The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

1299 / 2024-09-20 23:48:49

Variations in paleoproductivity off northwestern Australian across the Middle Pleistocene Transition

MPT,orbital forcing,Australian Monsoon,Paleoproductivity

The Middle Pleistocene Transition (MPT, ∼1200-800ka) was characterized by a remarkable change in climate cyclicity from high-frequency 41 kyr before ∼1.2 Ma to a higher amplitude and lower frequency 100 kyr cycles. It’s still difficult to understand its driving mechanism because no significant changes in orbital forcing happened during this transition. Site U1483 (13°5.24’S, 121°48.25’E; 1733 m water depth) in the Timor Sea off NW Australia provided an ideal archive to reconstruct variations in paleoclimate prior to and following the MPT. It’s located at the southern edge of the Indo-Pacific Warm Pool (IPWP), which connects the Western Pacific Ocean and the Eastern Indian Ocean via the Indonesian Throughflow (ITF).

The upper water hydrology is not respond directly to the local precipitation but strongly responded to variations of the ITF. Previous studies of paleoclimate records over northwestern Australia more concentrated on the Holocene and the late Pleistocene. Here, I integrate analyses of different paleoproductivity proxies from Site U1483 drilled in the Timor Sea off northwestern Australia spanning the last 1.6 Ma, including Marine Isotope Stages (MIS) 53 to 1.  Paleoproductivity records consistently tracked glacial-interglacial variability over the past 1.6 Myr and displayed a distinct transition around 0.95 Ma.