Abstract:

The nappe structures in Huangbi mining district, North Wuyi, Southeast China are NNE oriented with dip angles towards WNW. It was found in field investigation that the nappe structures  destroyed the previous Mo deposit on one hand, while their secondary fissures  obviously controlled the distribution of later PbZn deposit. Integrating SHRIMP UPb zircon, ReOs and 39Ar40Ar dating results, this paper reports the order of the tectonicsmagmatismmineralization processes in Huangbi district. The ReOs dating result of 154 Ma shows that the molybdenite was formed during the Late Jurassic. The SHRIMP UPb zircon analyses yield consistent ages of 138±1 Ma for trachyandesite porphyry and 131±2 Ma for rhyolitic crystal tuff from Shengmikeng ore block in Huangbi ore field, indicating that the magmatic activity took place during the Early Cretaceous. And the 39Ar40Ar age of 129 Ma for Kfeldspar from fault zone F1 suggests that the regional nappe structures occurred no later than 129 Ma. PbZn ore body occupied the crannies caused by thrust faults, so its formation is later than that of the nappe structures, which indicating another magmatic hydrothermal activity once occurred after the one in the early Cretaceous. Thus, the nappe structures in Huangbi mining district have both ore destruction and  formation properties.

Key words: Huangbi mining district, thrust nappe structure, mineralization relevance, 39Ar40Ar dating, ReOs dating, SHRIMP UPb zircon analysis