Mineralogy, fluid inclusions, H-O isotopes, and trace element of the Dongzigou Pb-Zn deposit in the Sangmuchang metallogenic belt, China.

The Dongzigou Pb-Zn deposit is located in the south-eastern margin of Yangtze block, Midwest China. Ore bodies are hosted in Sinian carbonate rocks. The main metallic minerals are sphalerite and galena, while the non-metallic minerals are dolomite, barite, and quartz. Three stages of hydrothermal mineralization are an early quartz-pyrite stage (stage I), a middle sphalerite-galena stage (stage II), and a late sphalerite-barite stage (stage III). The main types of fluid inclusions for the Dongzigou deposit are liquid-rich inclusions (L₀-type). Laser Raman analysis indicates that the fluid inclusions within the hosted minerals are dominated by H₂O. Given the fluid inclusion data, the homogenization temperatures range from 220.0–300.0 °C (stage I), 126.7–243.9 °C (stage II), and 117.0–201.0 °C (stage III), respectively. Fluid salinities range from 3.4–11.8 wt% NaCl eq. (stage I), 3.6–10.7 wt% NaCl eq. (stage II), and 2.0–6.5 wt% NaCl eq. (stage III), respectively. Indicating that the ore-forming fluid of the Dongzigou deposit tends to decrease in salinity and homogenization temperature during the fluid evolution process. The δD (−63.4% to −49.8%) and δ¹⁸O_H2O (0.6 to 13.7%) data from stage I to stage III which indicate that the ore-forming fluids derived from formation water, and in the late stage of hydrothermal mineralization mixed with meteoric water. The LA-ICPMS results show that sphalerite enriched Cd (1272–3437 ppm), Ge (201–717 ppm), and Ga (0.1–130 ppm), but poor in In (0.01–0.1 ppm). Through comparative studies with the trace elements of sphalerite from different types of Pb-Zn deposits, it is found that the trace element characteristics of the Dongzigou deposit are most similar to the MVT deposits. Overall, the Dongzigou Pb-Zn deposit is an atypical MVT deposit, and the salinity of fluid inclusions is lower than that of typical MVT deposits. [ABSTRACT FROM AUTHOR]