculeataA. collacta
A. primitiva
G. triseriata
T. increbescens
?
H. primitiva
Jerboa-1(-771 m)
1134A(-701 m)
34X
35X
36X
37X
38X
39X
40X
41X
42X
43X
300
320
340
360
380
G. index
A. collactea
A. primitivaA. bullbrooki
A. aculeata
S. linaperta
early
Olig
o.
S. angiporoides
Depth(mbsf) Depth
(mbsf)
520
540
560
580
360
Depth(mbsf)
Depth(mbsf)
mid
dle
Eoc
ene
late
Eoc
ene
mid
dle
Eoc
ene
early
Olig
o.m
iddl
eE
ocen
e
Sand with thininterbedded clay
Ooze/wakestone
Limestone/packstone
Sandy limestone
Chert
First occurrence
Last occurrence
Core recovery
F7. Biostratigraphic correlation be-tween Leg 182 sites and Jerboa-1, p. 23.
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 9
and lower/upper Oligocene boundary, each with an estimatedduration of at least 1 m.y.
6. The major unconformity separating the upper Miocene from up-per Oligocene at Site 1130 indicates a long period of erosion ornondeposition during the early–middle Miocene. The thicknessof Oligocene sediments at this site (~35 m) is also considerablyless than those from upslope (~70 m at Site 1132) or downslope(~72 m at Site 1134 and ~130 m at Site 1126). Consequently, Site1130 likely resides on a hinge zone that had been active since atleast Eocene–Oligocene time.
REGIONAL CORRELATION AND DEPOSITIONAL ENVIRONMENTS
The drilling of Leg 182 confirms the stratigraphic record from neriticsediments that carbonate deposition in southern Australia began in theEocene during a new phase of marginal subsidence stimulated by accel-erated Australia-Antarctica separation (McGowran et al., 1997a). Theunconformity-bounded “sequences” (allostratigraphic packages) ofEocene–Oligocene age can be correlated with regional transgressions us-ing foraminiferal biostratigraphy. We attempt such a correlation in Fig-ure F8.
Wilson Bluff Transgression
Although a comprehensive biostratigraphy of the Wilson Bluff Lime-stone from the Eucla Basin is still lacking, previous studies by Ludbrook(1961), McGowran and Lindsay (1969), Lowry (1970), and McGowran(1989) indicate that sands and marls at the base of the limestone con-tain Zone P12 planktonic foraminifers. Several species, A. densa, S. fron-tosa, and A. primitiva, are in common with the present material, andthey do not extend above this stratigraphic package.
Tortachilla Transgression
Within the chronological constraints of the available fossils, there isa clear-cut hiatus preceding the second package, characterized by A. ac-uleata and A. collactea in the absence of the older species in adequateplanktonic facies. Both biopackages are evident in Jerboa-1, but sam-pling was too coarse to address the hiatus itself.
Tuketja Transgression
The third Eocene allostratigraphic package is characterized by the as-sociation of G. index, H. primitiva, P. insolita, and P. micra. The Hantken-ina warm ingression is within the uppermost Zone P15, constrained bythe presence of the calcareous nannofossil Isthmolithus restuvus, defin-ing the base of NP19/NP20 at 36 Ma (Fig. F8). Two of the sections areconsistent with this; the Jerboa assemblage is certainly Tuketja but,again, the underying hiatus is probable, not proven. Neritic sections insouthern Australia seem to bury two sequence boundaries within thishiatus, for we have been unable to demonstrate a package defined byboundaries equivalent to global sequence boundaries Pr1 and Pr2, andthe same applies to the present analysis, as seen in Figure F8.
23.80
25.38
27.49
28.50
29.40
32.00
33.70
34.65
36.00
37.10
39.07
42.62
Ch4/Aq1
Ch 3
Ch 2
Ru4/Ch1
Ru 3
Ru 2
Pr4/Ru1
Pr3
Pr2
Pr1
Bart1
Lu4T
RT
R
R
1126D
25
30
35
40
45
Eoc
ene
late
mid
dle
early
late
Olig
ocen
e
NP19/20
NP25
NN1
NP24
NP23
NP22
NP21
NP18
NP17
NP16
P21
P22
a
b
P20
P19
P18
P16
P15
P14
P12
NP15b
c
P11
Base of carbonate
1132CForaminiferdatums
Foraminiferzone
Nanno-fossilzone
Sequenceboundaries
Wilson Bluff
Tortachilla
Tuketja
Tuit
Aldinga
Jan Juc
Regionaltransgression
1130AC
?
(iv)
(iii)
(ii)
(i)
Jerboa1
?
?
?
?
(infe
rred
)
1134A
N4? ??
Age
(M
a)
? ?
B P. kugleri (23.8)
B Gq. dehiscens (23.2)
T P. opima s.s. (27.1)
B G. angulisuturalis (29.4)
T Ch. cubensis (28.5)
T T. ampliapertura (30.3)
T Pseudohastigerina (32.0)
T T. cerroazulensis (33.8)T Cr. inflata (34.0)
B T. cunialensis (35.2)
B Po. semiinvoluta (38.4)
T Gb. beckmanni (40.1)
Gs. primordius acme (24.3)
B Cr. inflata (35.5)
B Gb. beckmanni (40.5)
B Gk. index (42.9)
B P. pseudokugleri (25.9)
T Gt. labiacrassata (27.1)
T D. globularis (22.8)
B P. opima (30.6)
T Gk. index (34.3)
T A. primitiva (39.0)
T M. spinulosa (38.1)
T A. bullbrooki (40.5)
B Gs. primordius (26.7)
T Acarinina (37.5)
T S. angiporoides (30.0)
T T. frontosa (39.1)
T A. collactea (37.7)
B T. pomeroli (42.4)
B M. lehneri (43.5)
B Gb. kugleri (45.8)
T M. aragonensis (43.6)
F8. Eocene–Oligocene carbonates, p. 24.
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 10
Neritic sediments of the Tuketja Transgression include the upper Wil-son Bluff Limestone (Eucla Basin), Blanche Point Formation (St. Vin-cent Basin), Narrawaturk Marl (western Otway Basin), and Castle CoveLimestone (eastern Otway Basin). Almost all of these rock units aretruncated by unconformities at or close to the Eocene/Oligoceneboundary (McGowran et al., 1997a). The subsequent Aldinga Transgres-sion during the early Oligocene revived carbonate deposition in all ba-sins.
