?Q Survey--Marysville, Montana, USA

Abstract

This summary describes a relative heat flow, ?Q, survey that was carried out at Marysville, Montana. The selection of Marysville as a test site was predicted largely on previous work by Blackwell and others, 1973. Their work defined clearly a thermal anomaly extending over several square miles. The relative heat flow technique developed by Mattox in 1974 was employed with the addition of refinements which consisted primarily of large insulating pads to protect the transducers from thermal radiation from above. The purpose of the survey was to determine if the known anomaly could be detected at the surface. The survey results indicate that surface measured relative heat flow values are capable of delineating thermal anomalies if relative changes in excess of 5 heat flow units are present in the area. The data also suggest that change in elevation with attendant change in seasonal near surface geothermal gradient, severely limit the relative heat flow technique as presently practiced.