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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Porphyry copper deposit ： ウィキペディア英語版 Porphyry copper deposit Porphyry copper deposits are copper orebodies that are formed from hydrothermal fluids that originate from a voluminous magma chamber several kilometers below the deposit itself. Predating or associated with those fluids are vertical dikes of porphyritic intrusive rocks from which this deposit type derives its name. In later stages, circulating meteoric fluids may interact with the magmatic fluids. Successive envelopes of hydrothermal alteration typically enclose a core of disseminated ore minerals in often stockwork-forming hairline fractures and veins. Because of their large volume, porphyry orebodies can be economic from copper concentrations as low as 0.15% copper and can have economic amounts of by-products such as molybdenum, silver and gold. In some mines, those metals are the main product. The first mining of low-grade copper porphyry deposits from large open pits coincided roughly with the introduction of steam shovels, the construction of railroads, and a surge in market demand near the start of the 20th century. Some mines exploit porphyry deposits that contain sufficient gold or molybdenum, but little or no copper. Porphyry copper deposits are currently the largest source of copper ore. Most of the known porphyrys are concentrated in: western South and North America and Southeast Asia and Oceania - along the Pacific Ring of Fire; the Caribbean; southern central Europe and the area around eastern Turkey; scattered areas in China, the Mideast, Russia, and the CIS states; and eastern Australia.〔http://geopubs.wr.usgs.gov/open-file/of02-268/maps/map1.pdf〕〔(Base Metals )〕 Only a few are identified in Africa, in Namibia〔(Base Metals )〕 and Zambia;〔http://wayback.archive.org/web/20100307202424/http://www.mawsonwest.com.au/multimedia/1/ASX%20Chimpantika%20160407.pdf〕 none are known in Antarctica. The greatest concentration of the largest copper porphyrys is in Chile. Almost all mines exploiting large porphyry deposits produce from open pits. ==Geological overview== 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「Porphyry copper deposit」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.