Characterization of the aeolian terrain facies in Wadi Araba Desert, southwestern Jordan

The sand dunes in Wadi Araba Desert, southwestern Jordan, conform to the influence of two main wind systems: (1) the Shamal “ north wind”, the main determinant of dune patterns, and (2) the southerly winds caused by the Red Sea Trough and Khamasin winds. Wadi Araba is a narrow elongated morphotectonic depression bordered by the high eastern and western mountain ranges that would obstruct most of westerlies in winter and the hot dry easterlies in summer. Wadi Araba Desert is caused by the rain shadow of the eastern and western topographic highs, with an arid–hyperarid climate and moisture index between 0.1 and <0.05. An aeolian terrain occupies about 16% of Wadi Araba Desert divided into four sand dune fields that contain different dune types, interdunes, and sand sheet facies. The development of the aeolian terrain was more likely in the interglacial periods of latest Pleistocene–Holocene during which wind deposition and fluvial erosion were prompted. The variability of wind direction, wind speed and rates of sand supply led to a variety of simple, compound and complex dune formations. Barchanoid (barchan, barchanoid ridge, transverse dunes) are very common. Linear dunes, nabkhas and climbing dunes are less common. The dunes in Wadi Araba are either mobile (active) or stabilized. Dune fixation is primarily by desert shrubs or cementation in case of aeolianites. Interdune troughs vary from dry to damp. Sand sheets are mainly unvegetated or barren. Dune sands are well sorted to moderately well sorted with more than half the sand falling in fine–medium sand fraction. Interdune areas and sheet sands are moderately–poorly sorted with grain size between 0.06–5 and 0.1–0.5 mm, respectively. Angular-subrounded grain shapes are relatively common on all sides of barchanoid dunes. The sediments of the aeolian terrain are chiefly composed of quartz, feldspar, mica and kaolinite. Calcite and dolomite are less predominant minerals.