‘Dinosaur-killer meteorite crashed off India’s west coast’

[Sridhar]

‘Dinosaur-killer meteorite crashed off India’s west coast’ Washington: A meteorite more than 40 km wide and hurtling towards Earth at 58,000 miles an hour that killed dinosaurs 65 million years ago, had actually crashed off India’s west coast, an Indian-origin professor has claimed.
“Largest crater” Sankar Chatterjee of Texas Tech University, who presented his research this month at a meet in the Geological Society of America in Portland, Oregon, on Sunday, said, “If we are right, massive Shiva basin, a submerged depression west of India is the largest crater known on our planet.”
Mr. Chatterjee, who along with a team of researchers took a close look at the Shiva basin that is intensely mined for its oil and gas resources, said: “It is probably the largest, multi-ringed impact crater the world has ever seen and a bolide of this size, perhaps 40 km in diameter, creates its own tectonics.”
“Work done by a research team of Indians and Americans, working with information released by the companies operating in the area, has provided the strongest evidence to date that this was the spot where the dinosaur-killer hit,” he said.
He rejected earlier arguments that dinosaurs were killed after a giant asteroid slammed into the planet near Mexico’s Yucatan Peninsula.
‘Dramatic’ According to the Geological Society of America, the geological evidence is dramatic. Shiva’s outer rim forms a rough, faulted ring some 500 km in diameter, encircling the central peak, known as Bombay High.
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. — PTI



The Hindu : Front Page : ‘Dinosaur-killer meteorite crashed off India’s west coast’

 

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Dinosaurs 'could have been wiped out by 25 mile wide meteor'

Dinosaurs may have been wiped out by a massive 25 mile wide meteor - four times bigger than the asteroid previously though to be behind their extinction.



Published: 7:00AM BST 19 Oct 2009

The deepest part of the Shiva basin, in red in this elevation diagram, is three miles below the surface of the Indian Ocean Photo: KYLE MCQUILKIN


Researchers believe they have discovered the world's biggest crater off the coast of India which they think may be responsible for the extinction of dinosaurs 65 million years ago.
The mysterious Shiva basin, named after the Hindu God, has a diameter of 310.7 miles along the seafloor and has a central peak of some 3 miles, as tall as Mount McKinley, the highest mountain in North America.


This dwarfs the meteor that was thought to have killed off the dinosaurs which measured between five and six miles and lies in the Yucatan Peninsula in Mexico.
That impact left a crater with a diameter of 180 kilometres.
Sankar Chatterjee of Texas Tech University, who led the research, said: "If we are right, this is the largest crater known on our planet.
"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."
Asteroids are rich in iridium, and such anomalies are thought of as the fingerprints of an impact.
Mr Chatterjee believes the impact of an asteroid or comet of this size would have vaporized the Earth's crust on collision, killing most life and leaving ultra-hot mantle material to well up in its place.
The force of the impact broke the Seychelles islands off of the Indian tectonic plate and sent them drifting towards Africa. Much of the 30-mile-thick granite layer in the western coast of India was also destroyed.
Most of the crater lies submerged on India's continental shelf, but some tall cliffs rise above the sea, bringing active faults and hot springs. The area is a rich source of oil and gas reserves.
The team plans to visit India again to drill into the centre of the crater for clues to prove the basin was formed by a gigantic impact.
Mr Chaterjee will present his research this month at the Annual Meeting of the Geological Society of America.



Dinosaurs 'could have been wiped out by 25 mile wide meteor' - Telegraph

 

[Sridhar]

Shiva Basin – the largest Crater



By Shree
Mumbai: Sankar Chatterjee of Texas Tech University presented his research of a meteorite more than 40 km wide and speeding 58,000 miles an hour towards the Earth, which had killed dinosaurs 65 million years ago, had crashed off India’s west coast.
He put forward the study to the Geological Society of America in Portland, Oregon, on Sunday. According to the study the massive Shiva basin which is a submerged depression on west of India is the largest crater known on the planet with 40 km diameter.
Work done by a research team of Indians and Americans, working with information released by the companies operating in the area, has provided the strongest evidence to date that this was the spot where the dinosaur-killer hit.
Chatterjee rejected former arguments that dinosaurs were killed after a giant asteroid slammed into the planet near Mexico’s Yucatan Peninsula.


Shiva Basin ? the largest Crater | Duniyalive.com

 

[Sridhar]

'Mega meteor that crashed off Indian coast' may have wiped out dinosaurs



By Daily Mail Reporter
Last updated at 12:55 PM on 19th October 2009

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The dinosaurs may have been wiped out by a meteor four times bigger than the one previously thought to have caused their extinction.

