Pedogeomorphic evolution of an alluvial fan in central Iran

Despite of suitable geological and climatic conditions for forming and evolution of alluvial fans and importance of this landform as soil and water resources in arid regions, there are limited studies about this landform in Iran. In the present study, evolution and pedogenic development of geomorphic surfaces of an alluvial fan in Eastern Isfahan were studied by using remote sensing, field and laboratory analyses. Results show that watershed of studied alluvial fan was tectonically active and two main depositional events were occurred for fans of Eastern Isfahan. Geomorphic surfaces were identified according to topographic position and pedogenic development. Geomorphic surfaces of studied alluvial fan were identified using topographic position, dissection rate and pedogenic development of soils. Using of dissection index for geomorphic surfaces suggest that this index is more expedient for use in active surfaces. Soils on geomorphic surfaces are calcareous with distinctive carbonates morphology. Results of dissection index are in corroboration with carbonates morphology in soils of geomorphic surfaces. So, morphology of pedogenic carbonates can be considered as an index of relative age of geomorphic surfaces. Usage of clay accumulation index also show great corroboration with results of dissection index and morphology of carbonates and application of this index is recommended for paleosols. Suggested systems for paleosol classification truly able to classify paleosols and application of these modern models recommend for other regions.