Stratigraphic Sequence And Basin Properties Of Carboniferous In Zhurihe Area,Inner Mongolia

The study area is the Zhurihe area,which is located in the northern part of the Bainaimiao Island arc zone,south of the Xilamulun fault zone and the Wendulmiao subduction-accretionary complex zone,and is part of the Xingmeng orogenic belt.This paper has a certain understanding of the Carboniferous rock association,sedimentary characteristics,stratigraphic sequence,sedimentary facies,sedimentary environment,etc.in Zhurihe area.Through the study of sandstone clastic zircon age and sandstone clastic composition analysis,the conclusions about the formation age of Carboniferous,the source of sedimentary materials and the nature of the basin are obtained.In this paper,through the analysis and research on the lithology,lithofacies,sedimentary features,Stratigraphic superposition lawand sedimentary cycles of the Carboniferou,the composition of Shizuizi is divided into four sections,its sedimentary environment is divided intoalluvial fan,fan-delta,lagoon,and isolated platform sedimentary environment;the composition of baijiadain is divided into three sectionsand its sedimentary environment is divided into isolated platform and lagoon sedimentary environmen.In general,the Carboniferous sedimentary environment gradually changed from continental facies to transitional facies to marine facies,and the sea level continued to rise.Through the U-Pb zircon age study of the sandstone and intrusive rocks of the Shizuzi Formation and combined with the research results of the project team and the predecessors,this paper considers that the age of the Shizuizi Formation is the Late Devonian-Early Carboniferous and the age of the Baijiadian Formation is Late Early Carboniferous-Early Late Carboniferous,which provides a new basis for the tectonic evolution of Xingmeng orogenic belt.The age composition characteristics of detrital U-Pb zircons in the sandstones of the Shizuzi Formation are analyzed,and it is believed that the provenance mainly comes from the Bainaimiao Island arc,the interior of the Xingmeng orogenic belt,the Northeast microplate and the North China plate.Based on the analysis of sandstone skeleton composition,the provenance mainly comes from the nearby cutting island arc,continental plate,collision suture zone and fold-and-thrust belt.It is preliminarily believed that the paleo-asian ocean has been closed before the deposition of Shizuiziformation,and the material source of the bottom of Shizuizi formation mainly comes from the BAInaimiao island arc.With the erosion of the new continental crust,the island arc has been completely denuded,the material source transportation distance has increased,the maturity has become higher,and the material source has gradually come from the the interior of the Xingmeng orogenic belt,North China Craton and northeast micro plates.Comprehensive research and analysis of Carboniferous systemcan be concluded that the basin represented by Carboniferous strata is is a rift-type basin.It evolved from the Shizuizi Formation which represents the early stage of the intracontinental rift to the Baijiadian Formation which represents an isolated platform facies formed by further crustal stretching and faulting.