Paleoceanographic evolution of the Tasmanian Seaway and its climatic implications

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doi: 10.1029/151GM19
Author(s): Kennett, James P.; Exon, Neville F.
Author Affiliation(s): Primary:
University of California at Santa Barbara, Department of Geological Sciences, Santa Barbara, CA, United States
Other:
University of California at Santa Barbara, United States
Texas A&M University, United States
Geoscience Australia, Australia
Volume Title: Cenozoic Southern Ocean; tectonics, sedimentation, and climate change between Australia and Antarctica
Volume Author(s): Exon, Neville F., editor; Kennett, James P.; Malone, Mitchell
Source: The Cenozoic Southern Ocean; tectonics, sedimentation, and climate change between Australia and Antarctica, edited by Neville F. Exon, James P. Kennett and Mitchell Malone. Geophysical Monograph, Vol.151, p.345-367. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0065-8448. ISBN: 978-1-118-66621-0 CODEN: GPMGAD
Note: In English. 147 refs.; strat. col., sect., 1 table, sketch maps
Summary: The opening or closing of major oceanic gateways or seaways through plate tectonics can significantly change surface and/or deep ocean circulation. This clearly has led to fundamental changes in the Earth's environmental system, global climate, and marine and terrestrial biogeography. Ocean circulation changes resulting from gateway development can significantly affect global heat transfer, and thus climate. However, these climatic effects should be considered within an Earth System context involving a variety of integrated environmental feedbacks. The opening of the Tasmanian Gateway during the Eocene-Oligocene transition, and later Seaway expansion, led to critical changes in Southern Hemisphere Ocean circulation resulting from the development of the Antarctic Circumpolar Current (ACC). Gateway opening initiated thermal isolation of Antarctica leading to the crossing of a major global climatic threshold and to significant Antarctic ice expansion. Much of this climate change resulted, not from circulation changes alone, but through environmental feedback mechanisms associated with ice expansion and cooling. These included increased albedo, ice sheet elevation, atmospheric changes, increased Southern Ocean productivity, and intensification of thermohaline circulation leading to expansion of deep cold waters. Cooling of the deep ocean and the continents also likely led to decreased atmospheric greenhouse gases CO2 and CH4 that, in turn, contributed to pronounced cooling in the earliest Oligocene. Antarctic circumpolar circulation continued to strengthen during the Oligocene through early Neogene in response to further Seaway expansion, increasing thermal isolation of Antarctica and related development of the Antarctic System. (modif. j. abstr.)
Year of Publication: 2004
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Antarctic Circumpolar Current; Antarctic ice sheet; Antarctica; C-13/C-12; Carbon; Cenozoic; Climate change; Cooling; Diatoms; Dinoflagellata; Discoasteridae; Drake Passage; East Antarctic ice sheet; East Australian Current; Foraminifera; Glaciation; Global change; Greenhouse effect; Heat transfer; Ice sheets; Icehouse effect; Invertebrata; Isotope ratios; Isotopes; Land bridges; Leg 189; Marine environment; Microfossils; Miospores; Nannofossils; O-18/O-16; ODP Site 1168; ODP Site 1170; ODP Site 1171; ODP Site 1172; Ocean Drilling Program; Ocean circulation; Organic carbon; Oxygen; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Paleotemperature; Palynomorphs; Plantae; Pollen; Productivity; Protista; Radiolaria; South Pacific; Southern Ocean; Southwest Pacific; Spores; Stable isotopes; Tasman Current; Tasmanian Gateway; Tertiary; Thermohaline circulation; West Antarctic ice sheet; West Pacific
Coordinates: S423700 S423600 E1442500 E1442400
S483000 S482900 E1490700 E1490600
S471000 S470900 E1460300 E1460200
S435800 S435700 E1495600 E1495500
Record ID: 2005035038
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