Soils, landforms and lacustrine sediments in arid regions preserve paleoenvironmental signatures, and, therefore they are good indicators of environmental factors responsible for landscape evolutio in these regions. Study area is located in eastern part of Isfahan . Despite the importance of Isfahan as agricultural and industrial center of Iran , only a few studies have been carried out on paleoenvironmental changes in the study area. The objectives of this research were to identify major landform, prepare the map of geomorphic surfaces, study the soil formation on landforms and reconstruct the past environmental and climatic conditions. Major landforms and geomorphic surfaces were identified using aerial photographs, satellite images and field survey. Eleven soil profiles on landforms and geomorphic surfaces and eight sections on old landscape were studied. Results show that tectonic has played a major role in evolution of alluvial fan generations. In contrast, climatic changes with great influence on vegetation and streams have affected the evolution of surfaces on younger generation of fans. Pedological study indicates that buried and relict paleosols have developed on Qf1 and Qf2 geomorphic surfaces, but Qf3 lacks pedogenic development. Carbonate morphology was used as relative age proxy. The distribution of salinity and gypsum content was strongly influenced by geomorphic position and landform hydrology. Carbon isotopes in pedogenic carbonates indicate that C4 plants were dominant during carbonate formation. High density C4 dominated grassland appears to have caused landscape stability and soil formation. Paleotemperature determination based on oxygen isotope in calcretes shows that carbonate formation occurred in cooler condition than today. Clay mineralogy analysis indicates that petrocalcic horizons have more smectite than palygorskite in comparison with calcic horizon. This correlates well with isotopic data. Also Argillic horizons on Qf1 and Qf2 geomorphic surfaces have a lot of smectite and palygorskite, respectively. This can be an indication of higher weathering rate as well as the older age of Qf1 geomorphic surface. Stratigraphy study shows paleoenvironmental changes in the study area from a lacustrine to fluvial, pedogenic and eolian environment.
