Petrochemistry and trace element geochemistry of the Besshi type Cu-Zn deposit at Faziba, SE Gansu, NW China

摘要

The Faziba Cu-Zn deposit is the first economic Besshi type volcanogenic massive sulfide deposit in China. Comparative studies of petrochemistry indicate that the mafic volcanic rocks, hosting the Cu-Zn orebodies of the Faziba and the Yangba districts, might have been formed in an island arc-setting on the northwest margin of the Yangtze Plate. Chlorite schist of the Yangba Formation of the Bikou Group is characterized by higher Cu, Zn, Co, and Ni contents and higher Co/Ni ratio. This implicates that the Besshi type Cu-Zn mineralization at Faziba and Yangba were genetically related to the basic volcanic activity and rocks. There are some differences in the trace element geochemistry between the Faziba Cu-Zn and the Yangba Cu-(Co) deposit although both of them belong to the Besshi type deposits in the same metallogenic belt.