|
|
|
|
|
5th Muharram 1436 | Saturday, Nov 01, 2014
Science

Volcanic eruptions in India, not meteorite, killed dinosaurs

Sunday, 9 December 2012
Comments(0)
Washington, December 09:

Volcanic activity from the Deccan Traps in India, not a meteorite impact, may have killed the dinosaurs, according to a new study.

The research argued that tens of thousands of years of lava flow from the Deccan Traps, a volcanic region near Mumbai in present-day India, may have spewed poisonous levels of sulfur and carbon dioxide into the atmosphere and caused the mass extinction through the resulting global warming and ocean acidification.

The findings are the latest volley in an ongoing debate over whether an asteroid or volcanism killed off the dinosaurs about 65 million years ago in the mass die-off known as the K-T extinction.

"Our new information calls for a reassessment of what really caused the K-T mass extinction," said Gerta Keller, a geologist at Princeton University who conducted the study.

For several years, Keller has argued that volcanic activity killed the dinosaurs.

But proponents of the Alvarez hypothesis argue that a giant meteorite impact at Chicxulub, Mexico, around 65 million years ago released toxic amounts of dust and gas into the atmosphere, blocking out the sun to cause widespread cooling, choking the dinosaurs and poisoning sea life. The meteorite may impact may also have set off volcanic activity, earthquakes and tsunamis.

The new research "really demonstrates that we have Deccan Traps just before the mass extinction, and that may contribute partially or totally to the mass extinction," said Eric Font, a geologist at the University of Lisbon in Portugal, who was not involved in the research.

In 2009, oil companies drilling off the Eastern coast of India uncovered eons-old lava-filled sediments buried nearly 2 miles (3.3 kilometers) below the ocean surface.

Keller and her team got permission to analyze the sediments and found that they contained plentiful fossils from around the boundary between the Cretaceous-Tertiary periods, or K-T Boundary, when dinosaurs vanished.

The sediments bore layers of lava that had traveled nearly 1,000 miles (1,603 km) from the Deccan Traps.

Within the fossil record, plankton species got fewer, smaller and maintained less elaborate shells immediately after lava layers, which would indicate it happened in years after the eruptions. Most species gradually died off. In their wake, a hardy plankton genus with a small, nondescript exoskeleton, called Guembilitria, exploded within the fossil record.

Keller''s team found similar trends in their analysis of marine sediments from Egypt, Israel, Spain, Italy and Texas. While Guembilitria species represented between 80 percent and 98 percent of the fossils, other species disappeared.

Fossils in India revealed that plankton species became smaller, with less elaborate shells, suggesting that sulfur and carbon dioxide from volcanism caused ocean acidification and led to a mass die-off in the seas.

"We call it a disaster opportunist. It''s like a cockroach — whenever things go bad, it will be the one that survives and thrives," Keller told LiveScience.

Guembilitria may have come to dominance worldwide when the huge amounts of sulfur (in the form of acid rain) released by the Deccan Traps fell into the oceans. There, it would''ve chemically binded with calcium, making that calcium unavailable to sea creatures that needed the element to build their shells and skeletons.

Around the same time in India, fossil evidence of land animals and plants vanished, suggesting the volcanoes caused mass extinctions on both land and in the sea there.

In past work, the team has also found evidence at Chicxulub that casts doubt on the notion of a meteorite causing the extinction.

Sediments containing iridium, the chemical signature of an asteroid, show up after the extinction occurred, contradicting the notion that it could have caused a sudden die-off, Keller said.

A meteorite impact also would not have produced enough toxic sulfur and carbon dioxide to match the levels seen in the rocks, so it may have worsened the mass extinction, but couldn''t have caused it, she said.

"The meteorite is just too small to cause the extinction," he claimed.

The findings were presented at the annual meeting of the American Geophysical Union. (ANI)

Latest News

Public awareness needed to check breast cancer: Experts

With around 1.5 lakh breast cancer cases being diagnosed every year in India, health experts Saturda ...

Quitting Ganderbal: Omar's decision stumps all, angers many

Chief Minister Omar Abdullah's decision to quit family political bastion Ganderbal has come as a bol ...

Chandy defends finance minister over graft allegation

Kerala Chief Minister Oommen Chandy Saturday defended Finance Minister K.M. Mani following a graft a ...

Related News

NASA's Mars spacecraft ready for test flight

The US space agency National Aeronautics and Space Administration (NASA) has fully assembled the Or ...

China completes first return mission to Moon

China on Saturday successfully completed its first return mission to the moon with its unmanned orb ...

New drug to generate self-destruct process in lung cancer cells

A drug combination has been discovered which can trigger the self-destruct process in lung cancer ce ...

Post new comment

To combat spam, please enter the code in the image.

Rs. 26020 (Per 10g)

Opinion Poll
Do you think formation of 'She' teams would be beneficial for women's safety?
YesNoCan't say

Matrimony | Photos | Videos | Search | Polls | Archives | Advertise | Letters

© The Siasat Daily, 2012. All rights reserved.
Jawaharlal Nehru Road, Abids, Hyderabad - 500001, AP, India
Tel: +91-40-24744180, Fax: +91-40-24603188
contact@siasat.com