Quantifying glacial-interglacial climate shifts in the Armenian highlands using landsnail shells – a multi-proxy approach combining mutual climatic range analysis and shell isotope transfer functions

Subfossil gastropod assemblages in geological deposits can be used to reconstruct past environmental and climatic conditions. We present new results from loess-palaeosol sequences in the Armenian highlands that provide insights into multiple glacial-interglacial transitions across the past 400 ka. Hereby our main aim was to reconstruct quantitative information that can serve as reference data e.g. for cross-validating earth system models. Our approach combines stable oxygen isotope (δ¹⁸O) analysis of snail shells with the ecological interpretation of species assemblages. The latter includes mutual climatic range analysis, supported by climatic niche modelling based on modern species distribution data. The gastropod assemblages showed distinct variations within the sequences, indicating different ecosystem characteristics and associated climatic conditions. We observed a significant relationship between specific ecological groups of gastropods and oxygen isotope signals in the shells. Predominantly xerophilous assemblages linked to stadial phases showed more negative δ¹⁸O_shell signals, while mesophilous assemblages linked to warmer phases corresponded to more positive signals. δ¹⁸O_shell signals provide valuable information on the isotopic composition of ingested precipitation, which in the studied region is strongly related to average temperatures. Temperature estimation based on transfer functions indicated a difference of 5.4°C between stadial and interglacial phases. Climatic range modelling turned out to be suitable for precipitation reconstruction, pointing to mean annual precipitation amounts centering around 425+-75 mm during glacial and 775+-75 mm during interglacial phases. This study provides new evidence-based palaeoclimate data for the Caucasus region highlighting the potential of snail shells as a quantitative proxy for palaeoclimate reconstruction.