Genesis,geochronology and Hf isotopic compositions of the magmatic rocks in Galinge iron deposit,eastern Kunlun

The granodiorites,adamellites,quartz monzodiorites and quartz diorites in Galinge deposit are closely related with Fe mineralization.The results of LA-ICP-MS U-Pb isotope dating showed that quartz monzodiorite formed in 228.3±0.5 Ma,and the quartz diorite formed in 234.4±0.6 Ma.Major and trace element data of quartz monzodiorites and quartz diorites showed similar characteristics,with SiO_2 58.4%～64.3%, w(FeO~T)/w(MgO) 0.62～1.38,A/CNK(0.52～0.86)1,LREE enrichment,medium to strong negative Eu anomalies (δEu 0.33～0.82),rich LILEs such as Rb and Th,depleted HFSEs such as Sr,P,Nb,Ta and Ti,w(Rb)/w(Sr) 0.12～0.39,all of which imply that the quartz monzodiorites and quartz diorites might be the crust-mantle mixedⅠ-type granites.TheeHf(t) values of quartz monzodiorite vary from—4.15 to 3.44,and the value of T2DM varies from 1042 to 1523 Ma.TheeHf(t) values of quartz diorite vary from-5.06 to 1.7,and the value of T2DM varies from 1157 to 1 587 Ma.The similar Hf isotopic composition indicates that their parental magmas were consistent,which might be a mixture with a mantle source and ancient crust.It is suggested that the middle Triassic magmatic rocks in Galinge deposit might have been formed by underplating and magma mixing,and emplaced at the same time with subduction-collision stage from 218 to 242 Ma in east Kunlun.The water-rock interaction between middle-high temperature magmatic fluid and wall rocks could be closely related with the formation of Skarn type ore bodies.