Kern Canyon Fault Quartz Piezometry and Thermometry: How Weak are Rocks in a Deep Fault?

Abstract

This project is an investigation of the strength of rocks from 10-25 kilometers depth in the Kern Canyon Fault in the Sierra Nevada. When this fault was active, it behaved similarly to the San Andreas Fault in California and the Denali Fault here in Alaska. Deep sections of this ancient fault were brought to the surface of the Earth through erosion. Using a method known as piezometry, I was able to measure the sizes of deformed quartz grains in rock samples, which inversely relates to the amount of stress that the rocks experienced during faulting. I also used a technique known as titanium-in-quartz thermometry (TitaniQ) to determine the temperature of the rocks during faulting deformation episodes. Via the Electron Microprobe in the Analytical Facility at UAF, I was able to measure the amount of titanium present in the deformed quartz grains which directly correlates to the temperature at which these crystals formed. In combining the calculations for stress and temperature of deformation, the strain rate exhibited on these rocks was determined which is used to better understand how weak or strong rocks are at different depths within fault zones.