The Study Of Argillaceous M(?)lange In Toudaoqiao-Onor,Inner Mongolia

Toudaoqiao—Wunuer structural mélange belongs to eastern Xingmeng orogeny belt,Southwest of the Xinlin—Toudaoqiao matching belt,previous studies on the main structural-rock assemblage features and their tectonic evolution in this matching belt have been carried out,but there is a lack of research on the argillo arenaceous tectonic mélange in the collage belt.Based on the investigation of tectonic-rock assemblage in collage belt,the author focused on the study of the spatial distribution characteristics,rock material composition and its structural characteristics of mud—sandaceous structural mélange,and the structural evolution model of the Mudan road to the early Permian is established.The argillaceous mélange in Toudaoqiao—Wunuer matching belt is distributed in the northeast direction,its outcropping is usually hundreds—thousand meters wide,wider even to 2 km.and coexist with the ophiolitic mélange and radiolarian siliceous rocks.The argillaceous mélange is composed of weak deformation tectonic rocks and strong deformation matrix.The "matrix" surrounds the "tectonic rock block",and the long axis of the "tectonic rock block" is basically parallel to the matrix and mylonite foliation,which is a "net knot" structure.The size of "tectonic rocks" is different,including early-Middle Ordovician grey metamorphic quartz sandstone,metamorphic acid volcanic rock,metamorphic fine-grained diorite,metamorphic granite porphyry,early-Middle Devonian grayish yellow gravel metamorphic coarse sandstone,sandstone,microcrystalline limestone,bioclastic limestone,dacite-rhyolite volcanic rock,metamorphic basic volcanic rock,and white marble which belongs to Jiagedan group of Qingbaikou system.The muddy-sandy mélange in this area is a hyperplastic wedge formed by the scraped and scraped deposits on the top of the subduction plate.With the continuous subduction,the wedge enters the lower part of the fractured layer adjacent to the old sedimentary layer,and continuously pushes up and upwards,and finally formed by the thrust nappe during the collision process,forming in early-middle Devonian to late Carboniferous—Early Permian.The muddy sandstone mélange records the formation process of the Toudaoqiao—Wunuer collage.