The Cenozoic Southern Ocean: Tectonics, Sedimentation, and Climate Change Between Australia and Antarctica

367 Pages·28.779 MB·English

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Geophysical Monograph 151
The Cenozoic Southern Ocean:
Tectonics, Sedimentation, and
Climate Change Between
Australia and Antartica
Neville F. Exon
James P. Kennett
Mitchell J. Malone
Editors
88 American Geophysical Union
Washington, DC 2004
Published under the aegis of the AGU Books Board
Jean-Louis Bougeret, Chair, Gray E. Bebout, Cari T. Friedrichs, James L. Horwitz, Lisa A. Levin, W. Berry Lyons,
Kenneth R. Minschwaner, Andy Nyblade, Darrell Strobel, and William R. Young, members.
Library of Congress Cataloging-in-Publication Data
The Cenozoic Southern Ocean : tectonics, sedimentation, and climate change between Australia and Antarctica / Neville
F. Exon, James P. Kennett, Mitchell J. Malone, editors,
p. cm. ~ (Geophysical monograph ; 151)
Includes bibliographical references.
ISBN 0-87590-416-5 (alk. paper)
1. Geology, Structural-Antarctic Ocean. 2. PaleocUmatology-Cenozoic. 3. Climatic changes-Antarctic Ocean. 4.
Antarctic Ocean-Climate. 5. Marine sediments-Antarctic Ocean. I. Exon, N. F. H Kennett, James P. HI. Malone,
Mitchell J., 1962- IV. Series.
QE690.C437 2004
551.7,8'09167-dc22
2004062267
ISBN 0-87590-416-5
ISSN 0065-8448
Copyright 2004 by the American Geophysical Union
2000 Florida Avenue, N. W.
Washington, DC 20009
Front and back cover: Three-dimensional topographic image of the Tasmanian Gateway showing the tectonic
features of the region: the main continental blocks that dispersed to form the Southern Ocean (opening direction
shown by arrows on back cover detail); the Antarctic Circumpolar Current that led to the global climate change; and
the locations of the ODP Leg 189 sites (courtesy Peter J. Hill, Petroleum and Marine Division,Geoscience Australia).
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CONTENTS
Preface vii
Introduction
Neville F. Exon, James R Kennett, and Mitchell J. Malone 1
Cretaceous Through Cenozoic
Cenozoic Reconstructions of the Australia-New Zealand-South Pacific Sector of Antarctica
Steven C. Cande and Joann M. Stock 5
Tectonics and Basin Development of the Offshore Tasmanian Area Incorporating Results
From Deep Ocean Drilling
Peter J. Hill and Neville E Exon 19
Cenozoic Environments in the Tasmanian Area of the Southern Ocean (ODP Leg 189):
Inferences From Bulk and Clay Mineralogy
Christian Robert 43
On the Magnetostratigraphy of the East Tasman Plateau, Timing of the Opening of
the Tasmanian Gateway and Paleoenvironmental Changes
Mike Fuller and Yannick Touchard 63
Magnetostratigraphy of the Pliocene-Pleistocene Sequence and of the Eocene-Oligocene
Transition at ODP Leg 189 Hole 1168
Y. Touchard and M. Fuller 79
Eocene And Older
The Cretaceous/Paleogene Transition on the East Tasman Plateau, Southwestern Pacific
Stephen A. Schellenberg, Henk Brinkhuis, Catherine E. Stickley, Michael Fuller, Frank T. Kyte,
and Graham L Williams 93
On the Search for the Paleocene/Eocene Boundary in the Southern Ocean: Exploring ODP
Leg 189 Holes 1171D and 1172D, Tasman Sea
Ursula Rohl, Henk Brinkhuis, Appy Sluijs, and Mike Fuller 113
Sea Level and Astronomically Induced Environmental Changes in Middle and Late Eocene
Sediments From the East Tasman Plateau
Ursula Rohl, Henk Brinkhuis, Catherine E. Stickley, Mike Fuller, Stephen A. Schellenberg,
Gerold Wefer, and Graham L. Williams 127
A Chemostratigraphic and Geochemical Facies Analysis of Strata Deposited in an Eocene
Australo-Antarctic Seaway: Is Cyclicity Evidence for Glacioeustasy?
