Northwestern Chilean Patagonia sediment record supports YDB cosmic impact triggering of biomass burning, climate change, and megafaunal extinctions (~12.8 ka)

Abstract

Younger Dryas (YD) impact theory posits that fragments of a disintegrating giant comet struck North America, South America, Europe, and western Asia ~12,800 years ago. These airbursts/impacts produced the YD boundary layer (YDB), containing anomalously high concentrations of platinum, high-temperature spherules, meltglass, and nanodiamonds, providing an isochronous datum at 50 sites across ~50 million km² of Earth. This event triggered extensive biomass burning, “impact winter,” the YD climatic episode, and extinction of millions of late Pleistocene megafauna. In the first extensive investigation south of the equator, we report a 12,800-year-old stratum at Pilauco in northwestern Chilean Patagonia (~40° S), exhibiting peak abundances in impact-related platinum, palladium, gold, high-temperature Fe-rich and Cr-rich impact spherules, and native iron grains rarely found on Earth. Furthermore, a major peak in charcoal marks an intense biomass-burning episode, synchronous with a dramatic decrease in seeds and shift in vegetation, reflecting abrupt climatic warming at the YD onset, anti-phased with cooling over the Northern Hemisphere. The sudden disappearance of megafaunal bones and dung fungi (Sporormiella) at Pilauco is synchronous with megafaunal extinction over the Americas. The Pilauco evidence is consistent with the occurrence of local cosmic impacts, coeval with other 12,800-year-old YDB cosmic impacts on four continents.