Discussion On The Source Of Metallogenic Materials In Yimen Copper Deposit In Yunnan Province

Yimen Tongchang copper is one of the representative deposit types in Yimen Copper Mine Belt in central Yunnan Province, whose mine lots are located at the western edge of Mesoproterozoic Yimen Fault Basin and sandwiched between Yimen fault and Lvzhijiang fault from south to north with a middle and large-sized predicted reserves. Because the grade of deposit is low and the core of Cu=0.2-0.4% grade accounts for 93.91% of the total quantity of core, the previous comprehensive researches are few and relevant research links are weak. In the thorough field geological investigation, the paper conducts massive isotopes testing and analysis, temperature measuring of fluid inclusion and element geochemical testing and analysis and detailedly studies the deposit features, geochemical features, isotopes and features of fluid inclusion of two kinds of deposits. The achievements are as follows:(1) The mine lots have two kinds of mineralization types with different causes of formation:the main mineralization type in Tongchang Mine Section is sedimentary diagenesis which is influenced by hydrothermal reformation in the later period; the main mineralization type in Dajianshan Mine Section is hydrothermal type.(2) In Tongchang Mine Section, a handful of dolomite and teh features of rare earth element indicate that the ore has the typical features of marine deposit. In Dajianshan Mine Section, a handful of calcite and quartz in ore and rare earth element indicate Tongchang Miner Section and Dajianshan Mine Section in Tongchang Mine Lot have the same period and source.(3) Isotope geochemistry reflects that Tongchang Mine Section has the obvious genetic features of marine deposit. Dajianshan Ore Section mostly distributes between magmatic carbonatite and marine carbonate rocks,indicating the hydrothermal ores in the mind lot are related to the magmatic activities in the deep; the former has a discrete 834S which is the cause of depositional genesis, and its main sources of sulfur are carbonate formations or seawater sulfate; for the later, it main source of sulfur is magmatic sulfur which contaminates sour formation; the metallogenic material in Tongchang Mine Section mainly comes from the earth’s crust or sea water sulfate, which is influenced by hydrothermal metasomatism in the later period; the metallogenic material in Dajianshan Mine Section mainly comes from mantle source or old basement, which contaminates stratum.(4) The geochemistry of fluid inclusion reflects that the metallogenetic temperature is about 60℃-290℃ belonging to middle or low-temperature mineralization type. The metallogenetic depth is about 1 kilometer belonging to middle or shallow mineralization type. Owing to the functioning of stress, the metallogenetic materials in the deep rise constantly and gather together in the position which is beneficial for mineralization. With the rising of position and the penetration of mineral materials in the stratum, the temperature becomes middle or low and salinity begins to lower and approximate acidity. With the unloading and sedimentation of copper, deposits begin to be formed.(5) Pt2y and Pt2l stratums and Jinning-Chengjiang basic group rocks in research area may be the main sources of Cu in the mine lot.