Triassic Litho-stratigraphic Framework And Sedimentary Basin Evolution In Lancangjiang Region Of East Tibet

The LancangJiang area in eastern Tibet is an important polymetallic ore prospecting area and a potential area for various other deposits.Since the liberation of China,the study of the LancangJiang region in eastern Tibet has made tremendous achievements.The geological work done by predecessors has fully involved the characteristics of rock and sedimentary minerals in the Tibet LancangJiang area,and accumulated more perfect results.However,most of the research areas are small and localized,and there is no systematic summary of the Triassic geological characteristics in the study area.Many areas are still in the blank areas;although some of the geological research areas involve the LancangJiang region in eastern Tibet,they are not mainly studied in the eastern Tibet areas.In the LancangJiang region,many research achievements have only reached the level of research in the study area.It is hoped that through the study of Triassic Litho-stratigraphic and palaeogeography of the LancangJiang in eastern Tibet,the basic knowledge of Triassic Litho-stratigraphic and palaeogeographic features and evolution rules of the LancangJiang in eastern Tibet will be obtained.This paper explores the occurrence patterns of sedimentary minerals through the study of paleogeographic and sedimentary facies in the study area.This paper integrates regional geological surveys,rock lithology characteristics and other data,and draws on the principles and applications of paleontology,basin analysis,plate tectonic theory,sedimentary environment and facies and sequence stratigraphy;under the macroscopic guidance of plate tectonic theory,Taking the plate movement as the starting point,this paper analyzes and compares the sedimentary facies of the Triassic section according to various sedimentary facies flags,and comprehensively analyzes the characteristics of the sedimentary facies in the study area.Finally,the relationship between sedimentary facies and sedimentary facies during the formation of sedimentary minerals is discussed.Based on the research programs used by the predecessors,multiple stratigraphic divisions of the Triassic strata in eastern Tibet have been made from the three aspects of petromic stratigraphy,Litho-stratigraphic palaeogeography,and chronostratigraphy,and the rock stratigraphic framework has been refined;The reference sequence stratigraphy based on the theory of sedimentology,Litho-stratigraphic,paleontology,and other phases,the theory of sedimentary facies of the Triassic stratigraphic profile is well analyzed.Based on the analysis of the sedimentary facies,the paleostructure,paleontology,and stratigraphic thickness are combined.In this paper,the lithofacies palaeogeography of the Tibet Arc Basin is analyzed comprehensively,and the Litho-stratigraphic palaeogeography map of the early Middle Triassic of Tibet LancangJiang and the facies palaeogeography of the Late Triassic of the Tibet LancangJiang are plotted;combined with plate tectonic theory As well as the geotectonic theory,the evolutionary characteristics of lithofacies palaeogeography between the Triassic periods of the LancangJiang in eastern Tibet were systematically discussed.Based on the analysis of the sedimentary facies and the Litho-stratigraphic and palaeogeography of each section,the specific assignment of sedimentary minerals was discussed.Save the rules and constraints.Plate tectonic movement and its development and evolution directly determine the type and nature of sedimentary basins,and different stratigraphic subdivisions produce different paleo-geographical conditions and thus have different depositional environments.Different lithologic and paleobiological characteristics of different sedimentary facies indicate different depositional environments.Sedimentary mineral resources all have their specific metallogenic specificity,and it is possible to concentrate the ore in a certain depositional environment.Through the study of this paper,the Litho-stratigraphic characteristics and sedimentary facies of the Triassic LancangJiang were basically revealed,which contributed to the study of the development and evolution of the post-arc basin of the LancangJiang in eastern Tibet and further enriched the lithofacies palaeogeography of the LancangJiang in eastern Tibet.The research results can also provide comparisons and ideas for other similar regions.The genetic mechanism,the regularity of the occurrence of deposits,and the preservation of mineralization at the later stage are all influenced and restricted by the characteristics of Litho-stratigraphic and the sedimentary environment.It is very important to carry out the geological exploration of mineral resources in the future by studying the constraints of the depositional environment on the major types of mineral deposits.The analysis of the sedimentary facies of sedimentary minerals and the exploration of sedimentary environment can provide useful reference for the exploration of sedimentary mineral resources in the LancangJiang region in the east and provide more data support and data support for the search for sedimentary mineral resources.