Scientists say that mercury buried in old stone gives the strongest evidence that volcanoes caused the greatest mass extinction in the history of the earth.
252 million years ago, the extinction was so dramatic and widespread that scientists call it "The Great Dying." The catastrophe killed more than 95 percent of life on earth for hundreds of thousands of years.
Paleontologists at the University of Cincinnati and China's University of Earth Sciences said they found a nail in mercury in the geological record of nearly a dozen places around the world, providing convincing evidence that volcanic eruptions would blame this global catastrophe.
The study was published this month in the journal Nature Communications .
The outbreak ignited coal deposits, which releases mercury vapor high into the atmosphere. Eventually it rained down into the marine sediments around the world and created an elementary signature of a disaster that would mean the age of the dinosaurs.
"Volcanic activities, including the release of volcanic gases and the combustion of organic matter, released abundant mercury into the surface of the earth," said senior author Jun Shen, a professor at the University of China's Geosciences University.
Mass extinction occurred at which researchers call the Permian-Triassic Boundary. Mass extinction killed much of the terrestrial and marine life before the emergence of dinosaurs. Some were prehistoric monsters in themselves, like the grymonopsides that looked like a cross between a saber-toothed tiger and a Komodo dragon.
Outbreaks occurred in a volcanic system called Siberian traps in what is now central Russia. Many of the eruptions did not occur in cone-shaped volcanoes but through gaping cracks in the ground. The outbreaks were frequent and prolonged and their fury stretched over a period of hundreds of thousands of years.
"When you have large explosive volcanic eruptions, a lot of mercury is released into the atmosphere," said Thomas Algeo, a professor of geology at UC's McMicken College of Arts and Sciences.
"Mercury is a relatively new indicator for researchers. It has become a hot topic to investigate volcanic influences on major events in Earth's history," Algeo said. [1
The outbreaks drove as much as 3 million cubic meters of ash high up in the air during this longer period. To put it in perspective, the 1980 outbreak of Mount St. Helens in Washington only 1 cubic kilometer ash in the atmosphere, although ash fell on the car window as far away as Oklahoma.
In fact, Algeo said outbreaks of Siberian traps spewed so much material into the air, especially greenhouse gases, that it warmed the planet by an average of about 10 degrees Celsius.
The heat climate would probably have been one of the greatest sins of mass extinction, he said. But acid rain would have destroyed many water bodies and increased the acidity of the global oceans. And the warmer water would have had more dead zones from lack of dissolved oxygen.
"We have often left the scraping head about what was most harmful. Creatures that were adapted to colder environments would have been unlucky" Algeo said. "So my guess is that temperature change would be the No. 1 killer. The effects would be aggravated by acidification and other toxins in the environment."
Stretching over a long time prevented outbreaks after the outbreak of the earth's food chain to recover.  "It's not necessarily the intensity but how long it is," Algeo said. "The longer this went on, the more pressure on the environment."
Similarly, the earth was slow to recover from the disaster, as the ongoing disturbances continued to wipe out biodiversity, he said.
The Earth has witnessed five known mass extinctions over its 4.5 billion years.
Researchers used another elemental signature iridium to determine the likely cause of global mass extinction that obliterated the dinosaurs 65 million years ago. They believe that a huge meteor hit what is now Mexico.
The resulting plum of superheated soil blown into the atmosphere rained down material containing iridium contained in the geological record around the world.
Shen said the mercury signature provides convincing evidence that outbreaks of Siberian traps were responsible for the disaster. Now, researchers are trying to reduce the extent of the outbreak and what environmental impacts were mainly most responsible for the mass reduction, especially for ground animals and plants.
Shen said the perishing extinction could shed light on how global warming today can lead to the next mass extinction. If global warming was actually responsible for the Permian die-off, what warming gives rise to humans and wildlife today?
"Emissions of coal into the atmosphere of humans are similar to the situation in the late perm, where abundant coal was released by the Siberian outbreaks," Shen said.
Algeo said it's worrying.
"A majority of biologists believe we are facing another mass extinction – the sixth major. Share that perception, too," says Algeo. "What we should learn is that this will be serious business that will harm human interests so that we should work to minimize the damage. "
People living in marginal environments like dry deserts will suffer first. It will lead to more climate refugees around the world.
" We will probably see more famine and mass migration at the hardest hit sites. It is a global issue and one that we should recognize and proactively manage. It is much easier to deal with these problems before they reach a crisis. "
Geochemical analysis of Chinese stones was used to better understand the perm-triassic mass extinction
Jun Shen et al., Evidence of an Extended Permian-Triass Extinction Range from Global Marine Mercury Items, Nature Communications (2019). DOI: 10,1038 / s41467-019-09620-0
New evidence suggests that volcanoes caused the greatest mass extinction ever (2019, April 15)
downloaded April 15, 2019
This document is subject to copyright. Except for any fair trade for private study or research, no
Some may be reproduced without written permission. The content is provided for informational purposes only.