INVESTIGATION OF FOLDS AND FAULTS IN EOCENE CARBONATES OF THE SERAI FORMATION USING SATELLITE IMAGERY, WESTERN DESERT, EGYPT
In the western section of the study area, several prominent sets of paired NW/SE and WNW-ESE faults define narrow (~200 m wide) graben with no topographic relief. Folds at the same scale as the basin closures in the network of narrow synclines occur within these graben and are truncated by the graben-bounding faults. West of the study area, these graben are collinear with narrow synclines with basin closures, and the bounding faults cut pre-existing fold structures that extend beyond the width of the graben. These small graben are clearly distinct both in scale and in lack of topographic relief from graben with widths of several kilometers and topographic relief of many tens of meters that have been mapped by others as associated with Red Sea rifting.
The branching geometry of networks of very narrow synclines is unusual and not typical of folds in regional contractional settings. We suggest that mobility in the underlying Esna Shale may have developed new layer-confined faults or deformed an existing polygonal fault network in the Esna, causing deformation in the overlying Serai. Lack of topographic relief of the narrow graben plus collinearity with narrow synclines suggests that the narrow graben are distinct from larger, younger Red Sea Rift-related graben, perhaps representing a late phase of the process that formed the network of narrow synclines