Geochemical Characteristics And Significance Of Caiyu Pluton In West Shandong

The late Neoarchean is significant to the crust evolution of North China Craton(NCC).Neoarchean rock is widely exposed in western Shandong Province(WSP),it is an important area for our research.The Caiyu pluton is located in the Yishui terrane of WSP,which is the oldest pluton,a complex mainly composed of charnockites in Yishui terrane.We conducted a series of analyses of major elements,trace elements,zircon UPb dating and zircon Lu-Hf isotopic composition.The charnokites in the Caiyu complex was formed during 2537?2565Ma,which is produced by different stage of the same thermal event.According to the previous study,WSP terrane was in the state of normal subduction,we conclude that charnockites in Yishui terrane was the co-product of plate melting and partial melting of granulite in the lower crust during subduction.Chronologic study shows that some xenocrystalzircons with ages of 2702?2996Ma were captured in the complex,whose Lu-Hf isotopic evolution is similar to that of 3.2?2.6Ga trondhjemite.Therefore,an ancient nucleus should exist and involve with the magmatic event in late stage of Neoarchean.