Sign of Pedogenesis in loess-paleosol sequences as indicator of paleocilmate, Golestan Province, Iran.

Abstract:One of the best indicators of the geological and environmental events in the Quaternary is the alternation of loess-paleosol. In this study, for pale environmental identification of buried pale sols in loess sequences which located between 36? 49’ 15? north latitude and 54? 26 52? east longitude in the southern part of Gorgan, the disturbed soil samples for physico-chemical analysis and clay mineralogy and undisturbed samples for preparation of thin sections were collected. The physico-chemical results (calcium carbonate content, particle size distribution, cation exchangeable capacity and Feo/Fed) indicated that the soils had experienced several pedogenic periods. The result of mineralogy showed that a high amount of smectite, vermiculite and mixed layer mica-smectite in paleosols compared to loess deposits probably indicates moister regimes through interglacial compared to glacial periods. sign of climate oscillation has inherited in the shapes of pedogenic. The micro morphological observations revealed many evidences on the occurrence of pedogenic processes. One of the most important index of pedogenesis, clay coating and hypo coating around void are presented only in buried paleosols, which is the evidence for moist climate conditions, enough for leaching and translocation of clay. Formation of the studied loess and paleosols, have probably taken place in glacial and interglacial cycles with different climate condition, respectively.