东濮凹陷构造变形的物理模拟研究

An Analysis of Physical Modeling of Tectonic Deformation in Dongpu Sag

东濮凹陷是一个研究程度较高的含油气区,前人在构造变形研究方面多注重于伸展变形的几何学分析而忽略了形成机制中走滑分量的作用。本文在对区域地质背景和东濮凹陷构造特征分析基础上,设计平、剖面砂箱实验对该凹陷的构造变形进行伸展-走滑模拟研究。结果表明:(1)具走滑性质的断裂组合形成的构造样式更加复杂多样,走滑断层弯曲会产生挤压或伸展分量,在相邻的区域内形成局部的凹陷和隆起,主动盘的不同会形成不同的断裂组合;(2)在区域NNW—SSE向伸展变形下,形成了东濮凹陷两洼一凸的近对称格局,基底深断裂的张扭性开裂加速了凹陷的形成,主断层上、下盘均有明显的活动;(3)受基底断裂活动影响,大约Es^2-Ed沉积期凹陷存在一个明显的右旋走滑变形期,在凹陷的中部隆起带上出现了负花状、火焰状等典型走滑构造样式,走滑变形具有阵发性特点。

The Dongpu sag is a petroliferous area with relatively high research level.The previous research has focused on the geometric analysis of extensional deformation,but ignored the relationship between the strike-slip deformation and the sag.In order to analyze the tectonic deformation in Dongpu sag,the authors conducted the typical plane and profile sandbox experiments,combined with regional geological features.Some conclusions have been reached:(1)The tectonic style of strike-slip faults was very complex,and bending of strike-slip faults could bring compression or extension components,which caused partial extrusion uplift or slip extensional sag in the adjacent area.(2)In the regional NNW-SSE trending extensional deformation,the Dongpu sag was formed with the nearly symmetrical pattern of two depressions and one uplift.The activity of tenso-shear fault in deep basement accelerated the formation of the sag and the main faults in the hanging wall and footwall had both obvious activity traces.(3)Due to the effect of basal fault,there was an obvious right-lateral strike-slip deformation stage about in the Es2-Ed sedimentary period.The typical strike-slip tectonic styles,such as the flower structure and the flame structure in the central uplift belt of sag,could be caused by the deformation of the basement strike-slip fault with paroxysmal characteristics.