Australia: The Land Where Time Began

A biography of the Australian continent 

Antarctica - Geological History

The continent of Antarctica covers an area of about 14,200,000 km2, which is more that the combined area of the USA and Mexico, and is comprised of 2 major continental blocks. East Antarctica is comprised of a single large, stable continental craton of metamorphic basement rocks, mainly from the Precambrian, with intrusions of granite that are overlain unconformably by sedimentary rocks that are generally flat. West Antarctica is comprised of an archipelago of several microplates of mountainous terranes that are metamorphic and volcanic. The boundary zone between the 2 components of Antarctica is marked by the Transantarctic Mountains (TAM), one of the Earth's major chains of mountains.

As 98 % of Antarctica is covered by an ice sheet averaging 1-4 km in thickness geologic knowledge of this continent is limited, though the subglacial topography is known reasonably well from airborne radio-echo sounding technology. Vast areas of Antarctica are shown by subglacial topography maps to lie below sea level, and much of this area below sea level would remain below sea level even if the ice melted completely and the continent rebounded isostatically, these basins being part of the Antarctic marine geologic realm.

Information on the geologic history of Antarctica of necessity draws heavily on published descriptions of strata from continents that were contiguous as part of Gondwana because of the paucity of drill sites on the margins of the continent and outcrops on Antarctica. A framework has been constructed from this available information for predicting stratigraphic successions that should occur in marine and subglacial basins in Antarctica. A summery of Antarctica's geologic history in the context of its association with the other continents comprising Gondwana is the best that can be achieved given the present state of geologic knowledge of the continent.

General construction and components

The Transarctic Mountains, almost 3,500 km long, separates East Antarctica from West Antarctica. The main support for this division is topographic, though further information is gained from deep crustal investigations. An abrupt transition has been revealed along the eastern front of the Transantarctic Mountains by geochemical data, seismic refraction and gravity data (Robinson, 1964; Smithson, 1972; Bentley, 1973; Behrendt et al., 1974; Davey, 1981; Jankowski & Drewry, 1981; Bentley, 1983; Fitzgerald et al., 1986; Kim, McGinnis & Bowen, 1986; Cooper, Davey & Cochrane, 1987b; Kalamarides, Berg & Hank, 1987; Stern & ten Brink, 1989). According to the author1 it is considered that this abrupt change represents the boundary between the East Antarctic Craton, of Precambrian age, and the terranes of West Antarctica that are predominantly terranes of Mesozoic-Cainozoic age.

East Antarctica began forming in the Archaean and had mostly completed by the Cambrian. Most of the developmental history of West Antarctica occurred in the Mesozoic-Cainozoic, the continental blocks that comprise it moving into place much later than occurred in East Antarctica. When discussing the geology and plate tectonic reconstruction of the Antarctic continent this natural subdivision has proven to be convenient.

Sources & Further reading

  1. Anderson, John B., 1999, Antarctic Marine Geology, Cambridge University Press
Author: M. H. Monroe
Last updated 28/07/2013
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