Tuit Transgression and Eocene/Oligocene Boundary
McGowran et al. (1992) discussed, in detail, foraminiferal species da-tums and assemblage characteristics across the Eocene/Oligoceneboundary in sections from the St. Vincent Basin. The Tuit has been sub-sequently identified to represent a sequence bounded by Pr3 and Pr4/Ru1 equivalents (McGowran and Li, 1997). However, it has not beenrecognized biostratigraphically, being characterized unsatisfactorily byP. insolita and P. micra and the absence of older (Eocene) and younger(Oligocene) species. Nor can it be seen in this study (Fig. F8), likely be-ing subsumed in the boundary hiatus.
Aldinga Transgression
The lower Oligocene assemblage in the St. Vincent and Gambier Ba-sins is characterized by Cassigerinella chipolensis, Cassigerinella winniana,C. cubensis, S. angiporoides, and T. increbescens, plus some A. aculeata thatare probably reworked. Within available constraints, this carbonate-generating flooding occurred coevally at our sites. We have not mademuch progress in breaking out the three lower Oligocene (Rupelian) se-quences as biofacies packages, but a beginning has been made (Li et al.,2000). The lower Oligocene chert-carbonate facies are not known fromthe Eucla Basin because of mid-Oligocene erosion (Lowry, 1970; Li etal., 1996) (Fig. F8). This mid-Oligocene unconformity has been ob-served in other southern Australian basins, including the Otway, Mur-ray, and Gippsland Basins (McGowran et al. 1997a) (Fig. F5). In theGambier Basin (or western Otway Basin), the mid-Oligocene section iseither a shallow-water limestone or concealed by dolomitization (Li etal., 2000). At shallower localities of the Gambier, the Compton Con-glomerate and similar facies unconformably overlie upper Eocene sedi-ments (Ludbrook, 1961; White, 1996) (Fig. F4). Although dating theexact duration of the unconformity is difficult on few available markerspecies and datums in poorly preserved neritic assemblages, the indica-tions are that the mid-Oligocene hiatus could have ~2-m.y. duration.This hiatus is represented by the Marshall Paraconformity in NewZealand, presumably related to a glacioeustatic fall and the inception ofthe Antarctic Circumpolar Current (Carter, 1985; Fulthorpe et al.,1996).
Jan Juc Transgression
There are three sequences in the upper Oligocene (Chattian), andthey are clearly manifested in regional biofacies (Li et al., 1999). We donot make that subdivision here, but the Chattian package, as a whole, isseen above the mid-Oligocene hiatus. The assemblage in its lower partis characterized by G. triseriata, G. labiacrassata, and, in favorable facies,P. opima and G. angulisuturalis. Carbonates of late Oligocene age are
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 11
present more widely than the lower Oligocene sediments as limestonesof the Ehrick–lower Mannum Formations accumulated in a more in-land sea to the east of the Bight, the Murray Basin (Ludbrook, 1958a,1961; Lindsay, 1985; Lukasik et al., 2000). The Eucla carbonate platformadvanced again with the deposition of the Abrakurrie Limestone(Lowry, 1970; James and Bone, 1991; Li et al., 1996). Farther to the east,in Torquay, the Jan Juc Formation with its warm-water fossilassemblages typifies this regional event (McGowran et al., 1997b; Li etal., 1999) (Fig. F8).
It is noteworthy that the depocenter during the later Eocene was notin what is now the slope but the coastal area of the Bight where WilsonBluff Limestone as thick as 300 m has been reported (Lowry, 1970, fig.19). Carbonate production was probably stimulated by a warm nearlysubtropical oceanic environment, enhanced by the first flow of a proto-Leeuwin Current from the northwest (Shafik, 1990; McGowran et al.,1997b) interacting with nutrient-rich southern waters on a subsidingcontinental margin (McGowran et al., 1997a). The subsequent globalcooling in the latest Eocene and early Oligocene lowered sea level hasbeen confirmed isotopically from other deep-sea localities and conti-nental margins (Miller et al., 1991, 1998). The low sea level causedlarge-scale downcuttings and unconformities, such as those observed atLeg 182 sites. Sediment removal by underwater currents could havebeen also significant especially after the Tasman Gateway was fullyopen and the circumantarctic flow became intensified. Such erosionaland nondepositional activities appear to be stronger in areas next toSite 1130 with a present water depth of ~500 m. The late Oligocenewarming generated a warm-temperate environment in the region, sup-porting again a planktonic foraminiferal assemblage with subtropicalimmigrants.
A correlation of the Paleogene succession with global third-ordersequences and boundaries reveals some matching patterns, especially inthe four major unconformities falling close to four major sequenceboundaries: Bart1, Pr1, Pr4/Ru1, and Ru4/Ch1 of Hardenbol et al.(1998) (Fig. F8).
SUMMARY AND CONCLUSIONS
1. Paleogene sediments recovered at Sites 1126, 1130, 1132, and1134 in the Great Australian Bight contain middle Eocene to lateOligocene planktonic foraminifers correlated mainly to(sub)tropical Zones P12–P22. The biostratigraphic results con-firm previous studies that widespread neritic carbonate deposi-tion was initiated in the middle Eocene, probably responding toglobal warming and the accelerated separation between Austra-lia and Antarctica at ~43 Ma.
2. The fossil foraminiferal fauna is typically southern temperate,with some warm-water species present in middle–late Eoceneand late Oligocene time. The warm-water species were probablytransported as immigrants by a warm-water system similar to thepresent-day Leeuwin Current during warming periods.
3. Four major hiatuses were identified: (1) between Zones P12–13and lower P15 in the middle Eocene, (2) within Zone P15, (3) be-tween Zones P16 and P18 across the Eocene/Oligocene bound-ary, and (4) between Zones P19–20 and Subzone P21b in themid-Oligocene. At Site 1130, lower Oligocene ooze unconform-
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 12
ably overlies a middle Eocene Zone P12 sandy limestone and thewhole Oligocene was condensed in a 35-m package that is onlyhalf as thick as the contemporary sediments from up- and down-slope, indicating stronger erosion and/or minimal deposition atthis upper slope locality.
