Evidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis

• DOI: 10.1073/pnas.1110614109
• Publication Date: 2012-03-06T04:33:43Z
• Authors: Isabel Israde-Alc...; James L. Bischoff; Gabriela Domíngue...; Hong-Chun Li; Paul S. DeCarli; Ted E. Bunch; James H. Wittke; James C. Weaver; Richard B. Firestone; Allen West; James P. Kennett; Chris Mercer; Sujing Xie; Eric K. Richman; Charles R. Kinzie; Wendy S. Wolbach
• Keywords: Nanodiamond; Extraterrestrial Life

We report the discovery in Lake Cuitzeo central Mexico of a black, carbon-rich, lacustrine layer, containing nanodiamonds, microspherules, and other unusual materials that date to early Younger Dryas are interpreted result from an extraterrestrial impact. These proxies were found 27-m-long core as part interdisciplinary effort extract paleoclimate record back through previous interglacial. Our attention focused on anomalous, 10-cm-thick, carbon-rich layer at depth 2.8 m dates 12.9 ka coincides with suite anomalous coeval environmental biotic changes independently recognized regional lake sequences. Collectively, these have produced most distinctive boundary late Quaternary record. This contains diverse, abundant assemblage impact-related markers, including carbon spherules, magnetic spherules rapid melting/quenching textures, all reaching synchronous peaks immediately beneath largest peak charcoal core. Analyses by multiple methods demonstrate presence three allotropes nanodiamond: n-diamond, i-carbon, hexagonal nanodiamond (lonsdaleite), order estimated relative abundance. nanodiamond-rich is consistent numerous sites across North America, Greenland, Western Europe. examined hypotheses account for observations find evidence cannot be explained any known terrestrial mechanism. It is, however, impact hypothesis postulating major involving airburst(s) and/or ground impact(s) ka.