The Characteristics Of Peraluminous Granite And Its Metallogenic Potential In The Middle Of Gangdese

The Gangdese tectonic belt is located between the Bangonghu-Nujiang suture zone and the Yarlung Zangbo suture zone,and the exposed area of the intrusive rock accounts for about 20%.Although there is a thorough study on the evolution of tectonic-magma and its metallogenic relationship with copper polymetallics,the research on the metallogenic potential of regional tungsten-tin and peraluminous granite is relatively weak.In response to the above problems,based on the chronology and rock geochemistry data from the 1:250000 and 1:50000 regional geological survey reports,scientific research reports,published papers and thesises,as well as the data of the mentor team research results,we determined the peraluminous granite of middle Gangdese,and systematically studied the spatial distribution,petrology,geochemical characteristics and diagenesis environment of peraluminous granites of various ages.Through comparison and regional geochemical anomalies,the tungsten-tin metallogenic potential of the peraluminous granite in the study area is analyzed,and the metallogenic prospect area is delineated.The main conclusions are as follows:There are 291 peraluminous granites in the study area,involving 7 rock types and 12 geological ages.The rock types mainly include biotite adamellite,biotite syenogranite,granodiorite,etc.The diagenetic age is dominated by the late Yanshanian and early Himalayan.The geochemical characteristics show that the A/CNK of the peraluminous granite is between 1.01 and 1.78,with an average of 1.11,mainly for the high-potassium-calcium series;trace elements are generally enriched with elements such as Rb,Th,U,K,etc.,while depleting elements such as Ba,Sr,Nb,Ti;the total amount of rare earth elements varies greatly,light and heavy rare earth have obvious fractionation,but they all show a right-dip type with relatively enriched light rare elements.Most of them have obvious Eu negative anomalies,and a few Eu negative anomalies are not obvious.The diagenesis environment of the peraluminous granite is diverse.In addition to the syn-collision and post-collision environment identified by the predecessors,there are also rift environment,subduction environment and pre-collision environment.The metallogenic potential of tungsten and tin is large,we have delineated 12 tungsten metallogenic prospect areas and 8 tin metallogenic prospect areas in the study area.Among them,the northern part of the North-Gangdese has a metallogenic prospect of tin,the South-Gangdese has a tungsten metallogenic prospect,while the Middle-Gangdese and the southern part of the North-Gangdese have both tungsten and tin metallogenic prospects.