Prospecting for the ferromagnetic mineral accumulations using the magnetic method at the Eastern Desert, Egypt

Abstract

In this study we delineate the subsurface structures within an area of about 145 000 km2 in the Central Eastern Desert of Egypt (CED), using magnetic methods. The main goal is to establish the tectonic framework of the study area and to understand the role of tectonics in the mineralization process. Aeromagnetic data covering the study area were used, and also detailed land magnetic surveys were carried out along profiles. More than 300 rock samples were collected for laboratory measurements of magnetic susceptibility. The data set was processed using a series of techniques, namely trend analysis, 3D Euler deconvolution, Werner deconvolution and 2.5 direct modelling. Results indicate that the most predominant tectonic trends are E-W, N15°-25°W and N45°W. The depth to the basement estimates range from the surface to 1.8 km. These results agree with the drilled well data. The measured magnetic susceptibility values range between 0.0001 SI and 5 SI. The high susceptibility values strongly suggest that ferromagnetic minerals accompany the mafic metavolcanics along the shear zones at Barramiya, Hafafit, Dawi and Abu Swayel. We show a good correlation between the structures deduced from the magnetic analysis and the known mineral distributions. Most of these ore accumulations are restricted to the major tectonic shear zones with a NW-SE direction. We conclude that mineralization is structurally controlled by faulting, probably as a result of hydrothermal circulation along fault planes. © 2009 Nanjing Institute of Geophysical Prospecting.