Geological characteristics,metallogenic model and prospecting model of Sageke complex conglomerate type copper deposit,Wuqia,Xinjiang
Xinjiang Sareke complex conglomerate type copper deposit is located in the western margin of Tarim Basin.This paper studies ore-forming geological body,ore-forming structure and structural plane,ore fabric,the vertical and horizontal changes of main-trace elements and fluid inclusions in copper ore.The results show that the metallogenic geological body is the complex conglomerate in the upper member of Kuzgunsu Forma-tion(J3k2)of Upper Jurassic.The metallogenic structures are complex syncline and tangential fault in northeast direction.The metallogenic structural plane is between the marmaronian silty mudstone at the bottom of the first lithologic member of the Lower Cretaceous Group(K1kz1)and the complex conglomerate of the upper member of the Upper Jurassic Kuzigunsu Formation(J3k2),and the marmaronian silty mudstone on the upper wall of the ore body is the closed lithofacies layer of the ore-forming fluid in the basin.The gravel composition of copper ore of mixed conglomerate is mainly mudstone,ferric carbonate rock,quartz fine sandstone,argillaceous fine sandstone,basic volcanic rock,phyllitic argillaceous slate,quartz sandstone,quartzite,siliceous slate,etc.,with poor sorting ability,the particle size is generally between 0.3-5 cm,and the individual reaches more than 7 cm.The round-ness of the gravel is medium,most of the gravel is subroundness,and some of the gravel is fragmented by tectonic action in the later stage.The cement of the gravel is calcite,dolomite,chalcocite,a small amount of secondary quartz and asphalt.The analysis results of quartz and calcite inclusions show that the ore-forming fluid is medium-low temperature and medium-high salinity.The homogenization temperature has a weak positive correlation with salinity,the homogenization temperature has a significant positive correlation with gas-liquid ratio,and the salinity has a weak negative correlation with gas-liquid ratio.In the process of fluid evolution in the basin,the fluid has a trend of temperature from high to low,salinity from low to high,and quartz crystallizes earlier than calcite and dolomite.The main gas phase components in the inclusions are N2,CO2,CH4 and H2O.From 2685 elevation to 2790 elevation,the gas phase components have a trend of evolution from the combination of CO2,N2 and CH4 to the combination of N2,CH4 and H2O,indicating that the reduction of the fluid from the lower part to the upper part has a tendency to gradually weaken.On the basis of the above research,the metallogenic model of the complex conglomerate type copper deposit in this area is established,and the comprehensive prospecting model of this type of copper deposit is established through the effectiveness analysis of different scale geophysical and chemical exploration methods,aiming at providing help for the exploration of the same type of mineral deposits in this area.
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