Mapping the subsurface structural features of Al-Laqitah area, Central Eastern Desert of Egypt using aeromagnetic data

Abstract

The present study presents the analysis and interpretation of the aeromagnetic data of Al-Laqitah area in the Central Eastern Desert of Egypt to map the subsurface structural features and hence the tectonic framework of the area. The total field data were reduced to the north magnetic pole (RTP) and then subjected to regional-residual separation in order to isolate the deep-seated component from that near-surface one. In addition, the aeromagnetic data was subjected to several processing techniques that provide automatic delineation and depth estimation of the magnetic sources. These techniques include analytic signal, second vertical derivative, horizontal gradient, and Euler deconvolution in addition to the magnetic modeling. The results demonstrate a wide variety of magnetic anomalies reflecting different magnetic sources and features. The most pronounced subsurface features are the linear NNW-SSE reversely polarized diabasic dykes, the deeply rooted basic intrusions, and the wide basin in the central part of the area. The interpreted basin is dissected by fault systems dividing it into local subbasins. Moreover, the area is dissected by basement uplifts and troughs controlled mainly by dykes and faults of different directions and displacements. The magnetic modeling proved that the basement rocks, in subsurface, are of acidic composition and invaded with basic materials forming wide dykes of higher magnetic susceptibilities. It also illustrates variable depths for the basement relief coinciding, more or less, with the average depth estimated from the power spectrum as 3.5 Km and from Euler deconvolution for the deep-seated magnetic sources. Statistical analysis of the mapped structural elements proved that they are directed toward the NW, NNW, NNE, NE, and E-W directions as predominant trends and N-S and ENE as secondary trends.