Detrital input to spring‐fed fen deposits – a problem or an opportunity in palaeoenvironmental studies? A Holocene palaeoclimatic reconstruction from central Europe

Abstract

The sedimentary sequence of a spring‐fed fen located in north‐east Poland was investigated to verify the applicability of spring‐fed fen deposits in palaeoenvironmental studies. We hypothesize that spring‐fed fen deposits accumulated on the hill slope are a reliable proxy for regional hydrological changes, although they may be modified by local factors. Results of combined sedimentological, plant macrofossil, geochemical and isotopic analyses were compared with palaeoclimatic reconstructions at the nearby lakes Purwin, Kojle and Perty situated within the same sedimentary basin. The 700‐cm‐long sediment sequence from the fen was deposited between 10 900 cal a BP and recent times. The sequence starts with a lacustrine stage, but ca. 9200 cal a BP the lake changed into a spring‐fed fen functioning within a fen surrounding Lake Purwin. Highly variable SiO2 content and stable isotope (δ13C and δ18O) values of carbonates, both controlled by inwash of detrital material from young glacial deposits, were found to reflect changes in hydrology with major regional shifts in climate humidity being recorded. Links were found with lake level changes and peatland record of humidity in northern and eastern Poland, the Baltic area and Central Europe, and with climatic records in Scandinavia.

Holocene climate vs. catchment forcing on a shallow, eutrophic lake in eastern Poland

“…), and Volhynia Polesiye, Ukraine (Dobrowolski et al . ), south of LŁ, but also from NE Poland (Apolinarska & Gałka ) and southern Finland (Sarmaja‐Korjonen ).…”

“…a BP, from Lake Linówek (Gałka et al . ) and a spring‐fed fen in the vicinity of Lake Purwin (Apolinarska & Gałka ). These data correspond with the phase of decreasing temperatures and increasing humidity in the Baltic region since ~4300 cal.…”

“…a BP (Bałaga ; Lauterbach et al . ; Apolinarska & Gałka ; Fiłoc et al . ) and was evidenced by a spread of hazel (Bałaga ; Słowiński et al .…”

“…Decreasing lake depth at the AT/SB transition was reported throughout the Polesie by Szeroczyńska (), Bałaga () and Kulesza et al . () and in NE Poland by Gałka & Apolinarska () and Apolinarska & Gałka (). The decrease resulted from reduced precipitation over the Polish territory and triggered overgrowth of macrophytes in the lakes and finally resulted in a broad‐scale terrestrialization of the lakes as documented by Michczyńska et al .…”

“…A decrease in precipitation at the end of the PB occurred synchronously throughout E/NE Poland between 10 650 and 10 200 cal. a BP (Bałaga 2002;Lauterbach et al 2011;Apolinarska & Gałka 2017;Fiłoc et al 2018) and was evidenced by a spread of hazel (Bałaga 1991;Słowi nski et al 2018). It is worth mentioning that a decrease in the water depth in the upper PB were recorded in other lakes in the Polesie region (Bałaga 1991;Kulesza et al 2012).…”