Development of structural basins and domes on the Sinn El-Kaddab plateau, Egypt: Insights from in situ data and application of moderate resolution orbital imagery of the Seiyal Fault.

摘要

The Seiyal Fault, one of many east-west trending faults located in the Western Desert of Egypt, and associated structural basins and domes are investigated using remote sensing imagery and field studies. Analysis of Shuttle Reconnaissance Topography Mission data, multi-spectral data from the Landsat Thematic Mapper (LM), Landsat 7 Enhanced Thematic Mapper Plus (ETM+), the Advanced Spaceborne Thermal Emission and Reflectometer (ASTER) data, and imagery from Google Earth. Band combinations 3-2-1 and 7-4-2 in ETM+ and 3N-2-1 and 7-3-1 in ASTER, and Google Earth provided the most useful images for geologic mapping. The Seiyal Fault is best characterized as a zone comprised of multiple, straight to curvilinear, left-stepping en-echelon, fault segments that over-lap or intersect and can be traced for at least 100 km in length. Field studies of structural basins and domes cross-cut by the trace of the Seiyal Fault record a component of normal dip-slip down-to-the-north displacement. Locally, the trace of the fault is marked by polished cataclasite, a scarp within Tertiary gravel pediment (also down-to-the-north), and by the presence of sand-filled ground cracks. The low-relief basin and dome structures may have formed in regions of transpression (domes) and transtension (basins) created by the bends and step-overs along the trace of the fault zone. These observations are consistent with the Seiyal Fault Zone recording time-integrated strain beginning as early as with the deposition of Cretaceous sandstones and continuing to the present, as a result of multiple displacement events in response to changes in the orientation of the principal regional stresses over time.