Geology and controls on the Xiajiaping gold deposits in Tianshui, Gansu

The present paper deals with the geological background, geological characteristics and ore-controlling factors of the Xiajiaping gold deposits in Tianshui, Gansu. The Xiajiaping gold deposits is hosted in the Au-Ag-CuFe-Pb-Zn metallogenic belt in the eastern part of the western Qinling reversed "S" -type arcuate structures, and controlled by the meta-clastic rocks and carbonate formation in the Lower Palaeozoic Liziyuan Group sedimentaryvolcanic rock series, and associated secondary brittle and brittle-ductile fracture zones. Spatially, the ore bodies tend to occur in strip-shaped and lenticular forms characteristic of expansion, contraction, branching, combination and discontinuity. The host rocks consist of meta-sandstone, meta-mudstone, cataclastic quartz veins and silicified breccias. The ore types are dominated by tectonically altered rocks, locally with quartz vein type and oxidized ores near the surface. In addition, the Ag, Pb and Zn mineralization are also well-developed, indicating a polymetallic sulfide type. The alteration and mineralization generally become weak and simple from the mineralization center outwards. The wall-rock alteration exhibits the zoning patterns. The mineralization can be classified into two main stages:early Au mineralization and late Ag, Pb and Zn mineralization.