Access Type

Open Access Thesis

Date of Award

January 2016

Degree Type

Thesis

Degree Name

M.S.

Department

Geology

First Advisor

Sarah Brownlee

Abstract

Isotropic seismic properties are not sufficient to distinguish between many rock types believed to make up the middle and lower continental crust. Seismic anisotropy is the directional dependence of seismic velocity, which we can use to improve our understanding of the composition and structure of the middle and lower continental crust. Our rationale is that seismic anisotropy in the middle and lower crust is controlled by the crystallographic preferred orientation (CPO) of minerals. The effects of folding on mineral CPO in a folded gneiss from the Coweeta Group in North Carolina is used for this study, and we should be able to predict the effects on rock elastic tensors. From creating thin sections, analyzing the CPO, and collecting electron backscatter diffraction (EBSD) patterns, seismic velocities were calculated throughout the fold. It was found that CPO variations throughout a fold are unlikely to be the dominant cause of variations in seismic properties through a structure.

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