构造及气候对后裂谷盆地层序建造的影响:以松辽盆地西斜坡晚白垩世为例

盆地构造运动、气候变化对后裂谷盆地源汇系统、沉积体系和层序建造影响的研究尚待深入.松辽盆地是一个富含油气的晚白垩世大型后裂谷盆地.应用构造层序分析方法，利用测井曲线、岩心观察成果、三维地震和录井资料，在泉四段（K_1-2q₄）至嫩江组（K₂n）划分出两个二级层序和7个三级层序.这7个三级层序根据其发育的古地貌背景和气候条件，可识别出发育在二级层序底部、干旱气候环境的低可容纳空间层序建造和发育在二级层序中上部、湿润-半湿润气候条件下的高可容纳空间层序建造.高可容纳空间层序建造又可根据古地貌背景划分为缓坡和受挠曲坡折控制的高可容纳层序建造.研究区这两个二级层序及其三级层序建造特征是对盆地幕式构造运动和气候变化的响应.一个热沉降幕开始于盆地基底抬升后的沉降.基底抬升造成气候干旱、剥蚀，形成不整合，随后的沉积沉降发育低可容纳空间层序.当盆地基底沉降较快，且沉降速率大于沉积物供给速率、气候湿润、湖平面上升导致盆地可容纳空间快速增长时，发育以水进域和高位域为主的高可容纳空间层序建造.二级层序界面两侧发育的地层圈闭，沉积在高可容纳空间背景的层序其水进和高位域早期的重力流砂体为岩性油藏的主要圈闭，该类砂体在Sqqn1和Sqn1层序最为发育，在坡折带及其之下集中分布. 

Tectonic and Climatic Influences on Architecture of Sequences and Sedimentary Systems in a Post-Rift Basin: Insight from Late Cretaceous Northern Songliao Basin

The influence of basin tectonics and climate change on source and sink system, sedimentary system and sequence construction of post-rift basin still need to be studied.Songliang Basin (SB) is a Late Cretaceous large petroliferous post-rift basin. Based on tectonic-sequence analysis method, using log curves, observations of cores, 3D seismic data and logging data, two second-order sequences (SS) and seven third-order sequences are identified in the fourth member of Quantou Formation to seconder member of Nenjiang Formation in this study. Low accommodation sequences in the lower part of a SS and in dry climate, and high accommodation sequences (HAS) in middle to upper part of a SS and in humid to semi-humid climate, are identified in the seven sequences. It is found that the HASs can be divided into a sequence architecture in gentle slope and a sequence architecture controlled by in flexural slope break on the basis of paleo-relief. The architecture of sequences in SSs was responses to tectonic movement. A thermal subsidence episode started at a subsidence after uplifting of basin basement of basin uplifting, which resulted in dry to semihumid climate, erosion and unconformity, then the subsidence of basement of basin resulted in sequences deposited in a low accommodation space, while higher rate of subsidence and lower rate of supply resulted in quick increase of accommodation, humid to semihumid climate, and lake level rising, and a HAS characterized by thick TSTs and HSTs. Stratigraphic traps near surfaces of SSs, and sand bodies of gravity current deposits influenced by Paleo relief, flooding events associated with paleoclimate, shoreline trajectory associated with sediments supply, developed in TSTs and early HSTs of high accommodation sequences are dominant lithologic traps. A lot of gravity current deposits were developed in sequences Sqqn1 and Sqn1, corresponding to two maxim lake transgressive events of two second-order sequences respectively. The sand bodied of gravity flow deposits were deposited predominantly at downward slopes of flexural slope break zones.