Skarn Types and Mineralogical Characteristics of the Fe-Cu-polymetallic Skarn Deposits in the Qimantage Area,Western Qinghai Province

Fe-Cu-polymetallic skarn deposits are widely distributed in the Qimantage area of western Qinghai Province.Two main skarn deposits are recognized: calcic skarn and manganoan skarn,with magnesian skarn occurring in a few deposits.Calcic skarn consists mainly of diopside,hedenbergite,grossular,andradite,epidote,actinolite and scapolite,and often acompanys Fe,Cu and Mo mineralization,forming calcic skarn-type iron metallic deposit or Cu(Mo) deposits.The manganoan skarn are chiefly Mn-hedenbergite with minor pyroxmangite,associated with Pb,Zn and Ag mineralizations.Their associated mineralizations are Fe,Cu,and Mo,while for manganoan skarn are chiefly Mn-hedenbergite with minor pyroxmangite,associated with Pb,Zn and Ag mineralizations.The magnesian skarn is made up of diopside,forsterite,monticellite,and phlogopite,associated only magnetite and ludwigite.Therefore,the type of skarns is one of the important indicators to identify mineralization.