Genesis of the Linghu Au deposit in Xiaoqinling Region, Henan province, China: Constraints from fluid inclusions and isotope systematics

• Published in: Arabian journal of geosciences Vol. 13; no. 17
• Main Authors: Zeng, Wei, Wang, Zhi-gao, Wan, Duo, Sun, Feng-yue, Li, Cheng-dong, Yu, Reng-an, Wang, Jia-ying, Xu, Jian-chang
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.09.2020; Springer Nature B.V
• Subjects: Carbon dioxide; Cratons; Cross cutting; Earth and Environmental Science; Earth science; Earth Sciences; Field investigations; Field tests; Fluid inclusions; Fluids; Gold; High temperature; Hydrothermal activity; Hydrothermal systems; Isotopes; Lead; Lead isotopes; Low temperature; Mineralization; Minerals; Ores; Original Paper; Pyrite; Ratios; Salinity; Salinity effects; Sodium chloride; Sulfides; Sulfur; Sulphur; Systematics; Triassic; China; Henan China; Ar; S; Pb isotopes; H; Pyrite He; Xiaoqinling region; Linghu Au deposit; O; Fluid inclusions
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-020-05914-6

The Linghu Au deposit is located within the northeastern part of the Xiaoqinling region in the southern margin of the North China Craton. Field investigations, cross-cutting relationships, and mineral paragenetic associations have identified three stages of hydrothermal activity. To determine the origin and evolution of ore-forming fluids, and better understand genesis of the Linghu Au deposit, we have undertaken a series of studies including fluid inclusion and He–Ar–H–O–S–Pb isotope systematics. Fluid inclusion study indicates that the early stage of gold mineralization was characterized by a high-temperature and low-salinity H 2 O–CO 2 –NaCl hydrothermal fluids that have δD values of – 82.0 to – 78.6‰ and δ 18 O H2O values of 5.3 to 6.4‰. The intermediate stage of gold mineralization involved moderate temperature H 2 O–CO 2 –NaCl hydrothermal fluids with δD and δ 18 O H2O values of – 92.7‰ to – 87.9‰ and – 1.4‰ to 0‰, respectively. Pyrite samples from this mineralization stage have 3 He/ 4 He and 40 Ar/ 36 Ar ratios of 0.26–0.31 Ra and 2834.7–4300.6, respectively. The last mineralization stage involved (low-temperature and low-salinity NaCl–H 2 O system of hydrothermal fluids with relatively lower δD values of – 93.1 to – 92.3‰ and δ 18 O H2O values of – 5.7 to – 5.2‰. Moreover, sulfides in ores yielded δ 34 S values of – 3.6 to 5.9‰, with an average of 2.65‰. The sulfides have 206 Pb/ 204 Pb ratios of 17.101–17.804, 207 Pb/ 204 Pb ratios of 15.438–15.554, and 208 Pb/ 204 Pb ratios of 37.438–38.654. The results of fluid inclusions and H–O, S–Pb, and He–Ar isotopes indicate that hydrothermal fluids associated with the early stage of mineralization originated from magmatic fluids, with sulfur and lead being derived from both units of the Taihua Group and a Late Triassic magmatic–hydrothermal system. All of these data indicate that the Linghu gold deposit formed as a result of magmatic–hydrothermal mineralizing processes.