Abstract:

Mayuan PbZn deposit is a large PbZn deposit discovered in the South Dabashan intracontinental orogenic belt of the northern Yangtze plate recent years in China. According to the research of orefield structure, the mineralization was controlled by interlayer fracture zones of Sinian Dengying dolomite formation. Because of the large number of breccias at the bending of the tight folds in fracture zone, and the interstratified shearing glide fault zone near the footwall, it is suggested that the orecontrolling structure is a kind of faultfold occurring during the low angle thrustnapping procedure and the associated breccia. When mineral filled in the gap between the dolomite breccias of fracture zones, the miarolitic structure and comb structure of ore grew without destruction in the late period, which demonstrated that the deposit was formed during the structural forming stage. At the same time, we have got ReOs isotopic dating from the late mineralization asphalt with an isochron age of 126±8 Ma. Considering the tectonic setting, we believe that the deposit was formed in the middlelate Jurassic. The orecontrolling tectonic breccias are the product of the low angle thrustnapping structural effect.

Key words: Mayuan, Pb Zn deposit, breccia, origin