Timothy 5. White 153
Oligocene And Younger
Changes in South Ocean Circulation in Late Oligocene to Early Miocene Time
Helen A. Pfuhl, I. Nicholas McCave, Stephen A. Schellenberg, and Patrizia Ferretti 173
Quantitative Miocene Calcareous Nannofossil Biostratigraphy From the Tasmanian Gateway
Kristeen L McGonigal 191
Early to Middle Miocene Paleoceanography in the Southern High Latitudes Off Tasmania
Atsuhito Ennyu and Michael A. Arthur 215
Paleocenographic Change During the Middle Miocene Climate Revolution: An Antarctic
Stable Isotope Perspective
A.E. Shevenell andJ.P Kennett 235
Late Neogene History of Paleoproductivity and Ice Rafting South of Tasmania
Liselotte Diester-Haass and Stefan Nees 253
A Deep-Sea Record of the Late Miocene Carbon Shift From the Southern Tasman Sea
R.A. Tedford and D. C. Kelly 273
Paleo-Export Production, Terrigenous Flux and Sea Surface Temperatures Around Tasmania—
Implications for Glacial/lnterglacial Changes in the Subtropical Convergence Zone
Dirk Nurnberg, Natasja Brughmans, Joachim Schdnfeld, Ulysses Ninnemann, and
Christian Dullo 291
Syntheses
Tectono-Sedimentary History of Uppermost Cretaceous Through Oligocene Sequences From
the Tasmanian Region, A Temperate Antarctic Margin
Neville F. Exon, Henk Brinkhuis, Christian M. Robert, James P. Kennett, Peter). Hill and
Michael K. Macphail 319
Paleoceanographic Evolution of the Tasmanian Seaway and its Climatic Implications
James P. Kennett and Neville F. Exon 345
Preface
Ocean circulation and hence global climate are nowhere continental blocks together form one of the few locations
more strongly changed than through the opening or closing in the Southern Ocean where almost complete marine
of gateways or seaways that link major oceans. The break-up Oligocene to recent carbonate-rich sequences can be cored at
of Gondwana, and the northward flight of its continental present-day latitudes of 40-50°S, and paleolatitudes of up to
fragments from Antarctica, is a case in point. Profound cli­ 70°S. These little-altered carbonates are ideal for the stable
matic consequences resulted from shifts in ocean and atmos­ isotopic and faunal investigations so fundamental in under­
pheric circulation due to drastic changes in global geography. standing paleoceanographic and climatic evolution. In early
During the Cenozoic, the northward flight of southern 2000, Ocean Drilling Program (ODP) Leg 189 recovered
continents led to the opening of gateways at southern high 4500 m of continuous to nearly continuous sedimentary
latitudes while progressively restricting and closing gateways records from several deepwater sites off Tasmania, to provide
in the low latitudes. Considerable previous research has much improved definition of the sequence of paleoclimatic
dealt with the opening and expansion of the two Cenozoic and paleoceanographic events through this gateway and to
gateways - the Tasmanian Gateway south of Australia and test hypotheses that might account for such change. The
the Drake Passage south of America - which allowed the resulting sedimentary sequences provide an essentially con­
Antarctic Circumpolar Current (ACC) to develop and tinuous record of ocean and climate change over the last 75
progressively isolate Antarctica thermally. It is generally million years, since the Late Cretaceous.
