METALLOGENESIS OF JINDING GIANT PB-ZN DEPOSIT, SW CHINA

The Jinding deposit, the largest Pb-Zn deposit in China, is located geologically in the Lanping Mesozoic–Early Cenozoic sedimentary basin. Based on previous studies and detailed field investigations of the Jinding deposit, we propose that a new metallogenic model of Jinding Pb-Zn deposit. There exist two types of Ore-bearing rocks in the Jinding dome, i.e., the sandstone and the limestone breccia. Different sizes, aligned, Triassic bitumen- and oil-bearing limestone breccias are contained in the ore-bearing sandstones, which showed that the structures were formed by sand diapirism. “white ball”(quartz assemblage) and “black ball”(pyrite and sphalerite assemblage) structures indicate that the mineralization are simultaneous with the diagenesis of sandstone. The Jinding dome were formed by overburden subsiding as salt- and ore-bearing sands rises owing to the density inversion. The involvement of the low-angle thrust faults in the dome implies doming subsequent to thrusting, and the geological relations indicate that the mineralization of the Jinding deposit occurred after the regional large-scale thrust event in the late Eocene. During transition from compression to extension from late Eocene to Oligocene (around 33Ma), high-pressure ore fluids with salt-bearing sands, were driven by deep magma or hot fluid, and arose along intersection areas between the middle axial tectonic belt and E-W trending linear faults. The ore fluids with salt-bearing sands diapired into the upper organic-rich limestones and deposited in the structure trap.