Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago.

ABSTRACT: Airbursts/impacts by a fragmented comet or asteroid have been proposed at the Younger Dryas onset (12.80 ± 0.15 ka) based on identification of an assemblage of impact-related proxies, including microspherules, nanodiamonds, and iridium. Distributed across four continents at the Younger Dryas boundary (YDB), spherule peaks have been independently confirmed in eight studies, but unconfirmed in two others, resulting in continued dispute about their occurrence, distribution, and origin. To further address this dispute and better identify YDB spherules, we present results from one of the largest spherule investigations ever undertaken regarding spherule geochemistry, morphologies, origins, and processes of formation. We investigated 18 sites across North America, Europe, and the Middle East, pe

SUBMITTER: Wittke JH 

PROVIDER: S-EPMC3677428 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature