| Basis for focus area |
This focus area applies the Coles Hill genetic deposit model to the Piedmont physiographic province. This new uranium deposit model indicates favorable areas for concealed mineralization along the structural zones adjacent to Triassic basin sediments. This focus area covers the major structural zone that encompasses the Brookneal Shear Zone, Chatham Fault system, and boundaries between Neoproterozoic and early Paleozoic rocks of the Sauratown Mountains Anticlinorium, Smith River Allochthon, and the Triassic Danville-Dan River basins in Virginia and North Carolina. The locations of favorable areas in Triassic basins identified during the National Uranium Resource Evaluation (NURE) project (U.S. Department of Energy, 1980) were used to identify potential host rocks, which are Triassic rock in the Horton and others (2017) 1:500,000 map compilation. |
| Identified resources |
Identified resources for uranium. |
| Production |
None. |
| Status |
Past exploration. |
| Estimated resources |
Virginia: Coles Hill deposit NI 43-101 compliant: 133 million lbs of U3O8; Indicated resource is 134 M short tons @0.056% U3O8, cutoff grade 0.025% (Kyle and Beahm, 2013). |
| Geologic maps |
Horton and others (2017), scale 1:500,000; Henika (2002), scale 1:100,000; Henika and Thayer (1977, 1983), scale 1:24,000; Van Price and others (1980a, b); scale 1:24,000. |
| Geophysical data |
Inadequate Rank 4 aeromagnetic and Rank 5 aeroradiometric coverage. |
| Favorable rocks and structures |
Major structural terrane boundaries in the Piedmont geological province of Virginia and North Carolina. |
| Deposits |
Coles Hill uranium deposit (MRDS dep_id: 10084764). |
| Evidence from mineral occurrences |
MRDS; International Atomic Energy Agency (2020b); U.S. Environmental Protection Agency (2006). |
| Geochemical evidence |
See Smith (1997). |
| Geophysical evidence |
The Coles Hill U deposit was identified by an outcropping surface radiometric anomaly; also see Duval and others (2005). |
| Evidence from other sources |
NURE datasets indicate regional geochemical and geophysical anomalies associated with significant geological terrane boundaries in the southeastern Piedmont province. |
| Comments |
The Coles Hill U deposit model (Hall and others, in review) indicates favorable areas for concealed mineralization along the structural zones adjacent to Triassic basin sedimentary rocks; further refinement, including locations of structures to transport and host mineralization, is needed. NURE datasets indicate regional geochemical and geophysical anomalies associated with significant geological terrane boundaries in the southeastern Piedmont province. The large U deposit at Coles Hill is located along one of these structural zones, indicating the possibility of additional concealed mineralized zones in Virginia and North Carolina. The discovery of additional resources requires 3D modeling of structural features, permissive host rocks (lithologic and/or structurally prepared), mineral source rocks, and alteration including those controlling REDOX conditions. |
| Cover thickness and description |
The U deposit at Coles Hill is exposed at the surface, but the subsurface ore zone is mostly concealed. |
| Authors |
Susan Hall, Dwain Veach, William L. Lassetter. |
| New data needs |
Modern higher resolution geophysical data than what is available currently, coupled with additional geologic mapping and geochemical analyses. |
| Geologic mapping and modeling needs |
With the aid of geophysical survey data, additional 1:24,000 scale geologic mapping will focus on developing a 3-dimensional model of major segments of the Chatham Fault-Brookneal Shear Zone, a major terrane boundary in the western Piedmont. |
| Geophysical survey and modeling needs |
High resolution aeroradiometric data will identify U, Th, and K enrichment associated with mineralized and altered rocks at the ground surface. High resolution aeromagnetic data will help identify lithologic and structural features in 3D that may be tied back to surface geologic mapping. |
| Digital elevation data needs |
Lidar adequate. |
