A Study on the Kunyang Aulacogen

The Kunyang Aulacogen is a continental rift which initiated at the beginning of the Middle Proterozoic. It was generated on the rigid continental crust represented by the crystalline Kangding Complex, and is bounded by two N-S-trending deep faults?Anninghe-Luzhijiang Fault and Xiaojiang Fault. Its early stage of rupture was characterized by alkaline mafic igneous activities in the Dahongshan Group and Hekou Group. During the later tensile- depression stage the aulacogen evolved into a graben where sedimentation of the Kunyang Group took place. The sedimentary sequence comprises terrestrial red beds, algal dolomite, marine black shale and carbonate rocks which are quite typical of rift sedimentary association, and contains stratabound copper deposits of the well-known Dongchuan type.