断陷湖盆基底非线性沉降与Ⅱ型层序的形成——以冀东油田南堡凹陷为例

断陷湖盆基底幕式沉降过程中的加速和减速(非线性构造沉降)对层序形成有明显的控制作用,可以增强或减弱层序边界的信息.导致体系域的提前或滞后.Ⅱ型层序界面是在基底非线性加速沉降,并且构造沉降加速度大于或等于湖平面下降加速度的背景下形成的.基底的非线性沉降和湖平面升降的藕合关系对河流的作用方式以及河流沉积的展布特征有很强的控制作用.运用这一特点,可应用砂体等厚图来验证层序划分的正确性.这一特点还可作为Ⅱ型层序的识别依据.

BASEMENT NONLINEAR SUBSIDENCE OF FAULTED LAKE BASIN AND TYPE-

The acceleration and decelaration in the episodic subsiding process (nonlinear tectonic subsidence) of the basement of faulted lacustrine basin have distinct controlling effect on the formation of sequence, and could strenghthen or weaken the information of sequence boundary, result in the advance or delay of system tract. Type Ⅱ sequence interface was formed when the basement nonlinear subsidence speeded up and the tectonic subsidence acceleration was bigger than or equal to lake level falling acceleration. The coupling between basement nonlinear subsidence and lake level elevation and subsidence has strong control over fluviation manner and the deposit distribution. According to this and applying sandbody isopach map, the correctness of sequence division could be verified. The characteristics could also be used as the evidence in sequence recognition.