| Summary: | The role that the opening and deepening of the Drake Passage and the Scotia Sea played in the development of the first Cenozoic continental ice sheet in Antarctica and the onset of the Antarctic Circumpolar Current (ACC) during the Eocene-Oligocene Transition (EOT) is still uncertain. This limited knowledge stems from the poor age control of the separation of the different continental blocks leading to the opening of the Drake Passage; in fact, proposed ages for this opening range from 40 to 17 million years (Ma). Along with the progressive opening of Drake Passage, a number of small sedimentary basins developed in the southern Scotia Sea. These basins had a major impact on the establishment on deep-water circulation patterns due to their role as principal conduits for the exit cold Antarctic waters from the Weddell Sea (i.e., the Weddell Sea Deep Water: WSDW) and their interaction with the different fronts of the ACC in the Scotia Sea. In spite of this importance, the knowledge of the distribution and temporal variability of the water masses in the Scotia Sea is very limited. This PhD Thesis aims to: (1) reconstruct late Eocene to early Oligocene paleoenvironmental changes at the South Orkney Microcontinent (SOM) and their relation to the tectonic and climatic evolution of the Drake Passage-Scotia Sea; (2) reconstruct the recent deep-water sedimentation patterns in the western Scotia Sea to asses the paths and interactions between major bottom current patterns once the ACC and the WSDW were fully developed. These two objectives target two different temporal windows that represent the two end-member situations on the establishment of bottom currents around Antarctica, and their eventual links with climatic changes. To achieve these aims, we have conducted a suite of analysis in marine sediment cores recovered in the SOM (ODP Site 696B), and using geophysical and hydrographic datasets collected in the westernmost Scotia Sea basin (Ona Basin). Firstly, this PhD Thesis shows that during the late Eocene (~37.6–35.5 ...
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