Contourite depositional system on the Argentine Slope: An exceptional record of the influence of Antarctic water masses

Abstract

A significant contourite depositional system (CDS) on the continental slope of the southern Argentine margin is described here for the first time. This system contains both erosive and depositional features that have resulted from several factors, including topographic intensification of the Antarctic-sourced water masses, the systematic northward decrease in speed of these water masses, a northward increase of downslope sedimentary processes, and local tectonic influences. This system is an exceptional example of a CDS that started to develop at the time of the Eocene-Oligocene boundary, potentially coeval with the opening of the Drake Passage. However, a new margin morphology, characterized by a complex terraced slope lacking any continental rise, developed after a major paleoceanographic change in the middle to late Miocene. We infer that this change resulted from the extension of North Atlantic Deep Water circulation into the Southern Hemisphere and the deepening of Antarctic Bottom Water circulation in the Argentine Basin.