Sedimentary record from Patagonia, southern Chile supports cosmic-impact triggering of biomass burning, climate change, and megafaunal extinctions at 12.8 ka

Title	Sedimentary record from Patagonia, southern Chile supports cosmic-impact triggering of biomass burning, climate change, and megafaunal extinctions at 12.8 ka
Authors	Mario Pino, Ana M. Abarzúa, Giselle Astorga, Alejandra Martel-Cea, Nathalie Cossio-Montecinos, R. Ximena Navarro, Maria Paz Lira, Rafael Labarca, Malcolm A. LeCompte, Victor Adedeji, Christopher R. Moore, Ted E. Bunch, Charles Mooney, Wendy S. Wolbach, Allen West, James P. Kennett
Magazine	Scientific Reports
Date	03/13/2019
DOI	10.1038/s41598-018-38089-y
Introduction	The Younger Dryas (YD) impact theory proposes that a large asteroid or comet fragmented and impacted North America, South America, Europe, and western Asia approximately 12,800 years ago. These numerous atmospheric bursts and impacts generated the YD boundary layer (YDB), characterised by elevated levels of platinum, high-temperature spherules, melt glass, and nanodiamonds, establishing a synchronised geological marker across over 50 locations spanning approximately 50 million square kilometres globally. This significant event is thought to have initiated widespread biomass combustion, a short impact winter, shifts in YD climate, and played a role in the disappearance of late Pleistocene megafauna. Our study in Pilauco, Chile (~40°S), examines a ~12,800-year-old geological sequence. This southern hemispheric site displays peak YD boundary concentrations of platinum, gold, high-temperature iron- and chromium-rich spherules, and naturally uncommon native iron particles. A pronounced increase in charcoal levels indicates an intense period of biomass combustion, coinciding with significant vegetation alterations, including considerable environmental disruption, fluctuating precipitation patterns, and warmer temperatures. This observation contrasts with the cooling observed in the Northern Hemisphere at the start of the YD, implying a rapid atmospheric connection. The abrupt absence of megafaunal remains and dung fungi within the Pilauco YDB layer aligns with megafaunal disappearances throughout the Americas. The evidence from Pilauco supports the YDB impact findings documented across four continents.
Quote	Mario Pino, Ana M. Abarzúa and Giselle Astorga et al. Sedimentary record from Patagonia, southern Chile supports cosmic-impact triggering of biomass burning, climate change, and megafaunal extinctions at 12.8 ka. Sci Rep. 2019. Vol. 9. DOI: 10.1038/s41598-018-38089-y
Element	Platinum (Pt) , Chromium (Cr) , Carbon (C)
Industry	Research & Laboratory