Geologic guides to prospecting for carnotite deposits on the Colorado Plateau

Abstract

This report describes the geologic features that can be used to appraise the favorability of ground in guiding diamond-drill exploration for carnotite deposits in the Upper Jurassic Morrison formation on the Colorado Plateau. It is based on a statistical study of the geologic logs of about 2,500 holes drilled by the Geological Survey. The most useful features consist of the thickness of the ore-bearing sandstone, the color of the ore-bearing sandstone, the altered mudstone associated with the ore-bearing sandstone, and the abundance of carbonaceous material in the ore-bearing sandstone. Although each feature can be used alone to appraise the favorability of ground, an appraisal based on all of them together is even more useful. A method of expressing this favorability in numerical values is suggested. The results obtained by the Geological Survey using these geologic guides appear to be at least twice as favorable as the drilling results obtained with little or no geologic guidance.