An integrated study of gravity and magnetic data on South Sitra area, Western Desert, Egypt

The potential field data (Bouguer gravity and total intensity aeromagnetic maps) carried out in the South-Sitra area had been analyzed and integrated with other Geophysical and geological studies to extract information about the regional subsurface structural and tectonic framework of the burried basement rocks, as well as locating promising sites that probably favoring for the hydrocarbon accumulations. The execution of this study was initiated by transformation of the total intensity aeromagnetic data to the Reduced to Pole (RTP) magnetic map. This followed by applying several transformation techniques and various filtering processes through qualitative and quantitative analyses on both gravity and magnetic data. These techniques include: qualitative interpretation of gravity, total magnetic intensity and RTP magnetic maps. Regional-residual separation was carried out using four methods are: nine-points, least-squares polynomial fitting, second vertical derivative and analytical signal analysis technique. Surface and subsurface statistical trend analysis was applied on both the surface lineaments of Landsat images to identify the surface structural features, and on gravity and magnetic maps to define the major subsurface tectonic trends of the buried basement rocks. In addition, depths to the basement rocks were estimated by using three empirical methods. The results of qualitative and quantitative techniques mentioned earlier were integrated together with other geological information to construct a tectonic basement map for the study area. This map is mainly composed of folded basement rocks of alternated synclinal and anticlinal structures cut across the study area in NNW-SSW and ENEWSW directions. It shows that the Abu Gharadig Basin was divided into two sub-basins; North-Abu Gharadig Basin and South-Abu Gharadig Basin separated by Apollonia-Kattania high. Also, the older NNW-SSE trending structures (folding and faulting) seem to be intersected by a younger set of E-W to ENE trending faults, resulted in large vertical as well as horizontal displacements that complicate the subsurface situations. The average depth to the basement rocks in the northern basin ranges between 4 and 5.5 km. meanwhile, the average calculated depth along South-Abu Gharadig Basin ranges from 3 km to 4 km. The southwestern area is occupied by the NNW-SSE trending Faghur Basin of Paleozoic age, with average depth up to 4.9 km. whereas, the depth to the northern anticlinal structure (Gib Afia High) is about 3 km and is considered to be approximately the same depth for the anticlinal uplift in the southeastern part (Cairo-Bahariya uplift).