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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