Genesis and Fluid Evolution of the Hongqiling Sn-W Polymetallic Deposit in Hunan, South China: Constraints from Geology, Fluid Inclusion, and Stable Isotopes

The Hongqiling is a vein-type Sn-W polymetallic deposit in southern Hunan (South China). It geologically located on the northern margin of Nanling metallogenic belt. Based mineral assemblage and vein crosscutting relationship, three mineralization stages were identified: (S1: cassiterite, wolframite, scheelite, arsenopyrite, molybdenite, pyrite, chalcopyrite, quartz), Pb-Zn (S2: pyrrhotite, galena, sphalerite, quartz, fluorite), late (S3: fluorite, calcite, pyrite). According to laser Raman probe analysis, H2O dominates fluid inclusions S1 S2 stage with CO2 trace N2 following close behind. ore has low salinity, density, wide temperature range, as per our microthermometric data: homogenization temperatures (Th) 236–377.6 °C (average 305.3 °C) salinity 3.5–10.7 wt.% NaCleqv; Th 206.5–332 280.7 1.6–5.1 S3 170.9–328.7 246 0.2–5.9 NaCleqv. results aforementioned investigation, calcite are mainly H2O-NaCl vapor-liquid two-phase. Additionally, examinations wolframite coexisting quartz using infrared microthermometry show that mineralizing likewise belongs NaCl-H2O system. ~40 higher than quartz. Moreover, experienced decrease accompanied by nearly constant which indicates precipitation due mixing simple cooling, earlier In situ S H-O isotope data samples have δ34S = −2.58‰ 1.84‰, fluids δD −76.6 −51.5‰ (S1 S2), δ18Ofluid −6.6 −0.9‰ (S1) −12.9 −10.2‰ (S2). All these indicate was derived from granitic magma at Qianlishan, substantial meteoric water incursion during stage. Such subsequent cooling most likely primary controls for deposition.