二连盆地层序地层单元统一划分及格架层序地层学

Unifying Division of Sequence Stratigraphy Unit and Framework Sequence Stratigraphy of Erlian Basin

在剖析二连盆地层序地层学研究现存问题的基础上,将构造地层学、成因地层学和层序地层学的理论、方法结合起来,把具有区域对比意义的盆地世代界面和盆地原型界面分别作为一级层序和二级层序的界面,把盆地(或凹陷)原型的每一个裂陷-反转旋回(亚原型)作为三级层序,把沉降-充填单元作为四级层序,尝试在构造-地层格架约束下进行层序地层格架分析,而在层序地层格架约束下进行成因地层格架分析.其优点是既吸取了经典海相层序地层学的等时地层界面、层序旋回和可容空间分析等精髓,又摒弃了不适合陆相裂陷盆地的海平面升降变化及体系域等部分内容,便于建立全盆地统一的层序地层格架,也便于揭示各层序地层单元的沉积特征、沉积演化史和不同构造岩相带的油气成藏条件,有助于提高对有利储集相带和有利储集体分布规律及其区域性差异的认识,进而有助于建立有指导意义的成藏预测模式.通过二连盆地各凹陷的实际分析,建立了可对比的、有规律可循的、统一的分级层序界面系统及层序地层格架.

Based on analyzing the previous problems relative to sequence stratigraphy researches on Erlian basin, this paper assoeiated with the theories and methods of teeto-stratigraphy, genetic stratigraphy and sequence stratigraphy. We take the boundaries of basin generation and boundaries of basin prototype with regional correlative significations as first-oder and seeond-orders in the scenario of framework sequence stratigraphy. And every cycle （para-type basin） representing rift and tectonic inversion within basin （or depression） type is divided as third-order sequences, and the subsidence-filling unit as fourth-order sequences. This paper is to analyze sequence stratigraphie framework based on the restriction of tectonic-sedimentation, and to analyze genetic stratigraphic framework under sequence stratigraphic framework. The merits in the scenario of framework se quence stratigraphy are that it inherits the analysis of chronostratigraphic boundary, sequence cycle and accommodation within marine sequence stratigraphy, and abandon part component of sea-level change and systems tracts in marine setting that are unsuitable in continental rift basin. Such scenario is convenient to construct the unifying sequence stratigraphic framework abroad entire basin, and to express sedimentary characteristics and developments of everv sequence stratigraphic unit as well as hydrocarbon pool forming conditions located on different structure-lithofacies zones, in me meantime, this scenario will help to pro mote cognizing distributions and regional differences of favorable reservoirs and their facies belts so as to establish the significant model of hydrocarbon pool formation and accumulation. Based ori 9tactical analyses in all sags within Eriian basin, this paper has constructed correlative, obviously disciplinary and unifying boundary-ordered systems and correlative sequence stratigraphic framework.