[meteorite-list] More Evidence Chicxulub Was Too Early

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Thu Mar 30 11:57:25 2006
Message-ID: <003a01c653cf$049afe40$5aea8c46_at_ATARIENGINE>

Hi,

    Can't tell the players without a program!
Harting is Keller's collaborator. For the other
side of the fuss, see Smits website:
http://www.geo.vu.nl/~smit/csdp/debates.htm
    This site is for folks who like specifics, cores,
thin sections, and lots of argument.
    Keller-Harting get lots of press, but nobody
is convinced by them but them... The press loves
a fuss.
    I think we ought to sort out all the exact
mechanisms of extinctions so as to better understand
the dangers of various kinds of objects, but Keller's
problem is this: is that 300,000 years really only
30 years? 300 years? 3000 years? Can they prove
it's 300,000 years? (No.)
    But even if it is... You're on the jury. The accused
freely admits to having plugged the deceased a number
of times with large caliber bullets. BUT, and here's the
crucial point (he says), none of those wounds were
mortal. The late Mr. Victim was alive and screaming
when he left him. In fact, Mr Victim didn't die until
many hours later, while the accused was enjoying the
veal with his friend Mr. Soprano. AND the victim
didn't die from gunshot wounds at all! No, no, he
died from some mysterious blood loss. Here the
accused smiles winningly, "so youse can see I
din't have nuttin' ta do wid it!"
    Convince you?


Sterling K. Webb
------------------------------------------------------
----- Original Message -----
From: "Ron Baalke" <baalke_at_zagami.jpl.nasa.gov>
To: "Meteorite Mailing List" <meteorite-list_at_meteoritecentral.com>
Sent: Wednesday, March 29, 2006 7:25 PM
Subject: [meteorite-list] More Evidence Chicxulub Was Too Early


