GEOMORPHIC AND PALAEOENVIROMENTAL IMPLICATIONS OF DUNE-DAMMING, AEOLIAN-FLUVIAL INTERACTIONS IN THE NORTHWESTERN NEGEV DUNEFIELD, ISRAEL, SINCE THE LGM - A REVIEW IN HONOR OF DAN MUHS

Aeolian-Fluvial (AF) interactions, in particular, dune-damming, deliver unique morphologies and stratigraphies, lead to dust emission hotspots and influence dunefield evolution. Not surprising that Dan Muhs published one of the first comprehensive papers on this topic (Muhs et al., 2000).

I review 4 decades of research on dune-damming at the eastern Sinai-Negev erg (Muhs et al., 2013) - the arid, NW Negev dunefield (Israel), where today, wadis usually flood 1-2 times a winter. Vegetated linear dune (VLD) incursions during the LGM, Heinrich1 and Younger Dryas, dammed and impounded dunefield margin, ephemeral fluvial systems (1-700 km²). The shallow impounded water bodies generated a landscape of playa-like flats comprised of sequences of fine (AF) sediments. These 1-10 m thick sequences possess sedimentologies such as massive loam & couplets that often truncate aeolian or fluvial sand. Couplets, indicative of single, dune-dammed impoundment fluvial events, amount to <dozen per section, representing only several flood seasons, despite being within an OSL-dated sequence spanning several kyr. This discrepancy may imply that impoundments were successive for only several years. More likely, the sequences are incomplete, having gone through depo-erosional cycles. Anomalic amounts of OSL/radiocarbon-dated upper Paleolithic to Chalcolithic lithic-dominated concentrations and hearths by A-F sediments testify to an attractive punctuated and short-term, arid aquatic environment.

Despite largescale post Younger Dryas VLD stabilization, AF sediments continued to accumulate until the early Holocene due to successions of dune-dammed impoundments penetrating the dunefield due to successive downstream fluvial propagation, dune damming and then dune-breaching. The resultant landscape is a result of a Terminal Pleistocene environmental transitions time-window of high up-basin loess availability and open fluvial domination to aeolian domination (dune-damming) and finally, partial and gradual dune-dam breaching, reopening of the fluvial systems and incision within A-F sediments.

Muhs et al. 2000. Geochemical evidence for an eolian sand dam across the North and South Platte Rivers in Nebraska. QR

Muhs et al. 2013. Origin of the Sinai–Negev erg, Egypt and Israel: mineralogical and geochemical evidence for the importance of the Nile and sea level history. QSR.