Large-scale geological structures of the Egyptian Nubian Shield

Integration of potential field- and structural data make it possible to trace surface and subsurface large-scale geological structures of the Egyptian Nubian Shield (ENS). Obtained results indicate that the Northern Eastern Desert (NED) of the ENS is dominated by relatively younger (c. 580 Ma) E-W and NE-SW trending extensional structures that were controlled by the evolution and retreat of the Cadomian Arc. Density of such extensional structures increases with depth as displayed by the potential data. The prevailing structural trends in the Central Eastern Desert (CED) are NW-SE and WNW-ESE. Both trends are highly prompted by the timing of deformation upon the Najd Fault System, and are themselves dissected by a relatively younger NE-SW shearing trend. Lineament density in the CED is subordinate for both subsurface and near surface structures. The South Eastern Desert exhibits compressional and extrusion-related structures of two main prominent trends; WNW-to-NW (to the western part) and the N-, NNE- to NE (to the eastern part). The previously mentioned Neoproterozoic trends are remarkably influenced by the Oligocene-Miocene Red Sea-Gulf of Suez rift related fractures in the vicinity of the rift shoulder. The remarkable change in trends and densities of structural trends, especially in the NED, is interpreted in terms of concealing of the older structures by the younger extensional structures which in turns reflect an N-ward progressive deformation in the entire ENS. Gravity data are more appropriate in delineating the structural trends compared to the magnetic data which are largely affected by lithological variations and/or alteration zones and magnetic mineralogy.