Impact of the Indonesian Throughflow on northwestern Australian biochronology during the Pliocene (IDEAL).
Final Report Abstract
International Ocean Discovery Program (IODP) Expedition 356 drilled a transect across 10° latitude of seven shelf and upper slope sites (Sites U1458-U1464) off Western Australia from the Perth Basin, through the Northern Carnarvon Basin, to the Roebuck Basin with the DV Joides Resolution. One of the main objectives was documenting the evolution of the Indonesian Throughflow (ITF) since the early Pliocene, a critical component of global thermohaline circulation and a driver of the southward-flowing Leeuwin Current. The setting of Site U1463, which is located directly in the outflow of the ITF, allowed accumulation of a unique sequence of sediments constituting a high-resolution record of ITF changes since the early Pliocene. Previous studies from the Maritime Continent and from further offshore western Australia have shown that significant changes in the ITF occurred during the Pliocene. However, high-resolution records from directly within the outflow, which have the potential to not only directly link these changes to the development of aridity and the monsoon across Australia, but also to improve the biostratigraphy for the Indian Ocean and its links to the Pacific and the Atlantic. The IDEAL project aimed to improve the biostratigraphy in the eastern Indian Ocean by testing the following hypotheses that: a) Biochronology off the Northwest shelf of Australia remained similar to the equatorial Pacific until 3.3 Ma; b) The Pliocene development of the biogeography of shallow- and deep-dwelling planktonic foraminifera was distinct due to restriction of the Indonesian Throughflow. Site U1463 was selected to create a reliable, high-resolution and orbitally-tuned reference record to put biostratigraphic datums on an independent timescale. Stable oxygen and carbon isotopes were analysed on a species of benthic foraminifera (Uvigerina spp.) and analysed for dominant orbital cyclicities like eccentricity and obliquity, which are controlling longterm climate changes. The resulting age model shows that many of the biostratigraphic datums for the NWS, both for shallow- and deep dwelling foraminifera are already different from those in the Pacific by the early Pliocene. This is earlier than the large paleoceanographic changes related to the ongoing restriction of the Indonesian Throughflow have reconstructed before, and may indicate that the exchange of water masses from the Pacific to the Indian Ocean decreased/shoaled earlier than was known.
Publications
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Australian climate controlled by the East Antarctic ice sheet dynamics during the Miocene. Science Advances 3, e1602567
Groeneveld, J., J. Henderiks, W. Renema, C.M. McHugh, D. De Vleeschouwer, B.A. Christensen, C.S. Fulthorpe, L. Reuning, S.J. Gallagher, K. Bogus and Expedition 356 Scientists
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The amplifying effect of Indonesian Throughflow heat transport on Late Pliocene Southern Hemisphere climate cooling. Earth Plan. Sci. Lett. 500. 15-27
De Vleeschouwer, D., G. Auer, K. Bogus, B. Christensen, J. Groeneveld, B. Petrick, J. Henderiks, I.S. Castañeda, E. O'Brien, S.J. Gallagher, C.S. Fulthorpe, H. Pälike
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Indonesian Throughflow drove Australian climate from humid Pliocene to arid Pleistocene. Geophys. Res. Lett., 44
Christensen, B.A., W. Renema, J. Henderiks, D. De Vleeschouwer, G. Auer, L. Reuning, J. Groeneveld, I. Castañeda, T. Ishiwa, K. Bogus, C.M. McHugh, S.J. Gallagher, C.S. Fulthorpe, and Exp. 356 Scientists
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The enigma of rare Quaternary oolites in the Indian and Pacific Oceans: a result of global oceanographic physicochemical conditions or a sampling bias?. QSR
Gallagher, S., L. Reuning, T. Himmler, J. Henderiks, D. De Vleeschouwer, J. Groeneveld, A. Rastigar, C. Fulthorpe, K. Bogus, Exp. 356 Scientists
