Deep water sedimentary processes in the Enderby Basin (East Antarctic margin) during the Cenozoic

The thick sequence of mid-late Cenozoic sediments preserved within the Enderby Basin of the East Antarctica margin contains key information regarding glacial history and palaeo-oceanographic conditions during the last 34 My. The interplay between glacial processes and ocean circulation can be reconstructed from seismic stratigraphic studies. Here, interpretation of seismic sequences and geomorphology from an extensive 2D seismic dataset (similar to 75,000 km) are correlated with lithological data of the ODP site 1165 drilled on the continental rise, and used to assess the age and origin of the sediment, and the possible influence of oceanic currents on its distribution. Mapping of seismic units and facies reveals that, in addition to glacial sediments derived from the Antarctic mainland, the upper Cenozoic succession includes drift units with prograding sequences building out from the Mac. Robertson Land margin, west of the Prydz Bay. Three contourite drifts grew on the western side of submarine channels and large sediment wave fields suggest a mixed system of turbidity currents influenced by west-flowing bottom currents. The drifts are composed of four seismic units representing stages of onset (Lower Oligocene), main growth (Early-Middle Miocene), maintenance (Middle-Late Miocene) and burial (Pliocene). The internal geometry and reflection patterns of the drifts imply an intensified current activity from the Early to Middle Miocene. The results plausibly reflect that the formation of proto Antarctic Bottom Water (AABW) started around the Eocene-Oligocene boundary and intensified episodically from the early to middle Miocene.