271-4 A Preliminary Investigation of Mine-Pool Viability as Coupled Geothermal and Rare Earth Element Resources in Northern West Virginia

Session: Geologic Energy Resources and Storage for Now and the Future (Posters)

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Flooded abandoned coal mines could potentially be underground reservoirs for direct-use geothermal resources in small-scale district heating and cooling systems. In the central Appalachian basin, there also is the potential for rare earth element (REE) recovery from the ~11℃ mine pool water, which could offset the expense of geothermal infrastructure. In order to better understand flooded mine-pools as coupled geothermal-critical element resources, a total of 48 samples of roof and floor rock were collected from outcrop and core associated with 3 Upper Pennsylvanian coal seams in northern WV (from oldest to youngest): the Upper Freeport coal, Elk Lick coal and Pittsburgh coal. Overall, northern WV hosts several larger population centers that could be served by direct-use geothermal energy, but Upper Pennsylvanian strata in this area are more poorly characterized compared to Lower-Middle Pennsylvanian strata that host mine pools in the southern part of the state. In thin-section, fine-grained mudrock and sandstone samples contain quartz, mica, clay minerals, sulfides, iron oxides and organic matter, and limestone samples contain carbonate, sulfides, and lesser amounts of iron oxides. Thirty-three samples were analyzed using a minipermeameter, with results ranging from 0.182 mD to 43.3 mD. Twenty-seven samples were analyzed for elemental abundances using a pXRF spectrometer. In all samples, Yittrium (Y) was the most abundant REE, with 22 samples (~81%) yielding between ~53-98 ppm. Four of the five samples with >100 ppm of Y are mudstones associated with the Upper Freeport coal from 4 different locations, including two floor rocks and two roof rocks. This includes the most Y-enriched sample (345.66 +/- 24 ppm), a shale roof rock from Preston county. The fifth sample with >100 ppm Y is a mudstone roof rock sample from the younger Pittsburgh coal seam. Cerium (Ce) is the second-most abundant REE found, with six samples containing >100 ppm of Ce. The most enriched sample is mudstone floor rock from the Pittsburgh coal seam, with 372.7 +/- 188 ppm of Ce. Most Ce abundance measurements show high error, which warrants further investigation to determine validity. Overall, these results suggest economically significant REE enrichment in low permeability rocks associated with some northern WV mine pools. Higher resolution sampling is needed to further constrain REE prevalence in mine-pool confining rocks.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10430

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