A STUDY OF THE HIDDEN EXPLOSIVE BRECCIAS AT GENGZHUANG GOLD-SILVER DISTRICT OF SHANXI PROVINCE
山西省耿庄金银矿区隐爆角砾岩研究

A series of explosive breccia pipes, related to acid rich-alkaline subvolcanic rocks of Yanshan period in origin, occur in the Northeast Shanxi Province. Gengzhuang breccia pipe is one of them as a well studied and a typical pipe. It is elliptic in plan and unsymmetrical funnel-shaped in vertical section, with a diameter up to 150m and a depth more than 600m at centre. The zoning pipe consists of seven types of breccias. There is a certain affiliation between some breccias and host rocks, and mosaic texture among the breccias. At least two explosion related to the pipe formation raked place. The main mineralization was followed by the secondary explosion, forming a medium gold-silver deposit with Pb, Zn, Cu, and controlled by the secondary annular-liked fractures within the breccia pipe and by the breccias.