Analysis On Geological Characteristics And Metallogenetic Potential Of Jiawu Tungsten Deposit In Tongde County,Qinghai Province

Jiawu tungsten deposit in Tongde County of Qinghai Province is located in Tongren Indosinian metallogenic subbelt of Gonghe–Zeku Indosinian Cu-Pb-Au metallogenic belt belonging to the Bukadaban–Qinghai Nanshan metallogenic province.Orebody is occurred in the middle Member of Longwuhe Formation(T_1-2l²),and the lithology of the strata is sandy slate with thin-bedded carbonaceous slate interlayer and sandstone.The data about this area is relatively less due to tungsten occurrences sporadically discovered during previous geological exploration,and it is only about simple description of objective characteristics of the occurrences instead of further study.The metallogenetic background,genetic type,ore-controlling factors,prospecting criteria,texture and structure of ore,and metallogenetic potential of Jiawu tungsten deposit has become an urgent problem and bottleneck of further exploration to be solved in order to guide the implement of further exploration work,enhance the pertinence and effectiveness of prospecting work and achieve better prospecting effect since this deposit has broken through large size.On the basis of previous exploration and research results,this paper analyzes regional geological,geophysical,geochemical background,studies the geological and geochemical characteristics of the property,summarizes the ore-controlling factors,concentration regularity of veins,prospecting criteria,and discusses the metallogenetic mechanism and potential through the application of mature metallogenetic theory about tungsten deposit,field geological investigation,verification of various working method and laboratorial assaying test,which can provide theoretical basis for further exploration of Jiawu tungsten deposit.The main conclusions acquired are showing as follows:1.The main ore-bearing strata regionally outcropped is Lower Triassic Longwuhe Formation with the lithology of epimetamorphic sandstone,in which W is intensively concentrated,it provided material basis for tungsten mineralization,reflecting the obvious selectivity of the formation of tungsten mineralization upon the set of strata.2.The epimetamorphic sandstone of Longwuhe Formation is characterized by brittle property,generally crushed,coarse mineral grain,large porosity and good percolation,which benefits for the migration and occurrence of hydrothermal solution,while carbonaceous slate and carbon-bearing silty slate with small porosity is bad for the migration and occurrence of ore-bearing fluid,acting as shield.3.The occurrence states of tungsten mineralization can be mainly divided into three types:occurred in quartz veinlets of different occurrence states,occurred on fissure faces of rocks and in pyrite fine veins,as well as in the matrix of sandstone,among which quartz veinlet type is dominated.The ore-forming temperature of tungsten is ranging from 180?to 280?according to the characteristics of fluid inclusions,therefore,the genesis of the deposit belongs to mesothermal–epithermal hydrothermal quartz-vein type.4.The mineralization and concentration of Jiawu tungsten deposit is controlled by the following three factors:NW-trending fault belt coinciding with the extension of ore-bearing tectonic crushed zone,epimetamorphic sandstone of Longwuhe Formation with high background value of W element,and small intermediate-acidic rock mass providing ore-forming fluid.Structure and strata are the main ore-controlling factors from the prospective of current studying level.5.The surficial tawny tectonic crushed zone is the most intuitional prospecting criteria,and W geochemical anomalies of different scales are the most effective prospecting criteria.6.On the basis of the current exploration level,it is considered that Jiawu tungsten possesses large metallogenic potential by summarizing the geological characteristics,analyzing the extension status of orebodies and studying the axial zonality of multielement samples sampled from drillings,and deep engineering should be continuously conducted at the eastern side of orebody to expand its scale.