Search

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 CO-rich inclusions, two-phase pure CO inclusions and two-phase aqueous inclusions, indicating boiling. Fluid inclusions in wolframite have relatively higher homogenization temperatures and salinities (239-380°C, 3.8-13.7 wt.% NaCl equiv) compared with those in quartz (177-329°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. δS values of the sulfides range from −1.6 to +0.1‰, indicative of a magmatic source of sulfur. δO values of wolframite are relatively homogeneous, ranging from +4.8‰ to +6.3‰. 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. [ABSTRACT FROM AUTHOR]

The article discusses the mineral chemical characteristics and indication of mineralization of Lengshuikeng silver-plumbum-zinc deposit in Jiangxi, South China. Topics discussed include geology of the Lengshuikeng ore district, electron microprobe analysis of sphalerites, and the difference of magmatic system.