DC Resistivity Survey (Dipole-Dipole Array) At Waunita Hot Springs Geothermal Area (Heinrichs Geoexploration Company, 1981)

From Open Energy Information

Exploration Activity: DC Resistivity Survey (Dipole-Dipole Array) At Waunita Hot Springs Geothermal Area (Heinrichs Geoexploration Company, 1981)

Exploration Activity Details
Location Waunita Hot Springs Geothermal Area
Exploration Technique DC Resistivity Survey (Dipole-Dipole Array)
Activity Date 1981
Usefulness could be useful with more improvements
DOE-funding Unknown

Exploration Basis
The aim of the resisitivity surveys was to try to identify the location of the geothermal reservoir feeding the hot springs
Heinrichs Geoexploration Company conducted two phases of eletrical resistivity tomography around the Waunita Hot Springs and Tomichi Dome area. The first phase consisted of mapping and profile dipole-dipole surveys and Schlumberger soundings. The mapping dipole survey consisted of 103 stations over a 3 by 4 mile area using a transmitting dipole 7,000 feet in length and an orthogonal pair of 300 foot dipoles at each station. Injected currents of 6-8 amperes and a filtering frequency of 3.0 Hz were used. The profile dipole survey used a dipole with a length of 200 feet and transmitting-receiving station separations of 1-9 dipole lengths. An injected current of 5 amperes and 3.0 Hz frequency was used. The second phase consisted only of dipole-dipole mapping, with a transmitting dipole length of 7,000 feet and 132 stations spread over several areas of interest identified in Phase I. All stations used an orthogonal pair of 300-500 foot dipoles. Injected currents of 2-8 amperes were used with frequencies of either 0.1 or 0.3 Hz to eliminate induced coupling effects. All measurements were obtained using a GEOEX Mark 4 induced polarization-resistivity system. The resistivity surveys identified a low-resistivity zone approximately 7 km by 3.5 km in area extending NW to SE between Waunita Hot Springs and Black Sage Pass. Apparent resistivities in the zone ranged from 33-300 ohm-meters, with the lowest readings in synclinal Mesozoic sediments 2-3 km west of Black Sage Pass. Henrichs Geoexploration Company [1981] interpreted this zone as a 50 ohm unit of Mesozoic sediments over a 2000 ohm Precambrian crystalline basement. Contour mapping also suggested a possible resistivity low beneath the southern flank of Tomichi Dome; however, poor access limited coverage beneath the dome itself [Henrichs, 1981]. It should be noted that these surveys were conducted prior to the advent of modern inversion techniques (and computing power) and, as such, a reanalysis of these data may prove fruitful in identifying or better characterizing anomalies potentially associated with geothermal reservoirs.

Additional References