Gamma-ray spectrometry and induced polarization (IP) studies were
carried out to determine the radioactive anomalous zones and to follow their
lateral and vertical extensions in El Atshan-II uranium prospect area, central
Eastern Desert, Egypt. This area and its surroundings are covered by different
Precambrian basement rocks, which intruded by younger bostonite rock, andesite
dykes and carbonate veins. Data of the gamma-ray spectrometry have been
analyzed qualitatively and quantitatively by applying specific interpretation
techniques. These data revealed a wide radioactivity range oscillating from
15.0 to 2362.0 Ur, 0.5 to 307.2 ppm, 0.1 to 55.1 ppm and 0.3 to 22.0% for the
total count (Tc), equivalent uranium (eU), equivalent thorium (eTh) and potassium
(K), respectively. The constructed radioelement concentration maps and
eU-composite image of the study area showed that the anomalously high
radioactivity levels are mainly associated with outcrops of the bostonite rock.
The induced polarization data were mathematically inverted to produce the true
resistivity and chargeability values of cross-sections below the surveyed lines
traverse in the area. The resistivity values are varied both vertically and
horizontally from 7.83 to more than 1042.0 ohm·m, while the chargeability
values are ranged from 0.195 to more than 204.0 mV/V, suggesting
variation of the rocks facies and mineralizations. Integration of the resistivity
and chargeability data indicates the presence of some mineralized zones, mainly
associated with the bostonite rock, with depths varied from the near-surface to
more than 70 m. Therefore, a core drilling is recommended at some stations
along three selected profiles to a depth of 70 - 100 m to test the depth,
structural model and grade of mineralization in the area.