129-23 UAV-Based Digital Outcrop Modeling for Stratigraphic Correlation Across the Carboniferous Succession of the Southern Appalachian Basin, Tennessee

Abstract:

Large roadcut exposures preserve critical records of depositional environments, facies changes, bedding variations, and lateral stratigraphic continuity. However, steep geometry, height, and highway safety constraints often limit direct field observation and physical measurement. Unmanned aerial vehicle (UAV)-based photogrammetry enables the generation of high-resolution, three-dimensional (3D) digital outcrop models (DOMs) for investigating stratigraphic relationships in otherwise inaccessible portions of an outcrop.

We surveyed and modeled six prominent roadcut exposures across the southern Appalachian Basin in Tennessee using an Autel EVO II Pro 6K RTK V3 UAV. Individual exposures reach up to 210 m in length and 35 m in height. For each outcrop, we captured ~700–800 high-resolution images with ≥80% spatial overlap. Image sets were processed using OpenDroneMap on a high-performance computing cluster to generate georeferenced 3D point clouds. The resulting point clouds were post-processed in CloudCompare to remove vegetation, noise, and non-geologic artifacts prior to interpretation.

Integrating field measurements with spatial calibration in the DOMs enabled tracing of marker beds, assessment of bed-thickness variations, identification of formation contacts, and stratigraphic correlation across paired opposing roadcut faces. The datasets include paired outcrops which expose the Upper Devonian Chattanooga Shale and Lower Mississippian Maury and Fort Payne Formations, as well as paired exposures of the Upper Mississippian Pennington Formation. Additional standalone models document the Lower Pennsylvanian Warren Point Sandstone of the Gizzard Group, and strata of the Lower Pennsylvanian Crab Orchard Mountains Group, formerly assigned to the Fentress Formation. Collectively, the DOMs capture a key Carboniferous stratigraphic transition from organic-rich marine shale and carbonate-bearing Lower Mississippian strata to fine-grained Upper Mississippian carbonate and siliciclastic deposits up to resistant Lower Pennsylvanian coal-bearing sandstone units.

These DOMs establish a high-fidelity digital archive of Carboniferous exposures across Tennessee’s Eastern Highland Rim and Cumberland Plateau, supporting remote quantitative stratigraphic analysis, cross-roadcut correlation, and virtual examination beyond normal field-access limits. They also preserve geologic information from the southern Appalachian Basin that is vulnerable to weathering and modification during highway maintenance.

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