The geometry and distribution of thrust-fold related fractures in limestone

Grodner, Mark William

Abstract

Outcrop study of fracture geometry and topology in limestones of high-level thrust sheets in the Frontal Himalayan Thrust, north of Islamabad, Pakistan has enabled the determination of convergent tectonic spatial geometries and distributions of thrust-fold related fracture networks. Multiple and superimposed stresses generate unique fracture patterns, within this environment and the characteristics had previously been difficult predict and relate to structural domains.

A new type of fracture mapping approach has been developed, combining the topological and fractal characteristics of fractures. Cross-plots of this data created a large amount of fracture information. All fractures are compiled and analysed, enabling complete analysis of the effects of successive tectonic stresses. Rock composition is divided based on percentage of shale and limestone studied, but no distinction is evident in the topological and fractal cross-plots of the various limestones. This consistency is interpreted to be because of their geomechanical similarity, a result of the pervasive abundance of pore-filling micrite and microspar cements in the wackestones which imparts brittle strength.

It is possible to:
1. Identify geological characteristics, especially topological and fractal relationships of the rockmass, allowing discrimination of fracture networks associated with thrusting and folding.
2. Utilise the topological and fractal characteristics to define and compare geological structures at depth and hence determine the fractures and dominant deformation mechanism.
3. Assess the fractal and topological characteristics to enable the evaluation of different fold and thrust belts, both from surface and subsurface to understand potential fracture distributions.

Citation

Grodner, M. W. (2024). The geometry and distribution of thrust-fold related fractures in limestone. (Thesis). Keele University. Retrieved from https://keele-repository.worktribe.com/output/849840

• Thesis Type: Thesis
• Deposit Date: Jun 13, 2024
• Publicly Available Date: Jun 20, 2024
• Public URL: https://keele-repository.worktribe.com/output/849840
• Award Date: 2024-06