Self-Potential Survey Results From the Chocolate Mountain Aerial Gunnery Range, California

Abstract

Abstract Self-potential (SP) geophysical surveys were conducted in the Hot Mineral Spa exploration area of CMAGR (California), Yuma MCAS, Arizona in November and December 2010 by the US Navy Geothermal Program Office (GPO) and Epsilon Service Systems (ESS). Over 1200 stations at 200 foot spacing were occupied in a ~20 mi2 region in the western piedmont of the Chocolate Mountains, upslope from known geothermal resource areas producing geothermal fluids for direct use, the Hot Mineral Spa and Bashford Spa. The survey was conducted in two phases. Phase one identified potential anomalies and phase two focused on reproducing previously measured anomalies and better defining the shape of the anomalies. Two major anomalies were identified in the survey area. A negative 108-mV anomaly in the North (Anomaly A) and a negative 96-mV anomaly in the South (Anomaly B), both of which appear to be narrow, electro-kinetically produced self-potential anomalies. The anomalies occur, from drilling data, in areas of known near-surface geothermal fluids. The linear trend and proposed coupling mechanism suggest that the flow of thermal fluids is structurally controlled by faults analogous to regional patterns.