Characteristics of geochemistry of Tuchushan cooper-iron deposit in the eastern Tianshan of Xinjiang and its geological significance
Shang Haijun1, Zhang Zhixin2,3, Li Weidong1, Zhang Yaoxuan1, Qiu Yinjiang1, Liu Feng4, Zhou Kefa2,3, Li Qiang4, Wang Jinlin2,3
1. Geological Prospecting Fund Project Management Center of Xinjiang Uygur Autonomous Region, Ürümqi 830002;
2. Xinjiang Research Center for Mineral Resources, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi 830011;
3. Xinjiang Laboratory of Mineral Resources and Digital Geology, Ürümqi 830011;
4. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037
Tuchushan copper-iron deposit is a representative iron-polymetallic deposit in Yamansu Carboniferous fore-arc/arc belt of eastern Tianshan, the orebodies occurs as lenses, veins and stratums, which is hosted in volcanic rocks of the Upper Carboniferous Dikan'er Lower Formation. Homogenization temperature of fluid inclusions in skarn period vary from 151℃ to >380℃, salinity range from 1.91% to 23.18% NaCl equiv, density range from 0.76 g/cm3 to 1.09 g/cm3, and homogenization temperature of fluid inclusions in hydrothermal period vary from 101℃ to 280℃, salinity range from 0.35% to 23.05 % NaCl equiv, density range from 0.74 g/cm3 to 1.13 g/cm3, which have the characteristic of high-middle temperature, middle-low salinity and density, also belong to NaCl-H2O system.(Chlorite)-epidote skarn and magnetite-(specularite)ore have similar chondrite-normalized REE distribution patterns and are riched in LREE, is characterized by negative Eu anomaly and no Ce anomaly, also similar to volcanic of the Dikan'er Lower Formation, indicating that ore-forming material was derived from the volcanic. The authors hold that skarn might have resulted from volcanic hydrothermal interaction with cabonate and deposit was formed in high-middle temperature, comparatively wide oxidation-reduction environment. The genesis of mineral deposit is belong to volcanic hydrothermal metasomatic type.