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

Le résumé fourni par la source

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.

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