Abstract Internal heat generation in the extraordinarily radioactive granite (45 ppm U and 114 ppm Th) beneath the Upper Mississippi Valley district was sufficient to heat rocks a few kilometers below the ore to temperatures higher than those of ore formation. At the time of mineralization (Permian), faulting formed fracture permeability in the granite and initiated thermal convection of basinal brines. The circulating brine leached radiogenic lead and pent-up heat from the granite. Radiogenic lead and other elements in the ores precipitated where concentrations of organic matter were encountered in the host rock. Salinity of the ore solution was provided by the circulating brine. Sulfur was obtained from the brine or from disseminated organic matter in the host rocks. Heat and metals were derived from the granite. No long distance transport of anything was required.

Abstract Statistical treatment of the chemical data for samples from the Church Rock, Smith Lake, Ambrosia Lake, and Laguna districts, all in the Grants uranium region, San Juan basin, indicates that primary ore-forming processes concentrated copper, iron, manganese, molybdenum, selenium, vanadium, yttrium, arsenic, organic carbon, and sulfur, along with uranium. The initial uranium and vanadium mineralization occurred before compaction of the host rocks. A barium halo associated with all of these deposits formed as a result of secondary processes. Calcium and strontium were also enriched in the ores by secondary processes. Comparison of the chemical characteristics of redistributed deposits in the Church Rock district with those of primary deposits in the Grants uranium region indicates that calcium, manganese, strontium, yttrium, copper, iron, molybdenum, lead, selenium, and vanadium are chemically separated from uranium during redistribution of the deposits in the Church Rock district. Comparisons of the chemical characteristics of the Church Rock deposits with those of the secondary deposits in the Ambrosia Lake district suggest some differences in the processes that were involved in the genesis of the redistributed deposits in these two areas.