Quartz Preferred Orientation and its Impact on Thermal Anisotropy
in Sandstone and Quartzite- Manzano
Mountains, New Mexico.
Trudy Watkins, Callum J. Hetherington, and Troy Mills
Nano Tech Center, Texas Tech University, Lubbock,
Texas
Thermal conductivity is an important mineral and rock property because heat transfer is a factor in understanding the development
of economic resources, including geothermal energy and hydrocarbon resource maturation. Quartz, one of the most
abundant minerals in the Earth’s crust and near-surface sediments is thermally anisotropic with higher thermal conductivity
parallel to its c-axis compared to its shorter a-axes. Its anisotropy
suggests that quartz-rich lithologies with preferred orientation
may have higher thermal conductivity. In this study the thermal conductivity of eight quartzite samples, with variable
degrees of shape-preferred orientation from the Manzano Mountains, (NM), has been measured. Quartz shape preferred orientation
data, measured on the basis of length to width ratios, were measured by optical microscopy. All samples have average
length to width ratios in quartz >2. Thermal conductivity was measured on 2.54 cm diameter, ~4 mm thick discs that were
cored parallel and perpendicular to the foliation in each sample. Preliminary measurements show that thermal conductivity
does vary between samples, and that those samples with a greater degree of shape-preferred orientation have high higher thermal
conductivity values when measured parallel to foliation. The importance of the preferred orientation and its proportional
relationship with bulk-rock thermal
anisotropy
can be used to improve models for heat transfer in the upper crust.
AAPG Search and Discovery Article #90152©2012 AAPG Southwest Section Meeting, Fort Worth, Texas, 19-22 May 2012