4. The dated unconformities represent regional events through theneritic realm in southern Australia, and they appear to be localmanifestations of the global sequence boundaries close to 39.1,37.1–36.0, 33.7, and 28.5 Ma, respectively. The estimated dura-tion of each hiatus between 1 and 2 m.y. from the present midand upper slope appeals to further studies of neritic sections inorder to better understand the timing and amplitude of uncon-formities and their bearing on the evolutionary history of thesouthern Australian margin.
ACKNOWLEDGMENTS
This research used samples provided by the Ocean Drilling Program(ODP). ODP is sponsored by the U.S. National Science Foundation(NSF) and participating countries under management of Joint Oceano-graphic Institutions (JOI), Inc. Funding for this research was providedby the Australian Research Council and ODP Australia Secretariat. Themanuscript benefited from comments by two anonymous reviewers.The Centre for Electron Microscopy and Microanalysis of Adelaide Uni-versity provided the electronic scanning facility.
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 13
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APPENDIX
Acarinina aculeata (Jenkins).Acarinina bullbrooki (Bolli) (Pl. P1, figs. 5, 6; Pl. P3, figs. 10, 13).Acarinina collactea (Finlay) (Pl. P1, figs. 7, 8).Acarinina densa (Cushman) (Pl. P1, fig. 1).Acarinina primitiva (Finlay) (Pl. P1, figs. 2, 3; Pl. P3, figs. 14, 15).Acarinina spp. (Pl. P1, fig. 4; Pl. P4, figs. 13, 14).Cassigerinella winniana (Howe) (Pl. P2, fig. 14).Catapsydrax dissimilis Cushman and Bermudez (Pl. P2, figs. 29, 30).Catapsydrax unicavus Bolli, Loeblich, and Tappan (Pl. P1, figs. 13, 14).Chiloguembelina cubensis (Palmer) (Pl. P1, fig. 12; Pl. P3, fig. 13).Dentoglobigerina globularis (Bermudez) (Pl. P3, fig. 5).Globigerina angulisuturalis Bolli (Pl. P3, figs. 2, 3).Globigerina bulloides d’Orbigny.Globigerina ciperoensis Bolli (Pl. P3, fig. 1).Globigerina officinalis Subbotina (Pl. P3, fig. 4).Globigerina praebulloides Blow.Globigerinatheka index (Finlay) s.l. (Pl. P1, figs. 9, 10; Pl. P3, fig. 9; Pl. P4, fig. 1).Globigerinatheka luterbacheri Bolli (Pl. P1, fig. 11).Globigerinita glutinata Parker.Globigerinita naparimaensis Bronnimann (Pl. P2, fig. 12).Globigerina primordius Blow.Globoquadrina praedehiscens Blow and Banner (Pl. P3, fig. 8).Globoquadrina pseudovenezuelana Blow and Banner (Pl. P2, figs. 17, 18).Globoquadrina tripartita (Koch) (Pl. P3, fig. 7).Globoquadrina venezuelana (Hedberg) (Pl. P3, fig. 6).Globorotalodes suteri Bolli (Pl. P1, figs. 15, 16).Globorotalodes sp. (Pl. P1, fig. 17).Globoturborotalita brevis (Jenkins).Globoturborotalita labiacrassata (Jenkins) (Pl. P2, fig. 16).Guembelitria triseriata (Terquem) (Pl. P2, fig. 13).Hantkenina alabamensis Cushman (Pl. P1, fig. 18).Paragloborotalia kugleri (Bolli).Paragloborotalia nana (Bolli) (Pl. P2, fig. 21).Paragloborotalia optima (Bolli) (Pl. P2, figs. 22, 23).Paragloborotalia pseudocontinuosa (Jenkins) (Pl. P2, figs. 26–28).Paragloborotalia pseudomayeri (Bolli) (Pl. P1, fig. 24).Paragloborotalia semivera (Hornibrook) (Pl. P2, figs. 24, 25).Planorotalites cf. australiformis (Jenkins).Praetenuitella insolita (Jenkins) (Pl. P2, figs. 2, 3).Praetenuitella praegemma Li (Pl. P2, figs. 4–6).Pseudohastigerina micra (Cole) (Pl. P2, fig. 1; Pl. P3, fig. 12).Subbotina angiporoides (Hornibrook) (Pl. P1, fig. 29; Pl. P2, fig. 15).Subbotina linaperta (Finlay) (Pl. P1, fig. 28; Pl. P3, fig. 11).Subbotina minima (Jenkins) (Pl. P1, fig. 30).Tenuitella gemma (Jenkins) (Pl. P2, fig. 7).Tenuitella munda (Jenkins) (Pl. P2, fig. 10).Tenuitella pseudoedita (Subbotina) (Pl. P2, fig. 9).Tenuitellinata angustiumbilicata (Bolli) (Pl. P2, fig. 8).Tenuitellinata juveniles (Bolli) (Pl. P2, fig. 11).Turborotalia topilensis (Cushman).Turborotalia ampliapertura (Bolli) (Pl. P2, fig. 19).Turborotalia cerroazulensis (Cole) s.l. (Pl. P1, figs. 19–22).Turborotalia euapertura (Jenkins) (Pl. P2, fig. 20).Turborotalia increbescens (Bandy) (Pl. P1, figs. 25, 26).Turborotalia pseudoampliapertura (Blow and Banner) (Pl. P1, fig. 27).Turborotalia sp. (Pl. P1, fig. 23).
7 8 9 10 11
13 14 15 16 17
19 20 21 22 23
25 26 27 28 29
1 2 3 4 5
18
12
6
24
30
P1. Planktonic foraminifers, Holes 1126D and 1134A, p. 25.
7 8 9 10 11
13 14 15 16 17
19 20 21 22 23
25 26 27 28 29
1 2 3 4 5
18
12
6
24
30
P2. Planktonic foraminifers, Holes 1126D and 1134A, p. 26.
100 µm
200 µm
50 µm50 µm
c
m
b
ch
s
50 µm50 µm50 µm
7 8 9
10 11
1 2 4 5
12
6
13
14 15
P3. Planktonic foraminifers, Holes 1134A and 1132C, p. 27.
br
br
in
in
g
200 µm
7
1 2
3 45
6
200 µm
200 µm
100 µm 100 µm
50 µm200 µm
P4. Planktonic foraminifers, Holes 1132C, p. 28.
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 17
Figure F1. A. Map showing the modern circulation around southern Australia and the location of Cenozoicbasins. B. Location of ODP Leg 182 sites and oil exploration drill hole Jerboa-1. Contours in meters.
