Study And Comparison Of The Typical Stratigraphical Sections Of The Devonian-carboniferous In Eastern Junggar

In this paper,the Typical Stratigraphical Sections of the Devonian and Carboniferous of the East Junggar,Xinjiang(hereinafter referred to as Standard Stratotype-Section)are studied,focusing on the exposed layer profile of the Beitashan strata community,from the establishment of name,history,profile location,rock composition,biofossil combinations,contact relationships,and depositional environments were systematically studied.At the same time,a comprehensive comparative study of the Devonian and Carboniferous stratiform profiles at the same time in the East Junggar region was carried out.The main results are as follows:Through the systematic study of the Devonian and Carboniferous Standard Stratotype-Section of the Beitashan strata community in eastern Junggar,the basic geologic information such as rock composition,biofossil combinations,and contact relationships in the strata section of the Beitashan strata community was comprehensively elucidated,and thus the regional stratigraphic comparisons were made,providing a certain reference.In the course of investigation and research,the location of the original layered section was selected as far as possible for investigation.However,due to partial sections being destroyed by natural disasters or human engineering,or better exposure of strata was found near the survey area.So the investigations and studies have adjusted and changed the position of the Standard Stratotype-Section of some of the Formations.The newly discovered profile is recommended to be a layered profile or a reference profile,such as Tuoranggekudouke Formation,Keankuduke Formation,Jiangbasitao Formation and Yaomoliang Formation.The geochronological data of some of the Standard Stratotype-Section were obtained,for example,the LA-ICP-MS zircon U-Pb age of the second basalt of the Tuoranggekudouke Formation was 400.7±8.4 Ma.The age was determined to be Early Devonian;In the Jiangzierkudouke Formation,the LA-ICP-MS zircon U-Pb age of Andesite was 347.2±2.6Ma,confirming that the era belonged to Early Carboniferous.Through the comparison of the rock composition,biofossil combinations,contact relationship,and sedimentary environment of Standard Stratotype-Section,it is believed that the vertical evolution trend of the section profiles of the Devonian and Carboniferous in the same period of East Junggar and the biofossil combinations are comparable.However,the differences in the overall rock composition are more obvious.There is basically no synonym,and this article supports each community to independently name rock strata.The evolution process of Devonian-Carboniferous sedimentary environment in East Junggar was discussed.During the Devonian-Carboniferous period,there was a number of sea-retreating events in East Junggar,but there was a general pattern: In the early Early Devonian,due to the influence of the Boluokenu movement,the marine regression in the early early Devonian study area.In the late earlyn Divonian,the area of marine transgression expanded;In the early Middle Devonian,the whole was in the marine transgression stage;In the late Middle Devonian,there was a marine regression;In the late Devonian,the scope of marine regression was expanded;The entire Carboniferous was in the marine regression stage,but due to tectonic movements,local areas are frequently interacting with marine transgression and marine regression.Because of the different tectonic settings of each community,the sedimentary evolution of the location of the respective layered profile is different: the Ertai strata communities: Middle Devonian Beitashan Formation(shore shallow sea-shallow sea)? middle Devonian Yundukala Formation(marine facies)? Late Devonian Kaxiweng(shore shallow sea-sea-land interaction facies);Beitashan strata community: Early Devonian Tutanggekudouke Formation(marine-shallow marine facies)? Early Devonian-Middle Devonian Wulusubasitao Group(Shallow-marine)? Late Devonian Keankuduke Formation(half-deep sea)? Late Devonian—Early Carboniferous Jiangzierkudouke Formation(Shallow marine facies-sea-land interaction facies-shallow marine facies)? Early Carboniferous Jiangbasitao Formation(Shallow shallow marine facies-marine-continent interaction facies)? Late Carboniferous Yaomoliang Formation(marine facies);Kalamaili strata community: Early Devonian-Middle Devonian Kalamaili Formation(Shallow Sea-Shore shallow sea)? Early Carboniferous Tamugang Formation(facies)? Early Carboniferous Dishuiquan Formation(sea-land interaction phase)? Early Carboniferous Batamayineishan Formation(terrestrial)? Late Carboniferous Huxingliang Formation(Land).