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Dating the northwest shelf of Australia since the Pliocene
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  • Jeroen Groeneveld,
  • David De Vleeschouwer,
  • Jackson, C. McCaffrey,
  • Stephen John Gallagher
Jeroen Groeneveld
University of Bremen

Corresponding Author:jgroenev@uni-bremen.de

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David De Vleeschouwer
MARUM, University Bremen
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Jackson, C. McCaffrey
School of Earth Sciences
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Stephen John Gallagher
University of Melbourne
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Accurate dating of marine sediments is essential to reconstruct past changes in oceanography and climate. Benthic foraminiferal oxygen isotope series from such sediments record long-term changes in global ice volume and deep-water temperature. They are commonly used in the Plio-Pleistocene to correlate deep ocean records and to construct age models. However, continental margin settings often display much higher sedimentation rates due to variations in regional depositional setting and local input of sediment. Here, it is necessary to create a regional multi-site framework to allow precise dating of strata. We create such a high-resolution regional framework to determine the ages of events for the Northwest Shelf (NWS) of Australia, which was cored by International Ocean Discovery Program (IODP) Expedition 356. We employ benthic foraminiferal oxygen and carbon isotopes to construct an astronomically-tuned age model for IODP Site U1463. The age model is applied to the IODP Site U1463 downhole-logging natural gamma radiation (NGR) depth-series, which was then correlated to the NGR of other IODP sites and several industry wells in the area. The IODP Site U1463 age-depth model provides geologic time anchors for numerous sedimentary archives on the NWS. This approach allows assigning ages to regional seismic reflectors and the timing of key climate-related siliciclastic phases in a predominantly carbonate-rich sequence like the Bare Formation. Finally, this age model is used to chronologically calibrate planktonic foraminiferal biostratigraphic datums showing that the Indonesian Throughflow had shoaled enough during the early Pliocene to act as biogeographical barrier between the Pacific and Indian Ocean.
Mar 2021Published in Geochemistry, Geophysics, Geosystems volume 22 issue 3. 10.1029/2020GC009418