This work is focused on a problem of distinguishing between contourites and turbidites in the southwestern Brazil Basin, which is crucial for better understanding of the Late Quaternary history of interplay between along slope and down slope sedimentation processes in the western South Atlantic. The study embraces an area between the Almirante Saldanha and São Tomé Seamounts, which is not linked to any known depositional system. This area was not previously studied in frame of the contourite paradigm. Very high-resolution seismic records and lithological data acquired during three cruises of the RV Akademik Ioffe (2011-2013) revealed domination of lateral sedimentation in the area of the São Tomé Seamount. Interplay between along slope and gravity driven sedimentation processes interacting with the ocean floor topography resulted in the formation of complicated sediment structures and a wide range of seismic facies. Along slope sedimentation processes are controlled by the Antarctic bottom water current, which reworked coarse-grained material derived from the continental slope through turbidity flows. The study area is divided into two zones, which are characterized by domination of either gravity flows or bottom current related sedimentation processes. The São Tomé Seamount marks a boundary between these zones. The obtained results improved knowledges about the formation history of the Upper Quaternary sediment cover on the continental rise of the southwestern Brazil Basin and about interplay between gravity-driven and bottom current related sedimentation processes during the last glacial-interglacial cycle.
Contourites, turbidites, continental rise, bottom current, AABW, seismic profiling, seismic facies
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