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Interplay between ice dynamics, ocean-induced basal melting and the morphology of continental margins
Florence Colleoni
Jeudi 25/01/2018, 11h00-12h00
Bât. 701, P. 17C, LSCE Orme des Merisiers

Marine sediment records from West and East Antarctic ice sheet (WAIS, EAIS) have shown that the ice sheet volume and extent have fluctuated substantially over the past millions of years.  The reconstruction of past Antarctic extent and dynamics highly depends on the reconstruction of the bedrock and seabed morphology evolution in time. Geophysical reconstructions based on marine reflection seismic interpretation combined with marine sediment cores analysis show that the major current marine basins or marine-based parts of Antarctica over-deepened through time. In addition, geological evidence also show that sedimentation rates decreased substantially from the Mid-Miocene (~15Ma), which suggests that most of the present-day seabed and continental margin morphology is inherited from pre-Miocene periods. Recent studies show that Antarctic ice sheet became more dynamical around about this time.

Here we illustrate this mechanism by means of an ice-sheet model forced by simulated Mid-Miocene and Last glacial cycle warm and cold climates. Conceptual simulations using idealised seabed bathymetries of Antarctica departing from BEDMAP2 are carried out to test the relative importance of ice fluxes, ocean water masses and bathymetry in the advance and retreat processes of the ice sheet on the continental margins. Results show the major dynamical differences between Miocene-like and Pleistocene-like Antarctic ice sheet and illustrate the increasing influence of ocean conditions on the Antarctic ice sheet while the Antarctic continental margins gradually over-deepened through time.

Contact : Sarah Amram
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