Friday, March 21, 2008
Did volcanic sulphur kill dinosaurs 65 million years ago?
A series of eruptions that formed India's hilly Deccan Traps also pumped huge amounts of sulphur into the atmosphere 65 million years ago - with devastating effects on the Earth's climate, the researchers believe.
Gigantic eruptions are one of two leading explanations for a series of mass extinctions that have killed off vast numbers of species periodically over the last 545 million years.
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Other scientists have blamed asteroids hitting the Earth - generally considered the prime suspect in the case of the extinction of dinosaurs 65 million years ago.
Up to now there had been doubts about the killing power of volcanoes because researchers had struggled to measure just how much toxic gas would have been released.
But excavations in the Deccan volcanic rock - known as flood basalt - led to the discovery of traces of glass, allowing the British-based team to analyse the gases it originally contained.
Writing in the journal Science, they conclude that the massive of amounts of both sulphur and chlorine released in the Deccan eruptions would probably have had a "severe" environmental impact.
"Gases from a series of eruptions of the Deccan Traps may have 'battered away' at life on the planet at the time, leading to the mass extinctions,” said volcanologist Stephen Self of the Open University in Milton Keynes.
"It certainly bolsters the case, though it doesn't prove it," he added.
"There have been several major mass extinctions and most of those have, uncannily, occurred while one of these huge flood basalt provinces was being formed."
Evidence: India's Deccan Traps were formed by lava from eruptions at the time of the dinosaurs' extinction.
The volcanoes may have spewed 10 times more sulphur into the atmosphere annually than humans have done recently by burning coal in power stations and through other industrial activities.
The result would have been sulphuric acid in the atmosphere and widespread acid rain, with the surface of the Earth being cooled down and normal patterns of weather circulation being disrupted.