Marine isotope stage M2 (~3.3 Ma) in the southern hemisphere: constraining the climatic drivers of a short-term glaciation event during the mid-Pliocene warm Period.

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Between 3.5 and 3.0 Ma, global climate was characterized by exceptional climate variability. A brief (<100 kyr) but intense glaciation interrupted the relatively warm climate of the Pliocene around 3.3 Ma. Until today, different hypotheses exist to explain why this glaciation event was so intense, and why the global climate system returned to warm Pliocene conditions relatively quickly. One of these proposed mechanisms is a reduced heat flow, from the low towards the high latitudes and from the Pacific to the Indian Ocean, through the Indonesian seaway. The flow through this seaway became restricted between 4 and 3 Ma because of the northward movement of the Australian continent and the uplift of the maritime continent (New Guinea and Indonesia). This proposal aims to evaluate this leading hypothesis by generating a 2-3 kyr resolution planktonic foraminiferal oxygen isotope record for the interval 3.5 - 3.0 Ma for Site U1463. Site U1463 was drilled during International Ocean Discovery Program Expedition 356 Indonesian Throughflow in September 2015 on the Northwestern Australian Shelf, and is located exactly at the outflow of the Indonesian seaway. When compared to the existing planktonic foraminiferal oxygen isotope record from Site 806 in the western equatorial Pacific, the newly generated record for Site U1463 will provide a unique opportunity to evaluate the role of the Indonesian seaway in regulating the heat flow between the Pacific and Indian Ocean.