INTERPRETATION OF GROUND GEOPHYSICAL SURVEY DATA OF WADI EL-BOLLA AREA, ENTRAL EASTERN DESERT, EGYPT

Wadi El-Bolla area, Centeral Eastern Desert, Egypt, is mainly covered by amphibolites, granodiorites, younger granites and pegmatites. This work deals with the application of magnetic, self potential (SP) and horizontal-loop electromagnetic (HLEM) techniques, to identify the main structural trends, delineate the mineralized zones and follow their extensions laterally and vertically in the study area.
The magnetic survey showed that, the estimated average depths for the shallow and deep magnetic sources, as calculated from the power spectrum curve, reach 15 m and 48 m, respectively. The ENE-WSW, NNE-SSW, N-S and WNW-ESE structural lineaments are related to shallow structures, which in economic terms, represent the most important targets for mineral exploration in the study area.
The self-potential (SP) electric data show that there are numerous of mineralized zones. Most of these zones are distributed mainly along the contacts between the granodiorites, younger granites, pegmatites and some fault zones. The quantitative interpretation revealed shallow depths to the centers of eight of the selected anomalies (ranging from 6.6 m to 25 m), with half-widths (ranging from 5 m to 20 m) and shallow to moderate dips towards south and north directions.
Three horizontal - loop electromagnetic (HLEM) profiles was conducted using four frequencies: 110, 440, 880 and 3520 Hz. The HLEM data revealed the presence of some conductive bodies with different magnitudes in their mineralizations. The quantitative interpretation of these data showed that the conductive bodies have narrow widths (less than or equal to 5 m) and depths ranging from 11 m to 26 m, dipping steeply towards the north and south directions and conductivity thicknesses varying from 11.4 to 181.9 Siemens/m. The integration of SP and HLEM data defined the most appropriate zones for exploration development at the investigated area.