Dear friends of Science, Astronomy and Geology,

What, then, created the worldwide iridium layer, if not a humongous impact?
EVERY ONE FORGETS SUCH A BIG THING on the world, the CREATION OF HIMALAYA!!!

During these period the world was having a biggest and the most catastrophic
changes of the surface of the planet Earth. The greatest Mountain formation was
in process by Indo-Asian plate collision process. That's the newest born
mountain in the world and it never happened since after that. The Biggest
structure on the Earth surface was in process of formation and that process
takes long time energy and many seismic and environmental changes to do such a
catastrophic to destroy every thing on the Earth.
Dr.BHUDIA-Science Group Of INDIA.
http://uk.groups.yahoo.com/group/venustransit_2004/
President:"Kutch Science Foundation".
Founder :"Kutch Amateurs Astronomers Club - Bhuj - Kutch".
Life Member:"kutch Itihaas Parishad".
kutchscience@..., kutchscience@...,
http://uk.geocities.com/wildlifeofkutch/ http://www.geocities.com/kutchscience
http://profiles.yahoo.com/kutchscience2000
http://in.groups.yahoo.com/group/scienceclubofindia
http://in.groups.yahoo.com/group/kutchscience
http://in.groups.yahoo.com/group/kachchh
http://in.groups.yahoo.com/group/bhuj

Do visit our ABOVE Clubs/Groups of Science club of India, Science
Group of India.

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 Asociación Geológica Argentina, with
collaboration of the Sociedad Geológica 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

a.. This material is not under embargo.
b.. In articles published, please reference Backbone of the Americas -
Patagonia to Alaska, co-convened by the Geological Society of America and
Asociación Geológica Argentina, with collaboration of the Sociedad Geológica de
Chile.
c.. 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.
d.. For assistance during the meeting, contact Ann Cairns at GSA headquarters,
+1-303-357-1056 or acairns@...
CONTACTS
Markus Harting
Department of Earth Sciences
Utrecht University, Budapestlaan 4
3508 TA Utrecht, The Netherlands
Phone: +31302535181
E-mail: M.harting@...

IMAGES AVAILABLE
Click on photos for high-resolution images.

Scanning Electron Microscope picture of isolated, and well preserved
Spherule from NE-Mexico (400 µm in diameter). [High-res file 402 KB]

Thin-section of Spherule-bearing sediment of the original spherule layer
(NE-Mexico). Both, well rounded Spherules (center and upper left side;~400 µm 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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