While the connection between the world's worst extinction and volcanic eruptions has been established before, this link has gotten even stronger. According to Science Alert, new mercury analyses have revealed proof that around 250 million years ago, distant areas in the Southern Hemisphere were filled with volcanic debris from Siberia.
Behind the Great Dying Is Earth's Worst Extinction
The most massive extinction event, dubbed the Great Dying, led to over 90% marine species loss and over 70% land-based vertebrate species loss. According to Live Science, recovery from the Great Dying was quite low compared to other mass extinctions. It was only after around 10 million years that the earth became repopulated and diverse once more.
Though the ending of such events was clear, the general understanding of how this mass extinction event unfolded still remains unclear despite the great efforts of specialists.
By working through pieces of chemical remnants that were trapped in oceanic sediments and rocks, the specialists are quite sure that various volcanic eruptions led to massive alterations in the oceans and atmosphere that led animals to become suffocated. However, an event as massive as the Great Dying requires solidity before geoscientists can draw conclusions.
Based on previous research, both nickel and zinc were used to connect oceanic chemistry changes with great volcanism and marine species loss. However, such elements get recycled within the surface of earth. This is unlike mercury isotopes, which give a sign of volcanic activity that is significantly steadier.
Aside from this, several studies on this extinction event intricately focused on northern hemisphere areas. This makes it hard to know how volcanoes affected the southern parts. Such a case is important because evidence suggests that this massive extinction event was not a singular deadly occurrence but several extinctions that episodically took place.
Was the Great Dying a Singular Event or a Series of Extinctions?
With this, Jun Shen, a paleoclimatologist from the China University of Geosciences, along with colleagues, tried to trace mercury isotopes within rocks across two locations in the Southern Hemisphere. These were, namely, the Sydney Basin and the Karoo Basin.
Within these basins, the researchers were able to find patterns that were almost identical. More specifically, they noticed how isotopes of mercury were peaking around the Permian end.
Science Alert reports that such evidence suggests that mercury could have been expelled from Northern Hemisphere volcanoes and transported throughout the globe. Study author Tracy Frank, a geologist from the University of Connecticut, notes how mercury volcanic explosions have a particular isotopic composition. He notes that by knowing the deposit age, they could conclusively time the extinction with Siberia's huge eruption.
The researchers' efforts were included in the Nature Communications publication. Such a work matches sulfur isotope signals that align with the Great Dying. On top of this, it also bases itself on previous research that proposes how such huge extinctions started happening on land. This was until around 600,000 years ago, before the lives of marine species got threatened and lost.
Geologist Christopher Fielding notes how this suggests that the Great Dying was not a singular and instant event. He notes how it required time for the buildup to take place.
The scientists agree that knowing the Great Dying's exact cause is not an easy feat.
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