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In paleogeography, Gondwana ,〔(【引用サイトリンク】url= http://www.merriam-webster.com/dictionary/gondwana )〕 also Gondwanaland, is the name given to the more southerly of two supercontinents (the other being Laurasia) that were part of the Pangaea supercontinent that existed from approximately 300 to 180 million years ago (Mya). Gondwana formed prior to Pangaea, then became part of Pangaea, and finally broke up after the breakup of Pangaea. Gondwana is believed to have sutured between about 570 and 510 Mya, thus joining East Gondwana to West Gondwana. It separated from Laurasia 200-180 Mya (the mid-Mesozoic era) during the breakup of Pangaea, drifting farther south after the split. Gondwana included most of the landmasses in today's Southern Hemisphere, including Antarctica, South America, Africa, Madagascar, and the Australian continent, as well as the Arabian Peninsula 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 the Gonds". The name had been used in a geological context, first by H.B. Medlicott in 1872.〔Eduard Suess, ''Das Antlitz der Erde'' (The Face of the Earth), vol. 1 (Leipzig, Germany: G. Freytag, 1885), (page 768. ) From p. 768: ''"Wir nennen es Gondwána-Land, nach der gemeinsamen alten Gondwána-Flora, … "'' (We name it Gondwána-Land, after the common ancient flora of Gondwána … )〕 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, including the Antarctic flora. For example, the Proteaceae family of plants known only from southern South America, South Africa, Australia, and New Zealand is considered to have a "Gondwanan distribution". This pattern is often considered to indicate an archaic, or relict, lineage. ==Formation== The assembly of Gondwana was a protracted process. Several orogenies led to its final amalgamation 550–500 Mya 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 Gondwanan assembly overlapped with the opening of the Iapetus Ocean between Laurentia and western Gondwana. During this interval, the Cambrian explosion occurred. Gondwana was formed from the following earlier continents and microcontinents, among others, colliding in the following 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 Congo–Tanzania–Bangweulu 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 some surrounding regions, including a piece transferred from Laurentia when the west edge of Gondwana scraped against southeast Laurentia in the Ordovician. This is the Famatinian block (named after Famatina in northwest Argentina) and it formerly continued the line of the Appalachians southwards.〔http://sp.lyellcollection.org/content/142/1/219.abstract Laurentia-Gondwana collision: the origin of the Famatinian-Appalachian Orogenic Belt (a review)〕 One of the major sites of Gondwanan amalgamation was the East African Orogeny (Stern, 1994), where these two major orogenies are superimposed. The East African Orogeny at about 650–630 Mya 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 Congo–Tanzania–Bangweulu Block. The later Malagasy orogeny at about 550–515 Mya affected Madagascar, eastern East Africa and southern India. In it, Neoproterozoic India collided with the already combined Azania and Congo–Tanzania–Bangweulu Block, suturing along the Mozambique Belt. At the same time, in the Kuunga Orogeny Neoproterozoic India collided with the Australia/Mawson continent. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gondwana」の詳細全文を読む スポンサード リンク
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