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SWEAT stands for southwestern United States and East Antarctica, which theorizes that the Southwestern United States was at one time connected to East Antarctica. A hypothesis for a late Precambrian fit of western North America with the Australia-Antarctic shield region permits the extension of many features through Antarctica and into other parts of Gondwana, specifically, the Grenville orogen may extend around the coast of East Antarctica into India and Australia. The ophiolitic belt of the latter may extend into East Antarctica. The Wopmay orogen of northwest Canada may extend through eastern Australia into Antarctica and thence beneath the ice to connect with the Yavapai-Mazatzal orogens of the southwestern United States. Counterparts of the Precambrian-Paleozoic sedimentary rocks along the U.S. Cordilleran miogeocline may be present in the Transantarctic Mountains. Orogenic belt boundaries provide useful piercing points for Precambrian continental reconstructions. The model implies that Gondwana and Laurentia drifted away from each other on one margin and collided some 300 million years later on their opposite margins to form the Appalachians.〔http://www.geosociety.org/news/pr/01-10.htm〕 ==Evidence== A paper published by an international team led by John Goodge, an NSF-funded researcher with the Department of Geological Sciences at the University of Minnesota-Duluth, gives significant support to the theory. Writing in the July 11, 2008 edition of the journal Science, this international team of U.S. and Australian investigators describe their findings, which were made in the Transantarctic Mountains, and their significance to the problem of piecing together what an ancient supercontinent, called Rodinia, looked like. The U.S. investigators were funded by the National Science Foundation (NSF).〔 Previous lines of scientific evidence led researchers to theorize that about 600-800 million years ago a portion of Rodinia broke away from what is now the southwestern United States and eventually drifted southward to become eastern Antarctica and Australia. They argue that the team's find provides physical evidence that confirms the southwestern United States and East Antarctica (SWEAT) hypothesis.〔 John Goodge's team was searching in Antarctica's Transantarctic Mountains for rocks carried along by ice rivers that could provide clues to the composition of the underlying crust of Antarctica, which in most places is buried under 2 miles of ice. One rock, found atop the so-called Nimrod Glacier, was later determined to be a very specific form of granite which has a particular type of coarse-grained texture.〔〔 Chemical tests run on the rock revealed that it has a chemistry very similar to a unique belt of igneous rocks in North America that stretch from California through New Mexico to Kansas, Illinois and eventually New Brunswick and Newfoundland in Canada. This belt of rock was a part of what is called Laurentia, thought by some geologists to be the core of Rodinia.This belt stops suddenly at its western margin, leading geologists to suspect that some piece of crust had rifted away from what is now the West Coast of the United States.〔〔 〕〔(【引用サイトリンク】title=A Positive Test of East Antarctica–Laurentia Juxtaposition Within the Rodinia Supercontinent )〕 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「SWEAT (hypothesis)」の詳細全文を読む スポンサード リンク
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