Structural Characteristics of the Jianchaling Gold-Nickel Orefield and Its Rock-controlling and Ore-controlling Roles

The cobalt-bearing sulfide nickel deposit in Jianchaling has entered the exploitation stage and gold-search is undergoing in its peripheral mines.Thus it is an important task to ascertain the structural characteristics and rock-controlling and ore-controlling roles of this orefield.We have analyzed the orefield structure,deposits and tectono-geochemistry.The result shows that this orefield has experienced frequent tectono-thermal events,folds of many periods controlled the stratigraphic distribution,and conjugate regional ductile shear belts controlled the emplacement of rock intrusion.The features of tectono-geochemistry indicate that ductile deformation was favorable to the activation of metallogenic elements,while ductile-brittle deformation promoted element migration and enrichment.Introduction and removal of large-volume materials occurred within regional ductile shear belts and ore-controlling ductile-brittle shear belts.The contents of K2O and Cr etc.in mylonitized serpentinite-type nickel ores are obviously less than that in regional ductile shear belts,and the elements,such as Fe2O3,FeO,P2O5,L0I,MnO,SiO2,CaO,Ni,and Co,have been carried into nickel ores.The ore-controlling ductile-brittle shear belts have determined the form,occurrence,ore structure and texture of gold and nickel ore-bodies.So,rocks and ores in the Jianchaling gold-nickel orefield are controlled jointly by folds,regional ductile shear belts and ore-controlling ductile-brittle shear belts,which can be described by a mineralizing model..The brittle fractures were formed later,and destructed the strata,rock bodies and ore-bodies to some degree.