A Novel Approach to Critical Mineral Prospecting using Airborne Radiometrics

Conventional airborne gamma ray spectrometric surveys, often referred to as “Radiometrics,” have proven extremely useful for geological mapping and mineral exploration targeting. Measurements taken every 40–80 m along 100–200m spaced flight lines provide sufficient sample density to support geological application at regional and property scales, but risk missing hot spots of potential interest to mineral exploration which may lie between the flight lines.. Ground follow-up to these conventional surveys thus requires considerable time, effort and money to locate the actual ground sources. A novel approach based on very low and slow, free-form flying guided by real-time gamma-ray anomalies was proposed as a type of “airborne geophysical prospecting” tool. This approach was designed to quickly distinguish and immediately identify individual occurrences within and between anomalies, achieving resolutions not possible with conventionally flown airborne surveys. This new approach included the use of a helicopter equipped with a console and two externally mounted 4L NaI crystals, a laptop with mapping software and an experienced operator using real-time results to direct the flight path. The software used to monitor the radiometric data in real-time was set up to alarm when values of K, eU and eTh or their ratios exceed predefined values.