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Spring-fed fen deposits (peat-tufa sequences) from northern Poland were investigated for Holocene environmental reconstruction (climate and hydrology) using multi-proxy analysis (lithofacies, molluscs, pollen, plant macrofossils, geochemistry, and stable oxygen- and carbon-isotopes). The main aims of these studies were: (1) comparison of several similar sites with the same type of groundwater supply and sedimentation on a widespread space scale, (2) detailed reconstruction of their long-term development, assessing their sensitivity to climate change, (3) verification of the synchronicity of the record of different proxies in distant sites in the context of Holocene climate changes in relation to specific well-known global and/or regional climate events (so-called Bond events), and (4) discussion on permafrost degradation as a driver of spring-fed fens development. Based on our palaeogeographical data, we have distinguished an asynchronicity of the beginning of the development of spring-fed fens in the eastern and western parts of the studied region that is associated with different times of ascending groundwater supply unblocking after complete permafrost degradation. Therein, asynchronicity of permafrost degradation was brought about by multiple climatic, geological and structural conditions. Our results also indicate significant differences in the trends of succession (ecological and lithological) caused by the geographical location of the studied sites. Asynchronicity of the occurrence of wet and dry phases, as well as significant differences in their duration were noted. This depended upon the influence of oceanic (western part) or continental climates (eastern part). Warm and humid oceanic climate promoted the domination and longer duration of wet phases (especially in the Eo- and early Mesoholocene), while the harsh continental climate promoted the more frequent occurrence of dry phases, with short episodes of increased humidity. From the middle Mesoholocene, this marked regional diversification becomes less pronounced. Results also allowed for the recognition of several palaeoclimatic events on a regional scale. Four main cold episodes (Bond events 8–5): during LG/H transition (11.5 ky cal BP), Eo- (∼10.25 ky cal BP, ∼9.4 ky cal BP) and at the beginning of the Mesoholocene (∼8.2 ky cal BP) are well-documented by multiple proxies at all study sites. Other cold episodes (Bond events 4–0) are slightly less documented and are not clear for interpretation. The results of our study demonstrate the importance of spring-fed fen deposits for detailed palaeoenvironmental reconstruction on a regional scale. • Start of spring-fed fens development was different in time and space. • Unblocking of the ascending groundwater supply after permafrost degradation was essential. • Asynchronicity of wet and dry phases depends on climate – either oceanic or continental. • Significant differences in duration of phases are noticeable. • Warm and humid climate promote longer duration of wet phases in the Eo- and early Mesoholocene. [ABSTRACT FROM AUTHOR]

14C concentration measurements together with carbon and oxygen stable isotope analysis in calcareous tufa give possibilities for reconstruction of time scale and palaeoclimatic conditions of sedimentary processes. Results of isotope examinations of 2 profiles with organic and tufa sediments from Eastern Poland and 8 calcareous tufa sites from Eastern India (Orissa) are given. A systematic error of 14C conventional age of carbonate fraction of tufa samples as reservoir age (TR) was estimated. The TR values of different type of tufa sediment are determined by stream water energy. On the basis of known experimental dependence between TR and δ13C for tufas deposited in high, average and low energy water, unknown values of TR and corrected 14C ages (TCCA) were calculated for samples from India tufa sites. Continuous deposition of organic and carbonate sediments in Polish profiles give the possibility to calculate the approximated TCCA ages on the basis of dependence between TCCA and a sample depth in a profile, and time scale reconstruction of δ13C and δ18O changes in carbonate fraction of tufa samples during the whole Holocene. [ABSTRACT FROM AUTHOR]

Measurements of δ18O and δ13C in tufa samples dated by 14C method have been used to reconstruct climatic changes in Southern and Eastern Poland and in Eastern India (Orissa) for the last ca 13,500 years. Stable isotope time record δ18O in calcareous tufa profiles can be interpreted as palaeoclimatic record if dependence between oxygen isotope composition and temperature for the specific climatic region is known. Estimated sedimentation temperatures of calcareous tufas from Polish sites indicate the mean year of air temperatures during the last 12,000 years and mean winter and summer temperature for Orissa state, using stable isotope analysis for calcareous tufa from Indian sites. The estimated temperatures have real values, comparable with contemporaneous sedimentation temperature. The characteristic trend of the temperature changes increasing for Poland and decreasing for Orissa, since the beginning of the Holocene till today, can be observed with climatic optimum ca 5 000- 6000 BP synchronous in both countries. [ABSTRACT FROM AUTHOR]