Late Paleozoic Pb-zn Deposit Mineralization, Yang Basin

Southern Qinling region is an important continental mineralization belt in China. The survey and study on precious and base metal sulfide deposits of Devonian have got progress successively in the region. Recently, important Zn-Pb mineralization zones have been discovered in Silurian system of Xunyang basin , southern Qinling.The main geological setting (environment of ore-forming) is Paleozoic extensional oceanic basin related to a mantle plume in the northern margin of Yangtze plate. Several middle scale Pb-Zn deposits, occurring in Silurian system of Xunyang, Shaanxi Province, can be taken as examples.This paper study on feature of geologicaK composition and sequence of the ore-bearing strata macro fabrics and microfabrics of the ore wall rock alteration physical and chemical condition in the oreforming process. Based on geochemistry of the ore deposits, I consider the type factors of lead-zinc deposits in Silurian system of Xunyang, Shaanxi Province are following dominant factors.1 Their ore-bearing sedimentary series are Lower and Middle Silurian weakly metamorphosed silt-mudstone and mudstone, the stratiform ore-body is conformable contact and synchronous deformation with Silurian strata. Hydrothermal sedimentary rocks, such as siliceous- and albite-rock, occur in the ore-bearing bed.2 The ore has a simple ore composition dominated by sphalerite, and little alteration of wall rocks can be seen. The low-middle temperature ore-forming process occurs at the seafloor, and the gaseous component of ore-forming fluids is mainly CO2 and H2O.3 The mineralization material came from the depth below the basins. Silurian hydrothermal sediment is the main metallogenic pattern, and the deformation caused during Mesozoic orogeny is the recrystallization.