Unknown
PANGAEA
In:
Supplement to: Röhl, Ursula; Brinkhuis, Henk; Stickley, Catherine E; Fuller, Michael D; Schellenberg, Stephen A; Wefer, Gerold; Wiliams, Graham L (2004): Sea level and astronomically induced environmental changes in middle and late Eocene sediments from the East Tasman Plateau. In: Exon, NF, Kennett, JP & Malone, M (eds.) The Cenozoic Southern Ocean: Tectonics, Sedimentation, and Climate Change Between Australia and Antarctica. American Geophysical Union (AGU), Geophysical Monograph Series, 151, 127-151, https://doi.org/10.1029/151GM09
Publication Date:
2024-01-09
Description:
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.
Keywords:
Ocean Drilling Program; ODP
Type:
Dataset
Format:
application/zip, 5 datasets
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