A rotating dipole survey of the Elura prospect, Cobar, NSW

Abstract

Rotating current dipole phase and field strength results are presented for three dipole sites occupied at the Elura prospect, Cobar, N.S.W. For the production of contoured anomalies, rectangular grid networks of phase differences and field strength ratios were corrected for closure errors and then reconstituted to phase and field strength in order to restore the inherent cylindrical symmetry of the rotating dipole field. Phase residuals are defined by removing the phase of a theoretical primary field based on the assumption of a homogeneous half-space of resistivity 12.5 ohm metres. This entails two corrections, called here the azimuthal correction and the propagation correction. Field strength residuals are similarly defined by subtracting a normalised theoretical field, again assuming a homogeneous half space. Results for all three dipole sites give large phase residuals (30?80°) and small field strength residuals (5%). Anomalies most closely associated with the target occur with the dipole transmitter positioned on the long (N?S) axis.