Rb-Sr Dating of Pyrite and Quartz Fluid Inclusions and Origin of Ore-forming Materials of the Jinshan Gold Deposit,Northeast Jiangxi Province,South China

The Jinshan gold deposit is located in the Northeast Jiangxi province, South China, which related to the ductile shear zone. It contains two ore types, i.e. the alteration‐type ore and the gold‐bearing quartz vein ore. Rb‐Sr age dating is applied to both gold‐bearing pyrite in the alteration‐type ore and fluid inclusion in the gold‐bearing quartz vein to make clear the time of the gold mineralization of the Jinshan deposit. Analytical results of this study yielded that the age of the alteration‐type ore bodies is about 838±110Ma, with an initial ⁸⁷Sr/⁸⁶Sr value of 0.7045±0.0020. However, the age of the gold‐bearing quartz vein‐type ore is about 379±49Ma, and the initial ⁸⁷Sr/⁸⁶Sr is 0.7138±0.0011. Based on the age data from this work and many previous studies, the authors consider that the Jinshan gold deposit is a product of multi‐staged mineralization, which may include the Jinninian, Caledonian, Hercynian, and Yanshanian Periods. Among them, the Jinninian Period and the Hercynian Period might be the two most important ore‐forming periods for Jinshan deposit. The Jinninian Period is the main stage for the formation of alteration‐type ore bodies, while the Hercynian Period is the major time for ore bodies of gold‐bearing quartz vein type. The initial values of the ⁸⁷Sr/⁸⁶Sr from this study, as well as the previous isotope and trace element studies, indicate that the ore‐forming materials mainly derived from the metamorphic wall rocks, and the ore‐forming fluids mainly originated from the deep metamorphic water.