Geological Characteristics And Tectonic Setting Of Volcanic Rocks In The Tuileudu Area,Inner Mongolia

The Tuliemaodu area of Inner Mongolia is located in the middle-south section of the Greater Xing'an Mountains.This area is active in volcanism,strong magmatism,widespread volcanic rocks,and complex tectonic evolution.However,there are few studies on magmatic activity in this area,and isotope dating data are scarce.The Mesozoic volcanic rocks in the Tuliemaodu area of Inner Mongolia are a combination of medium-acid volcanic lava and volcanic clastic rocks.In order to analyze the genesis of volcanic rocks and its influence on the tectonic environment,zircon LA-ICP-MS U-Pb dating and petrogeochemical studies were performed.Obtained the following knowledge: volcanic rock samples were selected as rhyolite,quartz coarse andesite and crustite tuff from the chronological test.The zircon morphology of the samples is good,all of which are self-shaped and semi-self-shaped,with obvious oscillation ring,and the ratios of U and Th are both greater than 0.6,reflecting the typical magmatic origin.The zircon U-Pb chronological analysis shows that the volcanic rocks in the Tuliemadu area range in age from 147.8 to 156.4 Ma,indicating that they formed in the Late Jurassic to Early Cretaceous.Rock geochemical analysis shows that the volcanic rocks in the study area are characterized by high silicon,alkali-rich,calcium-and magnesium-poor,deficient high-field-strength elements,rich ionic lithophile elements,and obvious thorium anomalies.Comprehensive analysis suggests that the magma originated from the crust and formed the active continental fringe environment.Based on the analysis of the fault structure in the study area,it is considered that the structure in this area is dominated by NW direction and NNE direction,which is caused by the NW direction subduction of the western Pacific plate.