Duration - 01/11/2004 - 31/10/2006
Funding - Embark Post-Doctoral Fellowship to Martin Schöpfer
Basic Aims
Brittle deformation of the Earths upper crust results in three different modes of faulting, normal, reverse and strike-slip, which accommodate crustal extension, compression and wrenching respectively. Although faults of each mode are effectively zones of localised shearing of the rock volume, the internal structure of fault zones associated with each mode can be strikingly different. This project will investigate the extent to which orientation of layering within rock volumes controls these differences.
Rock volumes are generally mechanically heterogeneous and anisotropic due to layering of rocks of different rheologies i.e. bedding. A propagating fault, of any mode, will bifurcate and refract in response to these spatial variations in rock strength. Fault surfaces of all modes are therefore initially irregular and segmented. However, the geometries of segmentation and fault surface irregularities, and their evolution with increasing fault offset, varies between faulting modes. This variation is attributable to the prevailing stress state and the different orientations of the faulting modes relative to generally horizontal bedding.
Although the same processes control the fault zone structure of each faulting mode, a general, mode independent, mechanical model for the interaction between layering and faults is currently unavailable. This project will use distinct element method (DEM) numerical simulations to provide such a model. The ability of DEM models to replicate natural fault zone structure in layered rock successions in 2D has previously been demonstrated. In this project 3D DEM models of layered sequences will be constructed. Applied model boundary conditions will be appropriate both to the study of the radial propagation of an entire fault surface through a rock volume and to detailed study of limited areas of a fault surface. Model results will provide the basis for examining fault zone evolution on a range of scales and for each mode of faulting.
Contact:Martin Schöpfer
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