Seismo-stratigraphic analysis of the Wilkes Land continental margin (East Antarctica): influence of glacially driven processes on the Cenozoic deposition

Multichannel seismic reflection data were collected from the Wilkes Land continental margin and particularly focusing on the lower rise area, by the international WilkEs basin GlAcial history (WEGA) project. Existing, lower-resolution seismic data also are used to understand the relationship between the basement and the sedimentary cover and to correlate the evolution of the rise and the shelf. basis of the acoustic character and the internal geometry, we recognise nine different sequences (named WL-S1–WL-S9, from the deepest to the shallowest) within the sedimentary section. Sequence WL-S1 represents syn-rift sediments deposited within tilted blocks of sedimentary, crystalline and volcanic basement. Sequences WL-S2–WL-S9 represent the post-rift sediments that show quite a complex architecture: sequence WL-S2 is a well-developed wedge downlapping onto the break-up unconformity; sequences WL-S3–WL-S7 are parts of a margin prograding/aggrading sequence during which large sediment ridges were deposited on the slope and rise. In particular, sequences WL-S5–WL-S7 began with the deposition of a turbidite fan system (sequence WL-S5), that developed in a braided channel–levee complex (WL-S6–WL-S7), dominated by downslope flows. Indirect correlation of the sequences WL-S4–WL-S6 with DSDP 269 about 600 km north of the study area suggests an early late Miocene age. Sequences WL-S8 and WL-S9 represent the smoothing and filling of the pre-existing morphology, in a generally low-energy environment with reduced bottom current activity. During this time, most of the sediment is deposited on the shelf and slope, while the rise is generally starved. ences in downslope current energy and in sediment load are interpreted to reflect variation of the terrigenous input from the shelf to the rise through time. We suggest that channel–levee systems on the rise reflect an increase in sediment supply from the continental shelf during the Early Miocene, marking the growth of wet-based, temperate ice sheet on the near continent. The youngest sequences on the rise and shelf reflect decreased sediment supply to the rise that may be related to the transition from a temperate to a polar glacial system.