新疆温泉岩群新元古代岩浆岩的锆石U-Pb年龄及地质意义OA

This study presents a systematic petrological,LA-ICP-MS zircon U-Pb geochronological,and whole-rock geochemical investigation on the Neoproterozoic augen-and granitic gneisses from the Wenquan Group,West Tian-shan.Results show that these granitic gneisses crystallized at 904.5±4.1 Ma to 902±4 Ma,representing an early Neoproterozoic magmatic event.The rocks are characterized by high silica(SiO2=65.23％～68.75％),high alkali(ALK=7.46％～8.89％),high potassium(K2O/Na2O=1.01～2.24),and strong peraluminous affinity(A/CNK=1.05～1.18),belonging to the high-K calc-alkaline series and typical S-type granites.They are enriched in Rb,Ba,Th,and light rare earth elements(LREE),depleted in Nb,Sr,Ti,and P,and exhibit moderate negative Eu anomalies.Comprehensive analysis indicates that the magmas were derived from high-temperature dehydration melt-ing of greywacke with minor pelitic rocks from the Paleoproterozoic Wenquan Group,and formed in a syn-collisional tectonic setting related to the Grenvillian orogeny during the assembly of the Rodinia supercontinent.This study provides precise geochronological and geochemical constraints on the Precambrian basement of the Yili Block and offers important insights into the tectonic affinity between the Yili Block,the Central Tianshan Block,and the Tar-im Craton.