2. West Antarctica: Tectonics and Paleogeography

West Antarctica is an ensemble of blocks that have moved independently of each other and of cratonic East Antarctica. The onset of Terra Australis orogenesis was responsible for the termination of passive margin sedimentation along the greater part of the Pacific margin of Gondwana and began a long-lived process of accretion that added much of the crust that defines eastern Australia, West Antarctica (domain 5 of Boger 2011), and western South America. By the Late Cretaceous, the Antarctic Peninsula and the remainder of West Antarctica are believed to have been comprised of a number of discrete micro-continental blocks forming a single elongated landmass that extended southward from southern South America. Since at least that time the Antarctic Peninsula has been in its present position relative to South America, at almost the same paleolatitude (South 60–65°).