Scotia Sea Region

Abstract

The Scotia Sea region developed in Cenozoic times as the largest and most complex and recent product of a history of changing relative motions between the South American and Antarctic plates. This history started in Jurassic times as NE-directed continental extension and breakup between eastern and western parts of Gondwana. The later N-directed phase of relative motion saw seafloor spreading in the Weddell Sea, central Scotia Sea, and Rocas Verdes Basin. The orientation of relative motion rotated further toward the NW, leading to closure and inversion of the Rocas Verdes Basin, the formation of a subduction zone in the northwestern Weddell Sea, and translation of the central Scotia Sea to the north of the Antarctic Peninsula. In late Paleogene times, the Weddell Sea subduction zone propagated northwards, isolating the South Orkney Microcontinent and neighboring central Scotia Sea between a trench in the east and continental South America in the west. A complex of basins formed in and around these isolated elements to accommodate the plate-divergent resultant of eastwards trench migration and WNW directed drift of South America. Starting in Paleogene times, the basins’ development cut off the possibility for terrestrial faunal exchange between South America and Antarctica, and instigated Pacific-to-Atlantic oceanic exchange in its place. As well as genes, heat and salt started to flow with seawater through the newly-generated Drake Passage, with possible further consequences for regional and global climate change.