Multi-proxy evidence of Holocene climate variability in Volhynia Upland (SE Poland) recorded in spring-fed fen deposits from the Komarów site

Radiocarbon-dated spring-fed fen deposits from the Komarów site (Volhynia Upland, SE Poland) with its multi-proxy data (macrofossils, molluscs, geochemistry, pollen, stable isotopes of oxygen and carbon) enable us (1) to distinguish four main stages of fen evolution, which reflected a distinct variability of water supply conditions and (2) to reconstruct the Holocene humidity–temperature changes. The beginning of peat–tufa deposition took place in a Boreal phase, after a significant cool fluctuation of climate occurring ca. 9.4 ka cal. BP. We suggest that climate was the most important factor conditioning the development of the spring-fed fen. Permafrost degradation, and then wet periods, intensified the activity of ascending springs. The impact of humans was possible since the Neolithic period and increased during the Middle Ages: therefore, the anthropogenic influence could have partially overlapped with the regional tendencies of climate changes. Autogenic development of deposit succession in the studied fen was definitely conditioned by hydrological changes induced by climate. Based on the multi-proxy data, 12 cold events of different ranks were identified. They are also recorded in other Polish and European sites. A record of distinct variability of depositional conditions at ca. 9.4, 8.2, 5.9, 4.6, 2.8, 1.4 and 0.55 ka cal. BP corresponds to quasi-periodical global climate changes in the Holocene named the Bond events. The majority of the cold events recorded in δ¹³C and δ¹⁸O of carbonates can be correlated to the Greenland oxygen isotope curve.