[meteorite-list] Giant Impact Near India -- Not Mexico -- May Have Doomed Dinosaurs

From: Mexicodoug <mexicodoug_at_meteoritecentral.com>
Date: Wed, 21 Oct 2009 18:59:37 -0400
Message-ID: <8CC20B94C8B913E-A2C-C929_at_webmail-m051.sysops.aol.com>

"encircling the central peak, known as the Bombay High, which would be
3 miles tall from the ocean floor(about the height of Mount McKinley)."

Hi Elton, List,

Lots of creativity in this article; A better comparison would have been
"almost half as high as Mauna Kea". By the same criterion they used
they also could have said it is higher than Mount Everest.

In any case, India did it. Mexico would never kill off the Dinosaurs,
the kids like them so much. Whether this works amounts to something
important or not, it struck me (again) how the passage of time
sometimes allows challenges and changes to thought about things that
were incredibly obvious to those who demand answers. But then they can
become uncomfortably complex ... adding grist to the scientific mill
and giving all those Dino-deprived kids something to do when they grow
up. That's better than eyes glazing over on textbooks or (Paleopedia)
written in the prior century when the wild frontier of problems awaited
conquest!

Kindest wishes,
Doug






-----Original Message-----
From: MEM <mstreman53 at yahoo.com>
To: metlist <meteorite-list at meteoritecentral.com>
Sent: Wed, Oct 21, 2009 10:44 am
Subject: [meteorite-list] Giant Impact Near India -- Not Mexico -- May
Have Doomed Dinosaurs



World's new largest impact crater just confirmed. 500km with a possibly
40km
impactor

Giant Impact Near India -- Not Mexico -- May Have Doomed Dinosaurs.

<http://www.sciencedaily.com/releases/2009/10/091015102246.htm>
*Three-dimensional reconstruction of the submerged Shiva crater (~500 km
diameter) at the Mumbai Offshore Basin, western shelf of India from
different cross-sectional and geophysical data. The overlying
4.3-mile-tick
Cenozoic strata and water column were removed to show the morphology of
the
crater. (Credit: Image courtesy of Geological Society Of America)*

Giant Impact Near India -- Not Mexico -- May Have Doomed Dinosaurs

ScienceDaily (Oct. 15, 2009) ? A mysterious basin off the coast of India
could be the largest, multi-ringed impact crater the world has ever
seen. And if
a new study is right, it may have been responsible for killing the
dinosaurs off
65 million years ago.

Sankar Chatterjee of Texas Tech University and a team of researchers
took a
close look at the massive Shiva basin, a submerged depression west of
India that
is intensely mined for its oil and gas resources. Some complex craters
are among
the most productive hydrocarbon sites on the planet. Chatterjee will
present his
research at this month's Annual Meeting of the Geological Society of
America in
Portland, Oregon.

?If we are right, this is the largest crater known on our planet,?
Chatterjee said. ?A bolide of this size, perhaps 40 kilometers (25
miles) in
diameter creates its own tectonics.?

By contrast, the object that struck the Yucatan Peninsula, and is
commonly
thought to have killed the dinosaurs was between 8 and 10 kilometers (5
and 6.2
miles) wide.

It's hard to imagine such a cataclysm. But if the team is right, the
Shiva
impact vaporized Earth's crust at the point of collision, leaving
nothing but
ultra-hot mantle material to well up in its place. It is likely that
the impact
enhanced the nearby Deccan Traps volcanic eruptions that covered much
of western
India. What's more, the impact broke the Seychelles islands off of the
Indian
tectonic plate, and sent them drifting toward Africa.

The geological evidence is dramatic. Shiva's outer rim forms a rough,
faulted ring some 500 kilometers in diameter, encircling the central
peak, known
as the Bombay High, which would be 3 miles tall from the ocean
floor(about the
height of Mount McKinley). Most of the crater lies submerged on India's
continental shelf, but where it does come ashore it is marked by tall
cliffs,
active faults and hot springs. The impact appears to have sheared or
destroyed
much of the 30-mile-thick granite layer in the western coast of India.

The team hopes to go India later this year to examine rocks drill from
the
center of the putative crater for clues that would prove the strange
basin was
formed by a gigantic impact.

?Rocks from the bottom of the crater will tell us the telltale sign of
the
impact event from shattered and melted target rocks. And we want to see
if there
are breccias, shocked quartz, and an iridium anomaly,? Chatterjee said.
Asteroids are rich in iridium, and such anomalies are thought of as the
fingerprint of an impact.
------------ --------- ---------
*Adapted from materials provided by Geological Society Of
America<http://www.geosocie ty.org/>
*.

Geological Society Of America. "Giant Impact Near India -- Not Mexico
-- May
Have Doomed Dinosaurs." *ScienceDaily* 15 October 2009.16October 2009
<http://www.sciencedaily.com/releases/2009/10/091015102246.htm>.

______________________________________________
http://www.meteoritecentral.com
Meteorite-list mailing list
Meteorite-list at meteoritecentral.com
http://six.pairlist.net/mailman/listinfo/meteorite-list
Received on Wed 21 Oct 2009 06:59:37 PM PDT