Recognition of two significant gold mineralization events in the Jinshan mineral field of the Jiangnan orogenic belt, South China

The Neoproterozoic Jiangnan orogenic belt (JOB) is an important Au-bearing belt in South China, yet the timing of gold mineralization has long been poorly constrained due to the lack of suitable dating minerals. This study presents integrated geochronological and geochemical data from five representative deposits in the Jinshan goldfield—the large Jinshan and Huaqiao altered-rock type deposits, the newly discovered Shiwu and Zhangjiafan deposits, and the Hamashi quartz-vein type deposit—located in the same district as the world-class Dexing porphyry Cu–Mo–Au system. In situ LA–ICP–MS U Pb dating of hydrothermal apatite and zircon, coupled with Hf isotopic and trace-element analyses, yields precise age constraints and genetic insights. Apatite from the Hamashi quartz-vein deposit records a mineralization age of ca. 173 Ma, while zircon from the Zhangjiafan granodiorite porphyry gives an emplacement age of 171 ± 2 Ma. These ages are coeval with the giant Dexing porphyry Cu–Au–Mo and Yinshan Cu–Au–Pb–Zn–Ag deposits, indicating a Middle-Late Jurassic metallogenic episode. Apatite from Zhangjiafan exhibits LREE enrichment, HREE depletion, and negative Eu anomalies, consistent with an igneous origin. Furthermore, hydrothermal apatite closely associated with gold in altered-rock type mineralization yields Early Cretaceous ages of ca. 129 Ma (Jinshan), ca. 128 Ma (Shiwu), and ca. 116 Ma (Huaqiao), with a corresponding quartz-vein age of ca. 125 Ma at Jinshan. This study defines, for the first time, revealing two discrete mineralization episodes in the Jinshan goldfield: Middle–Late Jurassic (ca. 178–166 Ma) and Early Cretaceous (ca. 130–116 Ma). The Rare Earth Element (REE) patterns of apatite closely related to the two periods of mineralization show significant differences. Early Cretaceous apatite shows higher total REE, Mn, Sr/Y, and (Gd/Yb) N values, but lower (La/Yb) N and (La/Sm) N ratios compared to Jurassic apatite, providing a geochemical fingerprint to distinguish the two mineralization events. These findings demonstrate that gold mineralization in the district is genetically linked to igneous intrusions associated with Jurassic and Cretaceous magmatism. The new geochronological framework, together with existing data from other Au–Sb–W deposits in the belt, significantly contribute to the understanding of metallogenic evolution in the JOB and highlights the high exploration potential for multi-episodic gold systems.