The Xihuashan tungsten deposit, Jiangxi province, China, is a world-class vein-type ore deposit hosted in Cambrian strata and Mesozoic granitic intrusions. There are two major sets of subparallel ore-bearing quartz veins. The ore mineral assemblage includes wolframite and molybdenite, with minor amounts of arsenopyrite, chalcopyrite, and pyrite. There are only two-phase aqueous-rich inclusions in wolframite but at least three major types of inclusions in quartz: two- or three-phase CO2-rich inclusions, two-phase pure CO2 inclusions and two-phase aqueous inclusions, indicating boiling. Fluid inclusions in wolframite have relatively higher homogenization temperatures and salinities (239-380A degrees C, 3.8-13.7 wt.% NaCl equiv) compared with those in quartz (177-329A degrees C, 0.9-8.1 wt.% NaCl equiv). These distinct differences suggest that those conventional microthermometric data from quartz are not adequate to explain the ore formation process. Enthalpy-salinity plot shows a linear relationship, implying mixing of different sources of fluids. Although boiling occurred during vein-type mineralization, it seems negligible for wolframite deposition. Mixing is the dominant mechanism of wolframite precipitation in Xihuashan. delta S-34 values of the sulfides range from -1.6 to +0.1aEuro degrees, indicative of a magmatic source of sulfur. delta O-18 values of wolframite are relatively homogeneous, ranging from +4.8aEuro degrees to +6.3aEuro degrees. Oxygen isotope modeling of boiling and mixing processes also indicates that mixing of two different fluids was an important mechanism in the precipitation of wolframite.

Publication name	MINERALIUM DEPOSITA　Volume: 47 　Issue: 6 　Special Issue: SI 　Pages: 589-605　 Published: AUG 2012
Author(s)	Wei, Wenfeng; Hu, Ruizhong; Bi, Xianwu; Peng, Jiantang; Su, Wenchao;Song, Shengqiong; Shi, Shaohua
Corresponding author	HU Ruizhong  huruizhong@vip.gyig.ac.cn  Chinese Acad Sci, Inst Geochem, State Key Lab Ore Deposit Geochem, Guiyang 550002, Peoples R China.

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