INTERPLAY OF CRETACEOUS – QUATERNARY FAULTING AND FOLDING IN THE SOUTH DESERT OF EGYPT: INSIGHTS FROM REMOTE SENSING ANALYSIS

The Southwestern Desert of Egypt is underlain by Neoproterozoic crystalline rocks, Cretaceous sandstones and limestone, Paleocene shale and chalk, and Eocene limestone. These rocks are deformed by prominent E-W trending faults and less prominent N-S and NW-SE trending faults that are thought to be of Cretaceous – Quaternary age and span an almost 200 km wide zone. Some of E-W trending faults are seismically-active such as the Kalabsha fault where a 5.6 M earthquake had occurred in 1981 along this fault. Associated the E-W trending faults are numerous E-W trending folds many of them are concentrated on the Eocene limestone where they form doubly-plunging synclines and anticlines. We have used the 2000 – present Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) data abroad Terra to generate detailed three-dimensional (3D) perspective views to examine the geometrical relationship between the faulting and folding in the region. ASTER data have 3 bands in the Visible and Near Infrared (VNIR) with 15 m spatial resolution, 6 bands in the Short Wave Infrared (SWIR) with 30 m spatial resolution, and 5 bands in the Thermal Infrared (TIR) with 90 m spatial resolution. In addition, band 3 of ASTER data is acquired in both nadir (3N) and back-looking (3B) geometry allowing for the generation of 15 m X-Y resolution Digital Elevation Models (DEMs). 3D perspective views are generated by draping 7-3-1 ASTER images on DEMs extracted from bands 3N and 3B of ASTER data. Our remote sensing analysis indicates that the doubly-plunging anticlines and synclines are localized on overlap zones between segments of the E-W trending faults in a geometrical relationship that strongly suggests dextral-strike slip movements along the E-W trending faults. This is in agreement with field observations and fault plane solutions extracted from seismicity along some of the active E-W trending faults. The trend and dextral strike-slip movement along E-W trending faults can not be reconciled with regional extension related to the Red Sea rifting. Here, we relate this dextral strike-slip movement to a NW shortening induced as a far-field effect of the incipient continental collision between Africa and Europe in the Mediterranean basin that in turn coincides with the young seafloor spreading in the Red Sea.