صالح سنجری

Magnetic susceptibility (MS) as a fast, non-destructive, and reasonable technique is very useful in soil genesis and evolution studies. The MS of soils along a climolithotoposequence in Jazmoorian Watershed was studied in the present research and the vertical distribution of MS in the representative pedons affected by soil forming factors (parent material, climate and relief) was also investigated. Rock pediment, mantled pediment, piedmont plain, alluvial fan, and playa geomorphic positions with two igneous (gabbro, diorite, granite, and andesite) and sedimentary (limestone, conglomerate and playa deposits) parent materials were selected. Thirteen representative pedons which best reflected the variations of soil forming factors were studied. Results of the study showed that the maximum (877.8 × 10–8 m3 kg–1) and the minimum (5.2 × 10–8 m3 kg–1) low frequency (χlf) MS were respectively determined in the soils formed on igneous and sedimentary parent materials. The χlf values were increased with depth in soils affected by igneous parent material, but the opposite trend was found in soils with a sedimentary origin. The activity ratio of Feo/Fed in xeric and aridic moisture regimes were 0.03 and 0.09, respectively. Meanwhile, MS value in surface soil of pedon 2 (with xeric moisture regime) is lower than its parent material which is a support for the higher weathering of this soil due to higher moisture compared to pedon 5 with an aridic moisture regime. Decreasing evolution trend of soils on igneous parent material was in the order of alluvial fan < piedmont plain < mantled pediment, but in the soils on sedimentary parent material was in the order of playa < rock pediment < mantled pediment < alluvial fan. Results of the study clearly showed that the soil χlf values changed with variations in climate, parent material, and topography.