Telluric and D. C. resistivity techniques applied to the geophysical investigation of basin and range geothermal systems. Part I. The E-field ratio telluric method

Abstract

This paper describes a natural field electrical exploration technique, the E-field ratio telluric method. The method employs a collinear three-electrode array to measure successive electric field ratios as the array is leap-frogged along a survey line. The 0.05 and 8 Hz responses observed over numerous simple resistivity structures, based upon numerical modeling, are presented. From the model study it can be concluded that: th~ method is well suited for the rapid electrical reconnaissance exploration of survey areas of several hundred square kilometers, in search of deep conductive targets such as might be associated with hydrothermal systems; the frequencies used for the model study (0.05 and 8 Hz) are appropriate to exploration in Basin and Range valleys, and afford a rudimentary means of depth discrimination.

Northern Nevada geothermal exploration strategy analysis

“…A technical summary report containing survey results and interpretations is in preparation and partial results have already been given in Open File Reports (Wollenberg et al, 1975;Beyer et al, 1976;Goldstein et al, 1976) and in topical reports (Beyer, 1977a, b, and C: Liaw and McEvilly, 1977;Morrison et al, 1977;Paulsson, 1977: Wollenberg et al, 1977).…”

Telluric traverse data release for the Getchell and Preble disseminated gold deposits, Humboldt County, Nevada

“…It was used as early as 1921 (Leonardon, 1928) by C. Schlumberger, but until recently has been little used in the United States. Beyer (1977) discusses the method in some detail and presents a series of model results computed for two-dimensional structures. He concludes that the method is well suited for rapid reconnaissance of regions several hundred square-kilometers in area searching for targets such as hydrothermal systems.…”

“…The horizontal electric field variations rather than the magnetic field, in general, reflect the variations in earth resistivity. For two-dimensional structures it can be shown (Beyer, 1977) that the electric field measured normal to strike (the transverse magnetic TM mode) is proportional to the square root of the resistivity variation measured with the electric field normal to strike and magnetic field parallel to strike. Because of this, telluric traverses are typically run normal to the expected regional trends in a survey area.…”

Assessment of surface geophysical methods in geothermal exploration and recommendations for future research

“…In this case signals are telemetered to a multi-channel recording system The method is most quantitatively useful when the profile is measured perpendicular to geologic strike or in the transverse magnetic (TM) mode (Beyer, 1977). In this mode results from profiles are repeatable and computer modeling can often be rewarding (Beyer, 1977).…”