Wednesday, August 14, 2013
Paper Confirms Cosmic Event for Pleistocene Nonconformity
This is the confirmation paper that establishes the existence of the major cosmic impact that generated what I have been calling the Pleistocene Nonconformity that triggered the thirty degree crustal shift that ended the Northern Ice Cap or at least reduced it to the Greenland Cap. I think we can dismiss any further need to prove its existence. Establishing the direct consequences is quite another matter. I have listed quite a number here in this blog both major and minor, but all depended on the impact itself.
Recall we began with no impact scenario whatsoever then arrived at its necessity and then the startling discovery that it existed but that it had been targeted. Geology has plenty of catching up to do in my world, but this paper is an excellent start. We know something big went bang and that all the large critters in the northern hemisphere were killed in a second.
My primary conjecture is that a comet more or less on the same path as Tunguska impacted the polar Ice Cap transferring its kinetic energy into the crust and the ice itself. It broke up coming into the atmosphere as well and huge amounts of carbon dust filled the atmosphere and a halo of smaller impacts took place. The energy release generally conforms to the present longitude of Hudson Bay and southward.
Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago
We present detailed geochemical and morphological analyses of nearly 700 spherules from 18 sites in support of a major cosmic impact at the onset of the Younger Dryas episode (12.8 ka). The impact distributed ∼10 million tonnes of melted spherules over 50 million square kilometers on four continents. Origins of the spherules by volcanism, anthropogenesis, authigenesis, lightning, and meteoritic ablation are rejected on geochemical and morphological grounds. The spherules closely resemble known impact materials derived from surficial sediments melted at temperatures >2,200 °C. The spherules correlate with abundances of associated melt-glass, nanodiamonds, carbon spherules, aciniform carbon, charcoal, and iridium.
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, performing nearly 700 analyses on spherules using energy dispersive X-ray spectroscopy for geochemical analyses and scanning electron microscopy for surface microstructural characterization. Twelve locations rank among the world’s premier end-Pleistocene archaeological sites, where the YDB marks a hiatus in human occupation or major changes in site use. Our results are consistent with melting of sediments to temperatures >2,200 °C by the thermal radiation and air shocks produced by passage of an extraterrestrial object through the atmosphere; they are inconsistent with volcanic, cosmic, anthropogenic, lightning, or authigenic sources. We also produced spherules from wood in the laboratory at >1,730 °C, indicating that impact-related incineration of biomass may have contributed to spherule production. At 12.8 ka, an estimated 10 million tonnes of spherules were distributed across ∼50 million square kilometers, similar to well-known impact strewnfields and consistent with a major cosmic impact event.
1. Edited by Steven M. Stanley, University of Hawaii, Honolulu, HI, and approved April 9, 2013 (received for review January 28, 2013)