Mid‐Holocene Grounding Line Retreat and Readvance at Whillans Ice Stream, West Antarctica

• Main Authors: Venturelli, R. A., Siegfried, M. R., Roush, K. A., Li, W., Burnett, J., Zook, Robert, Fricker, H. A., Priscu, J. C., Leventer, A., Rosenheim, B. E.
• Format: Text
• Language: unknown
• Published: DigitalCommons@University of Nebraska - Lincoln 2020
• Subjects: Earth Sciences; Ross Sea; West Antarctica; Ross Ice Shelf; Whillans; Whillans Ice Stream; Antarc*; Antarctica; Ice Sheet; Ice Shelf; Ice Shelves
• Online Access: https://digitalcommons.unl.edu/geosciencefacpub/669; https://digitalcommons.unl.edu/context/geosciencefacpub/article/1683/viewcontent/Venturelli_GRL_2020_Mid_Holocene_Grounding_Line.pdf; https://digitalcommons.unl.edu/context/geosciencefacpub/article/1683/filename/0/type/additional/viewcontent/Venturelli_GRL_2020_Mid_Holocene_Grounding_Line_SUPPL_1.pdf; https://digitalcommons.unl.edu/context/geosciencefacpub/article/1683/filename/1/type/additional/viewcontent/Venturelli_GRL_2020_Mid_Holocene_Grounding_Line_SUPPL_2.xlsx; https://digitalcommons.unl.edu/context/geosciencefacpub/article/1683/filename/2/type/additional/viewcontent/Venturelli_GRL_2020_Mid_Holocene_Grounding_Line_SUPPL_3.mp4

Understanding ice sheet evolution through the geologic past can help constrain ice sheet models that predict future ice dynamics. Existing geological records of grounding line retreat in the Ross Sea, Antarctica, have been confined to ice‐free and terrestrial archives, which reflect dynamics from periods of more extensive ice cover. Therefore, our perspective of grounding line retreat since the Last Glacial Maximum remains incomplete. Sediments beneath Ross Ice Shelf and grounded ice offer complementary insight into the southernmost extent of grounding line retreat, yielding a more complete view of ice dynamics during deglaciation. Here we thermochemically separate the youngest organic carbon to estimate ages from sediments extracted near the Whillans Ice Stream grounding line to provide direct evidence for grounding line retreat in that region as recent as the mid‐Holocene (7.2 kyr B.P.). Our study demonstrates the utility of accurately dated, grounding‐line‐proximal sediment deposits for reconstructing past interactions between marine and subglacial environments. Plain Language Summary Ice sheet grounding lines, where ice loses contact with the underlying bed and transitions to an ice shelf floating on the ocean, are critical areas that govern the stability of marine‐based ice sheets. However, the short period (years to decades) that we have been able to map grounding lines from ground, airborne, and satellite observations compared to the long periods over which ice sheets change (centuries to millenia) limits our knowledge of grounding line stability. We focus our geologic perspective of grounding line retreat in the Ross Sea, a region that has experienced a high degree of change throughout the last glacial‐interglacial cycle. Prior work reconstructing the timeline of ice sheet change in this region is based heavily on ice‐free marine sedimentary records, where dates of the first open marine sedimentation after ice retreat can be estimated. Dating sediments from beneath floating ice shelves and near grounding ...