Neoglacial readvance of the East Antarctic Ice Sheet to the northern Drygalski Basin (western Ross Sea)

Abstract Our study investigates late Holocene ice-sheet activity in the northern Drygalski Basin (western Ross Sea) using a multi-proxy approach, including sediment properties, geochemical indicators, and diatom assemblages, combined with AMS 14 C ages of a gravity core (RS19-GC02). Based on six sediment facies of core sediments, the depositional sequence was divided into four lithologic units (I to IV). Units I, II, and IV reflected a typical transition from the glaciomarine diamicton to open marine sedimentation associated with the retreat of the ice sheet and ice shelf. However, unit III was anomalous, representing gravity flow deposits (i.e., debrites and turbidites) characterized by sharp basal contact, upward-fining texture, and the inclusion of mud clasts/lumps. These gravity flow deposits were relatively enriched in biogenic materials and modern diatom species, indicating deposition after the establishment of seasonal open marine conditions. AMS 14 C ages from unit II constrained the timing of unit III to the late Holocene. The occurrence and characteristics of the gravity flow deposits in the northern Drygalski Basin may reflect the late Holocene readvance of the EAIS, which is related to Neoglacial climate cooling. These findings provide new insights into the Holocene instability of the EAIS and its sensitivity to regional climatic shifts.