The Geochemical Characteristics And Diagenesis Of Ore-Forming Granites From Chagandeersi Molybdenum Deposit, In Western Inner Mongolia

Chagandeersi molybdenum deposit, located in central-west Inner Mongolia,China, is a newly discovered large scale deposit. It is a porphyry molybdenumdeposit characterized by disseminated, spot and veinlet mineralizations hosted inmedium-fine grained monzonitic granite. Geochronological and elemental data arepresented for the ore-forming granites. The data(by Liu Yifei,2012) show that theore-forming granite was emplaced and crystallized in the Late Permian(253-254Ma).Compared with the molybdenite Re-Os dating(243Ma) form literature(CaiMinghai,2011), it indicate that the Chagandeersi molybdenum deposit was formedabout10Ma after the ore-forming granite.The major elements data show these granites are high K calc-alkaline series,metaluminous-peraluminous and characteristic of high silicon, high alkali.Combined with the trace elements features, it indicates that the ore-forming magmasis most plausibly originated by partial melting of previous subduction modifiedsource, and has inherited some features of subduction related magma. Theore-forming magma has undergone plagioclase and potash feldspar dominatedcrystal fractionation process before transported to the ore forming structure and werecontaminated by the baoyintu gneiss. The forming of these granites andChagandeersi molybdenum deposit were favored by the post-collision regime as thechemical features show.