Slowdown of circumpolar deepwater flow during the late Neogene: Evidence from a mudwave field at the Argentine continental slope

Abstract

Geochemical evidence from boreholes suggests enhanced transport of Northern Component Water (NCW) to southern latitudes from about 6 Ma onward. However, information on how this change in transport influenced the intensity and position of current systems is sparse. Here we use seismic reflection profiles interpreted together with bathymetric data to investigate current derived deposits at the central Argentine Margin. Upslope migrating mudwaves overlying a late Miocene erosional unconformity provide evidence that Circumpolar Deepwater flow slowed down with the onset of NCW inflow. During the last ∼3 Ma, changes in dimensions and migration rates of the waves are small indicating continuous bottom current flow conditions similar to today with only minor variations in flow speed, suggesting that the Deep Western Boundary Current in the western south Atlantic as observed today has been a pervasive feature of the global thermohaline circulation system during the Plio-/Pleistocene. © 2014. American Geophysical Union. All Rights Reserved.