New evidence on Cretaceous-Tertiary mass extinction - not a single meteor strike

Mickeroo

So a couple of new studies have found evidence that a combination of a huge series of eruptions at the Deccan Traps in India and a series of meteor impacts brought about the Cretaceous-Tertiary mass extinction rather than one single large meteor impact.

Princeton-led researchers found that a trail of dead plankton spanning half a million years provides a timeline that links the mass extinction to large-scale eruptions of the Deccan Traps, a primeval volcanic range in western India that was once three-times larger than France. A second Princeton-based group uncovered traces of a meteorite close to the Deccan Traps that may have been one of a series to strike the Earth around the time of the mass extinction, possibly wiping out the few species that remained after thousands of years of volcanic activity.

Researchers led by Princeton Professor of Geosciences Gerta Keller report this month in the Journal of the Geological Society of India that marine sediments from Deccan lava flows show that the population of a plankton species widely used to gauge the fallout of prehistoric catastrophes plummeted nearly 100 percent in the thousands of years leading up to the mass extinction. This eradication occurred in sync with the largest eruption phase of the Deccan Traps — the second of three — when the volcanoes pumped the atmosphere full of climate-altering carbon dioxide and sulfur dioxide, the researchers report. The less severe third phase of Deccan activity kept the Earth nearly uninhabitable for the next 500,000 years, the researchers report. A substantially weaker first phase occurred roughly 2.5 million years before the second-phase eruptions.

Another group based in Keller's lab found evidence in Indian sediment of a meteorite strike from the time of the mass extinction that would have been sufficient to finish off the few but weakened species that survived the Deccan eruptions, according to a report in the journal Earth and Planetary Science Letters (EPSL) in October. This same sediment -- located in Meghalaya, India, more than 600 miles east of the Deccan Traps -- portrayed the Earth during this period as a harsh environment of acid rain and erratic global temperatures.

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Rubecula

I was laughed at in a lecture for suggesting this scenario.

How times change eh?

Adam Khor

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