A seismic characterization of Antarctic glacial sediments in the Ross sea

We present a tomographic and modelling study of the Ross Sea glacigenic sediments (Eastern Basin) in order to reconstruct a 2-D multiparametric model of the geological structures involved in the erosion process of the WAIS (West Antarctic Ice Sheet). We analyzed a segment of the 2D seismic line IT-01, acquired in 1988, located in a zone very close to the continental margin. The combined use of traveltime and attenuation (quality factor Q) tomography provides a 2-D velocity-Q section, which can be used to map the spatial distribution of compacted sediments and occurrence of biogenic free-gas bearing sediments. The tomographic inversion revealed the presence of anomalous high velocity and Q values in the layer immediately above the RSU2 unconformity, which is an important erosion surface in the Lower Pliocene. This velocity-Q anomaly is correlated with sediments that were eroded and compacted by the load of the WAIS during its expansion on the continental shelf. These results are confirmed by a poroviscoelastic model of the analyzed sediments based on rock-physics theories that takes into account the partial saturation and the in situ pore pressure and temperature.