Abstract
An airborne gamma radiation survey was recently published for a region of the Salmon River Mountains which hosts deposits of cobalt and rare earth elements, both of which are listed as critical minerals. The airborne gamma radiation survey was collected due to the prospect for undiscovered critical mineral deposits within the region.
Airborne gamma radiation surveys measure the concentrations of potassium, uranium, and thorium in the top 30 centimeters of the Earth’s surface. Because individual rock lithologies typically have unique concentrations of potassium, uranium, and thorium, airborne gamma radiation data is used to delineate the distribution of geologic map units and to identify areas of anomalous gamma radiation signals, which may be related to alteration or mineralization.
Analyses of the survey were carried out to provide information for the improvement of the geologic framework and to identify areas where the gamma radiation data is anomalous for the mapped rock lithology. K-means clustering, principal component analysis, Kohonen self-organizing maps, and band ratios were used to analyze the airborne gamma radiation data. The clustering techniques were largely successful in delineating lithologies within the study area. Band ratios highlighted areas which may be altered. Through the clustering techniques, anomalous areas were identified, including both areas known to be mineral deposits and areas which warrant further investigation for the refinement of the geologic framework and for the possibility of mineralization.