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Palaeoclimate inferred from δO and palaeobotanical indicators in freshwater tufa of Lake Äntu Sinijärv, Estonia

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Author

  • Liina Laumets
  • Volli Kalm
  • Anneli Poska
  • Sándor Kele
  • Katrin Lasberg
  • Leeli Amon

Summary, in English

We investigated a 3.75-m-long lacustrine sediment record from Lake Äntu Sinijärv, northern Estonia, which has a modeled basal age >12,800 cal yr BP. Our multi-proxy approach focused on the stable oxygen isotope composition (δ18O) of freshwater tufa. Our new palaeoclimate information for the Eastern Baltic region, based on high-resolution δ18O data (219 samples), is supported by pollen and plant macrofossil data. Radiocarbon dates were used to develop a core chronology and estimate sedimentation rates. Freshwater tufa precipitation started ca. 10,700 cal yr BP, ca. 2,000 years later than suggested by previous studies on the same lake. Younger Dryas cooling is documented clearly in Lake Äntu Sinijärv sediments by abrupt appearance of diagnostic pollen (Betula nana, Dryas octopetala), highest mineral matter content in sediments (up to 90 %) and low values of δ18O (less than −12 ‰). Globally recognized 9.3- and 8.2-ka cold events are weakly defined by negative shifts in δ18O values, to −11.3 and −11.7 ‰, respectively, and low concentrations of herb pollen and charcoal particles. The Holocene thermal maximum (HTM) is palaeobotanically well documented by the first appearance and establishment of nemoral thermophilous taxa and presence of water lilies requiring warm conditions. Isotope values show an increasing trend during the HTM, from −11.5 to −10.5 ‰. Relatively stable environmental conditions, represented by only a small-scale increase in δ18O (up to 1 ‰) and high pollen concentrations between 5,000 and 3,000 cal yr BP, were followed by a decrease in δ18O, reaching the most negative value (−12.7 ‰) recorded in the freshwater tufa ca. 900 cal yr BP.

Publishing year

2014

Language

English

Pages

99-111

Publication/Series

Journal of Paleolimnology

Volume

51

Issue

1

Document type

Journal article

Publisher

Springer

Topic

  • Earth and Related Environmental Sciences

Keywords

  • Stable oxygen isotopes
  • Freshwater tufa
  • Palaeoclimate
  • Pollen analysis
  • Estonia

Status

Published

ISBN/ISSN/Other

  • ISSN: 0921-2728