Report and preliminary results of RV METEOR Cruise M78/3. Sediment transport off Uruguay and Argentina: from the shelf to the deep sea ; 19.05.2009 – 06.07.2009, Montevideo (Uruguay) – Montevideo (Uruguay)

Abstract

The waters off Uruguay and Northern Argentina offer the possibility to study sediment transport processes from ‘source-to-sink’ in a relatively small area. Quickly accumulated sediments are potentially unstable and might be transported downslope in canyons and/or on the open slope. Strong contour currents result in along-slope sediment transport. Within the scope of Meteor-Cruise M78/3 we investigated sediment transport and depositional patterns by means of hydroacoustic and seismic mapping as well as geological sampling with conventional coring tools and the new MARUM seafloor drill rig (MeBo). Geotechnical investigations were carried out with the aim to analyze the controlling parameters for the destabilization of the slope and the succeeding failure of a sediment body. Various types of sediment instabilities have been imaged in geophysical and core data, documenting particularly the continental slope offshore Uruguay to be locus of frequent submarine landslides. Apart from individual landslides, however, gravitational downslope sediment transport along the continental slope is restricted to the prominent Mar del Plata Canyon and smaller canyons identified in the bathymetric data. In contrast, many morphological features reveal that sediment transport is predominantly controlled by strong contour bottom currents. This suggests a significant impact of the western boundary currents on the overall architectural evolution of the margin. The investigations are related to projects of the DFG Research Center / Excellence Cluster 'The Ocean in the Earth System', University of Bremen, as well as the Excellence Cluster 'The Future Ocean', University of Kiel