Study On Sdimentary System And Sequence Stratigraphy Of Early Teriary-Late Teriary In Kuche Depression, Tarim Basion

Guided by the theory of sedimentology and sequence stratigraphy and combined with the data of outcrop, core and logging, this paper studies the feature of sedimentology and the revolution of sequence-lithofacies paleogeography of Kuche depression.According to the mark of sedimentary facies and combined with geology data, this paper divided the type of sedimentology system into alluvial fan- fan deltas facies, meandering rive deltas facies,lake facies and tidal flat-lagoon facies, and discusses the characteristics of sedimentary facies, sedimentary subfacies and sedimentary microfacies of these depositional systems, and establishes the sedimentary models of the settings of Early Teriary-Late Teriary of the studied area, based on which discussed the characteristics of the evolution of depositional systems. The research shows that Kuche Basion on the whole experienced a continuously marine invasion from the south-west to the north-east at the begging of Early Teriary , after that sea water gradually withdrawaled and the invironment of Kuche Basion gradually changed into continent which made Kuche Basion inland depositional basin. Influenced by stages of tectonic action,the sedimentation of lake invasion and retirement override in the vertical direction in the setting of Early Teriary of Kuche depression . Generally speaking, the basin was shallow and distributed to a large area, and nearly all the basin accepted lake sedimentation, featured by gypsum lake sedimentation.Based on the identification of sequence boundary, this paper divided Early Teriary into 4 third-order sequences, and Late Teriary 5 triple sequences,and discussed the characteristics of this sequences.Based on this, this paper compares sequences of well-tie profile,and makes maps of each sequences. Taking third-order sequence as the cycle unit, this paper makes the sequence-based lithofacies-p aleogeographic maps of the Early Teriary-Late Teriary of Kuche depression and discussed the characteristics of map and its evolution. At the early stage of Early Teriary period,the west of North mountain front zone depressed quickly and formed the sedimentation center. When at the late stage of Early Teriary period and the stage which formed Ji Dike formation of Late Teriary period,the sedimentation center gradually moved to the east. Because of the long stage of degradation,Kuche Depression became more flat,and stretches to the north, east, and south.