ALBERT

Description: To revise the chronology for the Lake Gościąż record, sediment cores were retrieved during two field campaigns in 2015 and 2018. Four overlapping sections were collected using a UWITEC Piston Corer (Ø 90 mm) in the deepest part of Lake Gościąż, Poland (52.583022 N, 19.339946 E). The chronology was obtained by triple varve counting on petrographic thin sections that was complemented by 137Cs measurements and 14C AMS dating of terrestrial plant remains. Additionally, part of the chronology between 520-758 cm was obtained through age-depth modelling. Pollen analysis was performed for seventy one samples, prepared according to standard procedure, and analyzed in three intervals: i) from 1859.9 cm to 1874.4 cm with 2 cm resolution, ii) from 1880.2 cm to 1896.7 cm with 1-2 cm resolution and iii) from 1741.4 cm to 1798.4 cm with 0.5-3 cm resolution. The record is mostly varved and the bottom of the composite profile coincides with the onset of lacustrine sedimentation in the late Allerød at 12,834 +134/-233 varve yrs BP.

Description: These datasets provide data for the lowest part of a new composite profile GOS18 from Lake Gościąż in central Poland. The composite profile was established using sediment cores recovered in 2015 and 2018 with an UWITEC Piston Corer at 19.6-21.5 m water depth (Bonk et al., in press). Our data covers the time interval from the onset of lacustrine sedimentation in the late Allerød to the early Preboreal. Since Lake Gościąż comprises a continuous, seasonally resolved (varved) and exceptionally well-preserved archive of the Younger Dryas (YD) climate variation, it is highly suitable for detailed investigations of lake system responses during periods of rapid climate cooling (YD onset) and warming (YD termination), respectively. Our varve chronology is the lowest part of a new floating varve chronology established for Lake Gościąż (central Poland) that has been anchored to the absolute time scale through radiocarbon dating and age modelling (Bonk et al., in press). The here presented varve chronology reaches from the onset of lacustrine sedimentation in the late Allerød until the early Preboreal. Uncertainties for the absolute ages are derived from radiocarbon age modelling and varve counting. The internal varve counting uncertainty for the observed time interval is generally low (+14/-22) due to the mostly excellent varve preservation. Microfacies analyses, including varve counting and measurements of varve and sublayer thickness, have been performed on overlapping large-scale thin sections under an Axioplan 2 and Axiolab pol imaging microscope at magnifications of 50-400x. Thin sections have been prepared from 10 cm long freeze-dried and resin impregnated sediment slices (Brauer & Casanova 2001; doi:10.1023/A:1008136029735). The dataset incorporates the composite depth, age [BP] and age uncertainties [BP] for the varve bottom, the total varve thickness, selected sublayer thicknesses, detrital sublayer occurrence, the different varve types and the varve quality index (VQI).