DID EGYPT'S WADI QENA DRAIN NORTHWARD DURING ITS EARLIER STAGES?

Wadi Qena is a prominent geomorphic and tectonic feature that covers approximately 18,000 km² in the Eastern Desert of Egypt. It represents one of the least understood areas, where further investigations would be most fruitful (Said, 1962). Its terraces, valley sediments, and delta on both sides of the present Nile need further study (Issawi, 1983). Integration of data, from satellite images, SRTM, and Radarsat-1 with field investigations was conducted to decipher the mysteries of its complex setting. The Recent regime of Wadi Qena is a key to its ancestral history. This study has shown that the present Wadi Qena is headless. It is aligned along unconformable contacts between Precambrian basement rocks to the east and Cretaceous-Tertiary sedimentary rocks to the west, until it is truncated at the Abu-Had prominence. There, it divides into two opposite routes that differ in slope and time of formation. The result is that two rivers flowed in opposite directions. The modern one is located to the west of Abu-Had, heads southward along a narrow gorge through the structurally controlled massive limestone scarp. The ancient route (20 km in width) exists east of Abu-Had and extends for 70 km northward. It detours 15 km westward at an acute angle to join the modern trace, also at an acute angle through a narrow loop. This is probably a route of an ancient mega river with an antecedent to the south. Investigations indicated the presence of a clear remnant in the south. Its path was forced to detour westward due to E-W faults, shear zones and lateral displacements that facilitated the ancient drainage to head westward instead of northward, i.e., Qena-Safaga shear zone. Radarsat-1 data reveal an ancient buried drainage aligned N-S parallel to the basement and sedimentary sequences. It might have linked Wadi Qena in the north to Wadi Allaqi to the south as an ancient mega river. The geomorphology of the ancient route matches Wadi Qena at its central and northern parts. Wadi Qena gained the southward slope probably in early Miocene (Garfunkel, 1988), so what was the slope from late Eocene to early Miocene? Where was the outlet of the ancient Qena system to the sea during its earlier stages? The study results stimulated rethinking and raised the question: Did Wadi Qena of Egypt drain northward during its earlier stages?