Andes - Geology

Geology

The Andes are a Mesozoic – Tertiary orogenic belt of mountains along the Pacific Ring of Fire, a zone of volcanic activity that encompasses the Pacific rim of the Americas as well as the Asia-Pacific region. The Andes are the result of plate tectonics processes, caused by the subduction of oceanic crust beneath the South American plate. The main cause of the rise of the Andes is the compression of western rim of the South American Plate due to the subduction of the Nazca Plate and the Antarctic Plate. To the east, the Andes range is bounded by several sedimentary basins such as Orinoco, Amazon Basin, Madre de Dios and Gran Chaco which separates the Andes from the ancient cratons in eastern South America. In the south the Andes shares a long boundary with the former Patagonia Terrane. To the west, the Andes end at the Pacific Ocean, although the Peru-Chile trench can be considered its ultimate western limit. From a geographical approach the Andes are considered to have their western boundaries marked by the appearance of coastal lowlands and a less rugged topography.