| 铜官山层控矽卡岩型铜矿床的蚀变分带及其成因 |
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| 引用本文：.1987.The Alteration Zoning And Origin Of The Tongguanshan Stratabound Skarn Type Copper Deposit[J].Mineral Deposits,6(1):35~44 |
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| The Alteration Zoning And Origin Of The Tongguanshan Stratabound Skarn Type Copper Deposit |
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| Abstract:The Tongguanshan copper deposit is one of the major iron and copper deposits in middle and lower valley of the Yangtze River. According to the location of occurrence, its orebodies might be divided into upper, middle and lower parts with the alteration zonation consisting mainly of four portions, i. e., metasomatic, metamorphic, metamorphic-metasomatic and metasomatic- metamorphic zones. Of these three parts, the middle one is the main orebody, which js layered or stratoid in form and is confined strictly to the dolomite member- of C2. Due to the effect of thermometamophism, it exhibits characteristic metam orphic zoning towards the intrusive body in order of kappa-pyrite→pyrite→pyrrhotite→magnetite for metallic minerals, dolomite→antigorite→lizardite→phlogopite for nonmetallic minerals, lamellar→ribbon→striped→massive for ore structure and colloidal (strawberry-shaped pyrite) →blastic→relict for ore texture. The zonation of metallic minerals implies a variation series of minerals from noncrystalline→crystalline, from lower temperature assemblage to high temperature one and from sulfides to oxides. The inclusion thermometry and the geothernometry indicate that the temperature varies from no decrepitation→340℃→380℃→540℃→851℃→987℃ and f02 from<10-44 →10-10→1.74×10-9→5×10-4 Pa. Based on these data, it may be reasonably considered that the temperature and oxygen fugacity are chief factors bringing about these variations. As temperature is dependent on thermometamorphism caused by intrusion, the metamorphic zonation must be a product of metamorphism. |
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