Submarine sedimentary basin analyses for the Aurora and Wilkes Subglacial Basins and the Sabrina Coast Continental Shelf, east Antarctica
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This dissertation focuses on the Wilkes Land region of the East Antarctic Ice Sheet (EAIS) that is predominantly characterized by two large subglacial basins, the Aurora Subglacial Basin (ASB) to the east and the Wilkes Subglacial Basin (WSB) to the west and immediately adjacent to the Transantarctic Mountains (TAM). The ASB and WSB are expansive covering an estimated 750,000 and 980,000 square kilometers, respectively. In addition, their bedrock geometry places them an average of 1.25 km below present day sea level, raising the possibility of fundamental instability through grounding line retreat. Subglacial sediment deformation has long been known to facilitate faster ice flow and significantly impact basal ice conditions including geothermal heat flux, groundwater flow, and frictional heat flux. Recently acquired aerogeophysical data over the interior ASB and WSB document extensive subglacial sedimentary basins that can be distinguished as smaller subbasins, each associated with adjacent topographic highlands and EAIS dynamics. The volumes of these interior subglacial subbasins vary between 26,349 +/- 10,885 km³ and 398,082 +/- 164,454 km³ in the ASB and 7,188 +/- 2,940 km³ and 128,094 +/- 52,399 km³ in the WSB (based upon 20% porosity values). Notably, the character of the basins varies substantially between the more southern ASB and WSB interiors and the more marginal, northern ASB and WSB reflective of different dynamic ice histories across geologic time. ASB sedimentary basin volumes, derived from airborne gravity and magnetic data with ice-penetrating radar constraints, are contrasted with recently acquired highresolution marine seismic sequence stratigraphy collected on the Sabrina Coast continental shelf. With targeted geologic sampling of outcropping strata, megasequence sediment volumes are estimated for a finite area adjacent to the Totten Glacier/Moscow University Ice Shelf catchment draining the ASB interior. Preglacial, temperate/polythermal glacial, and polar glacial sediment volumes of 278.6 +/- 148.8 km³ , 570.6 +/-51.9 km³ , and 1,658 +/- 389 km³, respectively, combined with a multitude of diagnostic glacial tunnel valleys, unconformities, and geologic data, reinforce recent dynamic Pliocene EAIS hypotheses for the Wilkes Land margin.