Sea level and astronomically induced environmental changes in middle and late Eocene sediments from the East Tasman Plateau

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doi: 10.1029/151GM09
Author(s): Röhl, Ursula; Brinkhuis, Henk; Stickley, Catherine E.; Fuller, Michael; Schellenberg, Stephen A.; Wefer, Gerold; Williams, Graham L.
Author Affiliation(s): Primary:
Bremen University, Geosciences Department, Bremen, Federal Republic of Germany
University of California at Santa Barbara, United States
Texas A&M University, United States
Utrecht University, Netherlands
Lamont-Doherty Earth Observatory, United States
University of Hawaii at Manoa, United States
San Diego State University, United States
Geological Survey of Canada, Canada
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.127-151. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0065-8448. ISBN: 978-1-118-66621-0 CODEN: GPMGAD
Note: In English with English summary. 50 refs.; illus., incl. sketch map
Summary: Eocene sediments drilled at the East Tasman Plateau (ETP) exhibit well-defined cycles, high-resolution magnetic stratigraphy, and environmentally-controlled dinoflagellate and diatom distribution patterns. We derive a cyclostratigraphy from the spectral analysis of high-resolution elemental concentration records (Ca, Fe) for this shallow marine time series spanning the middle to early late Eocene (C16n.2n-C21). Changes in carbonate content, the ratio between Gonyaulacoid and Peridinioid dinocysts, and relative abundance of "oligotrophic" diatoms serve as proxies for a high-resolution climatic and sea-level history with high values representing high sea-level stands and decreased eutrophy of surface waters. Changing ratios between high latitude dinocysts versus cosmopolitan species provide clues on sea surface temperature trends and water mass exchange. Our results show that the relatively shallow-water middle Eocene environments of the ETP are influenced by orbitally-forced climatic cycles superimposed on third order relative sea-level changes. Changes in the dominance of Milankovitch frequency at ∼38.6 Ma (late Eocene) is related to an initial deepening-step within the Tasmanian Gateway prior to the major deepening during the middle late Eocene (∼35.5 Ma). Decreasing sedimentation rates at 38 Ma and 37.2 Ma reflect winnowing associated with sea-level fall. This episode is followed by renewed transgression. Dinocyst distribution patterns indicate high latitude, probably cool temperate surface water conditions throughout, with the exception of a sudden surge in cosmopolitan species near the base of subchron C18.2r, at ∼41 Ma; this event is tentatively correlated to the Middle Eocene Climatic Optimum.
Year of Publication: 2004
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Biostratigraphy; Cenozoic; Climate forcing; Cyclostratigraphy; Depositional environment; Diatoms; Dinoflagellata; East Tasman Plateau; Eocene; Leg 189; Magnetostratigraphy; Marginal seas; Marine environment; Microfossils; Middle Eocene; Milankovitch theory; ODP Site 1172; Ocean Drilling Program; Orbital forcing; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Paleoenvironment; Paleogene; Palynomorphs; Plantae; Sea-level changes; Shallow-water environment; South Pacific; South Tasman Rise; Southwest Pacific; Tasman Sea; Tasmanian Gateway; Tertiary; Transgression; Upper Eocene; West Pacific
Coordinates: S435800 S435700 E1495600 E1495500
Record ID: 2005035028
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