Factors controlling uranium distribution in Upper Devonian-Lower Mississipian black shales of Oklahoma and Arkansas

Subsurface core and outcrop samples of the Upper Devonian-Lower Mississippian Woodford Shale and its lateral equivalents in Oklahoma and Arkansas were found to contain up to 121 ppM uranium. The uranium is primarily associated with the kerogen fraction of the organic material and generally increases with increasing organic carbon content. The uranium to organic carbon ratio, however, was found to vary significantly between samples which suggests that factors other than organic carbon content also influence the amount of uranium contained in a particular sample. Specifically, the effects of organic matter type, thermal maturation, mineralogy, and weathering were investigated