Exploration for uranium in southwestern Anatolia. A case history

The present project, a UNDP/IAEA technical assistance project with the Turkish Mineral Exploration and Research Institute, seeks unoxidized ore in the reduzate zone below the water table in southwestern Turkey. It employs a multi-method attack that utilizes reconnaissance geological mapping, scintillometer surveys, stream sediment surveys, water sampling for uranium and radon, rotary non-core drilling, multielement geochemical laboratory analysis of field samples, radiometric determinations for secular equilibrium, and computer treatment of the results. Ideally, the initial stages would include both radiometric surveys and reconnaissance geological mapping; the mapping also provides basic stratigraphic and structural control for drilling. More detailed follow-up surveys in anomalous areas consist of a scintillometer survey, soil gas (Rn), and soil geochemistry on a predetermined grid, and a detailed hydrogeochemical survey where numerous wells exist. The geochemical investigations are supported by a laboratory in Ankara that can perform over 1000 determinations a day with a five-man team. Non-core rotary drilling with 1-m samples of cuttings, together with gamma, spontaneous potential, and resistance logs provide adequate sub-surface information. About 25000 m have been drilled by the equivalent of two rig years. Only four holes have been cored for mineralogical and equilibrium information. Drilling to a nominal 100-m depth is accomplished to determine the stratigraphy and to evaluate the area for uranium favourability. Particular attention is given to carbon and pyrite content and to the possibility of redox interfaces. Mineralized zones have been penetrated in two areas. At one, the lead was a possible redox interface. The favourability of the area was confirmed by later geochemical surveys. At the other area, drilling was stimulated and guided by hydrogeochemical anomalies. It is concluded that the multi-method attack on exploration is effective in identifying favourable areas for drilling and that the areas involved could not reasonably be investigated otherwise. (author)