Scotia Arc

The Scotia Arc is the island arc system forming the north, east and south border of the Scotia Sea. The northern border, the North Scotia Ridge, comprises (from west to east): Isla de los Estados at the tip of Tierra del Fuego, the Burdwood, Davis, and Aurora Banks; the Shag, South Georgia Island and Clerke Rocks. The eastern border comprises the volcanic South Sandwich Islands flanked by the South Sandwich Trench. The southern border, the South Scotia Ridge, comprises (east to west): Herdman, Discovery, Bruce, Pirie, and Jane Banks; the South Orkney Islands and Elephant Island. Finally, the Bransfield Strait separates the arc from the South Shetland Islands and James Ross Island flanking the tip of the Antarctic Peninsula.^[1]

The Scotia Arc surrounds the small Scotia and South Sandwich Plates.^[1] The arc is formed by continental fragments that once formed a land bridge between South America and Antarctica, which was once part of the subduction margin that still forms the Andes. An ancestral arc, which formed a separate subduction system, broke through this land bridge and started to form the Scotia Sea by eastward back-arc extension driven by subduction of the South American Plate (also located east of the Scotia Arc).^[2] Today, the Scotia Arc forms a discontinuous link between South America and Antarctica. It is considered a continuation of the Andes, and the antarctic part of that mountain range is called the Antarctandes. The Scotia Arc is also an important barrier between the Pacific and Atlantic Oceans, and therefore for the Antarctic Circumpolar Current.^[3]