湘中盆地龙山穹窿叠加构造样式与形成过程的构造物理模拟

发布时间：2018-05-02 00:02

  本文选题：湘中盆地 + 叠加褶皱　； 参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：湖南省湘中盆地经多期次构造演化活动形成了一系列穹窿状构造,前人进行过详细的地质调查和研究工作,但对于穹隆体的构造性质及其叠加过程存在不同的认识,并进而制约了对雪峰山及其相邻区域大地构造的认识。为此,本文选取湘中地区的龙山构造穹隆体,通过详细的野外地质调查、构造解析和构造物理模拟工作,揭示叠加褶皱穹窿的形成过程。构造解析结果表明龙山穹窿属构造变形穹窿,是两次或多次褶皱横跨叠加变形的结果,穹窿的构造样式受断层相关褶皱叠加作用控制。依据剖面上区域性角度不整合和基底拆离断层的存在,确认两套可能为区域性潜在构造滑脱层。对龙山穹窿区域上系统地进行地层产状和劈理产状系统测量和赤平投影基础上,结合褶皱样式与轴面劈理的配套关系分析,并根据轴面劈理的错切关系确定NE-SW向褶皱叠加在近WNW ESE向褶皱之上。结合卷入叠加变形的地层,确定龙山穹窿是加里东期和燕山期褶皱叠加变形的结果。以区域性劈理和擦痕数据测量结果,对二期古构造应力场进行了恢复,并重建了区域构造演化。在此基础上,建立了穹窿体构造模式。设计了两组近似横跨叠加干涉的纵弯挤压砂箱构造物理模型。根据相似性原理,在模型中设立不同软弱层数、厚度。以观察褶皱叠加变形过程中强弱岩层的变形行为,进一步验证了软弱层的分层构造变形特征。叠加褶皱构造解析和砂箱构造物理模拟结果综合表明,二期横跨叠加干涉模型较好地模拟了龙山穹窿中加里东期纵弯褶皱作用形成的近WNW ESE向直立褶皱与燕山期NE-SW向褶皱的横跨叠加过程,并有以下主要变形特点:叠加褶皱发育过程中,早期褶皱轴面和枢纽在晚期褶皱作用过程中会发生弯曲和迁移,并被高角度逆冲断层改造;由于软弱岩层的拆离滑脱作用,导致分层变形作用,使得不同深度的叠加干涉样式不同。因此,岩层能干性差异导致的叠加褶皱构造样式和叠加类型的区别,可能是叠加褶皱穹隆形成的主要因素。在龙山穹隆野外露头尺度变形行为和叠加机制分析基础上,结合构造物理模拟实验中不同岩性层变形行为和叠加效果,并与前人相关叠加褶皱机制结果进行比较,探讨并提出了新的叠加过程成因机制模式。
[Abstract]:A series of dome structures were formed in Xiangzhong basin of Hunan province through multiple tectonic evolution activities. The predecessors have carried out detailed geological investigation and research work, but there are different understandings on the tectonic properties and superposition process of the dome. Furthermore, it restricts the understanding of Xuefeng Mountain and its adjacent regional geotectonics. Therefore, this paper selects Longshan structural dome in central Hunan, through detailed field geological survey, structural analysis and structural physical simulation work, reveals the forming process of superimposed fold dome. The structural analysis results show that the Longshan fornix belongs to the tectonic deformed dome, which is the result of two or more folds crossing the superimposed deformation. The structural style of the dome is controlled by the fault-related fold superposition. Based on the existence of regional angle unconformity and basement detachment faults in the section, it is confirmed that the two sets may be regional potential tectonic slip beds. On the basis of systematic measurement of stratigraphic and cleavage occurrence systems and plain projection in Longshan fornix region, the matching relationship between fold pattern and axial cleavage is analyzed. According to the shear relationship of axial cleavage, the NE-SW fold is superimposed on the near WNW ESE fold. Combined with the strata involved in superimposed deformation, it is determined that the Longshan Dome is the result of superimposed deformation of folds in Caledonian and Yanshanian periods. Based on the regional cleavage and scratch data, the second stage paleotectonic stress field was restored and the regional tectonic evolution was reconstructed. On this basis, the fornix structure model is established. Two sets of physical models of longitudinal bending extruded sand box are designed. According to the principle of similarity, different soft layers and thickness are established in the model. By observing the deformation behavior of strong and weak strata in the process of fold superposition deformation, the characteristics of stratified structural deformation of weak layers are further verified. The analysis of superimposed fold structure and the results of physical simulation of sand box structure show that, The two-stage cross-stack interference model well simulates the cross-stacking process of the vertical WNW ESE folds in the Calidon stage and the NE-SW fold in the Yanshanian period in the Longshan fornix. The main deformation characteristics are as follows: during the development of superimposed folds, the axial plane and hinge of the early fold will bend and migrate during the late stage of fold action and be transformed by high angle thrust fault. The effect of delamination deformation results in different superimposed interference patterns at different depths. Therefore, the difference of superimposed fold structure style and superimposed type may be the main factor in the formation of superimposed fold dome. Based on the analysis of field outcrop deformation behavior and stacking mechanism of Longshan dome, combined with the deformation behavior and superposition effect of different lithologic layers in the structural physical simulation experiment, the results of superimposed fold mechanism are compared. A new mechanism model of superposition process is discussed and put forward.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P542
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本文编号：1831561