F2. Paleogene geochronostratigraphy of Berggren et al. (1995) with P-zonation and datum levels of diagnosticon of Jenkins (1966, 1971, 1993) is also shown, together with datum levels found in southern Australia (McGow1997a). Numbers are estimated ages in million years mainly by Berggren et al. (1995) (cf. Feary, Hine, Malone
A. subsphaerica (59.2)P. pseudomenardii (59.2)Ig. albeari (60.0) M. angulata (61.0)Pr. uncinata (61.2)
Pr. inconstans (63.0)P. sompressa (63.0)
{
{
{
M. formosa (54.0){
Ch. cubensis
M. velascoensis
P. pseudomenardii
SP15
SP14
SP13
SP12
SP11
SP10
SP9
SP8
SP7
SP6
SP5
SP4
SP3
SP1SP2
Gq. dehiscens (23.2)
Gt. brazieri
Ch. cubensis (28.5)
S. angiporoides (30.0)
Gt. brevis
A. aculeata
Gk. index (42.9)
M. crater
P. pseudomenardii (59.2)
Gt. brevis
A. primitiva (39.0)
M. crater
M. velascoensis (55.9)
{
{
{
Pα & PO
M1aN4a
Geochonostratigraphy Nanno-plankton
Planktonic foraminifers Southern mid-latitude Southern Au
65.0
60.9
57.9
54.8
49.0
41.3
37.0
33.7
28.5
23.8
Pg. opima (30.6)
Acarinina aculeataChiloguembelina c
Chattian
Rupelian
Priabonian
Bartonian
Lutetian
Ypresian
Thanetian
Selandian
Danian
Olig
ocen
eE
ocen
eP
aleo
cene
early
late
early
late
mid
dle
early
late
C6CC7
C8
C9
C10
C11
C12
C13
C15C16
C17
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
C7A
P. wilcoxensis
T. euapertura
S. angiporoides
Gt. brevis
S. linaperta
T. inconspicua
Gk. index
A. primitiva
M. crater
S. triloculinoides
G. pauciloculata
Gt. brazieri
G. daubjergensis
P. wilcoxensis (54.5)
G. daubjergensis
G. pauciloculata
Globoquadrina deh
Paragloborotalia pGuembelitria triser
Chiloguembelina cCassigerinella winn
Subbotina angipor
Guembelitria triser
Cassigerinella chip
Globigerinatheka in
Acarinina primitivaAcarinina collactea
Hantkenina primitiv
Acarinina aculeata
Turborotalia fronto
Turborotalia pomeGlobigerinatheka in
Planorotalites aust
Morozovella caucaPseudohastigerinaAcarinina primitivaMorozovella caucaChiloguembelina w
Morozovella aequa
Morozovella acutaPseudohastigerina
Planorotalites pseu
Paragloborotalia kuGlobigerinoides pr
Pg. opima, Gt. lab
Globoturborotalita
Planorotalites aust
Acarinina collactea
Acarinina bullbrook
P21
P22
a
b
P20
P19
P18
P16
P15
P14
P12
P11
P10
P9
P7
P6a
b
P4
P5
P3
P1b
a
c
b
a
c
ba
P21
P22
a
b
P20
P19
P18
P16
P15
P14
P12
P11
P10
P9
P7
P6a
b
P4
P5
P3
P1b
a
c
b
a
c
ba
Top of
Bottom
Q. L
I ET A
L.E
OC
EN
E–OL
IGO
CE
NE P
LA
NK
TO
NIC F
OR
MIN
IFER
AL B
IOST
RA
TIG
RA
PH
Y1
9
Figure based on 38 samples (includ-ing six 10%, abundant (A) = >10%–30%, a
Ten
uite
lla s
pp.
Sub
botin
a lin
aper
ta
Tur
boro
talia
incr
ebes
cens
Tur
boro
talia
pse
udoa
mpl
iape
rtur
a
Tur
boro
talia
eua
pert
ura
P22
P19-P20
P18
P16/
P15
P12
early
Olig
ocen
ela
teO
ligoc
ene
late
Eoc
ene
mid
dle
Eoc
ene
Tur
boro
talia
cer
roaz
ulen
sis
Ten
uite
llina
ta s
pp.
Dep
th (
mbs
f)
200
220
240
260
280
300
320
340
360
380
400
420
440
460
?
?
Zone Age
cf.
cf.
C
P cf.
C
CPCRCRCC
PR
P
R
cf.
PA
A
cf.
R R
RRR
cf.
C
P
C
CR
C
P
?
R
P
F3. Distribution of planktonic foraminifers throughout the Eocene and Oligocene in Holes 1126A and 1126D thin sections). Foraminiferal relative abundance: present (P) = <1%, rare (R) = 1%–5%, common (C) = >5%–nd dominant (D) = >30%.
Aca
rinin
a bu
llbro
oki
Par
aglo
boro
talia
sem
iver
a
Glo
boro
talo
des
sute
ri
Sub
botin
a an
gipo
roid
es
Chi
logu
embe
lina
cube
nsis
Pse
udoh
astig
erin
a m
icra
Glo
bige
rinat
heka
inde
x
Glo
botu
rbor
otal
ita la
biac
rass
ata
Glo
bige
rinoi
des
prim
ordi
us
Glo
boqu
adrin
a tr
ipar
tita
Par
aglo
boro
talia
kug
leri
s.l.
6R
7R
8R
9R
28R
29R
30R
31R
32R
33R
10R
11R
12R
13R
14R
15R
16R
17R
18R
19R
20R
21R
22R
23R
24R
25R
26R
27R
Pra
eten
uite
lla in
solit
a
Glo
bige
rina
bullo
ides
s.l.
25X
26X
27X
28X
29X
30X31X32X
Aca
rinin
a ac
ulea
ta
Aca
rinin
a co
llact
ea
Aca
rinin
a pr
imiti
va
Han
tken
ina
prim
itiva
Par
aglo
boro
talia
opi
ma
Glo
bige
rinat
heka
lute
rbac
heri
Cat
apsy
drax
uni
cavu
s
Glo
bige
rina
angu
lisut
ural
is
Glo
bige
rina
cipe
roen
sis
Glo
boqu
adrin
a pr
aede
hisc
ens
Glo
boqu
adrin
a de
hisc
ens
Par
aglo
boro
talia
nan
a
Aca
rinin
a de
nsa
Glo
bige
rinita
spp
.
