Chinese scientists have found evidence that the Permian Extinction, the largest catastrophe in Earth's history, occurred in “moments” by geological standards, in a matter of thousands of years. Their findings were presented in the GSA Bulletin magazine.
“Most likely, 90% of the animal species that existed in the Permian period disappeared in a few thousand years or even less. Current dating techniques do not allow us to narrow this estimate down to less than 30 thousand years,”says Shen Shuzhong of the Institute of Geology and Paleontology of the CAS in Nanjing, China.
Scientists have identified the five largest mass extinctions of species in the history of life on Earth. The most significant is considered the "great" Permian extinction, when more than 95% of all living beings inhabiting the planet disappeared, including bizarre beast-lizards, close relatives of mammalian ancestors, and a number of marine animals.
There is evidence that large quantities of carbon dioxide and methane were released into the atmosphere and oceans during this time, dramatically changing the climate and making the Earth extremely hot and arid. As studies by Russian geologists show, these emissions came to the surface of the planet on the territory of Eastern Siberia, in the vicinity of the Putorana and Norilsk plateaus, where the most powerful outpourings of magma took place about 252 million years ago.
Most scientists today are confident that these outpourings of lava were implicated in the extinction of animals, but the exact mechanism of their action on the Earth's climate and ecosystems remains a matter of controversy.
Some geologists believe that its action was "instantaneous" - it immediately killed a huge number of animals, while their opponents believe that the extinction could extend over several million years and was associated with a number of indirect environmental consequences of these outpourings.
Shuzhong and his colleagues found that the proponents of the first theory were much closer to the truth, studying the rocks that were formed during eruptions in Siberia on the seabed that covered almost the entire surface of modern China in the late Paleozoic.
They managed to find extremely unusual deposits in the central regions of Guanxi province, which simultaneously told them about how quickly the animals died, and how the process of their extinction proceeded.
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This part of China at that time was covered with a large amount of shallow waters, the sediments on the bottom of which formed about 100 times faster than in other parts of the Earth. Thanks to this, traces of the end of the Permian era, including the fossilized remains of marine fauna, have been preserved much better here, which allowed scientists to very accurately calculate their age and understand when the disaster began and what it was connected with.
As their calculations show, the Permian extinction began about 251 million 939 thousand years ago, which coincides in time with the peak of the eruptions on the Putorana plateau. At this moment in time, as the remains of the Guanxi fauna of that time show, the sea floor was covered with a thick layer of volcanic ash, and about a third of the species of marine animals that lived in the seas at that time on the site of the future China disappeared without a trace.
The reason for this, judging by the changes in the proportions of isotopes of oxygen and carbon, was that the temperatures of air and water rose sharply by 5-10 degrees Celsius. This probably led to a sharp restructuring of oceanic and atmospheric "conveyors" of currents and winds and extremely dramatic changes in the work of ecosystems in all corners of the Earth.
All this, as scientists note, suggests that the outpouring of magma in Eastern Siberia almost instantly killed the flora and fauna of the Permian period, spending from a couple of thousand to 30 thousand years on it. This casts doubt on theories suggesting that the Permian extinction had several phases and stages, geologists conclude.
