Buried soils from the Holocene Humid Period in Wadi Shuwayhi, Al-Khashbah (Oman)

The paleosol horizons on the lower terrace of Wadi Shuwayhi are the first buried soils from the Holocene Humid Period in Central Oman have been studied; they occur in alluvial sediments (terrace fill) deposited approximately 11.5 to 7 ka, with radiocarbon ages of soil organic matter range from 10,600 to 5300 cal BP (8700-3500 cal BC). The youngest buried soil horizons in profile KS3 show disturbances in soil structure, consistent with Early Bronze cultivation at 4800-4400 cal BP (2800-2500 cal BC). Pedogenic features in the buried A and B horizons of all paleosols show subangular blocky and crumb macro- and microstructure, bioturbation features, and secondary calcification within root channels. In two soils, tabular and lenticular gypsum is particularly pronounced. Although the organic carbon content is low at all sites, soil formation suggests earlier vegetation establishment during the Holocene Humid Period as is also known from other arid areas. Alternating phases of alluvial aggradation and lateral erosion, i.e. stability and instability of the wadi terraces, are reflected in the preserved, albeit relic paleosol horizons. The study describes and classifies the buried soils, place them within a stratigraphic framework, and evaluates their significance as proxies of the HHP as well as early human-environment interactions in Southern Arabia.