TheTerra Australis Orogen (TAO) was a lateNeoproterozoic- toPaleozoic-ageaccretionaryorogen that ringed the ancient,active southern margin of thesupercontinentsRodinia and laterPannotia (also called GreaterGondwana). This vast orogenic belt stretched forc. 18,000 km (11,000 mi)along-strike and involved, from west to east (in the ancient,paleogeographic reference frame), landmasses belonging to the modern-dayAndean margin ofSouth America, theSouth African Cape,West Antarctica,Victoria Land inEast Antarctica,Eastern Australia,Tasmania, andNew Zealand. The formation of the Terra Australis Orogen is associated with thebreakup ofRodinia at the end of theNeoproterozoic Era and the creation ofPanthalassa, the paleo-Pacific Ocean, and it was succeeded by theGondwanide orogeny with the formation of thesupercontinentPangea in the middlePaleozoic Era.[1][2]
Terra Australis Orogen formed in theNeoproterozoic andPaleozoic. The decline oforogenic activity in the late Paleozoic is related to the assembly of thesupercontinentPangea. The orogeny did not end by acontinental collision and was succeeded by theGondwanide orogeny.[3]c. 18,000 km (11,000 mi) long and up to 1,600 km (990 mi) wide,[4] the TAO was one of the longest and longest-lived active continental margin in thehistory of Earth, lasting from the beginning of its formation during the break-up of the Neoproterozoic supercontinentRodinia.[1]
The TAO evolved through a series ofextensionalback-arcs separated by compressional events when the subducting oceanic plate got stuck in Gondwana's margin.[5]
As Gondwana was amalgamated in the Early Palaeozoic during the so-calledPan-African orogenies the TAO propagated along the southern (modern coordinates)Proto-Pacific/Iapetus margin of the supercontinent. The TAO endedc.300 to 230Ma with theGondwanide 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 orDelamarian orogeny. One end of the TAO was a series ofterranes (Avalonia–Carolina–Cadomia) which were rifted off the western margin of Gondwana and added toLaurentia in the Late Palaeozoic, while its other end probably reached past Australia into New Guinea.[4]
In 1937Alexander du Toit proposed theSamfrau 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.[4]
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