Geochronology And Petrogenesis Of Neoproterozoic Granitoid In Quruqtagh,Xinjiang

The Kuruketage is located in the northeastern of the Tarim Craton and the Precambrian crystalline basement rocks are widely crop out in this region.Neoproterozoic intrusive rocks are developed which continuation of a long time and has obvious stage,the rock type is complex,of which the granitoids are most widely distributed.The Kuruketage granitoids were selected in this article and their geochemistry,zircon geochronology and in situ zircon Hf isotope were systematically analyzed,Integrating with regional geology,discusses its formation age,genesis and source characteristics.Zircon U-Pb dating reveal that the granitoids of the western Kuruketage formed at 884Ma~735Ma,belong to the neoproterozoic.Integrating with previous works,the granitoids of the western Kuruketage can be divided into four stages,In this paper,only the first three phase are discussed.In the early neoproterozoic(~880Ma-~1000Ma)only less magmatic activity records in Kuruketage,in this study,we identified two granitic plutons,formed at ~880Ma,which make up the blank of early neoproterozoic magmatic activity records.the two is mainly quartz monzobiorite and tonalite which characteristic with Weakly peraluminous high alkaline potassium calcium and belong to I-type granite rocks,formed from partial melting of hydrous old basic lower continental crust.In the mid-Neoproterozoic(~840Ma-~780Ma),granitic magma activity is the most active,long duration and widely distributed in Kuluketage,mainly for the tonalite,monzonitic granite and granodiorite,there is also a small amount of rhyolite,also display I-type granite rocks characteristic.In addition,the granitoids display adakitic affinity which are characaterized by enrichment of Sr,strong depletion of Yb and Y,high ratio of Sr/Y and(La/Yb)N,these granitoids were probably produced at relatively low temperature in thickened lower crust by fluid present partial melting due to influx of external fluids and formed in a ocean-continentt subduction collision tectonic setting.In the late neoproterozoic(~740Ma-~730Ma),granitic magma activity is weak,mainly for the syengranite and rhyolite,belong to A2-subtype granite,the rocks were produced by partial melting of crystalline basement during Archean-Proterozoic which may have been derived from mantle magmas and formed in oceanic slab subduction to the extension tectonic setting,we argue that the Kuluketage block began to entered the decompression and extension setting in 735 Ma.