Climate oscillations in the 20 000–11 000 cal BP range recorded in the Piaski and Szerokie Formations in the Bełchatów Opencast Lignite Mine: a look through radiocarbon date analysis

Radiocarbon dates of organic sediments, taken from the soil horizon, gyttja, peats, plant remains and mineral-organic sediments – silts silty-sandy with admixture material were collected analysed. Age determinations made for samples over a number years upper part Piaski Szerokie Formations in Bełchatów Lignite Open Cast Mine (28 dates) their surroundings (2 (Fig. 1; Tab. 1). The analysed are mainly associated valleys Krasówka, Struga Żłobnicka, Świętojanka Widawka Rivers. They formed within alluvia (probably fillings oxbow lakes). Some deposits vicinity dunes or aeolian covers (mid-dune depressions). During Late Glacial this area, aggradation dominated river valleys. Fluvial processes accompanied by processes. A large proportion grains is characteristic profile sands formations. Despite filling fluvio-aeolian fluvial erosion also occurred places. Folwark 1 2 sites Żłobnicka River valley yielded 12 age (from 14 810±170 to 11 130±120 BP, i.e. 18 270–12 900 cal BP). In valley, 3/88 BM, JG, I/83/JG, II/83/JG, Buczyna 8, Rogowiec Wola Grzymalina falling pe-riod 350±580 10 160±140 240––11 400 BP. Kleszczów 3/90 site, only one date 460±120 BP (13 460–13 190 BP) related peat valley. last two determinations, archived as site unknown Kuców C–IIa, dated 15 850±180 (19 360–18 930 13 780±130 (16 950–16 520 area present Szczerców field, Parchliny-Chabielice three Krasówka 290±90 (12 450–11 830 BP), 840±110 800–13 440±160 (18 910–18 360 (Tab. Based on dates, so-called PDF (Probability Density Functions) curves drawn up range 20 000–11 000 3). analysis used shape method summed probability density distributions calibrated radiocarbon position peaks obtained time axis good agreement oxygen curve Greenland core NGRIP. There clear clustering around beginning GI–1, but GI–1d, GI–1c2 GI–1b. This was contributed preferential sampling dating locations where changes sediment lithology evident (bottom top layer, mineral deposits, bottom fill, etc.). Therefore, should not be linked warm periods, rather transitions cold conditions conditions. Although dataset smallscale, makes it possible identify environmental responses climate change several scales: - 19 500–18 (peak GS–2b); 17 800–17 300 at transition GS––2b/GS–2a); 16 800–16 600 located GS– –2a); 200–14 GS–2a/GI–1e transition); 100–13 800 GI–1d); 600–13 550 GI–1c2); 250–13 050 GI-1b); 500–11 700 second half GS–1) resolution analyses carried out does make determine whether there delays response study relation recorded Greenlandic core, any must less than average uncertainty analysed, ~100 years. using conventional techniques, which have relatively uncertainties. It probable that including new precise 14C AMS technique would contribute higher type analysis.