The dating of ore-bearing granite porphyry in the Yuejinshan skarn Cu-Au deposit, Heilongjiang Province, and its tectonic significance

Abstract: The Yuejinshan Cu-Au deposit, located in southeast Heilongjiang Province, is a typical deposit which occurs in the north of Mishan-Dunhua Deep fracture of the Wandashan metallogenic belt. The authors carried out LA-ICP-MS zircon U-Pb dating of main and trace elements in the granite porphyry, and discussed the chronology of the rock mass and the tectonic setting. The results indicate that the ore-related Yuejinshan granite porphyry has a concordia LA-ICP-MS zircon U-Pb age of (109.17±0.91) Ma, which is basically in good consistency with the weighted average age. The Yuejinshan granite porphyry has a geochemical affinity with subduction magmas, characterized by peraluminous nature, enrichment of LILIs (Rb, Ba, La, Nd and Hf), and depletion of HFSE (Nb, Sr, P and Ti). The geochronologic and geochemical characteristics of the Yuejinshan granite porphyry, combined with tectonic evolution of the Wandashan metallogenic belt, suggest that the deposit was formed in a island arc or active continental margin setting and that its formation was probably related to the subduction of the Paleo-Pacific Ocean during the Mesozoic.