Land snail shell abundance in the loess-paleosol sequence of Saadabad ۳, (Gorgan)

The Quaternary period includes various glacial and interglacial cycles, with glacial periods characterized by loess deposits and interglacial periods featuring paleosols. The most comprehensive Quaternary archive on land, is located inside loess deposits. In this way, loess is known as one of the most important archives of climate changes on land, which has utilized for climate reconstructions even beyond the Quaternary. In northern Iran, loess-paleosol sequences reveal multiple cycles of Quaternary climatic variations, studied through various approaches including micromorphology, mineralogy, magnetic properties, systematic luminescence dating, and radiocarbon dating. However, biological studies directly related to climatic conditions in this region are scarce. To address this gap, a ۲۳-meter-thick sequence located at geographical coordinates North "۰۳ '۴۹°۳۶ and East"۴۶ '۲۲°۵۴ near the village of Saadabad in the Gorgan County of Golestan Province, northern Iran, was studied. In this research, Quaternary loess-paleosol sequences are examined based on biological proxies within the framework of land snails (mollusks). These fossil records enable us to investigate environmental and climatic conditions related to past glacial-interglacial cycles up to approximately ۳۰۰,۰۰۰ years ago. For this purpose, ۲۳۰ samples with a total weight of ۲۳۰۰ kilograms of sedimentary materials were processed and moist-sieved. They contained mollusk shells from ۱۱,۶۹۵ individuals representing a minimum of ۳۴ species. Species such as Truncatellina cylindrica, Buliminus labrosus, Chodrula tridens, Zebrina detrita and … associated with dry climates and species such as Vitrea crystallina, Hygromia cinctella and … Trichia striolata, Papuina, Ganesella associated with warm and humid climates were identified, aligning perfectly with our soil and stratigraphic horizons. Our data cover up to Marine Isotope Stage ۷ (MIS۷).