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Research published today in the journal Science may suggest that the largest mass extinction on Earth was caused by enormous eruptions of lava in Siberia. The Russian and British scientists discovered lavas, known as basalts, in bore holes drilled 4 km deep into the Siberian crust. The basalts are identical to those of the Siberia Traps, an immense province of lavas known as flood basalts that erupted through fissures onto the Earth's surface 250 million years ago. The new discovery suggests that the Siberian Traps are partly buried and are twice as large as previously thought - representing a vast outpouring of lava over an area greater than 2 million square kilometres. The discovery supports claims that the enormous amounts of volcanic gas released by the eruption of the Siberian Traps changed the Earth's climate and caused the Permian-Triassic extinction. Over 85 percent of land creatures and 70 percent of those in the oceans became extinct at this time in what was the largest mass extinction in Earth history. Although some evidence also exists for the impact of a NEO, the fossil record suggests the extinction may have occurred gradually, consistent with climate change due to the eruptions. This contrasts with the sudden extinction 65 m years ago, in which the dinosaurs became extinct, where in addition to flood basalt eruptions a large impact occurred.
More info: Science
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