Sedimentary Characteristics Of Carbonate Platform Margin Of Early Feixianguan Stage In Northwest Sichuan Basin

Sichuan Basin is an area of about 19×104km2 superimposed basins of large gas—rich natural gas resources in our country one of the regions, the former Sinian metamorphic and igneous rocks in the basement, 6000 ~ 12000m thick deposited on the sea, continental formation, is currently developing the western region to succeed in the important West—East block. But previous to the Sichuan Basin, the Early Triassic Feixianguan characteristics of rocks and sedimentary environment of the key limitations in northeastern Sichuan, western Sichuan North the strata of the research is still at an early stage of attainment is low.In this paper, the northwest Sichuan basin (ie, Northwest Territories) Lower Triassic Feixianguan object of study, field data in the field, drilling cores, logging data, based on in sedimentology, palaeontology, geophysics Principles of structural geology study and the guidance for the rock composition, biological composition, sedimentary structure, the measured profile, the deposition of a detailed analysis of such features, divided into carbonate platform depositional system and basin depositional systems, carbonate platform which depositional system study area can be identified restricted platform, open platform, platform margin facies of three types, mainly in the County to the east of the south jiange, Yilong west. Can be further divided into restricted platform, open platform, platform margin reef and platform margin slope. Platform margin depositional environment for the main study area can be broken down introduction to the edge of reef facies, platform margin slope, mainly in the North River through mouth—Jiangyou water stump, Yudong beam—the Temple—Guangyuan Yang Yan—Shop Cangxi Yongning—South River area; from the north edge of the main platform is a siliceous carbonate basin, mainly by a set of—thin layers of dark gray, dark gray and gray—black chert, siliceous limestone clip very thin mudstone composition. From the structural point of view, different periods of deep faults and has grown to basement faults controlled the basin of deposition pattern. Their presence further affected the study area, the early Triassic succession of Changxing Feixianguan rimmed carbonate platform of the regional deposition pattern; and its distribution and the relative movements of exercise on the region of the Lower Triassic sedimentary facies distribution has obvious controls. The impact of sea level change from the point of view, the continuing transgression caused by deposition of carbonate plus ramp to the platform will facilitate the transformation. Distribution of sedimentary facies and obvious impact.