Study ties most severe extinction to ancient volcanic activity

August 31, 2015 by Bob Yirka report
volcanic ash
Credit: NASA

(Phys.org)—A pair of researchers with MIT has found a way to set a time line for volcanic activity in what is now Siberia, over 250 million years ago, and the worst mass extinction that ever occurred on our planet. In their paper published in the journal Science Advances, Seth Burgess and Samuel Bowring describe how they were able to precisely date both the volcanic activity and the mass extinction that occurred, tying the two events together.

Scientists have known for quite some time that a mass extinction occurred at the end of the Permian period, causing the extinction of approximately 90 percent of all , and 75 percent of land dwellers. They also knew that some massive volcanic activity had occurred in what is now Siberia, perhaps during roughly the same time period. Because of this, there were suggestions that the eruptions had caused the extinctions, but until now, no one had been able to time either event precisely enough to show that was what really happened.

To obtain such , the two researchers used radioactive dating techniques on hundreds of samples scattered across approximately 2.5 million square kilometers of land, noting the differences in crystals that would have come from material that was explosively ejected versus others that were likely part of voluminous magna (approximately 3 million cubic meters) that also came from the volcanoes. Ratios of uranium to lead in the crystals allowed for creating a timeline. Their analysis indicated that the period of began approximately 300,000 years before the start of the mass extinction and then continued on for another half million years. This suggests that the was indeed caused by the eruptions—high levels of carbon dioxide and other gases would have been spewed into the atmosphere, causing very serious climate change, including acidification of the oceans—making life very difficult for all living things on the planet.

Still unexplained, however, is why the planet took so long to make a comeback—prior research has shown it took between five and ten million years for the Earth's climate to return to a state that was capable of hosting a more diverse ecosystem.

Explore further: Timeline of a mass extinction: New evidence points to rapid collapse of Earth’s species 252 million years ago

More information: High-precision geochronology confirms voluminous magmatism before, during, and after Earth's most severe extinction, Science Advances  28 Aug 2015:
Vol. 1, no. 7, e1500470. DOI: 10.1126/sciadv.1500470

Abstract
The end-Permian mass extinction was the most severe in the Phanerozoic, extinguishing more than 90% of marine and 75% of terrestrial species in a maximum of 61 ± 48 ky. Because of broad temporal coincidence between the biotic crisis and one of the most voluminous continental volcanic eruptions since the origin of animals, the Siberian Traps large igneous province (LIP), a causal connection has long been suggested. Magmatism is hypothesized to have caused rapid injection of massive amounts of greenhouse gases into the atmosphere, driving climate change and subsequent destabilization of the biosphere. Establishing a causal connection between magmatism and mass extinction is critically dependent on accurately and precisely knowing the relative timing of the two events and the flux of magma. New U/Pb dates on Siberian Traps LIP lava flows, sills, and explosively erupted rocks indicate that (i) about two-thirds of the total lava/pyroclastic volume was erupted over ~300 ky, before and concurrent with the end-Permian mass extinction; (ii) eruption of the balance of lavas continued for at least 500 ky after extinction cessation; and (iii) massive emplacement of sills into the shallow crust began concomitant with the mass extinction and continued for at least 500 ky into the early Triassic. This age model is consistent with Siberian Traps LIP magmatism as a trigger for the end-Permian mass extinction and suggests a role for magmatism in suppression of post-extinction biotic recovery.

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Steve 200mph Cruiz
5 / 5 (3) Aug 31, 2015
I don't see why they think it's strange that it took so long for life to comeback.
The earths climate was fundamentally changed, the equatorial terrain and oceans became uninhabitable, lost its ice caps, different kinds of microbes proliferated and released more methane, the ph in the oceans dramatically changed, planktons changed, coral reefs disappeared, and the earth became largely devoid of forests.

Of course it took millions years to recover from that, it was a pretty big deal, and there might have been an asteroid impact/ more triggers on top of it.
KeithMcC
5 / 5 (2) Sep 02, 2015
"3 million cubic meters"

PhysOrg: That's KILOMETERS !!!

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