【摘要】 根据测井、录井、地震、岩心和古生物资料,运用层序地层学、沉积岩石学理论,建立松辽盆地北部西斜坡姚家组层序格架,分析四级层序格架沉积微相的分布和沉积体系的组合类型.结果表明:松辽盆地北部西斜坡姚家组划分为2个四级层序(Cp1-s3、Cs2),其中四级层序Cp1-s3划分为四级湖泊扩张体系域(Ep1)和四级湖泊萎缩体系域(Ss3);四级层序Cs2只发育四级湖泊扩张体系域(Es2).自下而上,Ep1地层分布范围最小,尖灭线位于西斜坡的东部;Ss3地层分布范围增大,尖灭线位于西斜坡的中部;Es2尖灭线继续向西推进,地层分布范围达到最大.剖面上,三级和各四级层序界面附近以富砂的下切谷充填、三角洲前缘和滨浅湖砂质滩坝为主;富泥的滨浅湖混合滩微相在四级层序最大湖泛面附近最为发育.平面上,姚家组沉积初期,湖岸线在西部斜坡区东部波动,物源供给充足,沉积相以三角洲相为主;至姚家组沉积末期,湖岸线向斜坡西侧大规模推移,发育下切谷充填—三角洲—湖泊沉积分布格局.不同的四级层序体系域的沉积微相分布有明显的差异性和一定的继承性.更多还原

【Abstract】 According to the data of logging,seismic,core data and paleontology,the forth-order sequence framework of No.3sections of Yaojia formation in west clinoform region of north Songliao basin has been constructed and the forth-grade sequence within the framework of sendimentary facies spatial distribution has been discovered.The Yaojia formation in the west clinoform of the Songliao basin was divided into 2forth-order sequences:Cp1-s3 and Cs2,the former can be divided into fourth lake expanding system tract(Ep1)and fourth lake contracting system tract(Ss3);the latter only developed fourth lake expanding system tract(Es2).From bottom to top,Ep1,the pinch-out line which was located in the east of the west clinoform region has the smallest area;Ss3,the pinch-out line which was located in the middle of the west clinoform has a larger area than Ep1.While Es2,with the largest area,has a pinch-out line migrating further toward the west.In the profile section,the main sendimentary microfacies was the sand-rich incised valley filling,delta front and shore-shallow lacustrine sandy beach-bars,and these microfacies are developed near the 3rd or 4th-order sequence boundary,while the mud-rich shore-shallow lacustrine mixed beach is well developed near the maximum flooding surfaces of the 4thorder sequence.In the plane,in the early time of the Yaojia formation depositing,because shoreline fluctuated in the eastern of the western slope and the supply of sediment was strong,the delta facies dominated the sedimentary facies.However,in the late period,the shoreline migrated strongly toward the west and it leaded to the form of a very special distribution pattern:delta-Incised valley fills-shallow lake deposits.The characteristics of microfacies distribution of different 4th sequences system tracts have obvious difference,and has the certain inheritance as well.更多还原