accepted that full opening of the Tasmanian Gateway Along the southern Australian and facing Antarctic
occurred earlier than that of Drake Passage, although the margins, detrital siliciclastic sediments were deposited in
time of opening of Drake Passage remains controversial. Cretaceous through Eocene rift basins in generally warm
It has long been proposed that a climatic threshold leading conditions as Gondwana broke up. When the Tasmanian
to major initial Antarctic ice sheet accumulation occurred Gateway opened over the Eocene/Oligocene boundary, the
during the Eocene-Oligocene transition as the Tasmanian onset of the ACC formed an erosional and non-depositional
Gateway opened, triggering ACC formation and resultant hiatus that can be traced from the Tasmanian region to east of
thermal isolation of the Antarctic continent (Gateway New Zealand. Thereafter, strong thermal zonation came into
Hypothesis). South of Australia, Paleogene rifting slowly force: glacial siliciclastic sediments or diatomites became
opened the Australo-Antarctic Gulf, but the Indian and typical for the Antarctic margin, but cool water carbonates
Pacific Oceans remained separated by the Tasmanian land were deposited on the southern Australian and New Zealand
bridge until the latest Eocene, preventing earlier development margins.
of the ACC; waters derived from low latitudes efficiently The contributions in this volume consider regional tectonic
transported heat towards the Antarctic continent, contribut­ changes that likely drove paleoceanographic and climatic
ing to the maintenance of global greenhouse conditions. change; related shifts in sediment patterns, geochemistry and
Early ocean drilling in the Tasmanian Gateway between biota; and paleoenvironmental changes related to the cooling.
Australia and Antarctica provided a basic framework of Many draw heavily on results of ocean drilling, but combine
paleoenvironmental changes associated with the opening, but this with other geological, geophysical and paleoceano­
stratigraphic resolution was too limited to fully test potential graphic information from the Australian sector of the
interrelationships of plate tectonics, circum-polar circulation Southern Ocean. The contributions provide new insights into
and global climate. So, until recently, the timing of events major climatic events including the Paleocene and Eocene
has been inadequately constrained. warm interval, a late Eocene transitional period, and major
The Tasmanian region, including the South Tasman Rise, and important cooling shifts that occurred during the
is ideally suited for studies of the opening and later expan­ Oligocene, Miocene and Quaternary. A broad suite of tec­
sion of the Tasmanian Gateway. The relatively shallow tonic, sedimentological, paleobiological, sedimentary and
geochemical skills are drawn on in the various contributions,
and the syntheses bring together key results and interpreta­
The Cenozoic Southern Ocean: Tectonics, Sedimentation, and
tions for a broader audience.
Climate Change Between Australia and Antarctica
Geophysical Monograph Series 151 The volume is clearly structured, with syntheses presented
Copyright 2004 by the American Geophysical Union. first, followed by other papers in an order designed to best
10.1029/151GM00 illustrate the sequence of change through the geological time
vii
viii PREFACE
scale toward the present: those that cover the full Cretaceous in an ever more complex world of science. As ever, the
to Quaternary range; then those related to Cretaceous reviewers are the unsung heroes in such a collection of
through Eocene siliciclastic sedimentation; and finally those scientific papers and we thank them for their considerable
related to Neogene and Quaternary pelagic carbonate efforts. We greatly appreciate the support of the AGU staff
sequences. in making this book a reality, and especially the advice
We editors thank the authors, who have written a valuable and support of Allan Graubard, AGU's books acquisitions
collection of papers and who did their best to meet deadlines editor.
