Seismic Stratigraphy Of The Sabrina Coast Shelf, East Antarctica: History Of Late Paleogene To Early Neogene Glacial Evolution

Abstract:

Sedimentary architecture of the Sabrina Coast (SC) shelf, East Antarctica is studied for the first time using 754 km of high (up to 3 m) vertical resolution multichannel seismic data and four piston cores acquired on board of RVIB Palmer in 2014. We interpret the sedimentary record of early glacial SC shelf stratigraphy based on analysis of seismic facies and morphological features. We identify at least nine erosional surfaces that indicate advances of the Totten Glacier - Moscow University Ice Shelf system, part of the East Antarctic Ice Sheet (EAIS), to the SC shelf. The most prominent features include two series of undulating, channelized erosional surfaces truncating strata below and showing highly irregular morphology with elevation amplitudes of up to ~120 m and widths of individual undulations of up to ~10 km. These surfaces are located stratigraphically above a core bearing IRD and assigned biostratigraphically to the Late Eocene and below a regional erosional surface of Late Miocene age. Our major results show that: (1) Oligocene-early Miocene evolution of EAIS consists of low-frequency, high-amplitude glacial expansions followed by long periods of ice-distal to open marine conditions; (2) the presence of grounded EAIS expansions on shelf is expressed in a series of deep, hummocky undulations and first Antarctic sedimentary tunnel valley system, suggestive of presence of subglacial meltwater and hence, a polythermal glacial regime; (3) at least nine erosional unconformities representing major ice advances have been found on the inner shelf; (4) the most intensive polythermal glaciations have occurred in late Eocene-early Oligocene; (5) no evidence of focused paleo- ice stream(s) draining Aurora Basin Complex prior to the middle Miocene was found in the study area.