Geochemical Characteristics And Genesis Of Dashui Gold Deposit In Western Qinling

As an important mineral resource and strategic mineral in China,gold deposits have various types and wide distribution.Since the Caledonian tectonic period,there have been multiple acidic magmatic activities in the west Qinling area,which is not only related to a variety of rare metals,but also provides the provenance for the formation of a large number of gold deposits.Dashui gold deposit belongs to superlarge gold deposit,which has the characteristics of large scale,unique mineralization and high grade.With the exploration and development and theoretical research of this gold deposit,there are great differences in the study of gold deposit genesis,and the study of alteration migration law is relatively weak.The discussion of this problem is helpful to deepen the understanding of the metallogenic process and to guide the prospecting direction.In this paper,the Au20-2 main orebody of the Dashui gold deposit in Maqu,Gannan is taken as the research object.By using the methods of microscopic identification,principal and trace elements and Carbon and Oxygen isotopes,the geochemical characteristics and genesis of the deposit are studied.The following conclusions are obtained:(1)The mineralization of the Dashui gold deposit is closely related to silicification,hematitization and calcite mineralization.The silicification and hematite mainly showed that Au,Th,Co,W were brought in,and Sr,Ba,Pb,Cr,Hf,Zr were brought out.Sc,Sr,U,Pb,Cr,Hf and Zr were brought in and brought out.Sc,Sr,Cs,Ba,U,Pb,Cr,Hf and Zr were brought in and brought out by silicification and calcite.(2)According to the characters of Carbon and Oxygen isotope speculated that the Dashui gold deposit may come mainly from granitic magma hydrothermal gold metallogenic fluid,deep high temperature hydrothermal along the tectonic fracture or fissure upward migration to Triassic strata,in the process of ore-forming hydrothermal has the replacement reaction with carbonate rock,Au ore-forming substances were extracted,when the physical and chemical condition changes,result in precipitation of Au,then enrichment and mineralization.(3)The symbiotic association of elements and minerals indicates that the mineralization of Dashui gold deposit is a process from high temperature to low temperature,but it is dominated by middle and low temperature hydrothermal fluid.The alteration of surrounding rock in Dashui gold deposit indicates that the ore prospecting potential is great.Hydrothermal alteration is an important precondition for regional prospecting,and the positive anomalies such as Au,As,Mo,Sb,Hg and W can be used as the indicator element combination of orebodies,on which the element migration model is established.