The soils of the Golan Heights plateau, in northern Israel, are underlaid by basaltic rocks ranging in age from ~5.5 to 0.1 Ma. Volcanism in this region is associated with the development of the Red Sea rift, and in accordance with the propagation of the rift, the age of the volcanic units displays a general northward decrease. Topographic position, field evidence and morphology, indicate that nearly all of the soils were formed in situ by weathering of the basaltic bedrock and it has been generally assumed the soils form a chronosequence. While the soils are predominantly of basaltic origin, the contribution of allochthonous aeolian sediments to the soils have long been recognized, mainly through the presence of quartz grains, typical to the regional dust.
Based on geochemical mass balance calculations, we found that not only are the soil ages decoupled from the ages of the underlying basalts, they represent up to a few thousand years of soil production, at most (Zaarur et al., 2024). This time frame is orders of magnitude shorter than the basalt age, challenging the prevalent assumption that the soils form a chronosequence. In addition, new OSL measurements provide independent soil ages, based on dust burial in the soils.
OSL measurements were conducted on soils collected from sites from the southern and central Golan, and include samples of mature Vertisols covering the oldest Pliocene basalts on the southern plateau, and soils collected from deep crevasses in the basalts. The ages of all measured samples range between ~0.4 and ~7 ka. Older particles are restricted to deep and protected microenvironments. These results strengthen the chemical modeling findings, that suggested that the soils represent up to a few thousand years of soils accumulation. Furthermore, these results point to a massive soil-loss event that pre-dates the accumulation and development of these soils.
In addition, our findings strongly suggest that erosion is a significant factor controlling soil formation and accumulation on the plateau, despite the generally flat morphology of the Golan Heights. The erosion is likely associated with tectonic activity along the Dead Sea transform, with the development of the Kinarot and Hula valleys, and with the consequential development of drainage systems of various sizes on the plateau.
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