Mineralogic investigation into occurrence of high uranium well waters in upstate South Carolina, USA

Richard Warner, Jason Meadows, Scott Sojda, Van Price, Tom Temples, Yuji Arai, Chris Fleisher, Bruce Crawford, Peter Stone

Research output: Contribution to journalArticle

Abstract

High levels of U (up to 5570 μg/L) have been discovered in well waters near Simpsonville, South Carolina, USA. In order to characterize the mineralogical source of the U and possible structural controls on its presence, a deep (214. m) well was cored adjacent to one of the enriched wells. The highest gamma-ray emissions in the recovered core occur in coarse biotite granite at a depth just below 52. m. A slickenlined fault plane at 48.6. m and narrow pegmatite layers at depths of 113, 203 and 207. m also yield high gamma-ray counts. Thin sections were made from the above materials and along several subvertical healed fractures. Uraninite and coffinite are the principal U-rich minerals in the core. Other U-bearing minerals include thorite and thorogummite, monazite, zircon and allanite. Primary uraninite occurs in the biotite granite and in pegmatite layers. Secondary coffinite is present as tiny (<5 μm) crystals dispersed along fractures in the granite and pegmatites. Coffinite also occurs along the slickenlined fault plane, where it is associated with calcite and calcic zeolite and also replaces allanite. Coffinite lacks radiogenic Pb, hence is considerably younger than the uraninite. Dissolution of partially oxidized Ca-rich uraninite occurring in the surficial biotite granite (or secondary coffinite in fracture zones) is likely the main source for the current high levels of U in nearby area wells. The high-U well waters have a carbonate signature, consistent with pervasive calcite vein mineralization in the core. Aqueous speciation calculations suggest U transport as an uranyl (U6+) hydroxyl-carbonate complex. Later reduction resulted in secondary precipitation along fractures as a U4+ mineral (i.e., coffinite).

Original languageEnglish (US)
Pages (from-to)777-788
Number of pages12
JournalApplied Geochemistry
Volume26
Issue number5
DOIs
StatePublished - May 1 2011
Externally publishedYes

ASJC Scopus subject areas

  • Environmental Chemistry
  • Pollution
  • Geochemistry and Petrology

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    Warner, R., Meadows, J., Sojda, S., Price, V., Temples, T., Arai, Y., Fleisher, C., Crawford, B., & Stone, P. (2011). Mineralogic investigation into occurrence of high uranium well waters in upstate South Carolina, USA. Applied Geochemistry, 26(5), 777-788. https://doi.org/10.1016/j.apgeochem.2011.01.035