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250px-Laurasia-Gondwana.svg

Map of Lurasia and Gondwana

Gondwana
(pronounced /ɡɒndˈwɑːnə/), originally Gondwanaland, is the name given to a southern precursor supercontinent. Its final suturing occurred between ca. 570 and 510 million years ago (Ma), joining East Gondwana to West Gondwana. It later separated from Laurasia 180-200 million years ago during the breakup of the Pangaea supercontinent that existed about 500 to 200 Ma into two large segments, nearly equal in area. While the corresponding northern-hemisphere continent Laurasia moved further north, Gondwana drifted south. It included most of the landmasses in today's southern hemisphere, including Antarctica, South America, Africa, Madagascar, Australia-New Guinea, and New Zealand, as well as Arabia and the Indian subcontinent, which have now moved entirely into the Northern Hemisphere.

The continent of Gondwana was named by Austrian scientist, Eduard Suess, after the Gondwana region of central northern India (from Sanskrit gondavana "forest of Gond"), from which the Gondwana sedimentary sequences (Permian-Triassic) are also described.

The adjective "Gondwanan" is in common use in biogeography when referring to patterns of distribution of living organisms, typically when the organisms are restricted to two or more of the now-discontinuous regions that were once part of Gondwana; as the Antarctic flora (e.g., the Proteaceae, a family of plants that is known only from southern South America, South Africa, and Australia are considered to have a "Gondwanan distribution". This pattern is often considered to indicate an archaic, or relict lineage).

FormationEdit

The assembly of Gondwana was a protracted process. Several orogenies led to its final amalgamation 550–500 million years ago at the end of the Ediacaran, and into the Cambrian. These include the Brasiliano Orogeny, the East African Orogeny, the Malagasy Orogeny, and the Kuunga Orogeny. The final stages of Gondwana assembly overlapped with the opening of the Iapetus Ocean between Laurentia and western Gondwana. During this interval the Cambrian Explosion occurred.

Gondwana was formed by these earlier continents and microcontinents, and others, colliding in these orogenies:

  • Azania: much of central Madagascar, the Horn of Africa and parts of Yemen and Arabia. (Named by Collins and Pisarevsky (2005): "Azania" was a Greek name for the East African coast.)
  • The CongoTanzaniaBangweulu Block of central Africa.
  • Neoproterozoic India: India, the Antongil Block in far eastern Madagascar, the Seychelles, and the Napier and Rayner Complexes in East Antarctica.
  • The Australia/Mawson continent: Australia west of Adelaide and a large extension into East Antarctica.
  • Other blocks which helped to form Argentina and around, including a piece transferred from Laurentia when the west edge of Gondwana scraped against southeast Laurentia in the Ordovician[5][6]. This is the Famatinian block, and it formerly continued the line of the Appalachians southwards.

One of the major sites of Gondwana amalgamation was the East African Orogen (Stern, 1994), where these two major orogenies are superimposed on each other:

The East African Orogeny (as later defined) at ~650–630 Ma affected a large part of Arabia, north-eastern Africa, East Africa and Madagascar. Collins and Windley (2002) propose that in this orogeny Azania collided with the CongoTanzaniaBangweulu Block.

The later Malagasy orogeny at ~550–515 Ma affected Madagascar, eastern East Africa and southern India. In it Neoproterozoic India collided with the already combined Azania and Congo–Tanzania–Bangweulu Block.

At the same time, in the Kuunga Orogeny Neoproterozoic India collided with the Australia/Mawson continent.

Continents in other Division
Terra Australis · Pangaea · Zealandia ·Pangaea Ultima · Gondwana · Lurasia · Euramerica · South China · Ur
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