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'Geochemical re-evaluation supports cosmic impact rather than volcanism at Younger Dryas onset, Hall’s Cave, Texas: Reply to Sun et al. 2020' - a recent article published in "Airbursts and Cratering Impacts" on #ScienceOpen 📄🔗 https://www.scienceopen.com/hosted-document?doi=10.14293/ACI.2025.0007

#YoungerDryas #ImpactHypothesis #CosmicImpact #Geochemistry

Geochemical re-evaluation supports cosmic impact rather than volcanism at Younger Dryas onset, Hall’s Cave, Texas: Reply to Sun et al. 2020

Hall’s Cave, situated on the Edwards Plateau of central Texas, contains a well-dated latest Quaternary sedimentary sequence containing a high-resolution record of faunal, climatic, and geochemical changes. In a recent study, Sun et al. (2020) examined trace element concentrations and osmium isotope compositions from this sequence and concluded that a peak in platinum group elements (PGEs) and a negative excursion in 187Os/ 188Os values near 151 cm depth were best interpreted as being more consistent with volcanic emissions from the Laacher See eruption in Germany (~12.9 ka) than with an extraterrestrial impact. Here, we re-examine their geochemical dataset from Hall’s Cave, including previously unreported data from a sample at 153 cm depth that exhibits the highest measured platinum concentration (1807 ppb) in the sequence. This critical sample aligns stratigraphically with the onset of the Younger Dryas cooling event, dated to approximately 12,800 cal yr BP and not with the timing of the Laacher See volcanic eruption in Germany. We assess the implications of these results in the context of both cosmic impact and volcanic hypotheses and highlight the importance of comprehensive data inclusion, high-resolution sampling, and stratigraphic consistency in evaluating proposed causal mechanisms for abrupt climate events and associated geochemical anomalies.

ScienceOpen

ScienceOpen Jul 14, 2025

'Evidence of a 12,800-year-old Shallow Airburst Depression in Louisiana with Large Deposits of Shocked Quartz and Melted Materials' - an 'Airbursts and Cratering Impacts' research article on #ScienceOpen:

🔗 https://www.scienceopen.com/hosted-document?doi=10.14293/ACI.2025.0004

#Airburst #PlanetaryScience #CosmicImpact #Archaeology #ImpactCratering

Evidence of a 12,800-year-old Shallow Airburst Depression in Louisiana with Large Deposits of Shocked Quartz and Melted Materials

We report evidence of a likely low-altitude cosmic airburst near Perkins, Louisiana, associated with semi-consolidated deposits containing abundant shocked quartz grains, a classical impact indicator, along with spherules, meltglass, and microbreccia. Analytical techniques employed on these materials include optical microscopy, the universal stage, electron microscopy (SEM, TEM, and STEM), cathodoluminescence, laser ablation (LA-ICP-MS), neutron activation (INAA), and radiometric dating. These analyses reveal that the deposits exhibit morphological and compositional similarities to known impact-related proxies. Radiocarbon dating and 40Ar/39Ar analyses constrain the likely age of deposition to between 30,000 and 10,000 calibrated years BP, with a concentration of dates clustering around 12,800 years BP (12,835-12,735 cal BP), coinciding with the age range of the Younger Dryas Boundary (YDB). Spherule and meltglass abundances, along with evidence of high-temperature mineral transformations, are consistent with the effects of a high-energy airburst or impact. Hydrocode modeling suggests that a touch-down airburst could plausibly account for the observed shallow depression, material dispersal patterns, and geochemical signatures. Our study suggests that a 300-m-long lake/depression at the Perkins site represents North America’s first identified YDB-age airburst crater.

ScienceOpen