期刊名称：Journal of Environmental Hydrology (ältere Jahrgänge)
印刷版ISSN：1058-3912
电子版ISSN：1996-7918
出版年度：2008
卷号：16
出版社：IAEH
摘要：Uranium exists in nature only as tetravalent (U4+) or hexavalent (U6+) compounds. From a geological point of view, the primary uranium mineral appears as tetravalent and is often found in acidic igneous rocks. It is converted in the surface oxidation zone to a secondary mineral where it becomes hexavalent. The latter is soluble and can be easily carried by surface or subsurface water until re-enters a reducing environment where it deposits again in tetravalent form. Even though no acidic igneous rocks occur in the exposed rock formations of Lebanon, the occurrence of sandstone as a derivative of these rocks makes it favorable for uranium occurrence. In addition, the interbedding of shales, clays and lignite (as reducing agents) contribute to the favorability of uranium ore deposition. The location of Lebanon within the Mediterranean phosphatic belt, where uranium deposits often exist, adds another possibility for the natural occurrence of uranium ores. A ground radiometric survey, using a portable scintillometer has been carried out on selective sites in Lebanon, with a special emphasis on Neocomian-Barremian (sandstone and clay), Albian (shale) and Senonian (Marl) rock formations. Preliminary results show anomalous gamma radiation, which exceeded in many instances three times the background radiometric values. This is well pronounced in sandstone and clayey rocks. A detailed investigation should be carried out using gamma-ray spectrometers to build up a comprehensive survey on radioactivity type and concentration in the rocks of Lebanon.
