Alluvial loess in the Central Sinai: Occurrence, origin, and palaeoclimatological consideration

Abstract

The layered silts of Wadi Feiran and its tributaries (Central Sinai, Egypt) form profiles up to 50 m in height. They have been the subject of numerous geoscientific studies, but their formation and origin is still under discussion (i.e. lacustrine? fluvial? glaciation? true loess? river terraces?). The investigations of the authors confirm the silts to be alluvial loess. Due to Miocene foraminifera embedded in some of the silts around the oasis of Feiran, the origin of the aeolian material can be traced back to the Gulf of Suez. After sedimenting on the slopes of the wadis (Feiran, Es Sheikh, Solaf) the silts were later washed out by the rain, transported by a meandering river and sedimented as “overbank fines” and “crevasse splays” next to coarser material. At some locations the sedimentation took place in a swamp-like environment. Thermoluminescence dating revealed the time of sedimentation (as overbank fines etc.) being between 27 and 12 ka old. Based on geological and geochemical data the palaeoclimatologic development of the region is discussed.