>
> http://www.geosociety.org/news/pr/06-14.htm
>
> News Release
>
> 29 March 2006
> GSA Release No. 06-14
>
> Contact: Ann Cairns, acairns_at_geosociety.org
> Director-Communications and Marketing
> (303) 357-1056, fax 303-357-1074
>
> More Evidence Chicxulub Was Too Early
>
> Boulder, Colo. - A new study of melted rock ejected far from the
> Yucatan's Chicxulub impact crater bolsters the idea that the famed
> impact was too early to have caused the mass extinction that killed the
> dinosaurs 65 million years ago.
>
> A careful geochemical fingerprinting of glass spherules found in
> multiple layers of sediments from northeast Mexico, Texas, Guatemala,
> Belize and Haiti all point back to Chicxulub as their source. But the
> analysis places the impact at about 300,000 years before the infamous
> extinctions that mark the boundary between the Cretaceous and Tertiary
> periods, a.k.a. the K-T boundary.
>
> Using an array of electron microscopy techniques, Markus Harting of the
> University of Utrecht in the Netherlands has found that chemical
> compositions of the spherules all match what would be expected of rocks
> melted at the Chicxulub impact. The spherules are now found in several
> layers because after they originally hit the ground, they were
> "reworked" by erosion to create later layers of sediments, he said. It's
> this reworking long after the impact that has misplaced some of the
> spherules into sediments that, based on the fossils in the same
> sediments, are misleadingly close to the K-T boundary.
>
> Harting is scheduled to present his latest findings on Monday, 3 April
> Backbone of the Americas-Patagonia to Alaska. The meeting is co-convened
> by the Geological Society of America and the Asociaci?n Geol?gica
> Argentina, with collaboration of the Sociedad Geol?gica de Chile. The
> meeting takes place 3-7 April in Mendoza, Argentina.
>
> "The whole story is that it's a single impact event," said Harting of
> his analysis of the multiple spherule layers. In fact, the original
> spherule layer is not particularly hard to make out, since its spherules
> are not as abraded and damaged as those which were moved around and
> re-deposited in later, higher sediments. Above these, and younger still,
> Harting has also identified the famous layer of extraterrestrial iridium
> in sediments worldwide which was originally touted as the smoking gun
> for an impact somewhere on Earth at the K-T boundary.
>
> "In most of the sections we found spherules we also found the iridium
> layer at or near the K-T boundary," said Harting. "That makes the
> mismatch with Chicxulub even more obvious."
>
> The sediments from the region are also providing clues to what
> transpired during those 300,000 years between the impact and the K-T
> boundary die-offs. "Nothing happened between them," said Harting. "The
> K-T iridium layer is a totally different event."
>
> Disconnecting the Chicxulub impact from the K-T boundary also helps make
> sense of some other oddities in the iridium layer. In the Gulf of
> Mexico, close to the impact site, iridium is found at a weak
> concentration, just one part per billion, says Harting. Yet farther away
> in Denmark, higher concentrations of iridium are found. "This doesn't
> really make sense," he said, unless, of course, the impact and iridium
> layer are not related.
>
> All this begs the question: What, then, created the worldwide iridium
> layer, if not a humongous impact? One possibility is that Earth and
> perhaps the entire solar system was passing through a thick cloud of
> cosmic dust 65 million years ago.
>
> "You probably have a time when lots of meteorites are coming down and
> never touching the ground," said Harting. Instead they burned up as
> "shooting stars," depositing their iridium in the atmosphere. There it
> was quickly rained out, washed into lakes and oceans and buried in
> contemporary sediments.
>
> Another burning question is whether the massive impact - which
> undoubtedly occurred and was certainly catastrophic - is responsible for
> any extinction at all. Maybe, answers Harting. There is the case of the
> ammonites, the once ubiquitous nautilus-like sea creatures that died out
> at about the same time as the Chicxulub impact and before the K-T
> boundary, he said.
>
> But whether the impact was the ammonite killer is not at all clear,
> according to Harting. Early models of the Chicxulub impact called on a
> "nuclear winter" scenario, in which a dust-shrouded world went cold and
> plant life died away for years, to cause mass extinctions. Yet
> sun-loving animals like crocodiles and turtles appear to have glided
> right through without any ill effects. And that is, perhaps the silver
> lining to Chicxulub's fall from the status of
> most-massive-of-all-murderers: Even giant impacts aren't necessarily
> global catastrophes.
>
>
> WHEN & WHERE
>
> Backbone of the Americas - Patagonia to Alaska
> Centro de Congresos
> Mendoza, Argentina
> Monday, 3 April
>
> View abstract at
> http://gsa.confex.com/gsa/06boa/finalprogram/abstract_101180.htm
>
> * This material is not under embargo.
> * In articles published, please reference Backbone of the Americas -
> Patagonia to Alaska, co-convened by the Geological Society of
> America and Asociaci?n Geol?gica Argentina, with collaboration of
> the Sociedad Geol?gica de Chile.
> * GSA will not operate an onsite newsroom at the meeting.
> Journalists are encouraged to contact presenters at their offices
> prior to or after the meeting.
> * For assistance during the meeting, contact Ann Cairns at GSA
> headquarters, +1-303-357-1056 or acairns_at_geosociety.org
>
> CONTACTS
>
> Markus Harting
> Department of Earth Sciences
> Utrecht University, Budapestlaan 4
> 3508 TA Utrecht, The Netherlands
> Phone: +31302535181
> E-mail: M.harting_at_geo.uu.nl
>
>
> IMAGES AVAILABLE
>
> Click on photos for high-resolution images.
>
> Chicxulub Spherule
>
> Scanning Electron Microscope picture of isolated, and well preserved
> Spherule from NE-Mexico (400 ?m in diameter). [High-res file 402 KB]
>
> Thin-section of Chicxulub Spherule
> Thin-section of
> Spherule-bearing sediment of the original spherule layer (NE-Mexico).
> Both, well rounded Spherules (center and upper left side;~400 ?m in
> diameter) as well as glass-shards (right- and lower center part) fresh
> preserved, without any alteration features. [High-res file 2629 KB]
>
> ###
>
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Received on Thu 30 Mar 2006 02:53:22 AM PST