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Chapter 6<br />
ANALYSIS AND RESULTS<br />
The Shatter Zone represents the brittle response to magma reservoir<br />
pressure fluctuations during evacuation. Reservoir overpressure occurs when the<br />
rate <strong>of</strong> pressure loading cannot be accommodated by visco-elastic deformation<br />
<strong>of</strong> wall rock. The differential stresses produced by overpressurization and<br />
subsequent evacuations are substantial enough to overcome the elastic limit and<br />
fracture wall rock, after which a volatile rich component <strong>of</strong> magma quickly<br />
intrudes the fractures. Luckily, these intrusive features chill relatively quickly,<br />
providing evidence for volcanic activity. The impetus <strong>of</strong> this <strong>thesis</strong> is to better<br />
understand the mechanics <strong>of</strong> rigid rock in a subvolcanic setting. The Shatter<br />
Zone formed from a subvolcanic reaction to volcanic eruption and I explore the<br />
possible brecciation mechanis<strong>ms</strong> that may have been active in the development<br />
<strong>of</strong> the Shatter Zone. Field observations within the Shatter Zone describe the<br />
gradational breccia characteristics. I discuss the methods used to collect CSD,<br />
CBS, and CCA data, then provide the results <strong>of</strong> the analysis and move on to<br />
confirm explosive brecciation as the likeliest developmental mechanism for the<br />
Shatter Zone.<br />
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