The geomorphic and palaeoenvironmental significance of water-induced horizontal layering in arid inland and coastal mediterranean interdunes

Abstract

Aeolian-fluvial processes on Earth and Mars are drawing recent attention. Hypothesizing that water-induced horizontal layering (WIHL) may serve as an important tool for the reconstruction of the paleogeomorphology and climatology of wind-driven dunefields and sandstone, the properties of three types of WIHL are analyzed. WIHL may stem from floods, runoff or high water table, the distinction of which may be complicated. To study their unique properties and the factors responsible for their occurrence in an inland (Nizzana, Negev Desert) and coastal (Nizzanim; southern coast of Israel) dunefields, basic soil properties were analyzed: the electrical conductivity (EC), silt and clay, i.e., fines content (FC), calcium carbonate (CC), and organic carbon (OC). The findings show thin (commonly ≤ 5–6 cm-thick) disconnected FC- and CC– enriched horizontally-laid lenses within the upper soil profile of the sandy interdune, interpreted as runoff-induced sediments. Flat thick (0.5–1.0 m) and 40–60 m-diameter patches (playas) of fines-enriched sediments, scattered within the Nizzana interdunes, were interpreted as flood-induced sediments. Albic (bleached) horizons at 10–30 cm depth at the coast, which did not exhibit significant changes in FC and CC, were interpreted to result from alternating oxidation and redox sequences during occasionally high water table. The current data indicate that variability in the spatial distribution of FC, CC and OC may point to the origin and factors responsible for the occurrence of variable WIHL. This may assist geologists and sedimentologists to reconstruct high-resolution paleoenvironmental and climatological aeolian-fluvial conditions of coastal, inland and past geological sand bodies and sandstones.