Cosmic-Impact Event in Lake Sediments from Central Europe Postdates the Laacher See Eruption and Marks Onset of the Younger Dryas

Kletetschka, Günther; Vondrák, Daniel; Hruba, J.; Procházka, Václav; Nabelek, L.; Svobodová-Svitavská, Helena; Bobek, Přemysl; Hořická, Zuzana; Kadlec, Jaroslav; Takac, M.; Stuchlik, Evzen

doi:10.1086/699869

Cited by 22 publications

(12 citation statements)

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“…The YDB hypothesis posits multiple airbursts/impacts across at least four continents 1,3,5,[8][9][10][11]20,69,[73][74][75][76][77][78] . These are proposed to have resulted from a one of a series of short-period, active comets known to break up frequently and to shed dozens to thousands of fragments that are 10 to 1000 m in diameter, each capable of producing catastrophic airburst/impacts, as discussed in detail in Napier 3,79 , Wolbach et al 13,14 , and Pino et al 9 (Appendix, Text S8).…”

Section: Discussionmentioning

confidence: 99%

Evidence of Cosmic Impact at Abu Hureyra, Syria at the Younger Dryas Onset (~12.8 ka): High-temperature melting at >2200 °C

Moore

Kennett

Napier

et al. 2020

Sci Rep

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, the 12,800-year-old Younger Dryas boundary layer (YDB) contains peak abundances in meltglass, nanodiamonds, microspherules, and charcoal. AH meltglass comprises 1.6 wt.% of bulk sediment, and crossed polarizers indicate that the meltglass is isotropic. High YDB concentrations of iridium, platinum, nickel, and cobalt suggest mixing of melted local sediment with small quantities of meteoritic material. Approximately 40% of AH glass display carbon-infused, siliceous plant imprints that laboratory experiments show formed at a minimum of 1200°-1300 °C; however, reflectance-inferred temperatures for the encapsulated carbon were lower by up to 1000 °C. Alternately, melted grains of quartz, chromferide, and magnetite in AH glass suggest exposure to minimum temperatures of 1720 °C ranging to >2200 °C. This argues against formation of AH meltglass in thatched hut fires at 1100°-1200 °C, and low values of remanent magnetism indicate the meltglass was not created by lightning. Low meltglass water content (0.02-0.05% H 2 O) is consistent with a formation process similar to that of tektites and inconsistent with volcanism and anthropogenesis. The wide range of evidence supports the hypothesis that a cosmic event occurred at Abu Hureyra ~12,800 years ago, coeval with impacts that deposited high-temperature meltglass, melted microspherules, and/or platinum at other YDB sites on four continents. Firestone et al. 1 first proposed that a cosmic impact event occurred ~12,800 years ago 1,2 , resulting in multi-continental airbursts, possibly caused by the debris stream from a short-period comet 1,3,4. This event is proposed to have created the Younger Dryas boundary layer (YDB), which contains peak abundances of magnetic spherules 1,5-11 , meltglass 7,8 , carbon spherules 1,12 , glasslike carbon 1,12 , charcoal 13,14 , platinum 15-18 , iridium 17,18 , nickel 19 cobalt 19 , and/or nanodiamonds 12,20-22 at ~40 sites across North America and Europe, including from Abu Hureyra, Syria (Appendix, Fig. S1). In this paper, the term "airburst/impact" refers to a collision of a cosmic body

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Section: Discussionmentioning

confidence: 99%

Evidence of Cosmic Impact at Abu Hureyra, Syria at the Younger Dryas Onset (~12.8 ka): High-temperature melting at >2200 °C

Moore

Kennett

Napier

et al. 2020

Sci Rep

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“…This suggests that the onset of lacustrine sedimentation in Prášilské Lake is younger than in other Bohemian Forest lakes. Namely for Černé Lake (Michler 2001), Großer Arbersee (Michler 2000), Plešné Lake (Pražáková et al 2006), Rachelsee (Carter et al 2018a) and two former lakes (Vočadlová et al 2015;Kletetschka et al 2018) the presence of several meters thick Late-glacial sediments is well documented. This asynchrony between timing of local deglaciation (Mentlík et al 2013) and sedimentation onset in Prášilské Lake may result from a lag time necessary to seal a permeable moraine.…”

