147-12 Tracking Antarctic Ice Sheet Variability During the Mid-Pleistocene Transition Using Ice-Rafted Debris (IRD)

Session: Climate, Ocean and Environmental Changes Through Earth History: From Marine and Terrestrial Proxies to Model Assessments (Posters)

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The Mid-Pleistocene Transition (MPT, ~1.2-0.8 Ma) marked a significant change in Earth's climate system, with glacial-interglacial cycles shifting from a periodicity of 41,000 to 100,000 years and glacial periods becoming more intense. Despite the significance of this event, the exact mechanisms that prompted this shift remain debated. In this study, we analyze relative ice-rafted debris (IRD) abundance in sediments from Ocean Drilling Program (ODP) site 745B in the Indian Ocean sector of the Southern Ocean. IRD was quantified through grain counts of the >250 μm fraction at a temporal resolution of 10 Kya spanning 1.117-1.793 Ma. We compare the IRD abundance to the global LR04 benthic δ¹⁸O stack to examine links between Antarctic ice sheet dynamics and global climate variability. This record will be compared to other IRD records from the region spanning this time interval to gain a more comprehensive understanding of Antarctic Ice Sheet dynamics. Our study finds that some IRD maxima occur during glacial periods, while others occur during interglacial periods. This suggests that multiple mechanisms for IRD transport and deposition are at play. This supports previous studies, which document a sedimentary cyclicity tied to glacial-interglacial climate changes, with terrigenous input and IRD peaks corresponding to interglacial intervals (Ehrmann and Grobe, 1991). By tracking changes in IRD abundance across the MPT, this study aims to clarify how Antarctic iceberg calving events respond to major climatic events.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10210

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