CONTROLS ON THE MUCHANGHE Ag-Au-Cu DEPOSIT,HENAN, BY DETACHMENT FAULTS

The Muchanghe area,Shangcheng County,Henan Province,is tectonically located in the east of the Qinling-Dabie orogenic belt,in the eastern segment of the Tongbai-Dabie tectonic subbelt.The structure in the area is mainly characterized by long-active WNW-nearly E-W-trending deep faults and their derivative WNW-and N-S-trending faults,as well as NE-trending faults parallel to the Tanlu fault zone to the east.Faults are marked by complex,open linear folds.Geological survey has confirmed that there are three tecto-lithostratigraphic units in the Muchanghe ore district:the core complex unit(CC),ultrahigh-pressure unit(UHP),high-pressure unit(HP),which are separated by large detachment faults.The activities of the detachment faults favored enrichment of ore-forming elements.The formation of the deposit in the area is closely related to extension and detachment following the exhumation of the Dabie UHP metamorphic belt.Most orebodies occur in a detachment fault zone above the CC unit and below the UHP unit.The detachment fault zones played an important role in controlling the mineralization in the area.