A Study on the Mineralization of the Woxi Au–Sb–W Deposit, Western Hunan, China

Abstract

The Woxi Au-Sb-W deposit in the western Hunan Province, China, is of hydrothermal vein type characterized by a rare mineral assemblage of stibnite, scheelite and native gold, of which gold fineness ranges from 998.6 to 1000. The mineralization sequence observed in the deposit is, from early to late, coarse-grained pyritescheelite -stibnite -Pb-Sb-S minerals -sphalerite (+ cubanite) -fine-grained pyrite. Native gold may have precipitated with scheelte. Microthermometric and LA-ICP-MS analyses of fluid inclusions in scheelite, quartz associated with scheelite and stibnite and barren quartz clarified that there may be at least three types of hydrothermal fluids during the vein formation in the Woxi deposit. Scheelite and native gold precipitated from the fluid of high temperature and salinity with high concentrations of metal elements, followed by stibnite precipitation. The later fluid of the highest temperature and salinity with low concentrations of the elements yielded the sphalerite mineralization. The latest fluid of low temperature and salinity with low concentrations of the elements is observed mainly in barren quartz. The remarkably high Au/Ag concentration ratios determined in the fluid inclusions in scheelite might be the reason for the extremely high gold fineness of native gold.

In Situ Trace Elemental Analyses of Scheelite from the Chuankou Deposit, South China: Implications for Ore Genesis

“…REEs 3+ have similar partition coefficients between scheelite and ore-forming fluids so that and REE composition of scheelite can be used to investigate the REE concentrations in ore-forming fluids. Such REE patterns appear in scheelite IIa and scheelite IIb in the Chuankou tungsten deposit (Figure 7B,C) as well as in the Shizhuyuan W-Sn-Bi-Mo deposit, the Xuebaoding W-Sn-Be deposit, the first generation scheelite from the Dabaoshan poly-metallic deposit and the Zhuxi giant tungsten deposit [11,15,31,42,43], showing that scheelite in these deposit have similar substitution mechanism.…”

“…Most of the deposits involved in this study are quartz-vein type tungsten deposits, which are located in granite (e.g., the Shizhuyuan W-Sn-Bi-Mo deposit and the Xingluokeng tungsten deposit) or in sedimentary rocks (e.g., the Xuebaoding W-Sn-Be deposit and the Woxi Au-Sb-W deposit). Previous studies of granitic rocks associated with tungsten mineralization in South China have documented that these granitic rocks are rich in tungsten and the compositions and temperature of ore forming fluids could remain similar during the transportation for hundreds of meters [2,4,6,21,26,31,43]. The Chuankou tungsten deposit is hosted in both granite and sedimentary rocks.…”

“…The major stratigraphic sequences in XUB are the Neoproterozoic Lengjiaxi and Banxi groups, which are composed of metasedimentary rocks, a turbiditic sequence of greywacke, siltstone and slate. Numerous Au-Sb-W deposits were identified in XUB, such as the Woxi Au-Sb-W deposit, Zhazixi Sb-W deposit and Cangziping Au-W deposit in Hunan Province [21,24,26,[28][29][30][31][32]. Unique element associations of Au, Sb and W suggested that these deposits are formed from a low-temperature hydrothermal system.…”

Trace elements mineral chemistry of sulfides from the Woxi Au‐Sb‐W deposit, southern China

“…Visible gold is observed as native gold (Au content >99 wt%) in the Woxi deposit (Figures 4g and 6e,i), which was also reported in a previous study (Liang et al ., 2015). The presence of invisible gold is also indicated by the mineral chemistry of pyrite presented in this study.…”

Complex Gold-Antimony Mineralization in the Process of Mineragenic Evolution of Terrane Structures in Asia

“…т, Au -2 т. Продуктивны гидротермальные жилы с антимонитом (Sb 2 S 3 ), шеелитом (CaWO 4 ) и высокопробным (998,6-1000) Au. Флюидные включения в шеелите содержат повышенные концентрации золота [21].…”