Uranium mineralization and use of resistance log character in deltaic point bars: Franklin mine, Karnes County, Texas

It is recommended that uranium exploration geologists become familiar with the resistance log responses in point-bar environments and use these characteristics in exploration in addition to the usual color and gamma guides. Point-bar sediments in deltaic environments and in close proximity to barrier-island deposits may contain two oxidation cells. One of these cells will generally be very narrow (less than 100 ft or 30.5 m), contained within the channel-fill subenvironment and should be recognizable from the color of cuttings. The other will be within the accretion-set subenvironment and may show only subtle color differences which can make recognition of oxidation from cuttings very difficult. The Franklin mine study shows that careful examination of resistance log character can help the recognition of the geometries of the point-bar subenvironments and delineation of the associated redox fronts and uranium mineralization. Applications of these observations can ensure that small ore pods or subtle oxidation would not be missed. These conclusions were obtained by correlating pit-wall mapping with resistance log character