Sources of Ore-Forming Fluids and Materials of Jiagangxueshan W-Mo Deposit

Jiagangxueshan W-Mo deposit, Shenzha County, is the first greisen-type W deposit in Tibet. Studying the deposit is of great significance in the regional metallogenic mechanism and prospecting. The mineralization is strongly linked with the monzogranite located in the center of the deposit, and ores usually occur in inner monzogranite or sedimentary wall rocks that are adjacent to the monzogranite. The orebody types of the deposit contain greisen-type and quartz vein-type. The majority of ores distribute in greisens and intensively greisenized monzogranites in the form of veinlets or dissemination, while the minority mainly precipitated in the sedimentary wall rocks, presenting as wide quartz veins. To investigate the sources of ore -forming fluids and materials of Jiagangxueshan W -Mo deposit, wolframites and quartzs, metal sulfides from greisen-and quartz vein-type orebodies are sellected for H, O and S-Pb isotope analysis, respectively. δ¹⁸O_V-SMOW (‰) values of wolframite of the deposit range from 3.7-4.7. The hydrogen and oxygen isotope compositions of the quartzs selected from ores show that the δ¹⁸O_water values of quartzs are ranging from 2.0‰-4.3‰, with the δD values range from -131‰ to -84‰. The H-O data indicate that ore-forming fluids were derived from residual magma water after degassing. δ³⁴S values of the sulfides range from +2.2‰ to +5.3‰, indicative of a magmatic source of sulfur. The values of ²⁰⁶Pb/²⁰⁴Pb、²⁰⁷Pb/²⁰⁴Pb、²⁰⁸Pb/²⁰⁴Pb are 18.582 2-18.797 1、15.671 7-15.760 6、39.462 5-39.501 2, respectively, which further show that the ore-forming materials were derived from Precambrian metamorphic basement of the central Lhasa subterrane.