Gamma-ray spectrometric and horizontal loop electromagnetic (HLEM) surveys were carried out to determine the radioactive anomalous zones and follow their lateral and vertical extensions west Um-Tomyem, southwestern Sinai, Egypt. The lithologic nature of the Paleozoic rocks played an important role in the localization of the various mineralizations associated with them such as manganese, iron ores, kaolin, turquoise, coal and glass sand. Recently, the uranium and thorium occurrences which are discovered in the Paleozoic sedimentary rocks (specially associated with um Bogma Formation) raised the economic potentiality of the area.
The ground gamma-ray spectrometric data have been analyzed qualitatively and quantitatively by applying specific interpretation techniques. These data revealed that, the study area has wide range concentrations, oscillating from 0.9 to 65.3 Ur, 0.5 to 55.7 ppm, 0.3 to 30.3ppm and from 0.1 to 6.8%, for the total count, equivalent uranium (eU), equivalent thorium (eTh) and potassium (K), respectively. The uranium composite image showed that, the high radioactive parts are mainly associated with Um-Bogma Formation, younger granites and wadi sediments. Also, the coefficient of variability and the uranium favorability index have been carried out and showed that Um Bogma is the highest Formation of all formations and rock units in uranium potentiality.
The result of HLEM has shown significant and well-defined conductive zones that are recorded along with the four used frequencies (110 Hz, 440 Hz, 1760 Hz, and 7040 Hz) at the stations 531950, 531900 and 3202200 of the three (HLEM) profiles (3202300 E, 3202220 E and 531630N) respectively. This may reflect the sources of the conductive bodies are situated at shallow depths and continued to considerable depths. A fair agreement was found among the radiometric and HLEM anomalies at some places of the study area. This may indicate that the surface radiometric mineralization continued to deeper depths at these parts.