Cas
sige
rinel
la w
inni
ana
Cat
apsy
drax
dis
sim
ilis
Gue
mbe
litria
tris
eria
ta
Par
aglo
boro
talia
pse
udom
ayer
i
Pra
eten
uite
lla p
raeg
emm
a
Hole1126A
Hole1126D
P
P
PP
P
C
PR
AC
Barren
R C
R P P
R RC CPPPC
CRP
RR
CCC
PP
CCC
R
P
P
CCCP
C A
R A
C A C
C
R
C
C
P
R
R
C
C
R
C
C
CPCPCARCR
R
PP C
P
PP
C
RP
C
PP
R
PP P
R
P
PPP
C
C
CRCCRCR
P
P
P
P
R
R
R
RR
P
R
PP
R
R
P
P
PR
P
PP
R
R
R
RP
R
cf.
No sample
No sample
No sample
No sample
No sample
No sample
No sample
C
P
CR
C
PP
PP
C
C
RR
Q. L
I ET A
L.E
OC
EN
E–OL
IGO
CE
NE P
LA
NK
TO
NIC F
OR
MIN
IFER
AL B
IOST
RA
TIG
RA
PH
Y2
0
Figure e in Holes 1130A and 1130C based on 32 samples (includ-ing 16 %–5%, common (C) = >5%–10%, abundant (A) = >10%–30%, a
P R R
Orb
ulin
a su
tura
lis +
O. u
nive
rsa
Glo
boro
talia
ple
siot
umid
a
late
Olig
ocen
em
iddl
eE
ocen
e
P R R
C
CP
Neo
glob
oqua
drin
a pa
chyd
erm
aG
lobo
rota
lia s
citu
la
P
late
Mio
cene
Pla
noro
talit
es s
pp.
Sub
botin
a an
gipo
roid
esP
seud
ohas
tiger
ina
mic
ra
Ten
uite
lla s
pp.
S
ubbo
tina
linap
erta
Tur
boro
talia
incr
ebes
cens
Tur
boro
talia
ven
ezue
lana
Tur
boro
talia
eua
pert
ura
Pra
eten
uite
lla in
solit
a
Tur
boro
talia
cer
roaz
ulen
sis
Par
aglo
boro
talia
sem
iver
a
Pra
eten
uite
lla p
raeg
emm
a
Ten
uite
llina
ta s
pp.
Tru
ncor
otal
oide
s sp
p.T
urbo
rota
lia a
mpl
iape
rtur
a
?
P?
cf.
C
C
C
R
R
P
RR
cf.
P
P
R
cf.N17
P22
P21b
P20/P19
P12
early
Olig
o.
320
340
360
380
400
Dep
th (
mbs
f)
Zone Age
F4. Distribution of planktonic foraminifers throughout the Eocene and Oligocen thin sections). Foraminiferal relative abundance: present (P) = <1%, rare (R) = 1nd dominant (D) = >30%. T.D. = total depth. Olig. = Oligocene.
Aca
rinin
a bu
llbro
oki
Aca
rinin
a ac
ulea
ta
Aca
rinin
a co
llact
ea
R
R
P
C P
P
Glo
boro
talo
des
sute
ri
Chi
logu
embe
lina
cube
nsis
Glo
bige
rinat
heka
inde
x
Glo
botu
rbor
otal
ita la
biac
rass
ata
Glo
bige
rinoi
des
prim
ordi
us
Glo
boqu
adrin
a tr
ipar
tita
+ G
. sel
lii
Par
aglo
boro
talia
kug
leri
s.l.
Glo
bige
rina
bullo
ides
s.l.
Aca
rinin
a pr
imiti
va
Han
tken
ina
prim
itiva
Par
aglo
boro
talia
opi
ma
Glo
bige
rinat
heka
lute
rbac
heri
Cat
apsy
drax
uni
cavu
s
P
Glo
bige
rina
angu
lisut
ural
isG
lobi
gerin
a ci
pero
ensi
s
Glo
boqu
adrin
a de
hisc
ens
Glo
boqu
adrin
a gl
obul
osa
Par
aglo
boro
talia
nan
a
Glo
bige
rinita
spp
.
Cas
sige
rinel
la w
inni
ana
Cat
apsy
drax
dis
sim
ilis
Gue
mbe
litria
tris
eria
ta
2R
3R
4R
5R
6R
7R
8R
9R
10R
T.D.395.2 mbsf
34X
35X
36X
37X
38X
39X
40X
41XT.D.
380.4 mbsf
?
cf.
RRC
R
R
CR
CR
cf.
C
C
Rcf.
R
C
RR
C
C
CC P
cf.R
cf.
R
P
R
P
PR
R
Glo
bige
rina
quin
quel
oba
Glo
bige
rinel
la o
besa
P
PCR P
Hole1130A
Hole1130C
cf.
Q. L
I ET A
L.E
OC
EN
E–OL
IGO
CE
NE P
LA
NK
TO
NIC F
OR
MIN
IFER
AL B
IOST
RA
TIG
RA
PH
Y2
1
Figure in Hole 1132C based on 47 samples (including 34 thinsectio (C) = >5%–10%, abundant (A) = >10%–30%, and dom-inant
PP
PR
C
R late
Olig
ocen
em
iddl
eE
ocen
ee. Mio
.
Pla
noro
talit
es s
pp.
R
Sub
botin
a an
gipo
roid
es
Pse
udoh
astig
erin
a m
icra
Ten
uite
lla s
pp.
Sub
botin
a lin
aper
ta
Tur
boro
talia
incr
ebes
cens
Tur
boro
talia
pse
udoa
mpl
iape
rtur
a
Tur
boro
talia
eua
pert
ura
Pra
eten
uite
lla in
solit
a
Tur
boro
talia
cer
roaz
ulen
sis
Par
aglo
boro
talia
pse
udom
ayer
i
Pra
eten
uite
lla p
raeg
emm
a
Ten
uite
llina
ta s
pp.
CC
CC
C
PRP
C
R
RRR
Tru
ncor
otal
oide
s sp
p.
PP
440
460
480
500
520
540
560
580
600
?
P
Tur
boro
talia
am
plia
pert
ura
PPC C
CCR
CC
R
early
Olig
o.
cf.
