雪峰山西侧陡山沱期沉积凹陷对优质烃源岩的控制

esinian paleogeography pattern.The sedimentary structure of doushantuo period is roughly bounded by enshi,which is divided into the paleouplift area to the west of enshi and the marginal depression area to the east of enshi.Due to the influence of paleogeomorphology and transgression of the doushantuo formation in the sedimentary period,the sedimentary environment and sedimentary lithology indifferent areas on the west side of xuefeng mountain are different.The dolomiteand argillaceous dolomite deposits of the shore-shore facies,the slope facies and the shallow-sea shelf facies are mainly deposited in the steep first section;the black carbonaceous mudstone and shale deposits of the deep-sea shelf facies are mainly deposited in the steep second section;the carbonate platform facies deposits are mainly deposited in the steep third section;and the deep-sea basin deposits aremainly deposited in the steep fourth section.The distribution of source rocks is greatly influenced by the sedimentary environment,and they were mainly deposited in the black carbonaceous mudstones of the second and fourth sections of thesteep sag in the western hubei trough and other marginal depressions between the ancient continents.In the shale,organic matter abundance and maturity are high.The distribution of source rocks is obviously controlled by marginal depressions.The paleocontinental marginal depressions such as the west hubei trough are favorable for oil and gas exploration.Key words sinian system;Thedousahntuo formation;Lithofaciespaleogeography;Edge of the sag;source rock