نوع مقاله : مقاله تحقیقی (پژوهشی)
Geophysics Department, Faculty of Science, Cairo University, Giza, Egypt
عنوان مقاله [English]
This paper represents the analysis and interpretation of the airborne magnetic data of central and northern Egypt to delineate the subsurface faults and other structures and also the tectonic framework of the area. The total observed magnetic field data was reduced to the north magnetic pole (RTP) and then using the power spectrum, the regional and residual magnetic fields were separated using the Butterworth filter to isolate the anomalies caused by each of them. In addition, the airborne magnetic data was subjected to several filters to enhance the signals from the different magnetic sources for better delineation and edge detection. Also, Euler deconvolution was applied to estimate the depth of the different magnetic sources.
The final outputs show a wide variety of magnetic anomalies reflecting different magnetic sources and subsurface features. The main subsurface structures are the linear NNW-SSE parallel to the Red Sea trend and the Gulf of Suez and the NE-SW faults and lineaments surrounding the basins in the northern and the western area, the deeply rooted basic intrusions, and the depo-centers (basins) in the western and central part of the area. Moreover, the area shows several basement uplifts and consequently faulted basins of different directions and displacements.
Aeromagnetic surveys are used to delineate the depth to the basement and the structures affecting them specially faults and other lineaments or contacts. The magnetic methods are widely used to detect and map the main geological features, structural trends and even the tectonic setting from the recorded magnetic anomalies (Dobrin and Savit, 1988; Nabighian et al., 2005; Nigm et al., 2015).
The subsurface of the northern and central parts of Egypt (Fig.1) is characterized by a complicated system of Mesozoic rift basins (Hantar, 1990; Sehim, 1993; Bosworth et al., 2008; Dolson et al., 2014; Bosworth et al., 2015; Mostafa et al., 2018). They form a series of grabens trending E-W to ENE-WSW and NE-SW that originated in the Jurassic and continued subsidence through the Cretaceous, such as the Abu Gharadig, Alamein, Matruh, and Shoushan basins (Sultan and Halim, 1988; Emam et al., 1990; Taha, 1992; Moustafa, 2008; Bevan and Moustafa, 2012; Bosworth et al., 2015; Mostafa et al., 2018).
The aim of this study is to map the subsurface structures in central and northern Egypt and define their main trends and directions via the analysis and interpretation of the acquired aeromagnetic data. The study area is located between latitudes 26o00'00'' and 34o00'00'' and longitudes 25o75'00'' and 36 o75'00''. The magnetic field data were transformed to the wave-number domain, and the total magnetic intensity is displayed as shown in Fig.2.