Tectonic Geomorphology of Alluvial Fans east of the Wadi Araba Fault (Dead Sea Transform), Jordan

This study deals with the development of alluvial fans at the foot of the fault-controlled eastern mountainous chain in Wadi Araba Desert (WAD). The alluvial fans are fed mainly by debris flows of ephemeral streams flowing westward across the eastern highlands to the desert plain and/or inland sabkhas. Morphometric analyses showed that fan surface area (FSA) is directly proportional to drainage basin area (DBA), whereas the fan slope (FS) is inversely proportional to FSA or decreases proportionally as the talus cones evolve into fans. The architecture and evolution of the fan/drainage network are controlled by vigorous tectonic forces that began in the Early Miocene. Bedrock geology, history and rates of sediment supply, and the intensity and duration of surface flow more likely contributed to the progressive changes of fans/drainage basin system. The increment of FS towards fan head pertinent to sediment buildup and the occurrence of steep normal fault scarps at mountain edges may reflect recent uplift in the catchment area. The alluvial fans were dislocated apart from drainage basins as a result of strike-slip movement along the Dead Sea transform (DST) and its subsidiary faults. Fanglomerates are compositionally immature and matrix-supported. The angular-subangular shape of clasts indicates a minimum or non-intensive abrasion has been occurred before sedimentation.