Geochemical Characteristics And Tectonic Significance Of The Permian Intrusive Rocks In The Xingxingxia Area,Hami,Xinjiang

The study area is located in the Xingxingxia area of the Meng-Gan-Xin intersection.The geotectonic location is at the northern edge of the Tarim board.The study area has experienced multiple tectonic movements and developed multi-stage magmatism.This paper selects the Permian intrusive rocks widely distributed in the study area as the research object.Through the field geological survey and indoor comprehensive test and analysis,the chronology and geochemistry of the Permian intrusive rocks are studied,and its tectonic significance is discussed.This study has important scientific significance for exploring the tectonic evolution,magmatism in the eastern Tianshan area and the formation and evolution of the orogenic belt between the Tarim plate and the Kazakhstan plate.Through the study of petrology,petrochemistry and chronology in the study area,it is believed that the Early Permian fine-grained monzonitic granite,the Middle Permian fine-grained granodiorite and the Late Permian fine-grained zonal granules The continuous evolution characteristics of the three rocks are obvious,showing the characteristics of the homologous magma sequence.All three have the characteristics of calc-alkaline or high-potassium calc-alkaline series.The trace elements of the spider web and rare earth elements are shown as type I granite.The total amount of rare earth is low,LR/HR=1.22~8.38 indicates that the differentiation of light and heavy rare earth is relatively large,and the sampled data show that the sample has moderate anomaly abnormality,weak anomaly-nothene anomaly,and the distribution diagram of rare earth is inclined to the right.A "V" shaped curve indicating that the rock mass is a type I granite.The data obtained by zircon isotope dating show that the chronological characteristics of the fine-grained monzonitic samples in the Xingxingxia area indicate that the age is 291.8±3.3 Ma,which belongs to the Early Permian.The chronology of the fine-grained granodiorite samples indicates that the age is 273.3±1.9 Ma,which belongs to the Middle Permian.The chronology of the medium-fine-grained granodiorite samples indicates that the diagenetic age is 253.5±2.6 Ma,which belongs to the Late Permian.Through the geochemical mapping characteristics of the intrusive rocks,the intrusive rocks studied can be formed in the collision period,which is the granite of subduction and collision properties.Combined with the chronology and the local tectonic setting,it can be obtained in the Late Carboniferous-Early Permian,the Hongshishan oceanic basin began to two-way subduction and subsidence to the southern part of the Kazakhstan plate and the Tali board,collisional orogeny,and finally the collisional orogeny at the end of the Permian,causing The area is fully uplifted.