Yunnan Yimen Lion Copper Deposit Base Intrusive Rock Geochemistry And Tectonic Significance

Shizishan Copper deposit in Yimen Yunnan is the one of typical deposit which located at the Kunyang Rift of Proterozoic。We discovered basic intrusive rock-gabbro in shizishan copper deposit in recent years。This paper describes geological features,petrology and geochemical characteristics of gabbro in the Shizishan Copper, and discussed the gabbro rock type,tectonic discrimination,source region,the causes of the process and ore。(1) The gabbros formed in initial continental rift environment, and has intraplate basalt feature。The gabbros are in the form of dyke or sill along the NE trending faults or NW-trending fault and fracture zone between layers penetrated into the each stratum of kunyang Group in the Shizishan Copper。Combined with regional geological background, the paper believe that the gabbros may be formed in the jinning-chengjiango(2) The concentration of SiO2 of The gabbros are between 44.65% and 48.35%, Na2O+K2O are between 4.62% and 7.63%, Na2O/K2O>1, which shows the characteristics of high Na low K; Harker diagrams of major elements show that the gabbro is the evolution of basaltic magma by assimilation of crustal material。(3) Relative neglect elements expressed as highly enriched in K,Rb,Th,lowly in Sr,Nb,Yb,Cr,Y, similar to the intra-continental rift basalts; The gabbros has higher contents such as Ti,Pb,Mo,Co,V, and Cr,Ni,Sc were lower, which show that the gabbros were related to the role of deep magma causes of type;The composition and characteristic of REE are relatively stable, LREE has better fractionation。no pronounced Eu and Ce negative anomaly and (La/Yb) N greater than 4 show that the role of crustal material involved in the result of magma。Shizishan gabbros are similar to the Dongchuan gabbros in the formation of age,rock characteristics,geochemical characteristics and ore-bearing rock characteristics。Numbers of gabbros has various degrees of Cu,Fe,Ti mineralization, and a few ore bodies had been found in Xintang and Baixila deposit, which show that the mafic magma intrusion can form ore。These will provide a new way to the next prospecting in this ore bodies。...