P14
P12-older
P19/
P18
P22/
P21b
Dep
th (
mbs
f)
Zone Age
F5. Distribution of planktonic foraminifers throughout the Eocene and Oligocene ns). Foraminiferal relative abundance: present (P) = <1%, rare (R) = 1%–5%, common(D) = >30%. T.D. = total depth. Olig. = Oligocene.
P
Aca
rinin
a bu
llbro
oki
Glo
boro
talo
des
sute
ri
Chi
logu
embe
lina
cube
nsis
Glo
bige
rinat
heka
inde
x
Glo
botu
rbor
otal
ita la
biac
rass
ata
Glo
bige
rinoi
des
prim
ordi
us
Glo
boqu
adrin
a tr
ipar
tita
+ G
. sel
lii
Par
aglo
boro
talia
kug
leri
s.l.
Glo
bige
rina
bullo
ides
s.l.
Aca
rinin
a ac
ulea
ta
Aca
rinin
a co
llact
ea
Aca
rinin
a pr
imiti
va
Han
tken
ina
prim
itiva
Par
aglo
boro
talia
opi
ma
Glo
bige
rinat
heka
lute
rbac
heri
Cat
apsy
drax
uni
cavu
s
R P C CPG
lobi
gerin
a an
gulis
utur
alis
Glo
bige
rina
cipe
roen
sis
Glo
boqu
adrin
a pr
aede
hisc
ens
Glo
boqu
adrin
a de
hisc
ens
P
Par
aglo
boro
talia
nan
a
R
Aca
rinin
a de
nsa
Glo
bige
rinita
spp
.
Cas
sige
rinel
la w
inni
ana
Cat
apsy
drax
dis
sim
ilis
Gue
mbe
litria
tris
eria
ta
RRRPRR
P
CRCRC
C
RRR
?
PR
P
R
RPPRP
P
? ?
PC
RR
P
C
R
P
P
C R
PC
R
R
R
P
RR P
cf.
T.D. 603.2 mbsf
?cf.
?
R
Hole 1132C
Rare
Barren
23R
24R
25R
26R
27R
28R
29R
30R
31R
32R
33R
34R
35R
36R
37R
38R
39R
Q. L
I ET A
L.E
OC
EN
E–OL
IGO
CE
NE P
LA
NK
TO
NIC F
OR
MIN
IFER
AL B
IOST
RA
TIG
RA
PH
Y2
2
Figure 34A based on 24 samples (including eight thinsectio %–10%, abundant (A) = 10%–30%, and domi-nant (
260
300
340
P22
P16/
P15
P21b
Sub
botin
a an
gipo
roid
es
Pse
udoh
astig
erin
a m
icra
Ten
uite
lla s
pp.
Sub
botin
a lin
aper
ta
Tur
boro
talia
incr
ebes
cens
Tur
boro
talia
pse
udoa
mpl
iape
rtur
a
Tur
boro
talia
eua
pert
ura
Pra
eten
uite
lla in
solit
a
P
Tur
boro
talia
cer
roaz
ulen
sis
C
CR
P
P
C
RP
P
PP
P
R
RR
P
P
R
R
C
C
C
C
CP
P
P
R
P
R
P
P
P
P12
Pra
eten
uite
lla p
raeg
emm
a
Ten
uite
llina
ta ju
veni
lis
R
R
P
P
P
P
P
R
P
P R
cf.
P240
280
320
360
380
R
P
Tur
boro
talia
am
plia
pert
ura
P
P19/
P18
?Dep
th (
mbs
f)
Zone Age
late
Olig
o.m
iddl
eE
ocen
ee. Mio
.ea
rlyO
ligoc
ene
late
Eoc
ene
F6. Distribution of planktonic foraminifers throughout the Eocene and Oligocene of Hole 11ns). Foraminiferal relative abundance: present (P) = <1%, rare (R) = 1%–5%, common (C) = 5D) = >30%. T.D. = total depth. Olig. = Oligocene. Mio. = Miocene.
P
T.D. 397.1 mbsf
27X
28X
29X
30X
31X
32X
33X
34X
35X
36X
37X
38X
39X
40X
41X
42X
43X
Aca
rinin
a bu
llbro
oki
Par
aglo
boro
talia
sem
iver
a
P
Glo
boro
talo
des
sute
ri
Chi
logu
embe
lina
cube
nsis
Glo
bige
rinat
heka
inde
x
Glo
botu
rbor
otal
ita la
biac
rass
ata
Glo
boqu
adrin
a tr
ipar
tita
Par
aglo
boro
talia
kug
leri
s.l.
Glo
bige
rina
bullo
ides
s.l.
Aca
rinin
a ac
ulea
ta
Aca
rinin
a co
llact
ea
Aca
rinin
a pr
imiti
va
Han
tken
ina
prim
itiva
Par
aglo
boro
talia
opi
ma
Glo
bige
rinat
heka
lute
rbac
heri
Cat
apsy
drax
uni
cavu
s
P
C
Glo
bige
rina
angu
lisut
ural
is
Glo
bige
rina
cipe
roen
sis
Glo
boqu
adrin
a pr
aede
hisc
ens
Glo
boqu
adrin
a de
hisc
ens
R
Par
aglo
boro
talia
nan
a
P
Aca
rinin
a de
nsa
26X
R
P
R
R
R
R
RR
P
PR
C
C
C
RC
C
CR
P
P
C
R
CR
P
P
P
R
R
R
R
R
C
C
C
R
CR
R
RR
P
P
P
P
P
P
Rare
PP
R
RP
PR
R
Cas
sige
rinel
la w
inni
ana
Cat
apsy
drax
dis
sim
ilis
P
P
P
P
R
P
P
P
RP
Glo
bige
rinita
spp
.
R
R P cf.
R
Gue
mbe
litria
tris
eria
ta
P
Par
aglo
boro
talia
pse
udom
ayer
i
P
P
P
P
R
R
R
R
P R P R R PRR cf.P
P
P
No sample
Hole1132A
Q. L
I ET A
L.E
OC
EN
E–OL
IGO
CE
NE P
LA
NK
TO
NIC F
OR
MIN
IFER
AL B
IOST
RA
TIG
RA
PH
Y2
3
Figure m this study and Jerboa-1 from McGowran (1991). Notethe di . = Oligocene. Mio. = Miocene.
