CHARACTERISTICS OF THE DAHEISHAN GOLD DEPOSIT IN-AOHAN QI,INNER MONGOLIA,AND THE STRUCTURAL-CONTROL OF MINERALIZATION

The Daheishan gold deposit located in the Nuluerhu uplift belt in the northern margin of the North China Platform developed in the Archean high-grade metamorphic complex.The origin of the gold deposit is closely related to the Yanshanian Daheishan granitic intrusion.The gold deposit belonging to fragmentation-alteration type and or alteration-quartz vein type is regarded as a mesothermal ore deposit since its mineralization temperature ranges from 235℃ to 300℃,W¹⁸O from 2.89‰ to 14.74‰,and W³⁴S from-1.30‰ to 4.27‰.The nearly W-E-trending faults,which are the major fractures that control industrial ore bodies,and NE-and NW-trending ones with weak mineralization developed widely in the mining area.The pay shoot,however,was usually formed where the W-E-trending faults join the NW-and NE-trending ones.Detailed study in the field suggests that the gold mineralization is mainly controlled by the brittle faults formed at shallow and medium depth,rather than by a ductile-shear zone formed at a deep level.