Stratigraphic analysis of the Scan Basin (south Scotia Sea, Antarctica): palaeoceanographic implications

The southern part of the Scotia Sea (Antarctica) is a key area for the deep-water circulation reconstruction across the South Scotia Ridge. Several small oceanic basins were developed in this area since the Middle Miocene, and their evolution have influenced the Circumpolar Deep Water (CDW) and the Weddell Sea Deep Water (WSDW) circulation. The eastern most of these basins is the Scan Basin, located northwards of the South Scotia Ridge and the Jane Basin. It is bound to the west and to the east by the Bruce and Discovery banks respectively. Seven Multichannel Seismic profiles (MCS) were obtained during the SCAN1997 and SCAN2004 oceanographic cruises onboard the BIO Hespérides. The seismic analysis of those profiles reveals the stratigraphic pattern and the morphostructural evolution of the Scan Basin. Four major seismic unit-packages are identified within the sedimentary record, called from bottom to top: Basal, Lower, Middle and Upper. The Basal Package consists of deformed depositional units, whereas the three upper packages exhibit similar seismic facies. The discontinuities bounding those seismic units are linked to major tectonic and palaeoceanographic events since the Miocene to the present.