Wavelet Analysis of Fabric in Deformed Granites

Well-established techniques exist for analyzing rock fabric at the scale of individual grains with the goal of determining strain history and/or rheology. Most techniques focus only on the size, shape, and orientation of individual grains, effectively ignoring inter-clast interaction. The Normalized Optimized Anisotropic Wavelet Coefficient (NOAWC) method is a relatively new technique for detecting and quantifying the location, size, shape, and orientation of both individual clasts and clusters of interacting clasts. We present results from wavelet analysis of K-feldspar porphyroclast populations (Mono Creek granite, east-central Sierra Nevada batholith, California). Tracings were taken across a strain gradient within the Rosy Finch shear zone, a major ductile dextral transpressional feature. As such, the outcrop tracings run the gamut from virtually unstrained to highly deformed in a syn-magmatic shear zone. More highly strained rocks exhibit stronger organization, both in terms of individual alignment and group distribution. This strengthened organization is represented by a greater wavelet coefficient and preferred alignment of clusters. The results allow us to investigate the presumed evolution of the rock fabric through time and evaluate models of clast rotation and interaction.