A study of the electrical properties of the Morrison formation in the Uravan mineral belt of the Colorado Plateaus province indicated that there is a significant correlation between electrical resistivity and the relative favorability for occurrence of ore. The differences in resistivity were not large enough to provide a recognizable target
for standard resistivity‘ field methods, especially where the ore-bearing sandstone member is more than a few hundred feet deep. Measurement of resistivity trends by placing one electrode in a drill hole and
spreading the others out radially on the surface seemed to offer a means
of exploiting the resistivity-favorability correlation.
Field tests of such directional resistivity measurements were
made in the Spud Patch area in San Miguel County, Colo., and the White
Canyon district) San Juan County, Utah. In the Spud Patch area two
methods were tried; in one a current electrode was placed in the drill.
hole, and in the other, a potential electrode. The second was the more
tedious but provided the more readily interpretable results. A comparison of the resistivity trends thus determined with the favorability
estimated from geologic indexes indicated that directional resistivity
methods could predict the location of favorable areas at distances of
600 to 1,000 feet with a high degree of success.
In the White Canyon district directional resistivity measurements
were made on the assumption that the conglomerate which is found in many
channels filled with the Shinarump member of the Chinle formation has
a high resistivity. The measurements were successful in tracing the
channel conglomerate where surface conditions were favorable.