Sediments in small endorheic basins as regional paleoenvironmental archives across a Mediterranean to arid transect

Abstract

In areas where environmental settings are changing across relatively small distances, using a limited number of proxies for paleoenvironmental interpretations may obscure distinctive responses in each environmental niche and the regional effects of climate change. Here we demonstrate the application of sedimentological, geochemical, and luminescence-based proxies in three small endorheic basins, located along a sharp climatic gradient of 150 km in the southern Levant. This approach yields a regional paleoenvironmental framework corresponding to three major established depositional phases, while the local response during each of these phases differs between sites. The earliest phase, coinciding with MIS 3 (∼57-29 ka), is marked by humid conditions leading to weathering and soil formation towards the paleoshore and loess washdown into a shallow waterbody at the southern, currently arid, edge of the studied transect. The uncomfortably overlaying deposits (∼20-6.5 ka) capture a phase of environmental instability, with fluctuating sea levels, southwesterly aeolian sand influx, and the establishment of a coastal wetland environment. The last stage began around 6.5 ka, with continuous accumulation in localized coastal paludal environments and the stabilization of Mediterranean atmospheric circulation. This stability was interrupted by distinct second-order variations in sedimentation resulting from short-term climatic perturbations. Larger environmental instability is seen at the southern tip of the transect during the middle to late Holocene. This spatial difference is attributed to decreasing Mediterranean-derived humidity coupled with the influence of southerly atmospheric systems, resulting in event-based deposition of recycled sediment.

These records can provide a regional framework to study how distinct environmental settings capture variations in environmental forcing through allochthonous and autochthonous processes. Such settings include the distance to sediment sources, location along atmospheric trajectories, and the geographical context. The decoupling of site-related effects from the compiled regional trend allows tracking the responses to established climatic trends, underscoring the importance of studying spatially spread and relatively temporally continuous archives.