Abstract:Geotectonically, Dongchuan mining district lies on the eastern margin of Sikang-Yunnan earth's axis, which is generally known as Dongchuan uplift. The major strata of this area, Kunyang group, are composed ofslate, phyllite, sandstone, quartzite and dolomite. Two stages of magmatic intrusion and eruption can be differentiated, i.e. Precambrian stageand Variscian stage. They both formed basic rocks. The ore bodies arestratiform and conformable to the sedimentary rocks surrounding them.Their principal geological and geochemical features may be summarized as follows: l.The ore bodies are chiefly located in the transitional beds between Yinmin purple beds and Loxue dolomites. The transitional beds have higher levels of copper and some other trace elements than all the otherrock formations, indicating that the transitional bed and the purple beds are likely to be the source beds of copper. 2.In this deposit, bornite, chalcopyrite and chalcocite comprise themajor copper-bearing sulfides, which demonstrate vertical zoning,i.e.,from top downward appear in sequence chalcocite zone, bornite zone,chalcopyrite zone and pyrite zone. 3.Copper content of the deposit shows positive correlation with Si02 and Al203 and negative correlation with Cao and MgO,suggesting a probably sedimentary origin of this deposit. 4.The δS34 Values give the impression that salfur of the copper sulfides derive mainly from the reduction of marine sulfate through theaction of biological agents. 5.The absolute age of the ores and the surrounding sediments havebeen determined isotopically to be undoubtedly larger than 1039 millionyears. 6.The exhibition of Alpine coppermineral-veinlets in the hanging wall, rarely in the footwall, of ore bodies indicates that there once happened remobiization and redeposition of copper, germanium and silverunder the influence of metamorphism.The data quoted above give the author an impression that Dongchuan copper deposit favours a sedimentary-metamorphic origin.
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王可南.1982.云南东川铜矿床沉积变质作用的地球化学[J].矿床地质,1(1):61~68.1982.Geochemical characteristics of sedimentation and metamorphism of Dongchuan copper deposits,Yunnan Procince[J].Mineral Deposits1(1):61~68
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