Identification of the Younger Dryas onset was confused by the Laacher See volcanic eruption.

0552688 - BC 2022 RIV US eng J - Článek v odborném periodiku
Stuchlík, Evžen - Vondrák, D. - Hořická, Zuzana - Hrubá, J. - Mijovilovich, Ana - Kletetschka, G.
Identification of the Younger Dryas onset was confused by the Laacher See volcanic eruption.
Proceedings of the National Academy of Sciences of the United States of America. Roč. 118, č. 4 (2021), č. článku e2022485118. ISSN 0027-8424. E-ISSN 1091-6490
Grant CEP: GA ČR(CZ) GA20-08294S; GA MŠMT EF15_003/0000336
Institucionální podpora: RVO:60077344
Klíčová slova: biomass-burning episode * sediments * lake
Obor OECD: Environmental sciences (social aspects to be 5.7)
Impakt faktor: 12.779, rok: 2021
Způsob publikování: Open access
https://doi.org/10.1073/pnas.2022485118

Cheng et al. (1) provide data on oxygen-isotope d18O in nine speleothems of Younger Dryas (YD) age from caves situated in several continents between 42°27′ N and 21°05′ S and dated by the U-Th method. They compare this data with d18O records in several ice cores from Greenland and Antarctica that were originally dated by the radiocarbon method. While the presented YD records of d18O and their bowlshaped pattern (e.g., in speleothems and ice cores from the Northern Hemisphere) are similar to earlier published YD structures [e.g., lake sediment-based pollen and Cladocera inferred temperature (2) and lake sediment Th/K ratio (3)], the interpretation of this data merits some criticism. Although the authors refer to several papers dealing with the Laacher See volcanic eruption (LSVE), they ignore any of its potential effects on climate. Unfortunately, this hampers the interpretation of their own data and confounds the role of the widespread Pt anomaly (4) and thus the actual onset of the YD, which they mistakenly associate with the first drop in d18O. The LSVE tephra is one of the most important chronological markers in European lacustrine varved sedimentary archives that resides close to the onset of the YD (5). The timing of this at least Europe-wide event, based on carbonatite U-Th zircon isochron age (12,900 cal. B.P.) (6) and lake varve age (12,880 cal. B.P.) (5), is within the error range of the YD onset provided by Cheng et al. (12,870 ± 30 cal. B.P.) (1). Results of our recent multiproxy study of a sedimentary archive in the Central European paleolake Stará Jímka (3) suggest that the first drop in d18O found by Cheng et al. (cave Seso, North Greenland Ice Core Project., figure 4 of ref. 1) originated from a previous warmer climate in combination with a long-term climate repercussion following the LSVE (7). Then, the subsequent major continuous decrease of d18O indicates the actual YD onset, as a reaction to an extraterrestrial impact event (ETIE) revealed by the Pt anomaly along with the occurrence of microspherules and nanodiamonds (8, 9). In addition, their data based on the identification of annual bends in speleothems (Cherrapunji and Rige cave samples Chy-1, Rige 3., figure S3 of ref. 1) support this interpretation. Furthermore, the lag estimated by Cheng et al. (1) of ∼50 y between their proposed YD onset and the Pt anomaly is within our error range of a ∼70-y lag (based on radiocarbon dates) found in the sediment of the Stará Jímka paleolake between the accumulation of LSVE tephra and magnetic impact microspherules that indicate an ETIE (3). Thus, while the data provided by Cheng et al. (1) are improperly interpreted, they support the validity of the YD impact hypothesis (10).
Trvalý link: http://hdl.handle.net/11104/0327818