Magnetic interpretation of north Gebel El Shallul area, central Eastern Desert, Egypt

The present work utilizes the aeromagnetic data supported by geology and remote sensing satellite data, to delineate surface and subsurface structural elements in north Gebel El Shallul area. Geologically, the area is covered by Precambrian basement rocks to the East (metasediments, metavolcanics, Hammamat sediments and younger granites) and Phanerozoic sediments to the West (Nubian Sandstones and Qouseir clastics). The Landsat image of the area gave additional detailed litholgic information which is very useful in identifying and discriminating the different lithologic rocks exposed in the area. Analysis of the structural lineaments of the Landsat image and the compiled geological map show that most of the well-developed structural lineaments have NW, NNW and ENE trends. The aeromagnetic data were analyzed and processed by several advanced techniques; reduction to the pole, regional-residual separation, second vertical derivative (SVD), analytical signal, Euler deconvolution and shadowgrams. The application of local power spectrum on the reduced to North Pole (RTP) aeromagnetic data indicated that the average depths to the near–surface and deep-seated causative magnetic bodies were found to attain 0.5 and 1.8 km, respectively. Therefore, the filtering of the aeromagnetic data at the two assigned interfaces was conducted to assist the discrimination of the residual (near-surface) and regional (deep–seated) magnetic anomalies. The prepared aeromagnetic maps have been interpreted qualitatively and quantitatively to deduce the structural elements which were used to construct a basement tectonic map for the area. The used analysis techniques helped to reveal many structural elements such as faults of different orders, uplifted blocks (antiforms or horsts) and subsided blocks (basins or synforms). It has been found that the NNW pronounced linear magnetic anomalies, normally and reversely magnetized, are associated with deep-seated diabasic dykes. The interpretation of the basement tectonic map of the area indicated the presence of a set of unexposed subsurface basic dykes running generally in NNW–SSE direction controlling the courses of major wadis in the study area. This set of NNW–SSE basic dykes are dissected by a NE–SW fault system. These two sets of fault systems were found to be matched well with that obtained from the Landsat image and geological map. It was found that the pronounced NNW direction is a predominant structural trend controlling the structural framework of the area