Evidence from Central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis

Proceedings of the National Academy of Sciences of the United States of America
By: , and 
Edited by: Steven M. Stanley

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Abstract

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

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Evidence from Central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis
Series title Proceedings of the National Academy of Sciences of the United States of America
DOI 10.1073/pnas.1110614109
Volume 109
Issue 13
Year Published 2012
Language English
Publisher National Academy of Sciences
Publisher location Washington, D.C.
Description 10 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Proceedings of the National Academy of Sciences of the United States of America
First page E738-E747
Country Mexico
Other Geospatial Lake Cuitzeo