Characteristics Of Sand Body Distribution And The Top Management Of Middle Jurassic Upper Shaximiao Formation In Western Sichuan Foreland Basin

Guided by sedimentology, sequence stratigraphy, structural geology, geophysics and soon, Integrated researched the outcrops, cores ,logging data from the Middle Jurassic upperShaximiao formation in the western Sichuan foreland Basin, realized the charaters ofdepositional system, sequence stratigraphy, discussion the dis-tribution of sedimentaryfacies and the characteristics of sand body distribution.According to the petrofabric, depositional fabric , sedimentary sequence, life assemblageand so on, combined with predecessor's research,Continental sedimentary system groupcontain alluvial fan sedimentary system, fluvial sedimentary system and lake sedimentarysystem were recognized in the western Sichuan foreland Basin.According to the outcrops and cores ,combined with logging data , the bottom surfaces ofsequence in upper Shaximiao formation in western sichuan foreland Basin mainly astransition surface of rock character and facies,the top surfaces of sequence were the interfaceof Suining formation and upper Shaximiao formation.one sedimentary sequence wererecognized in upper Shaximiao formation.According to the sediment level change,clastic component analysis,genetic types ofquartz grains,paleocurrent analysis and heavy mineral analysis,conducted the sourcs analysisof Middle Jurassic upper Shaximiao formation in western sichuan foreland Basin.Found outthere were tow sources of western sichuan fore-land Basin:Longmenshan thrust belt inwestern margin of basin and Micangshan-Dabashan thrust belt in northern margin of basin.According to discussion the distribution of sedimentary facies in the basin,re-searchedthe characteristics of sand body distribution. Found out that the tectonic movement ofLongmenshan thrust belt and Micangshan-Dabashan thrust belt were the top management of the distribution of sedimentary facies,and the characteristics of sand body distribution fullycontrolled by he distribution of sedimentary facies.And according to discussion sequencedevelopment short-term base level cycle,analyzied the structural characteristics of sandbody,found out the tectonic movement of orogenisc belt in the basin margin caused thechange in accommodation space control mechanism of the process of short-term base-levelmovements controlling the structural characteristics of sand body,genetic type and thedevelopment scale of Middle Jurassic upper Shaximiao formation in western sichuan forelandBasin.