方正断陷多期构造叠合构造解析及模式分析

Structural and Model Analysis of the Multi-period Structural Superimposed in Fangzheng Fault Depression

为了理清方正断陷多期构造叠合引起的盆地变形,断陷内部构造样式多样及构造解析存在多解性的问题,通过对地震资料的重新梳理、区域构造特征及郯庐断裂演化的分析,结合伸展、走滑拉分、走滑挤压以及后期抬升剥蚀等多期构造叠加对方正断陷的影响,对构造解析提出了新的认识和方法,并建立了方正断陷伸展—走滑—挤压三维应力模式。研究认为断陷西部改造程度弱,继承了断陷初期白垩系盆地的伸展模式,断陷东部后期挤压推覆改造强度大,伸展模式已不适用,必须考虑逆冲推覆构造的影响,断陷中部发育的伊汉通断裂走滑特征明显,花状构造发育,以伊汉通断裂为界断陷东西两侧表现为不对称差异走滑断陷特征,伊汉通断裂两侧应用走滑模式解析,因此,对于多构造叠合断陷盆地不能单纯地用伸展模式来解析,更应考虑后期的改造模式,在此基础上形成了一套复杂断陷盆地构造解析方法。

In order to clarify the basin deformation caused by multi-period tectonic overlap in Fangzheng Fault Depression,the complex structural styles in the fault depression and the problems of multi-solution in structural analysis,we combine the analysis of seismic data,regional tectonic characteristics and Tanlu Fault evolution with the analysis of extensional,strike-slip pull-apart,strike-slip compression and later uplift-denudation of Fangzheng Fault Depression.New understanding and methods are put forward for structural analysis,and a three-dimensional stress model of extension-strike-slip-compression in Fangzheng fault depression is established.The study shows that the western part of the fault depression is weakly reformed and inherits the extension model of the Cretaceous basin in the early stage of the fault depression.The compression-nappe reformation in the eastern part of the fault depression is strong in the later stage,and the extension model is no longer applicable.The influence of thrust-nappe structure must be considered.The developed Yihantong Fault has obvious strike-slip characteristics and floral structure.The east and west sides of the Yihantong fault are characterized by asymmetric differential strike-slip fault depression.The strike-slip model is applied to the analysis of both sides of the Yihantong fault.Therefore,the extension model can not be used to analyze the multi-structural superimposed fault basin,but the later transformation model should be considered,and on this basis,a set of structural analysis method for complex faulted basins has been found.