Terra Australis Orogen
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The Terra Australis Orogen (TAO) was the oceanic southern margin of Gondwana which stretched from
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...
to
Eastern Australia The eastern states of Australia are the states adjoining the east continental coastline of Australia. These are the mainland states of Victoria, New South Wales and Queensland, and the island state of Tasmania. The Australian Capital Territory ...
and encompassed
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...
, West Antarctica,
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
and
Victoria Land Victoria Land is a region in eastern Antarctica which fronts the western side of the Ross Sea and the Ross Ice Shelf, extending southward from about 70°30'S to 78°00'S, and westward from the Ross Sea to the edge of the Antarctic Plateau. I ...
in East Antarctica.


Origins

Terra Australis Orogen formed in the
Neoproterozoic The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago. It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is prec ...
and
Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...
. The decline of orogenic activity in the late Paleozoic is related to the assembly of the
supercontinent In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leav ...
Pangea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...
. The orogeny did not end by a continental collision and was succeeded by the Gondwanide orogeny. long and up to wide, the TAO was one of the longest and longest-lived active continental margin in the history of Earth, lasting from the beginning of its formation during the break-up of the Neoproterozoic supercontinent Rodinia. The TAO evolved through a series of
extensional In any of several fields of study that treat the use of signs — for example, in linguistics Linguistics is the science, scientific study of human language. It is called a scientific study because it entails a comprehensive, systematic, obj ...
back-arcs separated by compressional events when the subducting oceanic plate got stuck in Gondwana's margin. As Gondwana was amalgamated in the Early Palaeozoic during the so-called Pan-African orogenies the TAO propagated along the southern (modern coordinates) Proto-Pacific/ Iapetus margin of the supercontinent. The TAO ended with the Gondwanide orogeny. This and younger orogens covers most of the outboard margin of the TAO, and, likewise, the inboard margin is almost entirely covered by younger deposits and ice but remains exposed in Australia along the Torrens Hinge Line or Delamarian orogeny. One end of the TAO was a series of
terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust (geology), crust fragment formed on a tectonic plate (or broken off from it) and Accretion (geology), accreted or "Suture (geology), sutured" to crust lying on another pla ...
s ( AvaloniaCarolinaCadomia) which were rifted off the western margin of Gondwana and added to
Laurentia Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, althoug ...
in the Late Palaeozoic, while its other end probably reached past Australia into New Guinea. In 1937
Alexander du Toit Alexander Logie du Toit FRS ( ; 14 March 1878 – 25 February 1948) was a geologist from South Africa and an early supporter of Alfred Wegener's theory of continental drift. Early life and education Du Toit was born in Newlands, Cape Town in ...
proposed the Samfrau Orogeny as an evidence for Gondwana. His concept includes the orogenies of West Gondwana and orogenies that are now considered separate events but excludes those of East Gondwana.


See also

*
Terra Australis (Latin: '"Southern Land'") was a hypothetical continent first posited in antiquity and which appeared on maps between the 15th and 18th centuries. Its existence was not based on any survey or direct observation, but rather on the idea that ...


References

; Notes ; Sources * * * {{Major South American geological formations Orogenies of Africa Orogenies of Antarctica Orogenies of Australia Orogenies of New Zealand Orogenies of South America Cambrian orogenies Geology of Antarctica Geology of Argentina Geology of Australia Geology of Chile Geology of South Africa Devonian orogenies Ediacaran orogenies Neoproterozoic orogenies Silurian orogenies Ordovician orogenies