Study Of The Geological Characteristics And Genesis Of Wulonggou Gold Deposit, Qinghai Province

The tectonic position of Wulonggou gold deposit is located in the middle belt of east Kunlun, and it is between the north Kunlun belt and middle Kunlun belt. The majority stratum is Pt1 jn and Qb. There are so much structure in the mining area. Gold ore bodies are strictly controlled by the NW ductile shear zone and the NW-NNW brittle fracture which is belong to the NW ductile shear zone. The ore is mainly rock type gold ore, and the others is quartz vein type gold ore. Gold is closely with arsenopyrite, pyroxene(iron) antimony ore. The host rocks mainly experienced with silicification, sericit Ization, pyritization and arsenopyritization.The results of rock(ore) stone trace elements R type cluster and factor analysis showes that the Au is closely related with Sb and As. They have a significant positive correlation. The correlation coefficience of Au-As and Au-Sb is 0.905 and 0.62. Arsenopyrite, stibnite and pyrite which has As and Sb can be used As mineral prospecting indication because of strong activity of As and Sb.The majority rock is diorite and granite. Diorite magmatic rock has a direct relationship with mineralization. Diorite which is formed in the volcanic arc tectonic environment has I type characteristics of granite diorite mass intrusion. It is formed in the indosinian stage of tethys oceanic crust subduction process toward north. The intrusive activities of the granite was in the late caledonian period. Granite which is formed in the caledonian orogeny after collision environment has A type characteristics. Granite does not have a close relationship with gold mineralization.The study of sulfur and lead isotope shows that the metallogenic material mainly comes from the mantle source and has shell mixed. It is the results of the extraction of strata minerals.The specific ore-forming process:Oceanic crust subducted northwad in the late Caledonian, and it formed a ductile shear zone at the collision zone. Gold was preliminary activated. The tethys little basin which foemed in the early carboniferous period subducted northward in the early variscan – indosinian. The anatexis happened and the molten magma which carrying fluid intruded along the fracture. The earth’s crust uplifted and thickened, the lithosphere delaminated and thinned, and the bottom of the mantle-derived magma invaded when orogenic activitied in the late indosinian period. The crust-mantle mixing acted strongly. The partial neutral magma carried the ore-forming fluid and extracted a large number of ore-forming materials from the surrounding rock. Mineral precipitated when the physical and chemical conditions of the ductile shear zone and brittle fracture zone changed a lot. The gold had a secondary enrichment at the end.The study has showed the tectonic environment, metallogenic geological conditions, the ore-forming material conditions of the Wlonggou gold deposit was similar with the Orogenic gold deposit proposed by Groves(1988). So we conclude that Wulonggou gold deposit is Orogenic gold deposit altered rock type gold deposit.