High-resolution Sequence Stratum And Coal-bearing Model Of Xujiahe Formation Of Huang Jinkou Area

This paper based on collection many former data and actual research discusses Northeastern Sichuan foreland basin formation and evolution by Longmen Mountains and Micang Mountains-Daba Mountains tectonic belt asynchronous over thrusting role composite control,foreland basin in northeastern Sichuan class constructor late Triassic sedimentary basin of the Xujiahe Formation-deposition pattern and paleogeographic evolution characteristics of each stage.Consider that Xuanhan Huangjinkou exploration region Xujiahe Formation is mainly controlled by Micangshan-Daba Mountains thrust nappe tectonic activity.In the early days(T3X1-3)Micang Mountains-the Daba Mountain construct Mountains in the low amplitude stability uplifting,this period Kawanishi Longmen mountain ranges over thrusting more active role,but the study area only by its thrust covered the role of remote effects.In the late(T3x4-5),Micang Mountains-Daba Mountains thrust nappe belt into a more intense period of tectonic uplift in the study area is mainly affected by sedimentation of Micang-the Daba Mountains over thrusting role control.The main rock types of the exploration area of Huangjinkou is clastic rocks.Conglomerate mainly in the fourth member of Xujiahe formation appears,its composition is quartz.Coarse,medium,fine-grained sandstone and siltstone in Xujiahe paragraphs almost have appeared the lithic sandstone as the main rock classes.Argillaceous rocks in third member,fifth member sections of the special development,the main mineral components of Iraq-smectite minerals and kaolinite.A comprehensive study by detailed observation and analysis of field measurements of surface profile,combined with drilling data confirm the color of the rocks,structure,composition,sedimentary structures,fossils,and cross-sectional structure of sedimentary facies signs can be effectively applied Xujiahe depositional environment.Sedimentary facies analysis from the study area Triassic be Xujiahe group divided four sedimentary system of alluvial fan depositional system,braided river depositional system,braided river delta sedimentary system River lakes,and described in detail,and a synthesis of each depositional systems and sedimentary subfacies and microfacies characteristics.Come Xujiahe Formation of delta and lake sediments,Sec braided river deposits,three sections of braided delta front deposition,four alluvial fan,five sections of braided river delta front and lake sediments conclusions.Comprehensive analysis by high-resolution sequence boundary type identification and sedimentary sequence in northeastern Sichuan foreland basin structure-sedimentary evolution of sedimentary facies characteristics of the study area to be Xujiahe sedimentary filling is divided into three three-grade composite sequence and fourteen four-grade sequence.based on broad collecting of materials of the reasearch area,by adding practice data of measured stratigraphic section in exploration area,we get the geographic map of Sequence stratigraphic framework and Lithofacies palaeogeography of Xujiahe formation's major stage of northeastern Sichuan foreland basin.Braided river system,braided river delta sedimentary system are detrimental to the formation and preservation of the coal seam,favor the depositional environment of the coal seam formation and preservation of the delta lobes between the lakes and shallow bay environment.K4 coal seam in the study area is formed in such an environment.It summarized that the coal-bearing model of Xujiahe Formation is braided river delta coal accumulating mode.