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
Significance
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.
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, 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)
p
1 comment:
this tends to support Velokofsky's theories of 40 years ago ??
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