Ancient Volcanic Eruptions Caused Global Mass Extinction

A previously unknown giant volcanic eruption that led to global mass extinction 260 million years ago has been uncovered by scientists at the University of Leeds.

The eruption in the Emeishan province of south-west China unleashed around half a million cubic kilometres of lava, covering an area 5 times the size of Wales, and wiping out marine life around the world.

Unusually, scientists were able to pinpoint the exact timing of the eruption and directly link it to a mass extinction event in the study published in Science. This is because the eruptions occurred in a shallow sea – meaning that the lava appears today as a distinctive layer of igneous rock sandwiched between layers of sedimentary rock containing easily datable fossilised marine life.

The layer of fossilised rock directly after the eruption shows mass extinction of different life forms, clearly linking the onset of the eruptions with a major environmental catastrophe.

The global effect of the eruption is also due to the proximity of the volcano to a shallow sea. The collision of fast flowing lava with shallow sea water caused a violent explosion at the start of the eruptions – throwing huge quantities of sulphur dioxide into the stratosphere.

Oh, man I love igneous rock! I once got a very pretty girl to go out with me because I dazzled her talking about igneous rock! The things you remember as you get old!:)

Thanks LucyT for the ping, and george76 for the topic. Of course, the volcanism "explanation" will always be found wanting because it doesn't leave the proxy data found at the paleontological boundaries, but that's the gradualist ninnies for ya.

Asteroid 'destroyed life 250m years ago'
by Dr David Whitehouse
Friday, February 23, 2001
Earth's biggest mass extinction 251 million years ago was triggered by a collision with a comet or asteroid, US scientists say. They have reached this conclusion by looking at atoms from a star trapped inside molecular cages of carbon...

In rock layers laid down at the time, there is a much higher concentration of complex carbon molecules called fullerenes that have different types, or isotopes, of helium and argon trapped inside them. These molecules could only have been delivered from space, the researchers say...

The researchers believe these particular fullerenes are extraterrestrial because the gases trapped inside have an unusual ratio of isotopes that indicate they were made in the atmosphere of a star that exploded before our Sun was born...

The telltale fullerenes were extracted from sites in Japan, China and Hungary, where the sedimentary layer at the boundary between the Permian and Triassic periods had been exposed...

The research was made difficult because there are few 251-million-year-old rocks left on Earth. Most rocks of that age have been recycled through the planet's tectonic processes...

Researchers estimate the comet or asteroid was six to 12 km (3.7 - 7.4 miles) across, or about the size of the asteroid believed responsible for the extinction of the dinosaurs 67 million years ago...

The mass extinction of 251 million years ago was the greatest on record.



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This is the Permian/Triassic extinction, the one which separated the time of domination of mammal-like reptiles from the time of the dinosaurs, I guess. Isn’t there a really ‘gradualist’ theory that tries to blame the extinction on the existence of the Pangaea supercontinent, and the likely extreme continental climate? That one is really hard to credit.

There’s a real impact-denial (’: movement among some dimwits in the UK and various (mostly east coast) US camp-followers. Also, beginning with Dewey McLean, quite a number of nimrods have saddled on the lowly volcano as a vehicle for mass extinctions — that is, now that they’ve finally accepted the idea that there were mass extinctions. :’)

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