滑脱层性质对正反转构造变形影响的离散元数值模拟研究  

Discrete Element Numerical Simulation of the Influence of Detachment Layer Properties on Positive Inversion Structures

作　　者：谭志海 尹宏伟[1] TAN Zhihai;YIN Hongwei(School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]南京大学地球科学与工程学院,南京210023

出　　处：《高校地质学报》2025年第2期131-142,共12页Geological Journal of China Universities

基　　金：国家自然科学基金项目(42372264,41972219)资助。

摘　　要：正反转构造在中国乃至世界范围内的多个盆地中普遍存在。开展正反转构造变形模拟,可以深化主控因素认识,识别断层反转程度,助力油气勘探开发工作。文章采用离散元数值模拟的方法研究了滑脱层的有无、滑脱层的厚度、滑脱层的强度以及滑脱层的纵向深度等因素对含先存裂陷的褶皱冲断带变形特征与变形机制的影响,观察模拟结果中先存裂陷边界断层的反转时间及最终反转程度。实验表明:先存裂陷上部存在区域广覆性滑脱层,褶皱冲断带将随着挤压的进行由前展式逆冲叠瓦构造进一步转化为更具有流变性的揉皱构造,滑脱层之上地层沿着滑脱层远距离滑脱。区域广覆性滑脱层对下伏先存裂陷边界断层的反转有很强的抑制作用。当区域广覆性滑脱层厚度越大、能干性越弱、纵向深度越深时,对下伏先存裂陷边界断层的抑制作用越强,边界断层发生反转的时间更晚,最终的反转程度越小甚至不发生反转。四川盆地下三叠统嘉陵江—雷口坡组的膏岩层对下伏先存断层活化有很强的抑制作用,下伏德阳—安岳裂陷的边界断层在后期喜山运动时未发生明显的活化反转作用,具备了良好的油气保存条件。Positive inversion structures are prevalent in many basins in our country and even all over the world.The deformation simulation of positive inversion structures can deepen the understanding of the main controlling factors,identify the degree of fault inversion and help the exploration and development of oil and gas.In this paper,the discrete element numerical simulation method is used to study the effects of the presence or absence of detachment layer,the thickness of detachment layer,the strength of detachment layer,and the longitudinal depth of detachment layer on the deformation characteristics and deformation mechanism of folded thrust fault zones containing pre-existing rift traps,and we observe the reversal time of the pre-existing rifttrapped bounding faults in the simulation results,as well as the final degree of reversal.The experimental results show that there is a regional extensive detachment layer in the upper part of the pre-existing rift,which transform the fold-thrust belt from a forward thrust imbricate structure to a more rheological crumple structure with the progress of extrusion.and the strata above the detachment layer slides along the detachment layer for a long distance.The regional extensive overburden detachment layer has a strong inhibitory effect on the inversion of the underlying pre-rift boundary fault. When the thickness of the regional extensive detachment layer is larger, the capability is weaker and the longitudinal depth is deeper, the inhibitory effect on the underlying pre-existing rift boundary faults is stronger, the inversion of the boundary fault occurs later and the final degree of inversion is smaller or even no inversion occurs. The gypsum layer of the Lower Triassic Jialingjiang-Leikoupo Formation in Sichuan Basin has a strong inhibitory effect on the activation of the underlying preexisting faults. The boundary fault of the underlying Deyang Anyue rift did not have obvious activation inversion under the extrusion of the Himalayan Movement, good preservation condition

关 键 词：正反转构造 离散元 滑脱层 构造变形 德阳—安岳裂陷 

分 类 号：P542[天文地球—构造地质学]