Analysis of Antarctic glaciations by seismic reflection and refraction tomography

The Eastern Basin in the Ross Sea (Antarctica) contains a sedimentary sequence that is a direct record of advance and retreat of the West Antarctic Ice Sheet. We analyzed a sedimentary section ranging from the upper Miocene to present. The joint tomographic inversion of refracted and reflected arrivals of pre-stack multi-channel seismic data revealed in this area the presence of layers with anomalous high velocity. These anomalies are correlated with sediments that were eroded and compacted by the load of the West Antarctic Ice Sheet during its expansion on the continental shelf. The deepest and stronger velocity anomaly correspond to a basin-wide seismic unconformity (RSU2, Late Miocene­Early Pliocene in age). This anomaly is interpreted as evidence of a major advance of the West Antarctic ice sheet on the continental shelf that resulted in high velocity and low porosity in sediment immediately above the unconformity. D 2005 Elsevier B.V. All rights reserved.