Fluvio-lacustrine deposits reveal precipitation pattern in SE Arabia during early MIS 3

Abstract

On a global scale, Marine Isotope Stage (MIS) 3 (ca. 55–30 ka) was characterised by frequent and abrupt changes in climate. At the same time, humans may have dispersed out of Africa and populated the planet. For the Arabian Peninsula, a key region in both contexts, the paucity of suitable terrestrial records leaves our knowledge of the environmental conditions during this important period enigmatic. Here, we elucidate the environmental history for part of the Oman Mountains by analysing luminescence-dated fine-grained playa-like sediments from Wadi Mistal that formed in a landslide-dammed ephemeral lake. We identified 112 individual fining-upward sequences in the distal facies of the lake that are interpreted to represent major precipitation events during early MIS 3. The nature of sedimentation together with the presence of desiccation cracks and the absence of any faunal remains imply that the lakes had a temporary nature. It appears that the time of deposition was characterised by strong short-lived precipitation events, rather than continuous rainfall under a monsoonal regime. This points towards a climatic situation during early MIS 3 that was not so different from that of the present, at least in this part of Arabia.