30A/C488 m)
1132C(-218 m)
30R
31R
32R
33R
34R
35R
36R
37R
G. index, A. collactea
Planorotalites,Truncorotaloides
early
Olig
ocen
e
5X
6X
7X
8X
9X
0X
3R
4R
5R
6R
7R
8R
9R
10R
G. indexA. primitiva
P. opima
G. plesiotumida
late
Mio
.la
teO
ligo.
mid
dle
Eoc
ene
late
Eoc
ene
P
P
P
P
P
P12or
older
P12/
13
A. primitiva, A. bullbrooki
early
Olig
o.
S. angiporoides
520
540
560
580
Depth(mbsf)
mid
dle
Eoc
ene
early
Olig
o.m
iddl
eE
ocen
e
Sand with thininterbedded clay
Ooze/wakestone
Limestone/packstone
Sandy limestone
Chert
First occurrence
Last occurrence
Core recovery
F7. Biostratigraphic correlation between Leg 182 sites using foraminiferal data frofferent age of sediments at shallow sites in Holes 1130A, 1130C, and 1132C. Oligo
11(-
400
G. indexH. primitivaT. cunialensis
A. primitivaA. bullbrooki
A. collactea
1126D(-784 m)
21R
22R
23R
24R
25R
26R
27R
28R
340
360
380
400
420
Depth(mbsf)
3
3
3
3
3
4
320
340
380
15
13/12
16/15
260
280
300
320
340
P. micraG. index
A. aculeataA. collacta
A. primitiva
G. triseriata
T. increbescens
?
H. primitiva
Jerboa-1(-771 m)
1134A(-701 m)
34X
35X
36X
37X
38X
39X
40X
41X
42X
43X
300
320
340
360
380
G. index
A. collactea
A. primitivaA. bullbrooki
A. aculeata
S. linaperta
Depth(mbsf) Depth
(mbsf)
360
Depth(mbsf)
mid
dle
Eoc
ene
late
Eoc
ene
Q. L
I ET A
L.E
OC
EN
E–OL
IGO
CE
NE P
LA
NK
TO
NIC F
OR
MIN
IFER
AL B
IOST
RA
TIG
RA
PH
Y2
4
Figure sequences and their boundaries(Haq e ran et al. (1997a). The four re-gional Ru1 (iii), and R4/Ch1 (iv), eachinduc
25
30
35
40
45
1132C
Wilson Bluff
Tortachilla
Tuketja
Tuit
Aldinga
Jan Juc
Regionaltransgression
Age
(M
a)
F8. Stratigraphic positioning of the Eocene–Oligocene carbonates from the Great Australian Bight in global t al., 1988; Hardenbol et al., 1998). Regional transgressions after McGowran (1979, 1986, 1989) and McGow unconformities identified coincide, respectively, with major sequence boundaries Bart-1 (i), Pr1–Pr2 (ii), Pr4/ed by a major drop in sea level. T = top, B = bottom.
23.80
25.38
27.49
28.50
29.40
32.00
33.70
34.65
36.00
37.10
39.07
42.62
Ch4/Aq1
Ch 3
Ch 2
Ru4/Ch1
Ru 3
Ru 2
Pr4/Ru1
Pr3
Pr2
Pr1
Bart1
Lu4T
RT
R
R
1126D
Eoc
ene
late
mid
dle
early
late
Olig
ocen
e
NP19/20
NP25
NN1
NP24
NP23
NP22
NP21
NP18
NP17
NP16
P21
P22
a
b
P20
P19
P18
P16
P15
P14
P12
NP15b
c
P11
Base of carbonate
Foraminiferdatums
Foraminiferzone
Nanno-fossilzone
Sequenceboundaries
1130AC
?
(iv)
(iii)
(ii)
(i)
Jerboa1
?
?
?
?
(infe
rred
)
1134A
N4? ??
? ?
B P. kugleri (23.8)
B Gq. dehiscens (23.2)
T P. opima s.s. (27.1)
B G. angulisuturalis (29.4)
T Ch. cubensis (28.5)
T T. ampliapertura (30.3)
T Pseudohastigerina (32.0)
T T. cerroazulensis (33.8)T Cr. inflata (34.0)
B T. cunialensis (35.2)
B Po. semiinvoluta (38.4)
T Gb. beckmanni (40.1)
Gs. primordius acme (24.3)
B Cr. inflata (35.5)
B Gb. beckmanni (40.5)
B Gk. index (42.9)
B P. pseudokugleri (25.9)
T Gt. labiacrassata (27.1)
T D. globularis (22.8)
B P. opima (30.6)
T Gk. index (34.3)
T A. primitiva (39.0)
T M. spinulosa (38.1)
T A. bullbrooki (40.5)
B Gs. primordius (26.7)
T Acarinina (37.5)
T S. angiporoides (30.0)
T T. frontosa (39.1)
T A. collactea (37.7)
B T. pomeroli (42.4)
B M. lehneri (43.5)
B Gb. kugleri (45.8)
T M. aragonensis (43.6)
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 25
Plate P1. 1. Acarinina cf. densa; Sample 182-1126D-27R-CC, 0–2 cm. 2, 3. Acarinina primitiva; Sample 182-1126D-26R-CC, 23–25 cm. 4. Acarinina sp.; Sample 182-1126D-26R-CC, 23–25 cm. 5, 6. Acarinina bull-brooki; Sample 182-1126D-26R-CC, 23–25 cm. 7–8. Acarinina collactea; Sample 182-1126D-24R-CC, 30–33cm. 9, 10. Globigerinatheka index; (9) Sample 182-1134A-37X–CC, 32–35 cm; (10) Sample 182-1134A-35X-CC, 0–2 cm. 11. Globigerinatheka luterbacheri; Sample 182-1126D-21R-CC, 18–19 cm. 12. Chiloguembelinacubensis; Sample 182-1134A-39X-CC, 31–34 cm. 13, 14. Catapsydrax unicavus; (13) Sample 182-1126D-27R-CC, 0–2 cm; (14) Sample 182-1126D-26R-CC, 23–25 cm. 15, 16. Globorotaloides suteri; (15) Sample 182-1134A-35X-CC, 0–2 cm; (16) Sample 182-1134A-36X-CC, 29–32 cm. 17. Globorotaloides sp.; Sample 182-1126D-22R-CC, 15–17 cm. 18. Hantkenina alabamensis; Sample 182-1126D-21R-CC, 18–19 cm. 19–22. Tur-borotalia cerroazulensis s.l.; (19, 20) Sample 182-1126D-24R-CC, 30–33 cm; (21, 22) Sample 182-1134A-39X-CC, 31–34 cm. 23. Turborotalia sp.; Sample 182-1134A-35X-CC, 0–2 cm. 24. Paragloborotalia pseudomayeri;Sample 182-1134A-37X-CC, 32–35 cm. 25, 26. Turborotalia increbescens; Sample 182-1126D-22R-CC, 15–17cm. 27. Turborotalia pseudoampliapertura; Sample 182-1126D-24R-CC, 30–33 cm. 28. Subbotina linaperta;Sample 182-1126D-21R-CC, 18–19 cm. 29. Subbotina angiporoides; Sample 182-1126D-21R-CC, 18–19 cm.30. Subbotina minima; Sample 182-1134A-36X-CC, 29–32 cm.
