Electromagnetic (EM-60) survey in the Panther Canyon Area, Grass Valley, Nevada

Technical Report · Thu May 01 04:00:00 EDT 1980

DOI:https://doi.org/10.2172/5139469· OSTI ID:5139469

Wilt, M; Goldstein, N; Stark, M; Haught, R

Eight frequency domain electromagnetic soundings were measured over the Panther Canyon thermal anomaly in Grass Valley, Nevada. The data were collected with Lawrence Berkeley Laboratory's large moment horizontal loop system (EM-60). At the transmitter site located near the center of the thermal anomaly, square wave currents of up to 70 A were impressed into a fourturn 50 m radius coil at frequencies from 0.033 to 500 Hz. At the eight receiver sites, 0.5 to 1.5 km from the loop, magnetic fields were detected with a three-component SQUID magnetometer and vertical and radial magnetic field spectra were calculated. Data were interpreted with a computer program which fit filled spectra and associated ellipse polarization data to one-dimensional resistivity models and results were compared to interpretations from earlier dipole-dipole resistivity measurements. Comparison of these interpretations indicates fairly close agreement between the two, with both models clearly indicating the presence and dimensions of the conductivity anomaly associated with the thermal zone. Although the dc data was better able to resolve the high resistivity bedrock, the EM-data were able to resolve all major features without distortion at shorter transmitter receiver separations and in about one-third of the field time.

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5139469
• Report Number(s): LBL-10993
• Country of Publication: United States
• Language: English

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