Rates and modes of dust accretion and deposition in an arid region—the Negev, Israel

Abstract

Summary Rates of dust accretion and deposition are dependent on the amount of available dust and the trap efficiency of a particular site. Several types of dust-trapping terrains are widespread in deserts: (1) Gravelly (Serir) surfaces that turn with time into Reg soils; (2) vegetated surfaces in the desert fringe that may turn into löessial terrains; (3) stabilized sand dunes; (4) playa surfaces. Loessial terrains exhibit a high rate of dust accretion during the late Pleistocene—0.07–0.15 mm a −1 on the interfluves and ≤0.5 mm a −1 along the flood plains. Gravelly surfaces usually trap about 0.1 mm a −1 of dust initially but the rates decrease to several μm a −1 due to plugging with dust and salts and may ultimately remain constant as a gravel-free B horizon develops. The amounts of imported dust, from both local and distant sources, have changed during the Quaternary due to climatic fluctuations. Roofless ancient building—most efficient dust traps—show that although large amounts of dust were available (much of it from local sources) during the late Holocene, there was not intensive dust accretion during this period due to increasing aridity and decreasing trap efficiency. Wash and gullying led to destruction of the once widespread efficient trapping terrains.

Significance of primary hilltop loess in reconstructing dust chronology, accretion rates, and sources: An example from the Negev Desert, Israel

“…Accretion rates of reworked, fluvial loess were estimated to be higher, up to 0.2 -0.5 mm a À1 [Gerson and Amit, 1987]. In addition, the dust accretion rates found in this study shed new light on the lower threshold for accumulating recognizable loess at desert margins.…”

“…In earlier work, this was due to a lack of datable material by the methods then available, or to the use of methods that are not appropriate for determining ages of the loess deposits or paleosols [Enzel et al, 2008]. The published chronologies and the rates of dust accretion and erosion that have been inferred from them are based heavily on stratigraphic relations and association with human artifacts, and on radiocarbon analyses of pedogenic calcic nodules [e.g., Yaalon and Dan, 1974;Horowitz, 1979;Issar and Bruins, 1983;Enzel, 1984;Issar et al, 1984;Gerson et al, 1985;Goldberg, 1986;Magaritz, 1986;Gerson and Amit, 1987;Yair and Enzel, 1987;Goodfriend and Magaritz, 1988;Zilberman, 1992;Ben David, 2003]. Only recently have reliable optically stimulated luminescence (OSL) ages been reported for the late Pleistocene loess of the Negev [Avni et al, 2006], but even these ages are on reworked, secondary fluvial loess and not primary loess.…”

“…The suggested proximal sources are Wadi El-Arish in northern Sinai [Yaalon, 1971[Yaalon, , 1987Yaalon and Ganor, 1973;Yaalon and Dan, 1974;Ganor et al, 1991], the Mediterranean shelf exposed during periods of low sea level [Gerson and Amit, 1987;Crouvi et al, 2008;Enzel et al, 2008] and sand dunes that advanced into the Sinai and Negev during the late Pleistocene [Crouvi et al, 2008].…”

Dating desert pavements – First results from a challenging environmental archive

“…They are composed of a monolayer of clasts at the surface, associated with an underlying unit of eolian fines (sandy silt), which exhibits a several centimeter thick foamy pore structure directly beneath the clasts, the vesicular horizon (Springer, 1958;McFadden et al, 1998;Anderson et al, 2002;. Desert pavements form by dust trapping, causing vertical accretionary rise above a thickening eolian mantle (Mabutt, 1977;McFadden et al, 1986;Gerson and Amit, 1987). In some situations, the described sediment succession of pavement clasts and eolian mantle is underlain by another sediment unit of equal succession, interpreted as a buried desert pavement (Dietze et al, 2011;Dietze et al, 2013).…”

Dry aeolian dust accumulation in rocky deserts: �a medium-term field experiment based on short-term wind tunnel simulations

“…They also strongly affect, directly or indirectly, the biological activity in these regions (Jones and Shachak, 1990). Settling dust provides organisms with different kinds of nutrients (Esser, 1989;Offer et al, 1992;Littmann, 1997), and when it accumulates, it significantly contributes to soil development Ganor, 1973, 1975;Gile et al, 1981;Gerson et al, 1985;Gerson and Amit, 1987;McFadden et al, 1987;Reheis, 1990;. The dust also plays a fundamental role in the storage of water in a rocky desert, since its storage capacity is much larger than that of most desert lithosols.…”