A multiproxy record of the Younger Holsteinian Oscillation (YHO) in the Ossówka profile, eastern Poland. (19th February 2018)

• Record Type: Journal Article
• Authors: Nitychoruk, Jerzy; Bińka, Krzysztof; Sienkiewicz, Elwira; Szymanek, Marcin; Chodyka, Marta; Makos, Michał; Ruppert, Hans; Tudryn, Alina
• Is Part Of: Boreas. Volume 47:Number 3(2018)
• Page Start: 855
• Page End: 868
• Publication Date: 2018-02-19
• Subjects: Geology, Stratigraphic -- Quaternary -- Periodicals; 551.79
• DOI: 10.1111/bor.12308
• Languages: English
• ISSNs: 0300-9483

Abstract

Abstract : The laminated lacustrine succession at Ossówka in eastern Poland, which is largely the equivalent of MIS 11c, is amongst the best‐developed sites in Europe that cover this time period. Close inspection of the depth interval between 35.0 and 42.5 m in a 55‐m‐long core shows an environmental crisis at a depth of 40.95 m that lasted approximately 800 years and resulted in almost complete extinction of fir ( Abies ) from the communities existing at that time. Geochemical analyses reveal a simultaneous increase in sulphur in the deposits and a change in stable carbon and oxygen isotope ratios towards higher values, as well as a significant increase in the thickness of the laminae (up to 5 mm). Diatom studies show a clear increase in benthic diatoms in this interval, implying a decrease in water level. However, the predominance of such forms was probably caused by the elimination of planktonic diatoms by invasive blooms of Tetraedron, rather than lower lake levels, evidence of which was not noted in the pollen spectra. Hence, all these changes in the lake may have been triggered by the destruction of fir trees, the gradual decomposition of dead trunks and some inconspicuous geomorphological disturbances caused by wind throw. They resulted in a supply of micronutrients to the basin, an increase in varve thickness and rapid oscillations in the abundance and composition of algae and changes in the geochemical status of the lake. Rapid and significant drops in winter temperatures appear to be responsible for the extinction of fir. Alternatively, late frost in spring or hot and dry summers may have affected microsporophyll growth and the fir physiology as known from extant Abies populations. This environmental crisis, which is termed the Younger Holsteinian Oscillation (YHO), is noted at only a few sites. At Dethlingen (Germany), where hornbeam communities disappear at that time, a drop in summer temperatures is suggested to have been the driving force. We suggest that, at Ossówka, a drop in winter temperatures, late frost, or summer drought at the very start of the YHO are possible causes of the near‐extinction of fir.