New Mexico Geological Society Annual Spring Meeting — Abstracts

A rock pile in northern New Mexico has been investigated by a multi-disciplinary research team to define pile characteristics and weathering behavior. Geophysical techniques and trenches were used to assess the internal structure of the material for the Goathill North rock pile. Electromagnetic (EM) induction was used to measure the spatial variability in bulk apparent electrical conductivity of the rock pile, while ground penetrating radar (GPR) was applied to image the internal structures of the rock pile. Seven trenches were excavated for analysis of the stratigraphy and material properties.

The measurements show the characteristics of the top 5 to 8 meters of the rock pile. The electrical conductivities varied typically around 6 mS/m but on the southwestern part of the rock pile anomalously high values up to mS/m were found. These high values can be explained by a different texture, minerology or pore-water composition, or a higher water content. In this area the penetration depth of the GPR waves is significantly reduced and the reflection configuration is dominated by sub-horizontal reflections. In general, the GPR results have a character of reflectors whose dip directions and angles reflect the rock-pile deposition. The trench data show excellent correlation with the GPR survey.