Study On The Depositional System And Sequence Stratigraphy Of Jurassia In Western Sichuan Basin

Based on the theories of continental sequence stratigaphy and sedimentology , this paper examines the sedimentary system and sequence stratigraphy of Jurassic in Western Sichuan basin by using geologic, logging and seismic methods.On the basis of previous research, by comprehensively analysing the regional geotectonic setting and sedimentary setting data, observing outcrop and core, and then investigating geological, logging and seismic profile, this paper divids the sedimentary system of the Jurassic into 5 types of sedimentary systems, 14 sedimentary subfacies and 24 sedimentary microfacies. It deeply investigates the characteristics of sedimentary facies, sedimentary subfacies and sedimentary microfacies, and establishs the sedimentary models. The conclusion were made that Jurassic alluvial fan syatem was mainly developed in retrograding period ,while delta system was mainly developed in prograding periods .Based on the theory of Sequence stratigraphy, the Sequence features of the tertiary at The Jurassic formation have been analyzed and 3 type of sequences have been identificated.Be bounded by maximal flooding surface, every tectonic sequences can be divided into two system tract: Trangressive System Tract (TST) and Regressive System Tract (RST).Based on theTectonic sequence division ,it can be divided into eight three sequences or long-term cycle, Finally established the sequence stratigraphic classification and the sequence stratigraphic framework.This study of the Jurassic depositional systems and sequence stratigraphy in western Sichuan foreland basin,provide a detailed information for the lithofacies paleogeography mapping, sequence and evolution of sedimentary basins, combination of reservoir facies belts and projections.