Paleoenvironmental signatures of Pleistocene climate change in northern Iran: the loess-paleosol sequence of Baluchabad

The Pleistocene epoch, characterized by significant climatic fluctuations, is extensively documented in the geological archives like loess-paleosol sequences. These sequences serve as a geological repository, preserving valuable insights into historical climates, vegetation, and environmental conditions. The sedimentary layer spanning ۵۴ meters in the Baluchabad section, located in Golestan province, Iran, present significant potential for elucidating paleoenvironmental processes and ecological transformations in the area. A key feature in the Baluchabad loess-paleosol sequences indicative of Pleistocene paleoenvironment is the different deposition periods, mirroring the dynamic interplay between glacial and interglacial periods. To achieve our research objectives, multiproxy study have significantly enhance our understanding of the formation, age, and paleoenvironmental implications of the studied loess-paleosol sequence. Various analyses confirm the presence of ۱۱ paleosols with varying degrees of development which are well-maintained in the studied loess-paleosol sequence. These well preserved paleosols are a unique signatures to reconstruct the paleoenvironmental condition during the Pleistocene period in northern Iran. Notably, a set of paleosols (pedocomplex ۱) at a depth of ۲۰ to ۲۶ meters, correlating with MIS ۵ paleosols in terms of stratigraphy and primary dating results. The well-developed paleosol of this pedocomplex have been formed about ۱۲۵,۰۰۰ years ago, which is equivalent to MIS ۵e period. Furthermore, a ۹-meter dense loess layer separates the paleosols of pedocomplex ۱ from three paleosols in pedocomplex ۲, situated at a depth of ۳۶ to ۴۲ meters. Similarly, a ۹.۵-meter loess layer separates the paleosols of pedocomplex ۲ from three well-developed paleosols in pedocomplex ۳, formed at a depth between ۴۸ and ۵۴ meters. Based on dating results and stratigraphic correlation with adjacent loess-paleosol sequences, it can be conducted that the paleosols in pedocomplex۱formed during the MIS۵ period. Additionally it can assumed that second and third pedocomplexs originated during the MIS ۷ and ۹ periods, respectively. These findingsprovide a new avenue for exploring paleoclimate changes during the Middle Pleistocene in detail. The comprehensive analysis of studied paleosols, coupled with stratigraphic correlations and dating results, have been opened a valuable insight for understanding paleoclimate variations in northern Iran during the Middle Pleistocene.

کلیدواژه ها:

Paleoclimate ، Marin Isotope Stage ، Paleosol ، Middle Pleistocene ، northern Iran