34-5 Pliocene Glacial History of the Ross Sea, Antarctica: Microfossil Record from IODP Site U1522

Session: High latitude paleoceanographic discoveries from Scientific Ocean Drilling (IODP, ODP, DSDP). (Posters)

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Microfossils found in sediments from the Ross Sea continental shelf, Antarctica, provide details about Earth’s climate history and can help determine the extent of Antarctic Ice Sheet variability through time. We specifically look at the Pliocene Epoch (5.33-2.56 Ma), a notably warm interval in Antarctica’s past that can serve as an analogue for our current and near-future climate. The sensitivity of the West Antarctic Ice Sheet (WAIS) to climate and ocean changes by way of ice sheet variability makes this region useful for understanding Earth’s climate evolution. Analyzing Pliocene marine microfossils from the Ross Sea allows us to add to the profile of Antarctic microfossils, use the microfossils to interpret Antarctic glacial history during the Pliocene, and determine how the WAIS and Ross Ice Shelf may change with the current climate trajectory. The sediment studied is from International Ocean Discovery Program Expedition 374 Site U1522. Cores from this site provide continuous sedimentation of glacial and interglacial episodes. Biological components such as diatoms, radiolarians, sponge spicules, and foraminifera are found in various abundance through the U1522 cores, although foraminifera a generally very rare in the Pliocene of this site. Sediment samples were processed and scanned at the >63-micron size fraction. Microfossils and notable materials including coal and glauconite were identified and counted in each sample. The counts from each sample inform us of oceanic trends in the Ross Sea through the Pliocene. Preliminary results of this study show that the early Pliocene had abundant radiolarians, few diatoms, and few foraminifera which may suggest the dissolution of carbonate. Prominent increases in microfossil abundance can be compared with similar studies of foraminifera, silicoflagellates, and diatoms to determine comparative Pliocene warm intervals. A peak of foraminifera, including planktic specimens at ~281 m may correlate with a warm water peak recognized at Site U1523 on the shelf edge at ~3.7 Ma. Additionally, peaks in coal, glauconite, radiolarians, and sponge spicules may indicate possible erosion and winnowing and the occurrence of Ross Sea Unconformity 2 (RSU2) at  ~273 m. Further analysis of Site U1522 is critical to understanding the response of the WAIS to ocean changes in Earth’s past and what this means for Earth’s future.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

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