Research On Late Paleozoic Structural Deformation In Wunuer,Yakeshi,Inner Mongolia

Xinlin-Toudaoqiao collage through the Wunuer research area.About the understanding of the collage belonging to Eerguna block and Xing'an block,people had undergone a transition from the great Delbugan fault to Xinlin-Xiguitu collsion bent.However,with the recent discovery of ophiolitic melange and sandstones and mudstones melange,high-magnesian diorite,adakite,and blueschist in the Wunuer-Toudaoqiao area in the southern segment of the collage.Gradually figuring out the direction of extension of the collage and changing the previous understanding.That is,the collage between the Eerguna block and the Xing'an block is located on the Xinlin-Wunuer-Toudaoqiao line,rather than the Xiguitu area(now known as "Yakeshi").Previous work focusing on combination of ophiolitic melange and geochemistry was always on the northeastern section of the collage zone,and the research in the southern section is relatively weak.The research on structural deformation characteristics closely related to this collage is lack.Xinlin-Toudaoqiao collage slants across the Wunuer area.In this paper,the area of Wunuer in the southern section of the collage was selected as the research object.Through field investigation,it was found that the width of the collage band in the area of Wunuer reaches 2-5 km,and the geological bodies in different periods were broken by different sizes.In the form of block production,different rock masses are contacted by faults,and the structural deformation is complex.The local tectonic slices develop,and ductile deformation zoon is also seen.The Paleozoic strata in the collage belt and its two sides are strongly deformed to form complex folds and fractures,and the tectonic line is generally north east,which is consistent with the collage band spreading direction.The folds are mainly complex longitudinal folds.The fractures are mainly high-angle thrust faults,and the structural combination pattern has thrust imbricate structure,ramp thrust structure,and back thrust structure.The features of fold fault structure show that the area is located at the center of the collision between the Xingan block and Erguana block.The main stress direction is NW-SE direction.The comprehensive study shows that the main deformation period is late Paleozoic and late Permian.It is in accordance with the collision phase between the Erguana block and the Xingan block.The complex fold system in this area is the product of the collision orogenic effect of the Erguana block and the Xingan block,which is of great significance to reconstruct tectonic evolution of the Xinlin-Toudaoqiao collage belt.