METALLOGENIC AGE OF SHUJIGOU COPPER-ZINC DEPOSIT IN LIAONING PROVINCE: Constraints from the Zircon U-Pb Isotopes of Plagioclase Amphibolite Gneiss

The Shujigou Cu-Zn deposit of VMS type occurs in the granite-greenstone belt in east section of northern margin of the North China Platform. The crystallization age of 2564±2 Ma for the host plagioclase amphibolite gneiss is obtained with LA-ICP-MS zircon U-Pb dating technique, which can approximately represent the metallogenic age. According to the published mantle zircon U-Pb age (2517-2529 Ma), it is considered that the Shujigou Cu-Zn deposit underwent metamorphism, deformation and remobilization during the later Anshan Orogeny. Combined with the geochemical characteristics and evolution of the host rock, it is inferred that the mineralization is involved with partial melting of mantle to form base metal-rich magma during plate subduction. With upward migration, convergence, eruption, consolidation and diagenesis of the magma, ore-forming elements leached by seawater are infiltrated and enriched in the igneous rocks, which then erupt to the surface along faults with deep permeability. Finally, the hydrothermal fluid is mixed with surrounding seawater, followed by further metamorphism and deformation to form the Cu-Zn deposit.