4 High latitude paleoceanographic discoveries from Scientific Ocean Drilling (IODP, ODP, DSDP)

Scientific Ocean Drilling has retrieved thousands of meters of sediment cores from the high latitude oceans.  This session provides the opportunity to present the results of work to understand Cenozoic climate and oceanographic changes.

Sunday, 22 March 2026
8:00 AM - 12:00 PM
CCC, Room 27

Major Shifts in Antarctic Ice Sheet Calving Through the Onset of Extensive Bipolar Glaciation

Paper number: 4-7
Program: Technical Sessions
Time: 10:00 AM – 10:20 AM

Authors

Abstract

Marine sediments from International Ocean Discovery Program (IODP) Site U1537, located in the Scotia Sea’s “Iceberg Alley,” capture Antarctic Ice Sheet (AIS) variability at sub-orbital resolution across the Plio-Pleistocene Transition (2.58 Ma), a global climatic shift culminating in continental-scale bipolar glaciation. Here we present a record of ice-rafted debris mass accumulation rates (IRD MAR) and provenance from 3.35 –1.75 Ma to reconstruct changes in integrated and sectoral AIS stability. We find that the Dronning Maud Land sector of the East Antarctic Ice Sheet (EAIS) is the dominant source of debris-rich icebergs to the Scotia Sea for much of this interval. A pronounced shift in AIS calving, characterized by increased ice-rafting frequency and westward provenance expansion into Coates Land, occurs at Marine Isotope Stage G6, coincident with southward expansion of Northern Hemisphere marine-terminating margins. From 2.4 –2.1 Ma, a significant decrease in ice rafting is observed as EAIS-sourced debris disappears, with IRD instead sourced from the West Antarctic Ice Sheet, Antarctic Peninsula, and Weddell Sea Embayment. This interval is accompanied by a pronounced increase in biogenic silica as recorded by shipboard physical property measurements, split-core X-ray fluorescence (XRF) counts, and diatom counts. We interpret this ~300-kyr, diatom-rich, low-IRD interval as reflecting extreme warming resulting in a highly retreated EAIS margin, thus unable to contribute IRD to Site U1537. Because this warming is not expressed in globally integrated ice-volume proxies, our results indicate that regional atmospheric and/or oceanographic processes exerted a dominant control on AIS calving through this period. Spectral analysis of IRD MAR further reveals significant eccentricity power throughout the record, highlighting a dynamic Plio-Pleistocene AIS with sensitivity to atmospheric forcing through eccentricity modulation of local peak summer insolation.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411286

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