Ore‐forming Mechanism And Metallogenic Prediction Of Copper Deposit Of Silurian In Bayanbulak, Western Tianshan

Low degree of geological work has been done in Western Tianshan, especially for copperdeposit. Qiaohuote copper deposit is located in southern part of Nalati mountain close toYouludusi basin, which was discovered in the regional survey of the scale of1∶1000000in1958. Though geological exploration for many years, we determined mineral body in thevolcanic rocks of Brooke group of Silurian System with copper reserves of33.7milliontons,such as Qiaoxi, Daxigou, Bayi, Daheyan, and Dadonggou. The copper reserves ofQiaohuote copper deposit can regard as medium-sized volcanic hydrothermal type copperdeposits. On basisi of the genesis and mineralization type, Qiaohuote copper deposit can bedivided into southern, middle, and northern segement.The petrological and geochemical study and isotope ages show that it formed inisland-arc setting in Early Silurian (430.33±0.99Ma), with obvious copper mineralized syeniteporphyry veins. The geological conditions show a good prospecting potential in depth.The isotopic constitutions of hydrogen and oxygen of copper-bearing quartz veins showthat ore-forming fluids are the mixtures of magmatic water and precipitate water and most ofthe ore-forming fluids are magmatic water. The sulfur isotopes of sulfideores suggest thatsulfur souced from seawater sulfate. The lead isotopes of sulfide ores imply that ore-formingmaterials come from the mixtures of crust and mantle. Furthermore, ore-forming metal maysouced from metalsubducted oceanic crust. Geochemical characteristics show that tectonic-magmatic-hydrothermal is the basic controlling elements for Qiaohuote copper deposit.We used IP sounding to define the ore bodies at depth and select the four apparent highpolarizability zones. Combined with geological features, we proposed that Jieshuigailegoukouand xinxin potential target. In addition, we propose that porphyry deposit and related vein-typecopper deposit should be considered. Furthermore, drilling exploration has been done to testour prediction and many successive copper odebodies are found..