Scientists believe a 25-mile wide meteor crashed into the ocean off the west coast of India, creating the 310-mile wide Shiva basin.
Sankar Chatterjee of Texas Tech University and his team are now analysing the submerged basin, in the hope it will prove their theory.

A meteor impact is thought to have wiped out the dinosaurs, but scientists now believe the killer rock may have landed in India, not Mexico
'If we are right, this is the largest crater known on our planet,' Chatterjee said.
The meteor would dwarf the six-mile rock that left a 112-mile crater in the Yucatan Peninsula in Mexico, which is commonly thought to have killed the dinosaurs 65million years ago.


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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.

The impact would have also broken the Seychelles islands off of the Indian tectonic plate, and sent them drifting toward Africa.


Enlarge 3D reconstruction of the submerged Shiva crater on the western shelf of India. It is four times as large as the meteor crater in Mexico thought to be responsible for the demise of the dinosaurs
The geological evidence is dramatic. Shiva's outer rim forms a rough, faulted ring, encircling the central peak, known as the Bombay High, which would be three miles tall from the ocean floor. The area is heavily mined for its oil and gas.

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 centre 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.

Read more: http://www.dailymail.co.uk/sciencet...ega-meteor-wiped-dinosaurs.html#ixzz0US8ATRJU
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[Sridhar]

Did Mumbai Meteor kill the dinosaurs?

Scientists believe the biggest meteor to hit our planet was near Mumbai; and a new study says that it probably was what led to dinosaur extinction...


By Mumbai Mirror Bureau
Posted On Monday, October 19, 2009 at 03:15:49 AM

Sankar Chatterjee who headed the study​

Imagine a meteorite more than 40 kilometres wide hurtling toward Earth at 58,000 kilometres per hour. The impact would create mass extinctions, perpetual night for more than a year, tsunamis and massive volcanic activity. Aamchi Mumbai was host to just such a cataclysmic event about 65-million-years ago.

This scenario may sound like a predictible Hollywood movie but the event is more fact than just fiction. The exact scenario played out near present-day Mumbai, and could potentially be the smoking gun that ended the dinosaurs’ reign on Earth.

Though many scientists attributed the dinosaur extinction to the Chicxulub Crater off the coast of Mexico’s Yucatan Peninsula, scientists at Princeton University recently refuted this theory because evidence showed that meteor struck 3,00,000 years before the demise of dinosaurs.

However, Sankar Chatterjee, curator of palaeontology at the Museum of Texas Tech University and his colleagues recently published further evidence from the Indian impact site, known as the Shiva Crater, which suggests the meteorite struck at the same time as the mass extinction and created enough catastrophic force to destroy 70 per cent of Earth’s plant and animal communities on land and in the seas.

For the past few years, Chatterjee has used geophysical evidence and core samples collected by oil companies to reconstruct the Shiva Crater – a massive 483-mile-wide pock mark with peaks as high as Mount Everest. Though the actual crater is covered by more than five miles of sediment, Chatterjee says the geological evidence he collected allowed him to map out the crater.

Most of the crater , however, 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 also appears to have destroyed much of the 30-mile-thick granite layer in the western coast of India.

The massive Shiva basin is also intensely mined for its oil and gas resources. Some complex craters like Shiva are among the most productive hydrocarbon sites on the planet.

The impact might also be connected with massive volcanic activity on the Indian Continent, he said. This sudden activity, known as the Deccan Trap, resulted in half a million cubic miles of lava flooding the western part of India in a short amount of time. This great lava event coincides with the meteorite.

“The Shiva impact made the western coast of India seismically active and caused the plate movement separating India from the Seychelles Island,” Chatterjee said, adding that the meteorite probably led to the sudden northward acceleration of the Indian plate, then a continent located south of the equator, to collide with Asia and form the Hmalayas.

Chatterjee will present his research at this month’s Annual Meeting of the Geological Society of America in Oregon, US.


“If we are right, this is the largest crater known on our planet,” Chatterjee said. “A bolide of this size, perhaps 40 kilometres in diameter creates its own tectonics (folding and faulting of the earth’s crust).”

By contrast, the object that struck the Yucatan Peninsula, and is commonly thought to have killed the dinosaurs was between 8 and 10 kilometres wide.

“With a meteorite of this magnitude, it would create a huge crater as soon as it hit the surface. Rocks would be vaporised and send dust and debris into the air that would block out the sun,” he added.

The fallout from the meteorite, which Chatterjee calculated to have 10,000 times more force than the detonation of the world’s entire nuclear arsenal, would place the world into perpetual night for more than a year. Red-hot rock would rain from the skies, sparking massive global forest fires and causing acid rain that would kill shelled organisms in the oceans and cause massive collapse of the food chain.

