Geological Characteristics And Its Tectonic Significance Of The Early Paleozoic Volcanic Rocks From Kanasi Area In Altay,Xinjiang

This article focuses on petrological,geochemical perspective go on systematic dicuss for Early Paleozoic volcanic Rock in Kanasi erea,while the combination of the distribution of volcanic rocks,forming environment and the formation of the era were discussed and comprehensive understanding.With analysis and comparative study of geochemical data provide an important basis for the evolution of Paleozoic geological research in the area.There is a suit of volcanic-sedimentary strata that is Dongxileke Formation in Kanasi aera,.There is no accurate ages and geochemical study of those rocks,The genisis and geodynamical background exist controversy for a long time.For investigating this problem,we choose volcanic rocks in this area for our subjects of this work.LA-ICP-MS zircon U-Pb ages of 445.4±3.1Ma and 445.7±3.7Ma from two mylonitic dacite suggested that these volcanic rocks erupted in late Ordovician,it suggested that Dongxileke Formation formed in late Ordovician.The volcanic rocks is characterized by SiO₂ content from53.99%⁷1.04%,high Al₂O₃?13.83%¹6.27%?and low MgO?1.09%³.53%?,K2 O between1.11% and 3.83%,average is 2.84%,it belong to High alkline volcanic rock series.The volcanic rocks forms a LREE-enriched distribution pattern and the existence of negative Eu anomaly??Eu=0.65⁰.82?.Geochemical characteristic of volcanic rocks suggest that it shows island-arc volcanic characteristics being enriched in LILE such as Rb?Th?Ce and depleted in HFSE such as K?Nb?Ta.Combined with regional datum and result of the article,author consider that the volcanic rocks suit is generated during syn-collision of the late stage subduction in an active continental margin arc.the background from Paleo-Asia Ocean subducted northern under the Siberia plate to Altai micro landmass land conversion,formed late Ordovician volcanic rocks of active continental margin arc in Kanasi area.