Neville Exon
Geoscience Australia
Canberra
James P. Kennett
Department of Geological Sciences and Marine
Science Institute
University of California Santa Barbara
Mitchell Malone
Integrated Ocean Drilling Program
Texas A&M University
Introduction
Neville Exon
Geoscience Australia, Canberra, Australia
James Kennett
Department of Geological Sciences, University of California Santa Barbara, California, USA
Mitchell Malone
Integrated Ocean Drilling Program, Texas A&M University, College Station, Texas, USA
The aim of this volume is to document Late Cretaceous cryosphere developed as the Antarctic Circumpolar Current
and Cenozoic changes that occurred in the Australian sector (ACC) progressively thermally isolated the Antarctic conti­
of the Southern Ocean as Gondwana broke up, and the nent. This current resulted from the opening of the Tasmanian
Australian plate drifted northward, severing the last con­ Gateway south of Tasmania during the Oligocene, and the
nection between Australia and Antarctica and leading to Drake Passage south of South America somewhat later. This
initial development and later expansion of the Antarctic proposed mechanism for driving global cooling is currently
Circumpolar Current. Changes in this region profoundly under debate, with some global modellers unconvinced that
affected global climate, and the nature of regional sedimen­ the opening of the Tasmanian Gateway at 33.5 Ma, and
tation, oceanographic patterns, water temperatures, and land inferred thermal isolation caused by the onset of the ACC, trig­
and marine floras and faunas. Their studies have allowed the gered major Antarctic ice sheet accumulation and associated
authors of contributions in this volume to further examine global cooling at the beginning of the Oligocene [De Conto
driving mechanisms behind Cenozoic cooling and its many and Pollard, 2003]. These modellers argue instead that cool­
fluctuations. ing was caused by decline in atmospheric carbon dioxide con­
The nature of climatic change during the Cenozoic Era tent, but did not present a convincing mechanism to explain
has been unravelled over many years, with a major leap for­ that inferred decline. We suggest it improbable that there was
ward coming from the pioneering oxygen isotope studies of synchronous but unrelated opening of the Tasmanian
foraminifera in Cenozoic deep sea cores by Emiliani [1961]. Gateway, onset of the ACC, decline in atmospheric carbon
This and later studies demonstrated that progressive high- dioxide and major expansion of Antarctic glaciation. Complex
latitude cooling during the Cenozoic eventually formed feedback mechanisms were almost certainly at work.
major ice sheets, initially on Antarctica and later in the It is well established [e.g. Miller et al. 1991; Zachos et al,
Northern Hemisphere. This work raised the next question 2001] that there were three broad Cenozoic climatic phases:
which was "what drove this climate change?" Kennett the warm "Greenhouse" climate from Cretaceous times
[1977], using more detailed deep sea oxygen isotope curves through the end of the Eocene (33.5 Ma); a period of fluctu­
from planktonic and benthonic foraminifers in Southern ating "Doubthouse" climate and variable development of the
Ocean ocean drilling cores (Shackleton and Kennett, 1975), East Antarctic ice sheet, commencing with the cold period at
proposed the hypothesis that climatic cooling and an Antarctic the beginning of the Oligocene and continuing until the
middle Miocene (-14 Ma); followed by the cold "Icehouse"
climate related to major expansion of the East Antarctic ice
The Cenozoic Southern Ocean: Tectonics, Sedimentation, and
sheet and the formation of the West Antarctic and northern
Climate Change Between Australia and Antarctica
Geophysical Monograph Series 151 hemisphere ice sheets and continuing until the present day.
Copyright 2004 by the American Geophysical Union. However, more thorough documentation of events in key
10.1029/151GM01 regions during the Cenozoic has long been required to further
1
2 INTRODUCTION
address questions of mechanisms that created these global high-latitude climate zones, through study of pelagic car­
climatic shifts. Part of the value of such documentation is the bonate sequences.
