新疆东天山东戈壁钼矿矿床地质和地球化学特征

新疆东天山东戈壁钼矿床是迄今为止在我国东天山找到的最大规模的钼矿床,钼矿资源量超过5×10⁵ t。该矿床赋存于花岗斑岩外接触带中,矿石矿物以辉钼矿、黄铁矿为主,围岩蚀变以硅化、钾化、黄铁矿化、电气石化、碳酸盐化和萤石化为特征。其成矿作用可以划分为成矿期和成矿期后两个阶段,成矿温度为140℃～380℃,盐度为0.88～21.33 wt%NaCl,成矿深度为1.76～2.87 km,指示东戈壁钼矿为中低温、中低盐度的浅成矿床。对主要钼矿体8件辉钼矿样品进行Re-Os同位素分析获得的等时线年龄为234.3±1.6 Ma,表明该矿床的成矿时代为印支期。东戈壁钼矿床形成时代的厘定对于提高该矿床的理论研究水平和指导该区隐伏金属矿床的找矿勘查工作均具有重要意义。

Research on the fluid inclusion and Re-Os dating of Donggebi Mo deposit, eastern Tianshan, Xinjiang

The Donggebi Mo deposit,located in the eastern Tianshan,Xinjiang Province,is the largest molybdenum deposit ever found in the eastern Tianshan area.The Mo metal resources are more than 500 000 tons.The Donggebi Mo deposit formed in the outer contact zone of the porphyritic granite and its main ore minerals are molybdenite and pyrite.The wall-rock alteration is characterized by silicification,potassium alternation,pyritization,tourmalinization,carbonatization and fluoritization.The mineralization can be divided into two stages:the metallogenic period and the post-metallogenic period.Study on fluid inclusions indicates that the deposit is a meso-low temperature magmatic hydrothermal Mo deposit formed at depth ranging from 1.76 km to 2.87 km and at temperature 140℃ to 380℃ with the ore-forming fluid salinity 0.88～21.33 wt%NaCl.The Re-Os isotopic study of eight molybdenite samples yield the isochron age 234.3±1.6 Ma,which suggests that the Donggebi Mo deposit formed in Indo-Chinese epoch.This study plays great role in the further understanding of this deposit and further exploration of blind metallic ore deposits in this area.