The link between ancient volcanic eruptions and the deadliest extinction event the world has just witnessed is getting stronger. New analysis of Mercury The isotopes provided evidence that a quarter of a billion years ago, faraway places in Earth’s southern hemisphere were covered with debris from volcanic eruptions in Siberia.
While it’s clear how things ended—with the loss of more than 90 percent of marine species and more than 70 percent of vertebrates living on land—our understanding of how Earth’s largest death event occurred remains a bit cloudy, despite the efforts of geologists.
By piecing together chemical traces trapped in rocks and ocean sediments, geoscientists are fairly confident that a series of volcanic eruptions triggered a series of dramatic changes in the Earth’s atmosphere and oceans that Ultimately asphyxiated animals.
But a major extinction event occurred The great death It also needs a very strong case before geoscientists can conclusively say why and when it happened. They are revisiting back in time some 252 million years ago, after all.
In previous research, zinc and Nickel They have been used to link changes in ocean chemistry to supervolcanoes and loss of marine life. But these elements are recycled on Earth’s surface, unlike their isotopes Mercury which provide a more stable indication of volcanic activity.
Also, many studies of this mass extinction event have focused on locations from the northern hemisphere, making it difficult to understand the impact of volcanoes on the underside of the Earth. This is important because mounting evidence indicates that the Great Dying was not a single fatal event, but multiple extinctions that occurred in waves over a hundred thousand years.
So, paleoclimatologist Jun Shen of the University of Geosciences of China and colleagues set out to find out Mercury Isotopes in rock deposits at two locations in the Southern Hemisphere: the Karoo Basin in south-central Africa and the Sydney Basin on the east coast of Australia.
At the time of the Great Dying, the basins were united into one supercontinent called Pangea, but is now separated by about 10,000 km (6,200 mi) and the Indian Ocean. In them, the researchers found almost identical patterns: Mercury Isotopes peaked around the end of the Permian period.
This evidence suggests – from what are so far the most remote terrestrial sites of the Siberian Traps, gigantic lava flows formed by the epoch-ending volcanoes in question – Mercury The researchers said that the volcanoes are in the northern hemisphere and spread all over the world.
It turned out to be volcanic emissions Mercury It has a very specific isotopic composition of Mercury that accumulated on the horizon of extinction,” Explain Study author and University of Connecticut geologist Tracy Frank.
“Knowing the age of these deposits, we can definitively relate the timing of the extinction to this colossal eruption in Siberia.”
Their work corresponds to Signals of sulfur isotopes In conjunction with the “great death”, and also builds on it previous search Which indicates that mass extinctions occurred on land up to 600,000 years before marine life was sucked in its last few breaths.
“This indicates that the event itself wasn’t just one big blow that happened instantly,” he said. Explain Christopher Fielding, another University of Connecticut geologist.
“It wasn’t a very bad day on Earth, so to speak, it took some time to build and that feeds well into the new findings because it suggests that volcanism was the root cause.”
The researchers acknowledge that determining the direct cause of the Great Death is not easy. Ash plumes from Volcanic eruptions in southern China It was also implicated in the massacre, as well as the Siberian Traps.
So, trying to reconstruct the sequence of events that led to Earth’s largest extinction event, perhaps the most remarkable message to internalize is the fragility of life on a violent planet that is today under pressure from many of the same climate changes: rising temperatures and greenhouse gases.
Research published in Nature Communications.
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