See another blockbuster confirmation of the Younger Dryas cosmic impact below. I keep a pretty close eye on our subject but had no idea such intricate, original and thorough work was underway in the Czech Republic. Gunther Kleteschka has appeared on several YDB papers, but has clearly been busy in his own laboratory collecting entirely new, informative and well dated expressions of the YDB boundary in lake sediments. His work and that of his local colleagues is clearly exciting and in keeping with the predictions made by the Younger Dryas Impact Hypothesis.
Cosmic-Impact Event in Lake Sediments from Central Europe Postdates the Laacher See Eruption and Marks Onset of the Younger Dryas
Gunther Kletetschka,1,2,3,* Daniel Vondrák,4 Jolana Hruba,2 Vaclav Prochazka,2 Ladislav Nabelek,1,2 Helena Svitavská-Svobodová,5 Premysl Bobek,5 Zuzana Horicka,6,7 Jaroslav Kadlec,8 Marian Takac,2 and Evzen Stuchlik7
Institute of Geology, Czech Academy of Sciences, CZ-252 43 Průhonice 770, Czech Republic; 2. Institute of Hydrogeology, Engineering Geology and Applied Geophysics, Charles University, Albertov 6, CZ-128 43 Prague 2, Czech Republic; 3. Geophysical Institute, University of Alaska Fairbanks, 903 North Koyukuk Drive, Fairbanks, Alaska 99775-7320, USA; 4. Institute for Environmental Studies, Charles University, Benátská 2, CZ-128 01 Prague 2, Czech Republic; 5. Institute of Botany, Czech Academy of Sciences, Zámek 1, CZ-252 43 Průhonice, Czech Republic; 6. Branch of Applied Ecology, T. G. Masaryk Water Research Institute, Podbabská 30, CZ-160 00 Prague 6, Czech Republic; 7. Institute of Hydrobiology, Biology Centre, Czech Academy of Sciences, Na Sádkách 7, CZ-370 05 České Budějovice, Czech Republic; 8. Institute of Geophysics, Czech Academy of Sciences, Boční II 1401, CZ-141 31 Prague 4, Czech Republic
The Younger Dryas (YD) climate episode (∼12,850–11,650 calendar years before present [cal BP]) is an event recorded widely across the Northern Hemisphere. We conducted multiple analyses at high resolution of a YD-age sedimentary sequence from Stara Jimka, a paleolake in the Bohemian Forest, Czech Republic. Age-depth modeling indicates that a cen- tral European warming trend was interrupted at ∼13,020 5 110 cal BP by the sudden onset of cooling (!20 y) known as the Gerzensee climate oscillation and marked by the deposition of fine-grained sediment at this location. That cooling episode ended at ∼13,001 5 66 cal BP and was followed by a ∼121-y-long warming trend. After that, the Laacher See tephra depo- sitional event, dating to ∼12,820 5 20 cal BP, continued an overall warming trend. The composition of Laacher See volcanic tephra in this section likely corresponds to the middle eruption sequence. Finally, the deposition of glassy microspherules marked the onset of the YD climate change at 12,755 5 92 cal BP. The sequence across the YD onset is marked by (1) a peak in glassy microspherules (117,000/kg), (2) a peak in framboidal spherules (14,000/kg), (3) significant changes in the lake’s weathering proxies, and (4) major changes in fauna and flora, showing a shift to unfavorable environmental conditions (decrease in temperature and lake trophy status). Collectively, this evidence is consistent with the YD impact hypothesis and evidence of one or more cosmic airburst events occurring at this time.