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Understanding Ice-Sheet Vulnerability Using an Integrated Subsurface Sedimentary Geoscience Approach: Preliminary Results from Neogene and Quaternary Records Acquired During IODP Expedition 374 to the Ross Sea, Antarctica

Abstract

The sustainability of coastal communities and infrastructure in the coming decades to centuries will be impacted by sea-level rise. The marine-based West Antarctic Ice Sheet (WAIS) is currently retreating due to shifting oceanic currents that transport warm waters toward the ice margin, resulting in ice shelf thinning and accelerated mass loss. Modeling results suggest that WAIS variability is sensitive to such oceanic forcing but information about ice-sheet behavior and response from past climatic events in Earth history is needed to better evaluate the variability and feedbacks. An extensive grid of 2-D seismic-reflection surveys are combined with a new transect of boreholes drilled during International Ocean Discovery (IODP) Expedition 374 (January-February 2018) in the Ross Sea.

Two drill sites on the continental shelf, one on the outer shelf, and two sites on the continental slope/rise collectively recovered sediments spanning the early Miocene to latest Quaternary. Facies analysis of the cores allows for reconstruction of ice-sheet-proximal depositional environments (sub/proglacial, glaciomarine, and open-marine), which provides a physical record of ice sheet advances and retreats. This fundamental sedimentology, when integrated with a refined and chronologically constrained seismic stratigraphic framework and core-based paleo-environmental (e.g., ocean temperature) proxy studies, allows for a robust assessment of WAIS stability/instability during past warming events.

Our preliminary results are presented within the context of an integrated subsurface sedimentary geoscience approach, including seismic characterization, downhole log analysis, sedimentological description of cores, and analysis of physical properties measured on cores and core samples. Thus, tools and approaches that are common in the petroleum industry are being applied to the goal of improving our understanding of how ice sheets respond to environmental change. The role of sedimentary geoscience in documenting and highlighting examples of Earth’s past ‘experiments’ is critical for improving the predictive models that coastal planners and citizens will increasingly rely on to aid risk assessment and decision making.