“Anything bigger than 25 pounds (11.3 kilos) was wiped out,” he said. “Animals that lived in the river water, such as crocodiles and alligators, survived, but most animals on land and in the oceans were the main victims.” Did Mumbai Meteor kill the dinosaurs?, Specials - SciTech - Pune Mirror,Pune Mirror

 

[Sridhar]

New dinosaur extinction theory causes debate

Scientist says crater in India shows space rock impact that killed dinos

An artist rendering of a space rock streaking toward Earth. Most experts think an impact off the Yucatan Peninsula 65 million years ago was the primary cause of the dinosaur demise. Others think volcanism and climate change may have played a role. A new and controversial idea suggests there was another, larger impact in India that was responsible.

By Clara Moskowitz

updated 3:57 p.m. ET Oct. 19, 2009

The extinction of the dinosaurs has often been traced to a giant space rock impact on the Earth 65 million years ago. But now a scientist is saying experts have blamed the wrong impact. The new thinking was met with sharp criticism from other researchers, however.
Paleontologist Sankar Chatterjee of Texas Tech University says a giant basin in India called Shiva could also be an impact crater from the time of the dinosaurs' demise, and the crash that created it may have been the cause of the mass extinction scientists call the KT (Cretaceous–Tertiary) event, which killed off more than half the Earth's species along with the dinos. This argument runs counter to the widely-held wisdom that the Chicxulub impact on the Yucatan Peninsula off Mexico was behind the cataclysm.
Chatterjee presented his argument Sunday at the Annual Meeting of the Geological Society of America in Portland, Ore.
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Some of his fellow scientists are skeptical, though.
Volcanoes or space rocks
The cause of the dinosaurs' demise is far from an open-and-shut case. Though many experts support the Chicxulub impact theory, some question whether the extinction was caused by an impact at all, and suggest that climate changes and volcanism were responsible. One line of reasoning holds that all three phenomena were to blame.
Gerta Keller, a geoscientist at Princeton University, found evidence for massive volcanic activity coinciding with the time of the extinction in an area called the Deccan Traps in India. Keller has advocated that this volcanism was the main culprit behind the dinosaurs' downfall. Her idea has long been controversial and remains so. She is bluntly dubious of Chatterjee's argument.
"We have worked extensively throughout India and investigated a number of the localities where Sankar Chatterjee claims to have evidence of a large impact he calls Shiva crater," Keller wrote in an e-mail along with colleague Thierry Adatte of Switzerland's Universite de Neuchâtel. "Unfortunately, we have found no evidence to support his claims. ... Sorry to say, this is all nonsense."

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Chatterjee cites a number of geologic features found near the Shiva site to suggest that it's a crater, including shocked quartz known to be created during impacts, and iridium, an element found abundantly in meteorites and which is relatively rare in the Earth's crust.
"These are the things which only can be found by impact," Chatterjee told SPACE.com.
But Keller said each of these signals can be ascribed to causes other than a space rock impact. For example, the shocked quartz lacks the telltale signs denoting a high velocity impact shock, and the iridium dates from another time period than the KT era, she contends.
And though Chatterjee's abstract was approved by conference organizers for the Geological Society of America meeting, this research has not been peer-reviewed in a scientific journal.
The impact idea
The prevailing theory behind the mass extinctions remains the Chicxulub impact idea.
"I would say 95 percent or more of the earth scientists who study the KT boundary are in agreement that Chicxulub is the event that brought on the KT mass extinctions," said geophysicist Sean Gulick of the University of Texas at Austin.
As for the Shiva hypothesis, Gulick was very doubtful.
"There's a bunch of problems to say the least," Gulick said of Chatterjee's hypothesis. "There is no evidence that he's presenting of it actually being a crater."
Gulick said that the Shiva impact features noted by Chatterjee could easily have resulted from the Chicxulub impact, which is thought to have kicked up material that circled the globe.
"There is an event layer caused by the impact that is everywhere," Gulick said in a phone interview. "There's evidence globally for the shocked quartz, the iridium. As you approach Mexico the event layer gets thicker and thicker. He's got no local evidence it's an impact."
Gulick also objects to the size of the supposed Shiva crater, which Chatterjee claims is the largest impact crater known on Earth with a diameter of about 310 miles. That would make it about three times wider than Chicxulub, which has a diameter of about 110 miles.


Such a large impact occurring at the same time as the confirmed Chicxulub impact seems unlikely, Gulick said.
The oblong shape of Shiva is also suspect for an impact crater, as most are round, Gulick said. To have created an oval-shaped crater an incoming asteroid would have had to skim in at a very shallow angle, which is a rare occurrence.
Chatterjee admitted these are coincidences, but suggested that maybe both the Chicxulub and Shiva impacts spawned from one massive space rock, which broke apart into two main pieces. And as for the angle — it's rare but not unheard of, he said.

New dinosaur extinction theory causes debate - Space- msnbc.com