Fracture system genesis and organization in the Toulumne Instrusive Suite, Sierra Nevada Batholith, CA

The formation of fractures and how they organize are fundamental topics for understanding deformation near the Earth's surface. This dissertation investigates two fracture systems developed in the Tuolume Intrusive Suite, Sierra Nevada Batholith, California. The first fracture system, Tabular Fracture Clusters (TFCs), occurs in the Cathedral Peak granodiorite as tabular zones of sub-parallel, densely spaced extension fractures. TFCs are spatially correlated to the Johnson granite porphyry, which intruded the Cathedral Peak granodiorite. Field and lab data suggest that TFCs accommodated the release of volatile overpressure from the Johnson granite porphyry through the Cathedral Peak granodiorite, during doming associated with intrusion. I interpret the TFCs to result from dynamic fracturing in this fluid-rich, rapid strain rate environment. Transect data consisting of fracture spacing measurements from TFCs, joint sets, and synthetic data are then used to investigate two methods for quantifying fracture systems in mechanically non-layered rock. The two methods --- calculation of the correlation dimension and the maximum Lyapunov exponent --- quantify the distribution of fracture spacings and how those spacings are ordered, respectively. The two methods can be used in conjunction to distinguish fracture sets with different genetic histories.;The second fracture system investigated consists of polygonal fracture networks developed in the Half Dome granodiorite and Johnson granite porphyry. The polygonal fracture networks have polygons ranging from 3- to >10- sided, occur in exfoliation sheets, and are constrained by the exfoliation sheet thickness. Preferentially oriented, elongate, fracture-bound polygons suggest that the polygonal fracture networks evolved under an anisotropic stress state. Most geometric characteristics of the polygonal fracture networks are scale-invariant; large (m-scale) networks exhibit the same geometry as small (cm-scale) networks. It is hypothesized that repeated thermal contraction formed the fracture networks, that anisotropy arises from inclined exfoliation sheets, and that the polygonal fracture networks self-organize.