Australia: The Land Where Time Began

A biography of the Australian continent 

Antarctica - Borchgrevink Event

Metamorphic and igneous rocks in northern Victoria Land  are the primary evidence for the Borchgrevink Orogeny, a tectonic event that occurred in Antarctica in the Devonian-Silurian. It has been suggested that in other parts of the Transantarctic Mountains shallow marine clastic sediments don't appear to have been affected by the Borchgrevink Orogeny (Elliot, 1975a). In Marie Byrd Land, the Thurston Island region and the Antarctic Peninsula evidence has been found, in the form of a few radiometric dates from igneous rocks that were widely scattered and associated closely with metamorphic rocks, suggesting that a tectonic event occurred in West Antarctica in the mid-Palaeozoic (Halpern, 1968,Wade, 1972; Elliot, 1975a).

No evidence was found for compressional or deformation tectonics in the Devonian-Silurian, apart from intrusive activity, by the German Antarctic North Victoria Land Expedition (Tessenshon et al., 1981). Based on this lack of evidence the existence of the Borchgrevink Orogeny has been questioned, and it has been proposed that the "Borchgrevink Event" be used to refer to the intrusive activity. Evidence has been found of folding in the Bowers Supergroup (Wodzicki & Robert, 1986), though this folding is restricted regionally and the deformation is relatively mild with no clear metamorphic overprint. It was concurred by Wodzicki & Robert (1986) that the Borchgrevink tectonic activity be considered to be an event and not an Orogeny.

Sources & Further reading

1. Anderson, John B., 1999, Antarctic Marine Geology, Cambridge University Press