Discrete Element Simulations of Cohesive Contractional Wedges: Kinematics and Mechanics of Fold and Thrust Belts

这项研究将使用离散元方法对褶皱和逆冲带进行数值模拟，以便更好地了解在一系列条件下负责褶皱和逆冲带构造几何和演化的控制和机制。这种正演模拟是检验和完善野外观察到的褶皱和冲断带解释的重要工具，这些褶皱和冲断带往往曝光有限，被高度侵蚀，并在远离它们形成的条件下保存。需要解决的具体问题包括：(1)什么物理力学参数控制着褶皱冲断带的断层收敛，特别是最常见的油气圈闭--最前缘构造的起源和演化？(2)滑脱和基底非均质性在褶皱冲断带的力学状态和构造演化中起什么作用？以及(3)特定的基底构造和地层对褶皱和冲断带的构造影响是什么？这些模拟将使用莱斯大学开发的RICEBAL程序进行；将进行2D和3D模拟，以检查机械地层、非均匀滑脱性质和结构以及压痕的影响。结果将与自然例子进行比较，特别是加拿大经典的Cordillera和加拿大阿巴拉契亚山脉北部。褶皱和冲断带的发展代表了一个基本的造山过程，也是形成丰富的油气藏的原因。了解形成有利于油气聚集的独特锋面结构的条件，可以对未来前景的位置进行一级预测。该项目中进行的模拟将提供一种独特而安全的方法来探索相关的地球动力学过程，并将其广泛应用于许多其他问题。此外，该项目将进一步完善赖斯大学开发的离散元方法代码RICEBAL，该代码将通过地球动力学计算基础设施提供给更广泛的教育和研究人员。

The research will conduct numerical simulations of fold and thrust belts using the discrete element method in order to develop a refined understanding of the controls and mechanisms responsible for their structural geometries and evolution under a range of conditions. Forward modeling of this sort is an important tool for testing and refining interpretations of fold and thrust belts observed in the field, which often have limited exposure, are highly eroded, and are preserved under conditions far from those in which they were formed. Specific questions to be addressed include: (1) What physical and mechanical parameters control fault vergence in fold and thrust belts, with particular attention to the origin and evolution of the most frontal structures which are common traps for hyrocarbons? (2) What is the role of decollement and basement heterogeneity in the mechanical state and structural evolution of fold and thrust belts? And (3) What are the structural consequences of specific basement configurations and stratigraphy on fold and thrust belts? The simulations will be carried out using RICEBAL, a code developed at Rice University; 2D and 3D simulations will be carried out to examine the effects of mechanical stratigraphy, heterogeneous decollement properties and structure, and indentation. Results will be compared with natural examples, in particular, the classic Canadian cordillera and the northern Appalachians in Canada.Fold and thrust belt development represents a fundamental mountain building process and is also responsible for the formation of rich oil and gas reservoirs. Understanding the conditions responsible for distinctive frontal structures that favor hydrocarbon accumulations allow first-order predictions of locations of future prospects. The simulations carried out in this project will provide a unique, and yet safe, way to explore the associated geodynamic processes, with broad applications to many other problems. In addition, this project will enable further refinement of the discrete element method code RICEBAL, developed at Rice University, which will be made available for broader distribution for education and research through the Computational Infrastructure for Geodynamics.