| Title | Hidden Anomalies: Small Near-Surface Resistivity Variations Can Completely Mask Large, Deeper Anomalies |
|---|---|
| Authors | Shore, Greg A.; Clearwater, R. Peter |
| Year | 1992 |
| Conference | Geothermal Resources Council Transactions |
| Keywords | Exploration; Canada; B C; Meager Mountain; Dipole; Conductivity; Alteration; Permeability; Anomalies; Models; Meager Creek |
| Abstract | Recently completed research into the three dimensional interpretation of complex, multi body geo electric regimes (realistic earth conditions) has quantified the extent to which irregular (3D) near surface resistivity variation masks or distorts the signal form the large, deeper probing array separations of a resistivity survey transverse. The observed effects are much greater than previously anticipated. The signatures from large, buried conductive bodies can be completely obscured by much smaller near surface features. In pseudo sections manifesting surface influenced diagonal patterns, the apparent absence of other or "deeper' signatures of interest could influence a premature rejection of an exploration area. The research shows that only conclusion warranted by such data is: "Surface features present; deeper information uninterpretable. Additional geophysical or other data must be acquired to test this area at depth." These findings should influence strategies for future exploration to emphasize the importance of obtaining additional data wherever the effects of near surface features are recognized. Reconnaissance and other resistivity data from previously explored areas should also be reviewed for untested opportunities, where the misunderstanding of surface distorted pseudo sections may have led to premature withdrawal from an exploration area. |