三角剪切模型控制参数间定量关系的物理模拟研究

It has been established that there is an intimate relationship between folding of sedimentary sequence and underlying faults. Although the fault-related-fold models proposed by Suppe et al. have been successfully applied in a series of geological studies, its precondition of ‘constant layer length and thickness’ prohibits its effectiveness of explaining natural structures with inconstant layer length and thickness. In contrast to the well-established fault-related-fold models, the deformation of trishear algorithm is concentrated in a triangle zone in front of a propagating fault tip. The non-uniform deformation in the triangle zone allows the layer thickness and length within strain zones to change during deformation. By varying the key controlling parameters, i.e., the trishear propagation/slip ratio, the trishear apical angle and the fault dip, a wide spectrum of trishear geometry can be generated, which implies potential wide application of trishear algorithm in complex natural structures, particularly in structures where the layer length and thickness vary during deformation. However, the trishear algorithm has not been widely used to interpret natural structures, as it is normally difficult to find the unique trishear solution because of its multiple controlling parameters. Therefore, it is essential to identify the quantitative relationship between the controlling parameters before trishear algorithm can be successfully applied to interpret natural structures. In this research, physical modelling method will be employed to build the data cloud of trishear controlling parameters; the data cloud will then be quantitatively analysed to reveal the quantitative relationship between parameters and decrease the dimensions of controlling parameters; finally, the current mathematical trishear model will be modified and validated by natural geologic examples.

Suppe等提出的断层相关褶皱模型在大量地质构造研究中得到了较好应用，但其“层长层厚守恒”的前提条件也导致其难以合理解译层长层厚发生变化的地质构造。Erslev于1991年提出的三角剪切模型弥补了这一缺陷，可用于解译变形过程中层长层厚发生变化的地质构造。合理组合其关键参数可得到各种不同的几何学构造样式，使得三角剪切模型在复杂地区构造建模和平衡恢复中具有广泛的应用前景。然而，三角剪切模型多个控制参数的特点，也导致其在应用过程中往往存在多解性的问题。因此，探明三角剪切模型控制参数间定量关系对于其在实际地质问题中的应用十分关键。本研究拟通过物理模拟实验的手段建立三角剪切物理模型控制参数组合数据簇；进而对控制参数组合数据簇进行应变定量分析，建立各控制参数间定量关系，并进行控制参数降维分析；最后完善三角剪切数值模型，并通过典型野外露头的实例应用对完善后模型加以验证。

Erslev于1991年提出的三角剪切模型弥补了断层相关褶皱要求“层长层厚守恒”的缺陷，可用于解译变形过程中层长层厚发生变化的地质构造。然而，三角剪切模型多个控制参数的特点，也导致其在应用过程中往往存在多解性的问题。本项目基于物理模拟实验研究探明了三角剪切模型控制参数间定量关系，对于其在实际地质问题中的应用十分关键。本研究通过物理模拟实验的手段建立了三角剪切物理模型控制参数组合数据簇；进而对控制参数组合数据簇进行了应变定量分析，建立了各控制参数间定量关系，并进行了控制参数降维分析；最后完善了三角剪切数值模型，并通过典型野外露头的实例应用对完善后模型加以验证。