High-resolution portable-OSL analysis of Vegetated Linear Dune construction in the margins of the northwestern Negev dunefield (Israel) during the late Quaternary

Abstract

Abstract Vegetated Linear Dunes (VLDs) are elongated dunes whose construction is controlled by vegetation and wind. Common in southern hemisphere drylands, they were mainly active in the late Pleistocene. VLDs vertically accumulate sand during elongation episodes and their internal stratigraphy thus serves as a proxy for major periods of strong winds. However, the framework of VLD buildup and elongation is constrained by low-resolution luminescence chronology. To overcome this gap this study applies high-resolution Portable Optically Stimulated Luminescence (POSL) profiling coupled with OSL dating and sedimentology of an exposed VLD section, combined with successive sections along a fluvially truncated downwind elongation trace of the dune at the margin of the stabilized northwestern Negev dunefield, Israel. POSL profiling of the VLD section revealed three statistically distinct stratigraphic units. Winnowing of very fine sand and silt grains can explain a higher ratio between quartz and heavy minerals in the upper VLD unit. This winnowing decreased dose rates and, consequently, reduced bulk POSL luminescence signals and De values in the upper unit. The two upper units of the VLD section date to the Younger Dryas while the basal unit dates to the Heinrich-1 event. OSL ages at the lower unit and at the section bases along the downwind elongation trace of the dune indicate initial elongation during the Heinrich-1 event, and even prior. The study demonstrates that beyond delineating accumulation stages and assigning stratigraphic units, POSL is a sensitive sensor of sedimentological and mineralogical differences within a dune profile, enabling correlation with OSL measurements.