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From field studies during the last 80 years, the geology of Antarctica is sufficiently known to allow definition of two main provinces--East Antarctica (mainly east longitudes) and West Antarctica. East Antarctica is a continental landmass with an ancient basement complex overlain by a subhorizontal sedimentary and volcanic sequence. The basement rocks (Archean to early Paleozoic) include a variety of igneous and metamorphic types; granulitic rocks such as enderbite and charnockite are widespread. The overlying stratified sequence (Devonian to Jurassic) of mainly clastic sedimentary rocks contains coal, the Glossopteris flora, and mafic sills and flows. West Antarctica is a diverse and complicated terrane of Phanerozoic rocks. Fossiliferous Cambrian beds are present in on range, but no definitely Precambrian rocks are known, although some could be that old. Five tectonic zones have been identified in Antarctica--the ancient shield and four Phanerozoic orogenes.
To understand the history and resource potential of Antarctica, it must be considered as a central piece of Gondwanaland with ties to all the other major fragments. The supercontinent had obtained most of its area by late Precambrian time, and the Pacific border was an active continental margin from then until early Mesozoic time. Major orogenes are traceable into the other Gondwanaland fragments and provide important ties for reconstruction. Breakup began during the Jurassic with separation of South American and Antarctica from Africa, and continued into the Cretaceous with the separation of New Zealand, and probably India, from Antarctica. The parting of Australia and Antarctica occurred during Eocene time. Breaking of the last linkage with South America during middle Tertiary time ed to formation of the Antarctic Circumpolar Current and the modern isolation of Antarctica.
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