THE DUCTILE SHEAR ZONE AND ITS ORE CONTROLLING PROCESS-WITH AN EXAMPLE FROM KANGGUL GOLD DEPOSIT,XINJIANG

The Kanggul gold deposit is located within the northern Paleozoic Aqishan-Yamansu island arc belt in the north of Tarim plate.The outcropping stratum in the mining area is mainly Lower Carboniferous Aqishan formation,which consists of andesite,tuff and other volcanic rocks.The Kanggul gold deposit has rather unique metallogenic characteristics.It occurs in a second-order shear zone near the Qiugemingtashi-Huangshan large size ductile shear zone.The shear zone has experienced a history from ductile to brittle-ductile and brittle shear deformation.The distribution of gold deposits is strictly controlled by a brittle-ductile deformation zone,which spreads along NEE direction and inclines northwards with a dip angle of 75 o or so.The shear zone shows characteristics of ductile deformation such as S-C fabric,rotational mortar system,dynamic recrystallization, etc.Ore bodies,hosted by altered phyllonite and mylonitized volcanic rocks,are paralleled to the mylonite zone.Ore bodies always occur in the segments with the most intense deformation.Ore bodies show platy,lens-shaped and imbricated occurrence.The ore minerals are very simple.Pyrite and magnetite are major metallic minerals,while chalcopyrite,galena and sphalerite are secondary.Of the gold minerals,native gold is dominant,followed by electrum.Chloritization,sericitization and silication are the mostly common wall-rock alteration.The veinlet,dissemination and brecciform are major ore structures.