Ocean circulation variability in the western South Atlantic during the Holocene

Abstract

The western South Atlantic forms a key location in the global ocean conveyor belt. Different water masses formed in remote areas of the world extend into that area and generate a highly complex vertical stratification structure. In the upper ocean, this structure is dominated by the encounter of southward flowing Brazil Current and northward-flowing Malvinas-(Falkland) Current generating one of the most energetic regions of the world ocean; the Brazil-Malvinas Confluence (BMC). In the deep ocean, the vertical stratification structure is dominated by contributions from intermediate- and deep water masses, including the Antarctic Intermediate Water (AAIW) which represents an active player in the Atlantic meridional overturning circulation (AMOC). The western South Atlantic is thus critical in understanding global ocean-climate changes. However, a detailed insight into the past remains a significant challenge in climate research due to the lack of high temporal resolution climate archives. The presented research of this thesis focuses on the surface- and intermediate water circulation in the western South Atlantic during the Holocene with special emphasize on sedimentation processes in the Mar del Plata Canyon. Results of this research highlight the extraordinary potential of a submarine canyon for reconstructing paleoceanographic and paleoclimatic changes with high temporal resolution, and clearly demonstrate that a good knowledge of sediment transport phenomena is an indispensable precondition for understanding paleoceanographic/paleoclimatic changes, particularly in such highly energetic current regimes as the western South Atlantic.