THE NILE DELTA – NORTHERN SINAI – NORTHERN NEGEV EOLIAN SYSTEM:PROCESSES, PALEOCLIMATE AND PALEOENVIRONMENT

The Nile Delta-northern Sinai-northern Negev eolian system runs along a wind and precipitation gradient and includes active linear dunes in the northern Sinai Peninsula dunefield and vegetated linear dunes in the northwestern (NW) Negev Desert dunefield, which form the Sinai-Negev erg. Loess deposits dated from MIS 6 to MIS 2 surround the Negev dunefield. Based on mineralogy, geochemical proxies and sand grain coating rubification intensity, it is understood that the Nile Delta is the dominant source of the Sinai-Negev erg. These facts make it worthwhile studying inter- and intra-eolian-sedimentological processes of this eolian system and their links to past climates and environments.

In the NW Negev, between late MIS 7 and MIS 3, cycles of sand veneer (sheet) deposition, stabilization, pedogenesis, and erosion formed a spatially variable sequence of sandy calcareous paleosols in a fluctuating but generally windier and moister paleoclimate than today. At 23–11.5 ka (MIS 2) dune incursions overrode the sand veneer paths and covered the paleosols. Shape, coating redness intensity, mineralogy, and geochemistry of the quartz dune sand grains generally remained the same across the Sinai-Negev erg. Fine sand (125–250 μm) comprises a distinct and dominant fraction of the Sinai sand while in the Negev many sand units have relatively large quantities of very fine sand (50-125 μm), probably downwind indicating grain size fractionation. In the Negev, grain coatings did not redden after deposition, indicating that sand redness intensity is not correlated to the sand depositional (OSL) age.

Deltaic sand supply and consequent dune incursions are attributed to glacioeustatic and North Atlantic cold-event influences that may have been a control on global dune mobilizations at that time. Being of a similar sedimentological and chronological framework to the paleosol sands and dune incursions, the composition of the northern Negev loess suggests a partial genetic connection between the sands and dunes to the loess, due to grain-size fractionation and possibly eolian abrasion.

The interlinked processes between the sedimentological bodies of the studied eolian system mostly ceased with the onset of the Holocene. Since then each sedimentological body has been undergoing different and independent geomorphic processes.