Geochemical And Chronological Characteristics Of The Granitic Gneisses And Intrusive Rocks From Dongshengmiao Region,Inner Mongolia And Their Tectonic Implications

The study region is located in north margin of North China Block(NCB),Wulatehouqi, Inner Mongolia.which is key parts of the analysis of the Central Asian Orogenic Belt.Base on the Plate Tectonic Theory,by using petrology,rock geochemistry, tectonic geology and new test methods and combining with regional geological survey,we conducted a detailed field geology survey on Qgn and Hundibaishi, so we can analyze the division of important magma intrusion stages, and inverse the tectonic evolution proceeses of the study region. The results show that:(1) According to the geological features, forming invironments and Zicon chronology of the intrusive rocks, we found there are five tectonic evolution proceeses in study region,which are Neoarchean Era(2696-2563Ma)、Proterozoic(2180-1834Ma)、mesoproterozoic-Neoproterozoic (1523-1037Ma)、Carboniferous (320-296Ma)、Triassic period (253-227Ma).(2) The study of geochemical charactiristics about Qgn granitic gneisses showed that the origical rock is belong to Quasi aluminium,calc-alkaline series and I-type granitic.The forming environment is volcanic arc of active continental margin. We utilize TIMS U-Pb methods to date time of zircon and obtain the metamorphic age of about2500Ma.(3) The study of geochemical charactiristics about Hundibaishi monzogranite showed that the rock is belong to peraluminous,High-K calc alkaline series and S-type granitic at colliding tectonic invironment, which is important evidence about the forming history of Rodinia supercontinent at late mesoproterozoic.