| Summary: | [EN] This thesis shows that before 28 Ma a single water mass flowing westward, the proto-AABW, occupied the seafloor in the studied region. The first evidence for the onset of a current flowing eastward, the proto-CDW, is found at 28 Ma. Between 26 and 25 Ma ice sheets were mainly continental-based and an oceanic frontal system already existed and migrated during glacial-interglacial cycles that were paced by obliquity. The late Oligocene frontal system was however weaker than today´s Polar Front because we find evidence for intrusion of warm north component waters close to the Antarctic margin. The latest Oligocene (24-23.4 Ma) witnessed at least eight times of ice sheet advancing into the continental shelf and retreats inland, pointing to a highly dynamic ice sheet during the cooling trend leading to the glacial Mi-1 event. During this period, we interpret that the EAIS in the WSB becomes marine-based as a consequence of the erosion and overdeepening of the Wilkes Subglacial Basin by the repeated advances and retreats of the EAIS since it was formed in the early Oligocene (33.6 Ma).
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