The vegetated linear dune (VLD) field of the northwestern (NW) Negev Desert, situated at the downwind eastern end of the northern Sinai - NW Negev Erg, constitutes an ideal setting for dating and interpreting its Late Quaternary dune encroachment episodes. This study builds upon the results of Roskin et al. (Age, origin and climatic controls on vegetated linear dunes in the northwestern Negev Desert (Israel), Quaternary Science Reviews 30 (2011), 1649-1674) that presented the stratigraphy of 35 sections and 97 optically stimulated luminescence (OSL) ages from the NW Negev dunefield. Here we refine our analysis of the Negev Late Pleistocene dune mobilizations and stabilizations and interpret their palaeoclimatic controls in light of regional and global sediment records and proxies. While initial dune encroachment into, and stabilization in, the NW Negev took place during the Last Glacial Maximum (LGM) at ~23-18 ka, spatial and statistical analyses of the OSL dataset suggest that since the LGM, Negev dune activity was concentrated in two significant mobilization-stabilization episodes: a main episode at ~16-13.7 ka and a minor one at ~12.4-11.6 ka when the dunes reached their maximum spatial extent and stabilized. These episodes include rapid dune encroachment and accretion events and coincide with the Heinrich 1 and Younger Dryas cold events, respectively. The Late Pleistocene sand-transporting winds were characterized by a westerly direction that resulted in west-east VLD elongation. Dune mobilizations may have occurred in response to wintertime East Mediterranean cyclonic systems that brought storms of rainfall and strong winds. The rapid dune mobilization events and their concurrence with the Heinrich 1 and Younger Dryas cold events suggest a more global control. Despite the rainfall, the elongating VLDs were probably sparsely vegetated because of the high wind power; their stabilization resulted from a decrease in storminess, with the onset of a more arid Holocene climate. Other global low-latitude dune mobilizations and stabilizations are concentrated at the end of the Late Pleistocene, leading us to suggest that these were also controlled mainly by global cold-events and subsequent changes in windiness. The recurring discontinuous aeolian sedimentation pattern found in OSL-dated VLDs provides new and important chronological and sedimentological insight into prominent dune mobilization and stabilization processes. The suggested link between global drops in cold-event windiness and low-latitude dune stabilization episodes emphasizes the prevalence of winds over aridity regarding major dune mobilizations for low-latitude dunes, even if vegetated.
Bibliographical noteFunding Information:
The research was supported by the United States-Israel Bi-National Science Foundation (BSF) in Jerusalem and by the Earth Science Research Administration of the Israel Ministry of Natural Infrastructures in Jerusalem. Rivka Amit and Onn Crouvi are warmly thanked for providing me access to the sedimentological laboratory at the Geological Survey of Israel and guiding me in grain-size analyses. I thank Nigel Goring-Morris for fruitful discussions and for allowing unfettered access to his data; Omri Barzilai from the Israel Antiquities Authority for cooperation in sampling at the Nahal Sekher excavations; Zehava Siegal for data; Vered Refaeli for analytical advice; Roni Bluestein-Livnon for making the regional map; and Yossi Ashkenazi for introducing me to new palaeoclimate ideas. We would like to thank two anonymous reviewers for their insightful comments.
- Late Pleistocene
- Negev dunefield
- Vegetated linear dune