view that understanding past oceanographic and climate An understanding of Cenozoic climate evolution requires
changes and their driving mechanisms leads to better pre­ better knowledge of the timing, nature, and responses of the
diction of near future climatic responses due to natural and Paleogene opening of the Tasmanian Gateway. Early ocean
human-driven changes - a matter of universal concern. drilling in the seaway [Kennett, Houtz et al, 1975] provided
Climate changes are considered to be driven in part by a basic framework of paleoenvironmental changes associ­
changes in plate-tectonic configurations, and especially the ated with its opening, but was of insufficient quality and reso­
opening and closing of oceanic gateways as these affect lution to fully test the hypothesis of potential relationships
ocean and atmospheric circulation, and in part by long-term between plate tectonics, circumpolar circulation, and global
changes in carbon dioxide levels and other greenhouse gases climate. The drilling of ODP Leg 189 was designed to study
in the atmosphere (but what drives such changes?). Other the opening and later expansion of the Tasmanian Gateway
factors are orbital forcing and methane release from gas in the necessary detail to more fully address the Cenozoic
hydrates or sequestration in them. climate questions outlined above. The relatively shallow
We continue to employ and test the Gateway Hypothesis region off Tasmania was mostly above the present car­
that the opening of the Tasmanian Gateway and Drake bonate compensation depth throughout the Cenozoic, so is
Passage and subsequent expansion of the ACC system in­ strategically well located for studies of marine Eocene to
deed played a major role in Cenozoic cooling. This cooling Holocene sequences containing foraminifera and calcareous
came in part by the ACC isolating Antarctica from warm nannofossils, so vitally important for paleoceanographic
gyral surface circulation of the Southern Hemisphere investigations. The South Tasman Rise can be considered as
oceans, and also by providing necessary conduits that even­ a contiguous part of Antarctica until final severance at
tually led to ocean conveyor circulation between the north 33.5 Ma. During the Paleogene, paleolatitudes of the South
Atlantic and north Pacific Oceans. Both factors, in con­ Tasman Rise were as high as 70°S compared with today's
junction with positive feedbacks and other changes in the latitudes of 43-48°S. Yet at the still high latitudes of the
global system, were crucial for the development of the polar South Tasman Rise in the early Oligocene, carbonate bio­
cryosphere, initially in Antarctica during the Paleogene and genic sediments began to be deposited, providing crucial
earlier Neogene, and later in the Northern Hemisphere information on early gateway evolution.
during the latest Neogene. Furthermore, the continued expan­ A three-fold subdivision was apparent in the fairly com­
sion of the Southern Ocean during the Cenozoic, because of plete Upper Cretaceous to Holocene sequences drilled on
the northward flight of Australia from Antarctica, has clearly Leg 189 [Exon, Kennett, Malone et al, 2001; Exon et al.,
led to further evolution of Earth's environmental system and 2004]. Shallow-marine mudstones characterize the Upper
of oceanic biogeographic patterns. Cretaceous to middle Eocene sequences that were drilled
The offshore area between Australia's southernmost only east of the barrier between the Indian and Pacific
prolongation - Tasmania and the South Tasman Rise (STR) - Oceans. In the late Eocene, winnowed glauconitic marine
and Antarctica is a key to understanding Cenozoic changes siltstones dominated: west of the barrier the warmer and
in global climate and current patterns and for testing the more restricted environment is reflected in the cores. In the
Gateway Hypothesis. This region provides critical opportu­ Oligocene, despite the opening of the Tasmanian Gateway,
nities to investigate the potential effects of Eocene- the Indian Ocean cores remain different in that they are more
Oligocene separation of Australia and Antarctica on global clayey and were deposited in shallower water than the
paleoceanography. Australia and Antarctica were still locked pelagic carbonates in the Pacific Ocean. Thereafter, pelagic
together in the Tasmanian area until late in the Eocene, carbonates in both oceans faithfully record Neogene changes
preventing the establishment of Antarctic circumpolar circu­ as Australia moved steadily northward.
lation. At that time, and earlier, the water masses were sepa­ Although the results of Leg 189 are important to the study
rated by a barrier between the southern Indian and Pacific of the Cenozoic tectonic, climatic, oceanographic and biotic
Oceans. In the Tasmanian region, one would predict dif­ evolution of the Southern Ocean, the contributions in this vol­
ferences in physical, chemical, and biological properties, ume include results from many other sources and with a wider
because of greater restriction of the water mass and deposi- geographic extent. Two syntheses deal with (1) the Cretaceous
tional conditions west of the barrier in the narrow Australo- and Paleogene interplay of tectonics and sedimentation in the
Antarctic Gulf (AAG). The region is also well suited for region; (2) Paleoceanographic evolution of the Tasmanian
the study of post-Eocene development of Southern Ocean Seaway and its climatic implications, including a review of
climate, feedbacks that contribute to ice-sheet develop­ the regional Cenozoic biogeography of calcareous plankton.
ment and increased stability, and formation and variation of Key questions remain how and when the gateways opened.