7 8 9 10 11
13 14 15 16 17
19 20 21 22 23
25 26 27 28 29
1 2 3 4 5
18
12
6
24
30
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 26
Plate P2. 1. Pseudohastigerina micra; Sample 182-1126D-24R-CC, 30–33 cm. 2, 3. Praetenuitella insolita; (2)Sample 182-1126D-21R-CC, 18–19 cm; (3) Sample 182-1134A-36X-CC, 29–32 cm. 4–6. Paretenuitella prae-gemma; (4) Sample 182-1126D-21R-CC, 18–19 cm; (5, 6) Sample 182-1134A-35X-CC, 0–2 cm. 7. Tenuitellagemma; Sample 182-1134A-32X-CC, 16–19 cm. 8. Tenuitellinata angustiumbilicata; Sample 182-1134A-32X-CC, 16–19 cm. 9. Tenuitella cf. pseudoedita; Sample 182-1134A-30X-CC, 22–25 cm. 10. Tenuitella munda–Tenuitellinata juvenilis transition; Sample 182-1134A-29X-CC, 18–21 cm. 11. Tenuitellinata juvenilis; Sample182-1134A-29X-CC, 18–21 cm. 12. Globigerinita naparimaensis; Sample 182-1134A-27X-CC, 34–37 cm. 13.Guembelitria triseriata; Sample 182-1134A-29X-CC, 18–21 cm. 14. Cassigerinella winniana; Sample 182-1134A-30X-CC, 22–25 cm. 15. Subbotina angiporoides; Sample 182-1134A-32X-CC, 16–19 cm. 16. Globotur-borotalita labiacrassata; Sample 182-1134A-30X-CC, 22–25 cm. 17, 18. Globoquadrina pseudovenezuelana;(17) Sample 182-1134A-32X-CC, 16–19 cm. (18) Sample 182-1134A-30X-CC, 22–25 cm. 19. Turborotaliaampliapertura; Sample 182-1134A-30X-CC, 22–25 cm. 20. Turborotalia euapertura; Sample 182-1134A-27X-CC, 34–37 cm. 21. Paragloborotalia nana; Sample 182-1134A-30X-CC, 22–25 cm. 22, 23. Paragloborotaliaopima; Sample 182-1134A-29X-CC, 18–21 cm. 24, 25. Paragloborotalia semivera; (24) Sample 182-1134A-29X-CC, 18–21 cm; (25) Sample 182-1134A-27X-CC, 34–37 cm. 26–28. Paragloborotalia pseudocontinuosa;(26) Sample 182-1134A-30X-CC, 22–25 cm; (27, 28) Sample 182-1134A-27X-CC, 34–37 cm. 29, 30. Cata-psydrax dissimilis; (29) Sample 182-1134A-27X-CC, 34–37 cm; (30) Sample 182-1134A-29X-CC, 18–21 cm.
7 8 9 10 11
13 14 15 16 17
19 20 21 22 23
25 26 27 28 29
1 2 3 4 5
18
12
6
24
30
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 27
Plate P3. 1. Globigerina ciperoensis; Sample 182-1134A-29X-CC, 18–21 cm. 2, 3. Globigerina angulisuturalis;Sample 182-1134A-27X-CC, 34–37 cm. 4. Globigerina officinalis; Sample 182-1134A-27X-CC, 34–37 cm. 5.Dentoglobigerina globularis; Sample 182-1134A-27X-CC, 34–37 cm. 6. Globoquadrina venezuelana; Sample182-1134A-27X-CC, 34–37 cm. 7. Globoquadrina tripartita; Sample 182-1134A-27X-CC, 34–37 cm. 8. Globo-quadrina praedehiscens; Sample 182-1134A-27X-CC, 34–37 cm. 9. Planktonic assemblage dominated by Glo-bigerinatheka index; Sample 182-1132C-31R-1, 144 cm. 10. Acarinina bullbrooki; Sample 182-1132C-31R-1,82 cm. 11. Subbotina linaperta; Sample 182-1132C-43R-2, 27 cm. 12. Pseudohastigerina micra (m) and a cibi-cidid form (c); Sample 182-1132C-43R-2, 27 cm. 13. Acarinina bullbrooki (b), Chiloguembelina cubensis (ch),and a subbotinid form (s); Sample 182-1132C-31R-1, 11 cm. 14. Acarinina primitiva; Sample 182-1132C-31R-1, 11 cm. 15. Acarinina primitiva; Sample 182-1132C-31R-1, 66 cm.
100 µm
200 µm
50 µm50 µm
c
m
b
ch
s
50 µm50 µm50 µm
7 8 9
10 11
1 2 4 5
12
6
13
14 15
3
Q. LI ET AL.EOCENE–OLIGOCENE PLANKTONIC FORMINIFERAL BIOSTRATIGRAPHY 28
Plate P4. 1. Globigerinatheka index (in), small globgierinids (g), and bryozoans (br); Sample 182-1132C-31R-1, 44 cm. 2. A benthic nonionid form; Sample 182-1132C-35R-1, 80 cm. 3. Acarinina sp.; Sample 182-1132C-31R-1, 82 cm. 4. Acarinina sp.; Sample 182-1132C-31R-1, 82 cm. 5. A large benthic Victoriella?; Sam-ple 182-1132C-32R-2, 78 cm. 6. Another large benthic Victoriella?; Sample 182-1132C-32R-2, 78 cm. 7. Alarge benthic Maslinella adelaidensis; Sample 182-1132C-43R-2, 27 cm.
