Earth’s climate during the Plio-Pleistocene was characterized by a significant change from warmer-than-present conditions before 3 Ma to a global cooling trend with rhythmic glacial-interglacial cycles. Feedbacks associated with variability of the West Antarctic Ice Sheet have been implicated in amplifying this cooling, but its exact role within this framework remains uncertain due to lack of continuous proximal records. Sediment cores U1524A, recently drilled by International Ocean Discovery Program (IODP) Expedition 374, consist of an almost continuous Plio-Pleistocene sedimentary sequence. In this study, we refine the originally noisy shipboard magnetostratigraphy of U1524A using a statistical approach. Based on the refined age-depth model, we show that the low coercivity NRM component of Hole U1524A captures major climate transitions over the past 3.3 Myr and that its variations in intensity are indicative of changes in terrigenous material transported to the drill site, which is potentially linked to the glacial history of the West Antarctic Ice Sheet advancing and retreating across the Ross Sea continental shelf. Our improved chronology can provide an important foundation for future studies of U1524A for reconstructing the Plio-Pleistocene Antarctic glacial history, Ross Sea water mass variability, and high-latitude geomagnetic field variability.

Ross Sea, West Antarctic Ice Sheet, environmental magnetism, geochronology