Metallogenic Characteristics And Regularity Of Indosinian Magmatic Rock In Longyangxia Area,Qinghai Province

Longyangxia area is located in the Zeku back-arc foreland basin of Zongwulongshan-QinghaiNanshan,in the late Paleozoic-early Mesozoic rift trough.The complex and unique geological tectonic evolution and magmatic activity in the area provide favorable metallogenic conditions for endogenetic metallogenesis.According to statistics,15 metallogenic spots,mineralization points and mineralization clues have been found in the study area,showing great metallogenic potential and prospects.The basic geological work in this area is relatively high.However,due to different research purposes and technical means,the systematic summary and arrangement of mineral resources research and development,magmatic activities and mineralization has not been achieved.On the basis of fully collecting the predecessors'data and comprehensive analysis,and mastering the metallogenic geological background of the area,taking Dangjiasi acid intrusive rock mass and its related copper-polymetallic and tungsten ore?chemical?points in Longyangxia area as the research object,systematic field observation and sampling of metallogenic-related magmatic rocks are carried out by means of petrology,chronology,petrogeochemistry and Metallogenic.Combining with the necessary surface engineering,we can understand the main mineral geological characteristics in the area.U-Pb isotope dating of rock masses related to Metallogenic is carried out to determine the formation age and tectonic environment of intermediate-acid intrusive rocks and to construct their tectono-magmatic evolution framework.The relationship between intermediate-acid intrusive magmatism and Metallogenic is summarized,and the metallogenic prospects are put forward,which can provide reference for further prospecting.By studying the ore-forming rock mass,it is concluded that the Dangjiasi rock mass belongs to the calc-alkaline rock with medium to high potassium content and belongs to the light rare earth enrichment type.The characteristics of trace elements are similar to those of collisional granites according to the volcanic arc granite?VAG?standard,indicating that there is melting of crustal materials in the rocks.It is formed by the melting of crustal material and the intrusion of surface material during the rise of intermediate-acidic-metabasic magma in the lower crust.The depth of intrusion is in the middle zone,which belongs to the degree of Medium-Shallow denudation.The physical and chemical environment of emplacement formation is that the pressure PH₂O is greater than 1Kb and the temperature is between 700 and 800?.Zircon U-Pb isotopic ages of 247.2?+1.7 Ma?and 243.5?+2.9 Ma?have been obtained in the Dangjiasi intrusion rock mass.They are identified as Middle Triassic magmatic rocks of Indosinian epoch and metallogenic epoch in the study area.The tectonic environment belongs to intracontinental collision orogenic environment.The Middle Triassic granodiorite and Monzonitic granite is an important source bed of W,Sn,Cu,Pb-Zn polymetallic deposits in the study area.It is divided into one metallogenic prospect area and two prospecting target areas.