The Comparative Study Of Skarnmineralogical Characteristics In The Gaerqiong, Galale Copper-Gold Deposit, Tibet

The copper-gold deposit of Ga er-qiong and Galale are located in the west ofBangong Lake-Nujiang metallogenic belt, Under the jurisdiction of Geji town in Gejicounty, the two mining area are adjacent.The strata of Ga er-qiong mining area is carbonate rocks and volcano clasticrocks in Cretaceous Zenongqun Duoai formation（K₁l）, the mainly outcroppedintrusive rock is quartz diorite、 diorite-porphyrite、 granodiorite、granodiorite-porphyry、granite porphyry of late Yanshanian. The deposit is mainlycomposed of three ore body, the No. Ⅰ、Ⅱ ore body are located in a contacting beltbetween quartz diorite and carbonate rocks, the No. Ⅲ ore body is developed in F₁fracture zone.The strata of Galale mining area is lower cretaceous Langjiu formation（K₁l） andupper cretaceous Jiega formation（K₁jg）. The lithology combination of Langjiuformation（K₁l） is ryolitic-dacite pyroclastic rocks and coloradoite clip dacitepyroclastic lava. The lithology combination of Jiega formation（K₁jg） is dolomite、dolomitic marble and micrite. The magmatic rocks of mining area are composed ofquartz diorite、granodiorite、diorite-porphyrite and diorite. The ore body is located ina contacting belt of skarn between granodiorite and carbonate rocks.According to the microscopic identification and electron microprobe analysis of68points, the mineralogical study of skarn in both two mining areas was made, andfound that the dominant skarns of Ga er-qiong mining area are garnet and diopside,chlorite、epidote、quartz and carbonate minerals are also well developed; the dominantskarns of Galale mining area are forsterite、serpentine、diopside and phlogopite,tremolite、garnet、epidote、brucite and muscovite are also well developed.The two deposits are skarn deposits, but the skarn mineral assemblage andzoning are different. The study shows that the skarns of Ga er-qiong deposit aremainly from the intrusive rocks and marble by contact metasomatism, it is the typical calcareous skarn; the skarns of Galale deposit are mainly from the intrusive rocks anddolomite by contact metasomatism, is the typical magnesia skarn. At the same time,combined with the geological character、ore geological features、mineralization ageand geochemical characteristics of mass rocks of the two adjacent mining areas,established the mineralization pattern and for prospecting evaluation, thinking that thetwo mining areas have big potential to search the skarn and porphyry ore body.