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Characteristics And Petrogenesis Of The Binjiang Skarn In Fanchang, Anhui Province

Posted on:2011-04-03Degree:MasterType:Thesis
Country:ChinaCandidate:L F HuFull Text:PDF
GTID:2120360302492686Subject:Mineral prospecting and exploration
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The Fanchang area in Anhui province is one important segment of Middle–Lower Yangtze River metallogenic belt. Skarns and associated deposits are widely distributed in Fanchang area. In this thesis, a detailed petrographical, mineralogical and geochemical study has been carried out on the Binjiang skarn and associated rocks in Fanchang area.The following are major achievements obtained in this thesis:1. The Binjiang skarn is locaded on the contact between the Binjiang granite and the Middle–Upper Carboniferous quartz sandstone. The skarn–host rock contact is sharp with either granite or quartz sandstone.2. The mineralogy of skarn is relatively simple, and characterized by garnet. Most garnets are andraditic and some are optically and compositionally zoned on the scale of an individual crystal. Electronic microprobe analysis of zones of garnets show that the zoning is caused by the shift of Al3+ and Fe3+ in the crystal lattice of garnet that caused by the changes of temperature, pressure, pH, oxygen fugacity during the generation of garnet skarn. On the diagram of Spe+Alm-Gro-And, all samples plot in the field of Fe mineralization, suggesting that the Binjiang skarn has the potential for the formation of iron and is homologous with Taochong skarn.3. The Binjiang granite belongs to high-K calc-alkaline series and has experienced a high degree of fractional crystallization. The Qixia limestone is rich in CaO, but poor in Fe2O3, indicating it could provide adequate calcium for the formation of skarn. The Binjiang skarn is rich in calcium, but poor in silicon, iron, and alkaline..4. Petrological and geochemical data imply that both of the Binjiang skarn and granite come from the intermediate magma that possibly formed by the interaction between crust and mantle. The Binjiang granite and skarn derive from the alkali-rich melt and skarn melt that formed by liquation of alkali-rich melt and skarn melt in the intermediate magma chamber, respectively, followed by assimilation and fractional crystallization.
Keywords/Search Tags:Binjiang skarn, garnet, electronic microprobe, major elements, Fanchang in Anhui
PDF Full Text Request
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