Geochemical Characteristics And Tectonic Significance Of Permian Granites In The Wenduorihari Area Of Inner Mongolia

The study area is mainly located in the Wenduorihari area of Inner Mongolia,which is located in the southern part of the Xingmeng-orogenic belt.The tectonic and magmatic processes in the area are well developed,and many Paleozoic magmatic rocks,mainly intrusive ones,are exposed.For this reason,this paper selected the granite widely distributed in the research area as the research object,combined with the field geological survey,sampling,indoor data collection,experimental analysis and so on in the research area,and conducted a comprehensive study on the petrology,geochemistry characteristics and chronology of the Wenduorihari granite rock mass in the southern section of the Xingmeng-orogenic belt.The Wenduorihari granite body is mainly composed of monzonitic granite.Th e results of LA-ICP-MS zircon U-Pb isotope dating analysis of the monzonitic gr anite in the area show that the genomics test of the monzonitic granite in the stu dy area The result is 283±1.2Ma,belonging to the A-type granite with super-alu minum-high potassium calc-alkaline,enriched with light rare earth elements?LRE E/HREE=5.2⁹.3?and Rb,Ba,Th,U elements,relative loss Nb,Ta,Ti,P el ements,?REE is 102.22×10^–6194.65×10^–6,the average value is 149.46×10^–6,lower than the average value of the continental crust,and?La/Yb?N=6.73¹4.83,indicating light the rare earths are relatively enriched and the heavy rare earths a re relatively depleted.They are distributed in the right-wing"seagull type"with ob vious negative Eu anomalies.The content of SiO₂ in the main elements is higher?73.53%⁷7.79%?,the content of Al₂O₃ is higher?1.92%¹3.78%?,the content o f MgO is relatively lower?0.08%⁰.31%?,and the content of TiO₂ is lower?0.11⁰.34?.The content of Fe₂O₃ is low?0.97².07?.The characteristics of the main pri mary and rare earth elements are consistent with the characteristics of the A-type granite in the area.The characteristics indicate that the original magmatic rocks in the study area may be partially melted in the lower crust.Based on the above ch aracteristics,it is speculated that the Wenduorihari granite rock mass in the study area was formed in the post-orogenic environment.Combined with previous studie s,it is concluded that its formation is closely related to the large-scale orogeny i n the region,which provides new data for the intrusion activity time of magmati c rock and the tectonic evolution law in the Xingmeng-orogenic belt.