Processes of Progressive Deformation with Applications to Jointing, Faulting and Fluid Flow
AdvisorSchultz, Richard A.
Geological Sciences and Engineering
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The study of progressive deformation of fracture mechanical processes in earth and planetary sciences is applicable to all fracturing modes (opening-, sliding-, tearing-, and closing modes) and provides insight into evolution and behavior of fracturing on all scales. Hence, studying such processes helps to better characterizing fracture geometries and their temporal and spatial development. Understanding the processes is then crucial for evaluating the deformed rocks as media for fluid flow or reservoir. Knowledge about development and evolution of specific fractures and fluid flow through them can then be applied to deformation processes in general in order to help improving our understanding of, as well as highlighting connections between, the different processes and, thus, finds a wide applicability in the geosciences.Processes of progressive deformation were studied by characterizing the origin of a radial array of graben on the planet Mercury, the development of faulting in porous rock with formation of surrounding deformation band damage zones, fracturing micro-mechanisms, and fracture-governed fluid flow. Fracture geometries, development, and mechanisms were analyzed by field- and spacecraft imagery mapping, conceptual- and numerical modeling using finite element and discrete fracture network methods, and optical- and scanning electron microscopy. When this variety of techniques and methods is utilized it highlights the diversity of progressive deformation as found on all scales and for all fracturing modes. Studying deformation bands in two sandstone basins in south-central Europe yield new insights on the controls of deformation band growth and geometry development, quartz-cementation mechanisms associated with structural diagenesis, and evolution of deformation banding into fault damage zones. Evaluation of the hypotheses for the origin of the radial graben array on Mercury highlights the importance of testing data against the proposed formation mechanisms. Displacement-to-length scaling of opening mode fracturing was used to derive an improved flow law through such fractures, which is found to yield geologically more representative results. The results of this dissertation have important implications for fracture-, rock-, soil-, and fluid mechanics on terrestrial and planetary tectonophysical settings.