Origin for Uraniferous Organic Nodules, Hennessey Group (Permian), Oklahoma: ABSTRACT

Abstract

End_Page 560------------------------------Geologic field relations may be used to infer a coal- or petroleum-related origin for uraniferous organic nodules of the Hennessey Group (Permian), in Kiowa County, Oklahoma. The local presence of crude oil in the shallow subsurface and the local absence of commercial coal deposits suggest a petroleum-related origin for these nodules. This conclusion is compatible with the subsurface structure near the nodule site, which is dominated by several major near-vertical reverse faults, below the Permian unconformity. These faults may provide vertical conduits for petroleum sources below. Geochemical analyses of the uraniferous nodules, including infrared spectra and elemental analyses, reveal characteristics of both coal and petroleum. However, carbon isotopic analyses favor a petroleum-related origin. A model can be proposed whereby petroleum, migrating from depth, is initially altered near the surface to a more viscous material. Concurrently migrating, uranium-rich ground water is then stripped of its uranium by the degraded petroleum. Subsequent radiation damage in the uranium-rich nodules has resulted in unusual chemical characteristics. Such a model suggests that associated petroleums may geochemically correlate to the organic matter of the nodules. This is confirmed by carbon isotope ratios, which are very similar for both the petroleum and the uraniferous nodul s. End_of_Article - Last_Page 561------------