Investigation for uranium dispersion adjacent to cretaceous phosphatic outcrops in Al-Nassrieh Basin, southern Palmyrides, Syria

A detailed radiometric survey including soil gas radon measurements and field gammaray survey, in accordance with geochemical and geological investigations were carried out in Al-Nassrieh Basin (central Syria), for the purpose of uranium exploration. Thirty-six samples were collected from various lithofacies of the survey area and analyzed by γ-ray spectrometric technique for determining the concentration values of major radioelements. The relationships between the concentrations of equivalent eU, eTh, and their ratios were examined in order to define their trend of variations and evaluate the degree of uranium remobilization and redistribution. Although the initial results indicate that uranium enrichment is mostly restricted to the Upper Cretaceous phosphate rocks, a considerable portion of uranium appeared to be leached out of the primary phosphatic source and dispersed in the adjacent recent sediments. Further, notable increases of radon level associated with relatively high values of uranium concentration and gamma count rates were found to be spatially correlated with the transition zone between the marine Paleogene and continental Neogene formations throughout the study basin. This observation demonstrates the importance of the concerned zone as a suitable geological environment for hosting probable uranium mineralization along a chemically reducing interface where surface water of terrestrial and marine origin mingled at depth and away from surficial conditions.