Falkland/Malvinas Trough: Indications for Cenozoic tectonic and oceanographic evolution in the southwestern South Atlantic

The Falkland/Malvinas Trough (F/MT) bounds the southern extremity of the Falkland/Malvinas Plateau. This Cenozoic bathymetric depression developed as the orogenic foreland basin of the North Scotia Ridge. The sedimentary infill of the F/MT carries a history of development in a transpressional setting along the South American-Scotian Plate boundary, in association with the evolution of the Drake Passage-Scotia Sea zone. Since the F/MT is located on the pathway of the Antarctic Circumpolar Current, the current-controlled depositional and erosional features within its sedimentary infill provide valuable information on the palaeoceanographic modifications in the southwestern South Atlantic. Via a set of 2D high-resolution seismic reflection data, the structural and morphological features of these strata are investigated and discussed with respect to the tectonic evolution of the Drake Passage-Scotia Sea zone. Evidence of fold structures and normal faulting during Oligocene to mid-Miocene times in the study area argue for a transpressional regime linked with the development of the Drake Passage-Scotia Sea zone. The current-related depositional and erosional processes in the F/MT started between Oligocene to early Miocene times. With the full opening of the Drake Passage, the evolution of the Scotia Sea and the demise of the Ancestral South Sandwich Arc by the mid-Miocene, an oceanographic setting analogous to the present would have established. Evidences suggests that since then, with the enhancement of the abyssal circulation subsequent to the perennial Antarctic glaciation, a precursor of the Weddell Sea Deep Water has been circulating the F/MT, shaping a confined sediment drift deposit.