Section: Discussionmentioning

confidence: 99%

Postglacial succession of caddisfly (Trichoptera) assemblages in a central European montane lake

et al. 2019

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The Bohemian Forest lakes, situated along the Czech-German-Austrian border, were strongly affected by atmospheric acidification between the 1950s and the late 1980s. The subsequent chemical recovery of the lake water should precede and enable a biological recovery, including changes in caddisfly (Insecta: Trichoptera) assemblages. Nevertheless, local preacidification data and detailed knowledge of the lake district history are missing, making evaluation of lake recovery difficult. We performed high-resolution analysis of caddisfly remains in a 2.2 m long sediment profile from Prášilské Lake covering the complete history of the lake-catchment evolution. Caddisfly larvae are good indicators of environmental conditions and their subfossil remains are well preserved in unconsolidated waterlaid sediments. A total of 10 caddisfly morpho-taxa were found providing a record from 11,400 cal. yr. BP to the present. With the exception of Athripsodes aterrimus, all identified species are currently present in the Bohemian Forest glacial lakes or their inflow streams but not all of them are documented in Prášilské Lake. The caddisfly fauna consisted of acid-resistant, acidtolerant and eurytopic species since the Early Holocene. Based on our results, the acid, dystrophic state of Prášilské Lake has been occurring since the lake formation. We conclude that the first signs of natural acidification appeared not later than during the Holocene onset in the Bohemian Forest region. Furthermore, we did not detect any abrupt changes in the species composition connected to the period of anthropogenic acidification during the 20th century. This study provides for the first time a record of postglacial succession of caddisfly assemblages in a central European mountain lake.

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“…To counter this, van Hoesel et al (2014) suggest, without evidence, that the microspherules at the YD boundary at all YDB sites might have migrated through the sediment from the Laacher See volcanic boundary layer below. However, more recent work (Kletetschka et al, 2018) shows this is clearly not true at a location close to the Laacher See eruption (see Figure 5), and the chemical signatures in the GISP2 ice core of the YD event and volcanic eruptions are also clearly separated (Petaev et al, 2013a). In any case, the range of the Laacher See tephra is limited mainly to Central Europe (Reinig et al, 2020).…”

Section: Iron and Silica-rich Impact Spherulesmentioning

confidence: 89%

“…Figure 5. Sediment profile for Stara Jimka, a Palaeolake in the Bohemian Forest, Czech Republic, taken from Kletetschka et al (2018) showing clear separation between the Laacher See Tephra and Younger Dryas boundary microspherules. The right vertical axis measurement, Th/K, is a proxy for climate.…”

Section: Iron and Silica-rich Impact Spherulesmentioning

confidence: 99%

The Younger Dryas impact hypothesis: Review of the impact evidence

Sweatman

2021

Earth-Science Reviews

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Firestone et al., 2007, PNAS 104(41): 16016-16021, proposed that a major cosmic impact, circa 10,835 cal. BCE, triggered the Younger Dryas (YD) climate shift along with changes in human cultures and megafaunal extinctions. Fourteen years after this initial work the overwhelming consensus of research undertaken by many independent groups, reviewed here, suggests their claims of a major cosmic impact at this time should be accepted. Evidence is mainly in the form of geochemical signals at what is known as the YD boundary found across at least four continents, especially North America and Greenland, such as excess platinum, quench-melted materials, and nanodiamonds. Their other claims are not yet confirmed, but the scale of the event, including extensive wildfires, and its very close timing with the onset of dramatic YD cooling suggest they are plausible and should be researched further. Notably, arguments by a small cohort of researchers against their claims of a major impact are, in general, poorly constructed, and under close scrutiny most of their evidence can actually be interpreted as supporting the impact hypothesis.

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Cosmic-Impact Event in Lake Sediments from Central Europe Postdates the Laacher See Eruption and Marks Onset of the Younger Dryas

Cited by 22 publications

References 63 publications

Evidence of Cosmic Impact at Abu Hureyra, Syria at the Younger Dryas Onset (~12.8 ka): High-temperature melting at >2200 °C

Evidence of Cosmic Impact at Abu Hureyra, Syria at the Younger Dryas Onset (~12.8 ka): High-temperature melting at >2200 °C

Postglacial succession of caddisfly (Trichoptera) assemblages in a central European montane lake

The Younger Dryas impact hypothesis: Review of the impact evidence

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