GEOLOGY AND METALLOGENY OF THE COPPER DEPOSITS IN THE SHANGSHAXIMAO FORMATION IN NORTHWEST GUIZHOU: A case study of the Tiaotai copper deposit in Xishui County

The cupreous sandstone type of copper deposit in Renhuai-Xishui area, Northern Guizhou Province occurs in the red beds in the large inland basin on the edge of Sichuan platform-depression. The ore-bearing rocks are mainly the arkose containing silicified or carbonized wood of Middle Jurassic Shangshaximiao Formation. Taking the Tiaotai copper deposit as an example, this paper summarizes and studies the geologic characters and metallogenic conditions of the copper deposits in Shangshaximiao Formation. The metallogenesis experienced three stages, i.e. 1) primary sedimentation of cupreous sandstone layer; 2) surface oxidation; and 3) secondary enrichment and mineralization. The deposit is formed by the groundwater leaching after the primary sedimentation of the cupreous sandstone layer.