2.5-D Gravity/Magnetic Model Studies in Sahl El Qaa Area, Southwestern Sinai, Egypt
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Pure and Applied Geophysics
2.5-D Gravity/Magnetic Model Studies in Sahl El Qaa Area, Southwestern Sinai, Egypt AHMAD A. AZAB1 and ALI A. EL-KHADRAGY2 Abstract—The 2.5-D gravity-magnetic models of the upper crustal structures of Sahl El Qaa Area, Southwestern Sinai were constructed along seven profiles, focusing on the uppermost crustal layers to a depth of 4–5 km. In addition separation filtering process; spectral analysis and trend analysis were used to investigate the Bouguer and total intensity aeromagnetic field maps qualitatively and quantitatively. The study showed that the regional structures consist of tilted blocks in the form of a major NW-synclinal feature with an axis dipping northward. This feature is dissected by the NE trending cross faults forming horsts, grabens and step-fault structures. The tilted blocks are controlled by a major normal fault system and are greatly modified in the dip regime from north to south. They show a regional NW dip regime in northern and southern parts, where the depth to the basement reaches about 2–3 km in the down dip. In the central portion, the basin is dipping steeply to the east, with maximum depths attaining about 4–5 km. Key words: Sahl El Qaa, Southwestern Sinai, gravity and magnetic data, spectral analysis, 2.5-D model.
1. Introduction El Qaa Plain is a structural depression trending NNW-SSE, parallel to the main rift system of the Gulf of Suez (Fig. 1). It lies between Latitudes 28° 000 N AND 28° 500 N and Longitudes 33° 000 E and 34° 000 E, occupies about 3,500 km2 and covers about 110 9 60 km along the eastern part of the Gulf of Suez. It attains its maximum width to the north and gets narrower southward for the overlapping of the south Sinai basement massif, as well as a number of wells drilled in the El Qaa basin. Over the last few years, the development of Southern Sinai depends upon increasing the
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Exploration Department, Egyptian Petroleum Research Institute (EPRI), Nasr City, Cairo, Egypt. 2 Geology Department, Faculty of Science, Zagazig University, Zagazig, Egypt. E-mail: [email protected]
hydrocarbons exploration and groundwater aquifers of the El Qaa plain area. The water resources and oil productions in this area are very limited and need new discoveries in order to cope with the future demands. In respect to this, the delineation and detection of the subsurface situation are of prime importance for reasonable and convenient management. Integrated geophysical surveys such as gravity, magnetic, deep seismic, and well logging are the most suitable tools to help to achieve the exploration purposes. The aim of the study was directed to model the regional structures of the basement rocks and the overlying rock units, to define the regional subsurface configurations of the study area. Our integrated analyses provide a further investigation of the gravity and magnetic data, constrained by borehole information, relevant previous studies, reports and geophysical analysis carried out in the study area. The present study based mainly on the Boug
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