Stratigraphic Features And Their Geological Significance Of Late Carboniferous-Early Permian In Hongliuxia Area,Barkol County,Xinjiang

The Dahongliu area,in Barkol County,Xinjiang is located on the south side of the Kalamari-Takzal fault zone,and is located in the combination of the three tectonic belts of the Eastern Junggar orogenic belt,the Bogda Late Paleozoic rift belt,and the Harlik Paleozoic orogenic belt.It is one of the typical areas to study the basements of the Junggar Basin.This paper takes the late Carboniferous-early Permian strata in the study area as the research object,and discussed the characteristics of rock assemblage,lithology and lithofacies,eruption,petro chemistry,tectonic environment,age attribution and other in detail;this study provides a basis to further understand the late Paleozoic tectonic evolution process in East Junggar region.This time,on the basis of fully collecting and studying previous data,we conducted detailed field geological surveys,isotope chronology,and rock geochemistry research were carried out,and the following main understandings were obtained:1.We obtained zircon U-Pb age of(318.9±2.6)Ma and(279.1±1.5)Ma in Upper subgroup Formation which belong to lower Carboniferous Yamansu Formation,and According to the characteristics of chronology,stratigraphy,and petrology,the formation was disintegrated and re-identified as Upper Carboniferous Batamayinishan Formation,Upper Carboniferous Shiqiantan Formation,Upper Carboniferous Liukeshu Formation,Lower Permian Karagang Group;and the ancient crater was identified for the first time in the newly designated Batamayineshan Formation.The Upper Carboniferous Shiqiantan Formation and the underlying Batamayineshan Formation were re-defined as angular unconformities,and the Lower Permian Karagang Formation and the underlying Liukeshu Formation were eruptive unconformities,and multiple regional structural interfaces were identified.2.The Late Carboniferous-Early Permian sedimentary environment,tectonic background and evolution process in the study area are discussed:A large number of A-type(alkaline)rhyolites have been discovered in the Batamayinishan Formation which was new divided.The rock types include sodium amphibolite rhyolite and spherulitic rhyolite.Its combination with the rock of this formation of dolerite and basalt forms a bimodal volcanic rock.Based on this,this paper confirmed that this area was in a regional extensional tectonic environment during the Late Carboniferous.The characteristics of Sedimentary and magmatic activity support that the study area has experienced the evolution process of rift opening?closing?re-cracking during the Late Carboniferous to Early Permian.Its dynamic mechanism is directly related to the subduction of oceanic crust and plate collision in northern Xinjiang.The study area has experienced repeated ups and downs of continental facies-shallow marine facies-terrestrial facies from the Late Carboniferous to Early Permian.The early eruption mode of the Late Carboniferous was overflow eruption-strong eruption-overflow eruption,and the volcanic activity was strong;then the volcanic activity weakened and turned into shallow marine facies clastic rock deposition with a small amount of pyroclastic debris,animal and plant fossils Abundant;late retreat,transforming to continental in the early Permian,and volcanic activity strengthened again.