Continuous simulations over the last 40 million years with a coupled Antarctic ice sheet-sediment model

David Pollard, Robert M. DeConto

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Abstract

Much of the knowledge of Antarctic Ice Sheet variations since its inception ~34 Ma derives from marine sediments on the continental shelf, deposited in glacimarine or sub-ice environments by advancing and retreating grounded ice, and observed today by seismic profiling and coring. Here we apply a 3-D coupled ice sheet and sediment model from 40 Ma to the present, with the goal of directly linking ice-sheet variations with the sediment record. The ice-sheet model uses vertically averaged ice dynamics and parameterized grounding-line flux. The sediment model includes quarrying of bedrock, sub-ice transport, and marine deposition. Atmospheric and oceanic forcing are determined by uniform shifts to modern climatology in proportion to records of atmospheric CO2, deep-sea-core δ18O, and orbital insolation variations. The model is run continuously over the last 40 Myr at coarse resolution (80 or 160 km), modeling post-Eocene ice, landscape evolution and off-shore sediment packages in a single self-consistent simulation. Strata and unconformities are tracked by recording times of deposition within the model sediment stacks, which can be compared directly with observed seismic profiles. The initial bedrock topography is initialized to 34 Ma geologic reconstructions, or an iterative procedure is used that yields independent estimates of paleo bedrock topography. Preliminary results are compared with recognized Cenozoic ice-sheet variations, modern sediment distributions and seismic profiles, and modern and paleo bedrock topographies.

Original languageEnglish (US)
Article number109374
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume537
DOIs
StatePublished - Jan 1 2020

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All Science Journal Classification (ASJC) codes

  • Oceanography
  • Ecology, Evolution, Behavior and Systematics
  • Earth-Surface Processes
  • Palaeontology

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