The Study Of Mineralization Features And Fluid Metallogenetic Process Of The Super-large Tungsten Deposit In Dahutang, Northern Jiangxi

The Dahutang super-large W deposit is one of the giant tungsten deposits in northern Jiangxi Province. Mineralogy features in metal sulfides and isotope geochemistry of molybdenite related to the same ore-forming epoch, the metallogenic epoch of Cu, the ore-forming age difference between W and Cu have been studied in this paper. Meanwhile, the fluid property and origin of scheelite have been identified.Accordingly, the genesis of Dahutang W deposit is discussed and a simple model of the deposit is built up.The Dahutang giant tungsten-concentration area has three main types of ores which are veinlet-disseminated ores, breccia pipe-hosted ores and quartz-vein ores.The mineralization is closely related to the granite of middle-late Yanshanian period.The molybdenite Re-Os isotopic model average ages are 143.3Ma, 145.2Ma,144.5Ma, 143.6Ma respectively in porphyritic biotite granite, fine-grained biotite granite, biotite granite porphyry and thick-vein quartz in Shimensi ore region, which are basically same in error range, indicating that Cu、Mo mineralization are formed in one metallogenic epoch.The Dahutang W polymetallic deposit has a character of multi-stage mineralization. Based on the formation age of metallogenic mother rock, mineral assemblages, metasomatism relationship, ore mineral chemistry and ore-forming age of sulfides, we consider its ore-forming process in Shimensi and Dalingshang ore district have three metallogenic epochs which are scheelite epoch, metal sulfide epoch and quartz-wolframite epoch. The temperature data of fluid inclusion related to stratoid scheelite shows that the temperature range in feldspar-quartz shell stage is mainly centralized on 380℃~400℃ and the salinity range is mainly centralized on9% ~ 10%; the temperature range in greisenization stage is mainly centralized on360℃ ~ 480℃ and the salinity range is mainly centralized on 9% ~ 10%; the temperature range in scheelite-forming stage is mainly centralized on 360℃~480℃and the salinity range is mainly centralized on 8%~10%; the temperature range in late quartz stage is mainly centralized on 260℃ ~ 270℃ and the salinity range is mainly centralized on 8%~9%; Combining with the previous research on the isotope composition of H-O in quartz and S in sulfides, ore-forming fluid and material are mainly derived from magma.The comprehensive study of the formation age of mother rock, its geochemical features, source and evolution of ore-forming fluid, ore-forming material source,ore-forming age shows the Dahutang super-large W polymetallic deposit mineralization is controlled by Eastern China tectonic setting in Yanshanian period and is related to the setting where lithosphere of South China stretched and thinned in multiple stages. The magma of crust remelting type differentiated and evolved into ores during different stages and epochs, mixed with mantle materials in the late Yanshanian period.