The Middle to Late Pleistocene transition in the Azraq Oasis, Jordan: A phytolith-based reconstruction of wetland palaeoecology

Abstract

At the Azraq Oasis, located in the Eastern Desert of Jordan, late Middle to early Late Pleistocene wetland deposits contain abundant Lower Palaeolithic stone tools and faunal remains. Focusing on the southern portion of the Azraq Oasis, known as the Shishan Marsh, this study aims to establish the palaeoecological context of this palaeowetland and associated hominin occupations (c. 300–120 ka) using phytoliths and other biogenic silica microfossils. Phytoliths, diatoms, and sponge spicules were extracted from 24 bulk sediment samples from seven stratigraphic profiles across the Shishan Marsh, as well as from three surface sediment samples collected from the Azraq Wetland Reserve and Shaumari Wildlife Reserve. The results indicate that a shallow waterbody existed across the Shishan Marsh during the late Middle Pleistocene, which underwent drying and marsh development due to increasing regional aridity across Marine Isotope Stages (MIS) 8–6. The extensive marsh and associated grassland environment that existed across the Middle to Late Pleistocene transition represented an attractive and resource-rich habitat for fauna and hominins in an otherwise desert region, seemingly acting as a desert refugium during this time. • Phytoliths are a useful tool for palaeoecological reconstruction in arid wetlands. • Biogenic silica microfossils show shifts in vegetation distribution and water level. • Landscape change from shallow waterbody >270 ka to spring-fed marsh by c. 150 ka. • Local drying is associated with rising regional aridity during the early Late Pleistocene. • The Azraq Oasis acted as a desert refugium for hominins and fauna c. 150–110 ka.