Luminescence dating of fault-related alluvial fan sediments in the southern Arava Valley, Israel

Abstract

Infrared stimulated luminescence (IRSL) from coarse-grained alkali feldspars was used to date alluvial and colluvial deposits from Nahal Shehoret, situated in the hyperarid southern Arava Valley. Israel. Late Pleistocene gravelly and sandy wadi deposits, associated with fault-related colluvial sediments, were exposed in trench 17 (T-17) which was excavated across a distinct fault scarp. Deposition of the lower alluvial beds in T-17 took place between 90 and 100 ka. This was followed by the first period of' tectonic activity and by erosion. The age of the upper alluvial bed ranges from 75 to 60 ka. A period of stability and reg soil formation was then followed by two scarp-forming faulting events resulting in colluviation. The colluvium deposited after the second event was dated to 36 ka. Modern colluvial sediments from Nahal Shehoret have residual IRSL ages of a few hundred years, whereas modem alluvial sediments have ages of a few thousand years. Colluvial sediments may therefore be more suitable for luminescence dating in arid regions.