( ing worked out. Chenet is scheduled ...)India's smoking gun: Dino-killing eruptions

Chenet is scheduled to present the latest results of the team's work on Wednesday, 10 August, at Earth System Processes 2, a meeting co-convened by the Geological Society of America and Geological Association of Canada this week in Calgary, Alberta, Canada.

Chenet and her colleagues' new work on the Deccan Traps is just the latest in a series of discoveries which appear to weaken the case implicating the Chicxulub impact as the primary player in the Cretaceous-Tertiary (K-T) mass extinction.

"As originally proposed by Vincent Courtillot in 1986, the volcanism might be a key player in mass extinctions," said Chenet. "Research in India has shown the remnants of the impact - iridium in sediments - sandwiched between lava flows, implying that volcanism started before the impact."

In fact, most mass extinctions over the past 300 million years have coincided with large volcanic events, said Chenet. The general rule is that massive volcanism like the Deccan Traps correlates with all major mass extinctions in Earth's history, she said.

"In only one case is there evidence for both volcanism and impact," she said. And that is the K-T mass extinction that ended the reign of the dinosaurs. "Our view is that impact added to the stress already generated by an ongoing massive eruption, enhancing significantly the extent of the extinction, which would however have taken place even if the impact had not occurred."

Wiped out in the K-T mass extinction were 80-90% of marine species and about 85% of land species. All land animals larger than 25 kg (55 lbs) were obliterated.

The Deccan Traps are a huge pile of basaltic lava extending over more than 500,000 square kilometers. Its original volume likely exceeded 2 to 3 million cubic kilometers, says Chenet. The entire volcanic episode that created the traps took place over about one million years. The source of the massive lava flows is thought to have been the surfac
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Source:Geological Society of America