Microdrones in Field-Based Structural Geology: a Photogrammetry and Fracture Quantification Case Study from the North Mountain Basalt, Nova Scotia, Canada

The use of drones (i.e., uncrewed aerial vehicles; UAVs) in geoscience research and teaching is fast becoming widespread, with a range of highly diverse applications documented. Many of these studies favour consumer-level drones, however, recent developments in so-called 'microdrones' (total take off weight <250 g) necessitates further investigation to determine the possible benefits, limitations and future developments of these tools. Deployment of microdrones is often more advantageous in numerous jurisdictions (e.g., Canada, UK and USA) due the fact that there are fewer regulations, they are substantially cheaper, and are easily transportable to remote field sites. In this study, we deployed a DJI Mini 2 microdrone to study the ca. 201 Ma North Mountain Basalt exposed in largely coastal outcrops along the Bay of Fundy, Nova Scotia, Canada. Here we report on the benefits of the microdrone as a field aid with three related approaches: 1) general site location and characterisation, 2) drone-based photogrammetry using ArcGIS Drone2Map, and 3) quantitative fracture mapping using FracPaQ. Application of these methods at 4 coastal sites on the Bay of Fundy, showed that microdrone-acquired imagery from the NMB exposures provides a valuable resource for structural interpretation post-fieldwork. Our interpretation of the microdrone-derived data shows, two near-perpendicular fracture sets in the NMB: ~NNE-SSW and ~ESE-WNW, although there is some variation along the coastline. Overall, through this work we determined that microdrones offer field-based geoscientists a valuable data acquisition tool and predict that this approach to enhancing fieldwork will continue to advance over coming years.