Australia: The Land Where Time Began

A biography of the Australian continent 

Pangaea - A Proposed Formation 

According to the authors1 amalgamation of continents and microcontinents on a large scale led to the formation of Pangaea, the process beginning at the closing stage of the Neoproterozoic with the formation of Gondwana. Micro-continents, with a ribbon-like shape, were detached from the African and South China side of Gondwana on its Antarctica, Australia, South American side. These micro-continents were:

Late Neoproterozoic: Cadomia
Ordovician:                Avalonia and Hunia
Devonian:                  Galatia
Permian:                    Cimmeria

Cadomia was re-accreted to Gondwana and the other ribbon-continents were accreted to Baltica, North China, Laurussia or Laurasia. The authors1 say it was a major geological challenge to find the origin of the many terranes, and they overcame this problem by the use of a recently developed global plate tectonic model in conjunction with a large geological/geodynamic database at Lausanne University, that covered the last 600 Ma of the history of the Earth. They gave special attention of the placement of the terranes that had been derived from Gondwana in their original position, and using all possible constraints. In this paper the authors1 propose a solution for the Variscan terranes, and in a separate paper they deal with the Altaids. As Palaeotethys opened in the Devonian the Galatian super-terrane was detached from Gondwana and was soon split into 4 sub-terranes that began bypassing each other, the leading terranes colliding with the Hanseatic terrane that had been detached from Laurussia at the end of the Devonian. Gondwana began impinging onto the amalgamated terranes in the Carboniferous, thereby creating the Variscan chain and the supercontinent of Pangaea. Until the Triassic the Palaeotethys remained open to the east of Spain, subducting beneath Laurasia. The collapse of most of the European Variscan orogen was triggered by role-back of the Palaeotethyan slab to be replaced by a series of rifts in the Permian, some of which became oceanised back-arc basins in the Triassic. At the end of the Triassic major changes of force at the limits of the Pangaean plate provoked its breakup by the opening of the Protocaribbean, central Atlantic, and Alpine Tethys oceanic seaways.

 

Sources & Further reading

  1. Stampfli, G. M., C. Hochard, C. Vérard, C. Wilhem, and J. vonRaumer. "The Formation of Pangea." Tectonophysics 593, no. 0 (5/8/ 2013): 1-19.

 

Author: M. H. Monroe
Email:  admin@austhrutime.com
Last updated 21/05/2013
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                                                                                           Author: M.H.Monroe  Email: admin@austhrutime.com     Sources & Further reading