Soil formation is a complex process influenced by five factors: parent material, time, climate, topography, and biological activity. Additionally, aeolian sediments may contribute to soil development by adding mass and nutrients. In the Golan Heights (GH), soils are primarily thought to form from the weathering of local basalts. While these soils were traditionally linked to basalt age, recent studies suggest that they are relatively young, having formed mostly over the last several thousand years, regardless of the age of the underlying basalt. Furthermore, recent research indicates that allochthonous inputs, particularly dust from both proximal and distal sources, may also significantly influence the mineralogical and chemical composition of these soils. However, the impact of dust ( < 80 µm) on these soils is not well understood, particularly regarding the mineralogical and chemical contributions of dust to the soils of the GH.
This study investigates the influence of dust input on soils developed on basalts in the GH. The distinct geochemical signature of the basalts (mafic minerals), compared to that of the dust (felsic minerals), enable us to clearly differentiate between basalt-derived and dust-derived contributions, making the GH an ideal study area.
Soil samples were collected from seven sites across the GH, developed on basalts of different ages and under a precipitation gradient of 300–1,300 mm/year.
Particle size distribution (PSD) was measured using laser diffraction, and samples were separated into grain size fractions according to the modes identified in the PSD. Each fraction was characterized visually by SEM, mineralogically by X-ray diffraction, and chemically by ICP-MS analysis of acid-digested soil. All samples exhibit a polymodal PSD with 3–5 main modes, depending on the location and depth of each sample. The medium sand (250–2000 µm) fraction is primarily composed of basalt fragments, the fine sand fraction (63–250 µm) contains mainly basalt fragments, other minerals , and quartz. The quartz grains are mostly very fine sand (60 - 80 µm). The silt fraction (6 –63 µm) consists mostly of clay minerals and quartz, while the finest clay fraction (<1.5 µm) is composed mainly of clay minerals. The composition of the 1.5–6 µm fraction is still under analysis.
Quartz content is highest in the silt fraction (6–63 µm) and decreases with depth. The Chemical Index of Alteration values generally increase from coarse to fine fractions, reflecting the progressive weathering of both basalt and dust-derived particles, indicates dust, from proximal and distal sources, is a component in GH soils.