CHALLENGES AND OPPORTUNITIES OF SUAS APPLIED TO GEOTHERMAL SYSTEMS, NORRIS, MT, USA

The advent of small uncrewed aerial systems (sUAS), or drones, has unlocked new possibilities for data collection in the geosciences, enabling unprecedented temporal and spatial resolution. However, application of these techniques presents some challenges. This study explores the application of sUAS in geothermal resource assessment, focusing on the integration of thermal infrared (TIR) remote sensing and structural analysis. We evaluated the efficacy of the FLIR Duo Pro R radiometric thermal camera, tested photogrammetric workflows, and attempted to apply machine learning (ML) models within ArcGIS Pro to predict geothermal anomalies.

Our multidisciplinary approach encompassed laboratory experiments, field surveys at the Norris Hot Springs in southwestern Montana, and computational modeling. Lab results revealed the FLIR Duo Pro R's overestimation of stable temperatures by 6-7°C under steady-state conditions, with significant instability under varying environmental conditions. The project combined UAV-based photogrammetry, traditional geologic mapping, zircon U-Pb geochronology, seismic data, and 3D geologic modeling to analyze structural controls on geothermal systems.

We found that photogrammetric techniques significantly affect the detection of thermal anomalies in sUAS TIR imagery, with inconsistent and unreliable results in most cases. Our ML model struggled to reliably identify influential variables or predict ground temperatures. Structural analysis indicated that the geothermal system at Norris Hot Springs is hosted by a network of faults and fractures in Precambrian gneiss, linked to deeper reactivated Laramide structures. High-angle NNW-SSE trending normal faults with pervasive alteration and polymetallic mineralization appear to connect surface features with deeper geothermal activity.

Despite the challenges, our findings highlight the potential of sUAS TIR remote sensing and multidisciplinary approaches in geothermal exploration. Advancements in sensor technology and photogrammetric processing will enhance the utility of these techniques, offering new opportunities for geoscience research. This study highlights the importance of integrating diverse data sources and methodologies to advance our understanding of geothermal systems, while also revealing current limitations.