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

William Marsh Rice University, Houston TX

Investigators

Abstract

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.