Geochemical features and LA-ICP-MS zircon UPb ages of the granite porphyry in the Dongxiang copper deposit of Jiangxi Province and their geological significance

In this paper, the authors investigated petrogenesis, tectonic setting, emplacement timing and metallogeny of the granite porphyry based on its petro-geochemistry and zircon U-Pb geochronology. The LA-ICP-MS zircon U-Pb dating of the granite porphyry yielded ages of 156.4±1.5~161.0±1.0Ma, indicating that the granite porphyry was emplaced during the Yanshannian period. The granite porphyry is characterized by high-K calc-alkaline series, enrichment of LREE and depletion of HREE. The REE curves show negative Eu anomaly. The granite porphyry is enriched in large ion lithophile elements and depleted in high field strength elements. The petro-geochemical analysis shows that the Dongxiang granite porphyry was formed in a plate collisional environment and that crustal contamination was involved in the evolution of the magma. The magma was derived from the mantle but caused crustal assimilation and partial melting during its upward migration. The ore has the same characteristics as the granite porphyry in REE composition, and the ore-forming age in the Dongxiang copper deposit is close to the age of magma intrusion. It is shown that magmatic intrusion had an important contribution to the formation of the Dongxiang copper deposit.