Genesis and distribution of different mineral assemblages controlled by environmental factors in soils and evaporitic deposits of Lut Desert, central Iran

Lut Desert with a warm and arid climate is a suitable environment for evaporites and palygorskite to be formed. The objective of the research is to identify the role of environmental factors using spatial and vertical distribution patterns of evaporitic minerals (halite, anhydrite, and gypsum) and palygorskite related to landscape positions in soils of Lut Desert. Fifteen representative pedons along transversal (A–Aʹ) and longitudinal (B–Bʹ) transects in central (hyper-arid regime) and marginal (arid regime) parts of Lut were studied. Continued long time hyper-arid climate has caused petrosalic layer to be formed in central Lut. Results of the sulfate minerals showed that gypsum dissolution, its re-precipitation, and anhydrite formation have been affected by increase of temperature and salt concentrations, but accumulation and distribution patterns of anhydrite were not a function of temperature and salt concentration. Besides, the source of hydrated illite and hydrous salts in anhydrite accumulations was attributed to the variations in the water table. Distribution pattern of palygorskite showed that hyper-arid climate, erosion and sedimentary processes, poor drainage, erodibility of surface soil (sandy loam and sandy clay loam textural classes), and presence of strong winds were among the most important factors controlling lack of formation and destruction of palygorskite in central Lut. Besides, the decrease of aridity gradient, development of pedogenic processes, and formation of secondary calcite provided ideal conditions for authigenic formation of palygorskite. Therefore, distribution and accumulation patterns of evaporitic minerals and palygorskite in Lut Desert are of great importance for understanding environmental interactions, also soil management purposes.