Suchergebnisse

The continental slope and rise seaward of the Totten Glacier and the Sabrina Coast, East Antarctica features continental margin depositional systems with high sediment input and consistent along-slope current activity. Understanding their genesis is a necessary step in interpreting the paleoenvironmental records they contain. Geomorphic mapping using a systematic multibeam survey shows variations in the roles of downslope and along slope sediment transport influenced by broad-scale topography and oceanography. The study area contains two areas with distinct geomorphology. Canyons in the eastern part of the area have concave thalwegs, are linked to the shelf edge and upper slope and show signs of erosion and deposition along their beds suggesting cycles of activity controlled by climate cycles. Ridges between these canyons are asymmetric with crests close to the west bank of adjacent canyons and are mostly formed by westward advection of fine sediment lofted from turbidity currents and deposition of hemipelagic sediment. They can be thought of as giant levee deposits. The ridges in the western part of the area have more gently sloping eastern flanks and rise to shallower depths than those in the east. The major canyon in the western part of the area is unusual in having a convex thalweg; it is likely fed predominantly by mass movement from the flanks of the adjacent ridges with less sediment input from the shelf edge. The western ridges formed by accretion of suspended sediment moving along the margin as a broad plume in response to local oceanography supplemented with detritus originating from the Totten Glacier. This contrasts with interpretations of similar ridges described from other parts of Antarctica which emphasise sediment input from canyons immediately up-current. The overall geomorphology of the Sabrina Coast slope is part of a continuum of mixed contourite-turbidite systems identified on glaciated margins ; We thank the Marine National Facility, the IN2017-V01 scientific party-led by the Chief Scientists L.K. Armand and P. E. O'Brien, MNF support staff and ASP crew members led by Capt. M. Watson for their help and support on board the RV Investigator . We thank laboratory staff from Geoscience Australia for sediment grainsize analysis, particularly Ian Long, Christian Thun, Aziah Williamson and Simon Webber. This Project is supported through funding from the Australian Government's Australian Antarctic Science Grant Program ( AAS #4333 ) and by the Australian Government through the Australian Research Council ( DP170100557 ). Seismic data acquisition and processing was supported by the Italian Programma Nazionale di Richerch in Antartide (PNRA) under the TYTAN Project . A. López-Quirós and D. Evangelinos acknowledge funding provided by Spanish Ministry of Science and Innovation (grants CTM2014-60451-C2-1-P and CTM2017-89711-C2-1-P ). A. Post publishes with the permission of the CEO, Geoscience Australia, under Creative Commons. We also thank the anonymous reviewers for their comments. ; Peer reviewed

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