Study On The Geological Characteristics And The Ore-controlling Factors Of Gold Mining Area In Northern Shiquan,South Qinling

The northern mountains of Hanyin is located in the Shiquan-Shenhe Ductile Decollement Thrust-nappe Belt in Southern Qinling. The Yangpingwan gold deposit, Changgou deposit and Huanglong deposit are found in the area. It is a large gold mineralized zone with characteristic of structural ore-controlling. The Jiangjunhe gold mineralized anomaly area in northen shiquan is located in the west side of the belt. Areas exposed strata have Meiziya group, Banjiuguan group of Silurian and Donghe Group of cambrian-ordovician. Tectonic deformation is complex and intermediate-acidic dike developmented. In the previous work, it was found that many gold mineralization anomalies, but it is lack of understanding of the ore bearing rule and ore controlling factors. Paper is based on the project of China Geological Survey "key basic geological research project of the whole-mount exploration in Shiquan-Xunyang, Shannxi". We studied the geological characteristics, ore controlling factors and prospecting marks in the area by structural-lithofacies mapping, thin section and polished section microscope observation, geochemistry and geochronology test of vein rock and the test of quartz veins fluid inclusion homogenization temperature. And we have achieved the following recognitions:(1) We recognize that the gold mineralization and anomalies in Jiangjunhe in northen shiquan are mainly concentrated in the Banjiuguan group which is characterized by carbon containing.(2) We found that the intermediate-acidic dike in the area is diorites though geochemical and geochronological study. U-Pb dating on the zircon shows that 2239±36Ma represents the age of basement in this area. 771.9±3.4Ma represents the crystallizing age in the study area, and it’s form background is in the volcanic arc environment relevanted to the subduction and the magma came from partial melting of earth crust. The neoproterozoic dikes and gold has no direct genetic relationship.(3) Quartz vein in the area is divided into three stages as S1,S2 and S3. The inclusion homogenization temperature of first phase quartz vein, produced by S1 foliation, is medium-low temperature, 170℃~220℃, and it’s high-salinity. The second phase quartz vein, produced by S2 foliation, shows medium-high temperature, 270℃~370℃,and high-salinity. The Third phase quartz vein, produced by S3 foliation, shows medium-low temperature, 170℃~220℃,and low-salinity. The gold mineralization is closely related to the second phase quartz veins.(4) The gold bodies in the area are mainly distributed along the ductile shear zone. Linear structural convergence positions with NW-trending, NE-trending and EW-trending have better mineralization potential.(5) Comprehensive study showed that The most important prospecting criterias in the area are alteration belt like pyritization and jarosite etc, srong-deformation zone, carbon containing zone, and quartz vein intensive development zone.