Molybdenite Re-Os and zircon U-Pb geochronology, Lu-Hf isotope and geochemistry constraints on the genesis of the Jinxi Cu deposit, southern Fujian, South China

• Granodiorite from the Jinxi Cu mine was characterized. • Granodiorite from the Jinxi Cu deposit belongs to the high-K calc-alkaline series. • Granodiorite diagenesis and mineralization occurred in the late Early Cretaceous. • Granodiorite in the Jinxi Cu deposit is supposedly a type I granite. Located on the southeastern margin of Cathaysian Plate, the Jinxi Cu deposit is part of the Shanghang-Yunxiao tectonic-magmatic metallogenic belt, is a magmatic hydrothermal deposit. The Mineralization limitations and era are of great significance for a deeper understanding of the mineralization process of the Jinxi magmatic-hydrothermal deposit. The granodiorite related to mineralization within the mining area is high-potassium calc-alkaline series, and is characterized by high K2O, low Si, and low TiO2. Analysis of rare earth (REE) and trace elements showed that the granodiorites are enriched in light rare elements, have weak negative Eu anomalies. Zircon LA-ICP-MS dating of the granodiorites indicated an age of 104.2 ± 0.4 Ma. Zircon ε Hf ( t ) values of granodiorites are −2.49–1.58, the two-stage model ages ( T DM2 ) is 1.08–1.32 Ga. Re-Os isotopic dating of the molybdenite samples revealed an isochronic age of 104.6 ± 3.7 Ma from the ore body, indicating that during the late Yanshanian period, the formation of the Jinxi Cu deposit is primarily related to intrusive rocks formed. Based on this study and other study results, it is reasonable to consider that the granodiorites of the Jinxi Cu deposit belong to the I-type, and during the late Early Cretaceous Period (110–90 Ma), the deposit’s formation and associated depositralization are related to Paleo-Pacific Plate subduction in the southeast coastal area.