An Explanation for Mass Extinction

The Permian–Triassic extinction devastated life on Earth 250 million years ago: it killed 96% of marine species and 70% of land-based vertebrate organisms. The reason may have been a volcanic explosion in coal deposits in Siberia. Some days later, ash from the eruption, raining down onto the Canadian Arctic, sucked oxygen from the water and threw toxic elements.

Stephen Grasby, a geochemist, and his colleagues have found three distinct layers of coal ash -fine particles that are freed when coal burns- in rock sediments just before the Permian–Triassic extinction.

 Experts have said for years that volcanoes in Siberian were responsible for the extinction event. There, some rock formations were formed by volcanic activity occurring about the same time as the mass extinction. But with volcanic eruptions so common in history, extra factors must have been involved. In this case, about 500,000–750,000 years before the extinction event, magma went up underground and hit a coal deposit. The mix was explosive and broke the Earth's surface.

Studies have suggested the volcanoes released 3 trillion tonnes of carbon, enough to cause massive climate change. The eruptions also caused acid rain and created an ozone hole. Toxic ash may have been the final blow.

The discovery is so crucial that other studies of extinction events should be examined for the presence of ash.

Extracted from an article by Gayathri Vaidyanathan in Nature News.