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The Sudbury Basin, also known as Sudbury Structure or the Sudbury Nickel Irruptive, is a major geological structure in Ontario, Canada. It is the second-largest known impact crater or astrobleme on Earth, as well as one of the oldest. The basin is located on the Canadian Shield in the city of Greater Sudbury, Ontario. The former municipalities of Rayside-Balfour, Valley East and Capreol lie within the Sudbury Basin, which is referred to locally as "The Valley". The urban core of the former city of Sudbury lies on the southern outskirts of the basin. The Sudbury Basin is located near a number of other geological structures, including the Temagami Magnetic Anomaly, the Lake Wanapitei impact crater, the western end of the Ottawa-Bonnechere Graben, the Grenville Front Tectonic Zone and the eastern end of the Great Lakes Tectonic Zone, although none of the structures are directly related to each other in the sense of resulting from the same geophysical processes. ==Formation== The Sudbury basin formed as a result of an impact into the Nuna supercontinent from a bolide approximately in diameter that occurred 1,849 million years ago in the Paleoproterozoic era. Debris from the impact was scattered over an area of and traveled over away — rock fragments ejected by the impact have been found as far as Minnesota.〔Associated Press: "Ontario crater debris found in Minn.", ''Star Tribune'', July 15, 2007〕 Models suggest that for such a large impact, debris was most likely scattered globally,〔Melosh, J. (1989)''Impact Cratering: A Geologic Process''. Oxford University Press.〕 but has since been eroded away. Its present size is believed to be a smaller portion of a round crater that the bolide originally created. Subsequent geological processes have deformed the crater into the current smaller oval shape. Sudbury Basin is the second-largest crater on Earth, after the Vredefort crater in South Africa, and larger than the Chicxulub crater in Yucatán, Mexico. 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「Sudbury Basin」の詳細全文を読む スポンサード リンク
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