Piston cores from the Wilkes Land Rise: data and consideration

Abstract

Deep-sea ridges-channel systems have been recognized in some places on the continental rise around Antarctica. They are object of interest because of their relation to the ice sheet dynamics and their generally continuous record of paleo-climatic changes. The Wilkes Land continental margin is one of the areas where these morphological features are well developed; it is also particularly important because of its location close to the Mertz Glacier, which is one of the few outlet glaciers of the Eastern Antarctic Ice Sheet. The Wilkes Land continental margin was investigated induring the Austral Summer 2000 by the joint Australian and Italian WEGA(WilkEs basin GlAcial history) Project, onboard the R/V Tangaroa. During this cruise, about 600 km of multichannel seismic reflection profiles, 3.5 kHz acoustic profiles and 11 piston cores with trigger cores were acquired on the continental rise (Fig. 1). The Wilkes Land continental margin morphology is characterised by several submarine canyons cutting the slope while the lower rise, investigated by the WEGA Project, is characterised by a network of generally low relief channels separated by large sediment ridges. The detailed bathymetric map of the rise area shows three ridges named from west to east respectively “C”, “A” and “B”, bounded by the Jussie Canyon, the WEGA Channel and the Buffon Canyon (Fig. 1). This channel-ridge system has an approximately North-South elongation, perpendicular to the continental margin. The sediment ridges are ca. 150 km in length and more than 40 km of width and their relief is about 1000 meters in the proximal part, decreasing to ca. 300 meters offshore. They are asymmetrical, showing a long gentle eastern flank and a short steep western side, lying between 2500 and 3600 meters water depth in the upper and lower part respectively. The Jussie Canyon and the Buffon Canyon reach the shelf break, while the WEGA Channel seems to start lower, in the upper rise.