Geological Characteristics And Metallogenesis Of The Copper Polymetallic Deposit In Duocai,Qinghai

The copper polymetallic deposit in Duocai region is located in the northwestern part of the Sanjiang polymetallic metallogenic belt,where is rich in ferrous metals,non-ferrous metals,precious metals and non-metallic mineral resources.During the early Carboniferous to the mid-late Triassic,the Paleo-Tethys subducted the North China block to the north,forming a multi-island arc basin system,which is a favorable tectonic background for the formation of massive sulfide deposits(VMS)hosted by volcanic rocks.By far the exploration work has been completed in the mining area that the copper,lead and zinc resources have reached 950,000 tons,which make the scale of the deposit to be a large one.The orebodies are mainly controlled by the NW-trending fault structures,and the ore-bearing rocks are acidic volcanic clastic rocks.The copper-rich polymetallic ore found in the deposit has a massive and layered structure with a copper grade of 0.5-15% and a copper grade of 2.1%.It is the first copper-rich massive sulfide deposit type found in Qinghai Province.Therefore,the study on the genesis and metallogenic model of the deposit in Duocai region has important theoretical implications for the exploration of the same type of deposits in the Sanjiang metallogenic belt.Based on the field exploration and exploration report,this paper makes a thorough theoretical study,uses the volcanic rock major elements and rare earth elements to distinguish the structure,and combines with the theory of "Sanjiang" multi-island arc basin system,puts forward that the tectonic setting of the mining area is the island arc environment of the convergence margin of the Paleo-Tethys Ocean Plate and the North China Block.By the study of the geological structure,ore structure and mineral composition,and the analogy with typical VMS type deposits at home and abroad,it is proposed that the genetic type of the Duocai polychromatic deposit belongs to the Kuroko-type.Through the study of the geological characteristics of the deposit and the theory of seismic pumping mechanism,the genetic model of the Duocai deposit was finally established.