Gamma-ray analysis of the sediments overlying the Helez and Kochav oil fields, Israel

A very sensitive, low-background gamma-ray spectrometer was used to show that a negative total gamma-ray intensity anomaly over the Helez and Kochav oil fields is due to the depletion in all three radionuclides (⁴⁰K, ²³²Th, and ²³⁸U). The location of the radiometric anomalies at the surface above petroleum reservoirs at depth, suggests a genetic connection. It is proposed that the soil radioactivity is not the result of vertical radionuclide transport from the reservoir, rather that migrating hydrocarbons interact and degrade clays and other soil minerals which then release these large cations that substitute for each other diadochously.