摘要
A number of Fe-Ti oxide and Fe-Cu sulfide exsolution phases are found in amphibole cumulate xenoliths from Mesozoic granodioritic plutons at Jiguanshi and Jin- kouling in Tongling, Anhui Province. Most of amphiboles in the xenoliths have been identified as pargasite, and deter-mined as a crystallization phase in the lower crust. The oxide exsolutions commonly acicular, are distributed parallel to [100] of amphibole with a typical Schiller texture. They con-tain 0.29%—51.07% of TiO2, and correspond to magnetite, titaniferous magnetite, titanomagnetite or ilmenite. All ex-solved sulfide grains, being rounded to extended rounded in shape, are regularly arranged in sub-paralleled or closely beaded groups, except for a few of grains that are scattered or isolated. The exsolved sulfide phases comprise mostly pyrrhotite, secondarily cubanite and chalcopyrite, and rarely pyrite. A few grains of magnetite can coexist with pyrrhotite in most samples. The sulfide phases are poor in nickel (usu-ally Ni < 0.5%, Ni/Fe < 0.003), while relative enrichments in copper (up to 2.93%) typify the pyrrhotite. Additionally, both oxides and sulfides may be exsolved in the same area of amphibole. Occurrence of Fe-Ti oxide and Fe-Cu sulfide exsolution phases in the xenoliths leads to inference that ore-forming materials such as S, Fe, Cu, etc. have been pri-marily dissolved in Mesozoic magma within the lower crust beneath the Tongling area.
A number of Fe-Ti oxide and Fe-Cu sulfide exsolution phases are found in amphibole cumulate xenoliths from Mesozoic granodioritic plutons at Jiguanshi and Jin- kouling in Tongling, Anhui Province. Most of amphiboles in the xenoliths have been identified as pargasite, and deter-mined as a crystallization phase in the lower crust. The oxide exsolutions commonly acicular, are distributed parallel to [100] of amphibole with a typical Schiller texture. They con-tain 0.29%—51.07% of TiO2, and correspond to magnetite, titaniferous magnetite, titanomagnetite or ilmenite. All ex-solved sulfide grains, being rounded to extended rounded in shape, are regularly arranged in sub-paralleled or closely beaded groups, except for a few of grains that are scattered or isolated. The exsolved sulfide phases comprise mostly pyrrhotite, secondarily cubanite and chalcopyrite, and rarely pyrite. A few grains of magnetite can coexist with pyrrhotite in most samples. The sulfide phases are poor in nickel (usu-ally Ni < 0.5%, Ni/Fe < 0.003), while relative enrichments in copper (up to 2.93%) typify the pyrrhotite. Additionally, both oxides and sulfides may be exsolved in the same area of amphibole. Occurrence of Fe-Ti oxide and Fe-Cu sulfide exsolution phases in the xenoliths leads to inference that ore-forming materials such as S, Fe, Cu, etc. have been pri-marily dissolved in Mesozoic magma within the lower crust beneath the Tongling area.
基金
supported by the National Natural Science Foundation of China (Grant Nos.40272034 and 40133020)
Chinese Ministry of Science and Technology(Grant No.G1999043206)
Korea Science and Engineering Foundation (Grant No.KOSEF-20005-131-03-02).
