贝尔凹陷贝西斜坡沉积层序特征研究

The Research on Sedimentary Sequence Character of Beixi Slope in the Bei′er Depression

陆相盆地层序的形成和演化主要受控于区域性构造事件或幕式构造旋回,断陷湖盆则主要受盆地边缘的断裂控制。构造沉降级次控制着层序的级别,同时也控制着盆地沉积体系的空间展布。通过对海拉尔盆地贝尔凹陷南屯组的研究可知,一次完整的继承性构造沉降形成一个Ⅱ级层序,整体显示由细变粗的水退旋回;该沉降期内部又以稳定的湖平面为界分为两个沉降旋回,分别形成3个三级层序,各层序都是由粗—细—粗的水进水退旋回组成;每一个层序自下而上发育LST、TST、HST三个体系域,各体系域在三维地震剖面上呈现不同的反射结构,岩性和电性曲线都有所变化。

The formation and evolution of the stratigraphic se- quence of continental basins is mainly controlled the territorial tectonic event or episodic tectonic cycle, while the fault basin is con- trolled by the fault of the basin margin. The degree of tectonic settlement controls the level of sequence and the three-dimensional al- location of the basin sedimentary system. The research of Nantun formation of Bei＇ er depression in Hailaer basin shows that once entire inheritance tectonic settlement creates an II level stratigraphic sequence which displays the reliction cycle from fine to coarse. This sequence interior also is divided into two falling cycle from steady lake interface and creates two III level sequence which are composed of the transgression regression cycle. Each sequence develops three systems of LST, TST and HST which display the different reflecting structure on three-dimensional seismic section and their lithological and electrical property curves also alter.