山东沾化凹陷沙河街组湖泊层序地层研究

LAKE SEQUENCE STRATIGRAPHY OF THE SHAHEJIE FORMATION IN THE ZHANHUA DEPRESSION

沾化凹陷下第三系沙河街组沉积地层可分成两个层序。在古构造、古地形、古气候、古物源供给及古海侵等因素控制下,层序内部发育了低水位体系域、湖侵体系域及高水位体系域。笔者建立了该地区沙河街组综合层序地层剖面,并针对体系域、准层序组及准层序界面的识别、湖泊层序地层及沉积演化等方面进行了详细阐述,讨论了控制湖平面升降的各种因素。文中表明了湖泊层序地层研究与海相层序地层研究之间的差异之处。湖泊层序地层研究必须基于构造演化、古地磁、古气候变迁、地质录井、地震及测井资料、古生物资料及全球海平面升降等资料的综合分析。层序地层演化与整个盆地的发育和消亡以及沉积演化之间有着密切的联系。

Two sequences can be identified in the sedimentary strata of the Lower Tertiary Shahejie Formation in the Zhanhua depression. The low-stand, lake-transgressive and high-stand systems tracts were formed under the control of ancient structure, paleotopography, paleoclimate, sediment supply, marine-transgression, and so on. The authors have established a composite sequence stratigraphical section of the Shanhejie Formation in this area, and expound the boundaries of parasequences, parasequences set and systems tract and evolutions of lake sequence stratigraphy and sedimentology and discuss various controlling factors of lake level fluctuation. The differences between lake and marine sequence stratigraphy have also been indicated. The lake sequence stratigraphical study should be based on a synthetic analysis of structural evolution, paleomagnetism, paleoclimatic changes, geological well logs, seismic and logging data, paleonto-logical data, global sea level eustasy, and so on. The sequence stratigraphical evolution is closely related to the formation, development and extinction and sedimentary evolution of the basin as a whole.