INFLUENCE OF POST-TERTIARY UPLIFT ON PALEOCHANNEL COURSES IN NORTH SINAI: A STUDY BY SPACE-BORNE RADAR DATA

Since the last pluvial cycle in the Eastern Sahara that ended about 5.5 ka ago, the ancient rivers dried up and were concealed under an aeolian sand cover. These Paleorivers have been deviated from their original courses probably due to the influence of the Post-Tertiary tectonic activity that was associated with the rotation of the Sinai and Arabian Peninsulas. Such activities may have continued to the present day. This study detects and investigates the paleoriver courses in North Sinai that could be used as indications to understand the recent tectonic activities in the area and their influence on development of the mega watersheds. Space-borne radar data including RADARSAT-1 and SRTM satellite images were utilized to construct a mosaic for the Sinai Peninsula in order to unveil potential buried channels. These channels were than compared with the present courses of the ephemeral rivers, such as Wadi El-Arish and Wadi El-Bruk, to calculate the direction and the amount of deviation between them. This provides tangible indications on the trend and magnitude of Post-Tertiary activity, and consequently deduces locations of structural controlled basins that would hold water accumulation in past. The results revealed that Wadi El-Arish, the largest watershed in Sinai, was flowing in NNW direction toward the Mediterranean Sea through two main channels separated by Gebel Yelleg. The eastern channel has been detected east of Gebel Yelleg, while the western channel, which has been uncovered here for the first time, occupies the present course of Wadi El-Bruk. It was directed to NNW, prior to its sharp deviation to ENE direction in the wake of a recent uplifting deformation. Both channels could have been connected in the past through a vast plain south of Gebel Maghara, which probably formed a mega paleolake. These findings could contribute in understanding the ambiguous origin of the sand fields in the northwest part of the Sinai Peninsula, as well as the influence of Post-Tertiary activity on hydrologic regime.