The First Mass Extinction

[Hervé]

Large volcanic eruption may have caused the first mass extinction (https://phys.org/news/2017-05-large-volcanic-eruption-mass-extinction.html)

PhysOrg (https://phys.org/news/2017-05-large-volcanic-eruption-mass-extinction.html) Wed, 17 May 2017 14:09 UTC



https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2017/largevolcani.jpg
The researchers found Hg enrichments in sedimentary rocks deposited in North America and southern China 445-443 million years ago. Hg enrichments are products of multiple phases of a large igneous province volcanism. This, they say, could have led to the environmental changes that caused the disappearance of many marine animal species. Credit: Kunio Kaiho


Researchers in the U.S. and Japan say they may have found the cause of the first mass extinction of life on Earth.



There have been five mass extinctions since the divergent evolution (https://phys.org/tags/divergent+evolution/) of early animals 600 to 450 million years ago (Figure 1). Volcanic activity was the cause of both the third and fourth, while an asteroid impact led to the fifth. But triggers of the first and second mass extinctions had, until now, been unknown. The new study strongly suggests volcanic activity (https://phys.org/tags/volcanic+activity/) caused the first mass extinction.

It occurred at the end of the Ordovician. This age is between the divergence of the Ordovician and land invasion of vascular land plants and animals. Animals in the Ordovician-Silurian comprised marine animals like corals, trilobites, sea scorpions, orthoceras, brachiopods, graptolite, crinoid and jawless fish. Approximately 80 percent of species disappeared at the end of the Ordovician.


https://3c1703fe8d.site.internapcdn.net/newman/csz/news/800/2017/1-largevolcani.jpg (https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2017/1-largevolcani.jpg)
Ordovician-Silurian marine fossils from the museum of Tohoku University. Credit: Kunio Kaiho


A team led by Dr. David S. Jones of Amherst College and Professor Kunio Kaiho of Tohoku University looked into possible triggers of the first mass extinction. They took sedimentary rock samples from two places—North America and southern China—and analyzed their mercury (Hg) content. They found Hg enrichments coinciding with the mass extinction in both areas. This, they believe, is the product of large volcanic eruptions (https://phys.org/tags/large+volcanic+eruptions/), because the Hg anomaly was also observed in other large igneous province volcanisms.

Huge volcanic eruptions can produce sulfate aerosols in the stratosphere. Sulfate aerosols are strong, light-reflecting aerosols, and cause global cooling. This rapid climate change (https://phys.org/tags/rapid+climate+change/) is believed to be behind the loss of marine creatures.

Kaiho's team is now studying the second mass extinction (https://phys.org/tags/mass+extinction/) in the hopes of further understanding the cause and processes behind it.


https://3c1703fe8d.site.internapcdn.net/newman/csz/news/800/2017/2-largevolcani.jpg (https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2017/2-largevolcani.jpg)
Outcrop of the Upper Ordovician studied at Monitor Range in Nevada. Credit: David S. Jones https://cf3e497594.site.internapcdn.net/tmpl/v5/img/1x1.gif (https://phys.org/news/2017-05-large-volcanic-eruption-mass-extinction.html#)


Explore further: Recovery after 'great dying' was slowed by more extinctions (https://phys.org/news/2017-03-marine-recovery-mass-extinction-biotic.html)

More information: Authors: David S. Jones, Anna M. Martini, David A. Fike, Kunio Kaiho, A volcanic trigger for the Late Ordovician mass extinction?: Hg data from South China and Laurentia, Geology, DOI: 10.1130/G38940.1 (http://dx.doi.org/10.1130/G38940.1)

Journal reference: Geology (https://phys.org/journals/geology/) https://cf3e497594.site.internapcdn.net/tmpl/v5/img/img-dot.gif (https://phys.org/journals/geology/) https://cf3e497594.site.internapcdn.net/tmpl/v5/img/img-dot.gif (http://geology.geoscienceworld.org/)
Provided by: Tohoku University (https://phys.org/partners/tohoku-university/) https://cf3e497594.site.internapcdn.net/tmpl/v5/img/img-dot.gif (https://phys.org/partners/tohoku-university/) https://cf3e497594.site.internapcdn.net/tmpl/v5/img/img-dot.gif (http://www.tohoku.ac.jp/english/)

[wnlight]

Thank you. Most interesting But there likely were mass extinctions previous to the Ordovician that we do not know about.

[Hervé]

[...]
... But there likely were mass extinctions previous to the Ordovician that we do not know about.
Warren... are you playing a "Corey Goode" on me? :bigsmile:

[ghostrider]

We could be heading for the last extinction ... they say history repeats, the circle of life and all, I hope we survive our technology this time ...

[Atlas]

What if a Supervolcano Erupted?
JA7a9nnxNvM

[Hervé]

Mercury in fossilised ferns revealed as hidden driver in mass extinctions (https://cosmosmagazine.com/earth-sciences/mercury-revealed-as-hidden-driver-in-mass-extinctions)

Barry Keily Cosmos Magazine (https://cosmosmagazine.com/earth-sciences/mercury-revealed-as-hidden-driver-in-mass-extinctions)
Thu, 24 Oct 2019 18:56 UTC


https://www.sott.net/image/s27/542815/large/191023_fern.jpg (https://www.sott.net/image/s27/542815/full/191023_fern.jpg)
Mutated ferns point to a new culprit in prehistoric mass extinctions, researchers say.
© GEUS


Bad news loves company. Researchers have discovered that it wasn't just erupting volcanoes, massive amounts of carbon dioxide, oceans full of sulphuric acid, runaway global warming and a thinning ozone layer that caused the end-Triassic mass extinction 201 million years ago.

It was also large quantities of lethal mercury causing plant life to mutate and die.

Four out of the five mass extinctions that occurred over the past 600 million years have been linked to huge and prolonged bursts of volcanic activity.

In the case of the Triassic event - which saw the end of an estimated 40% of land animal genera and 30% of ocean-dwelling groups - there is ample evidence that volcanoes sprang to life across an area known as the Central Atlantic Magmatic Province (CAMP) 100,000 years before the great dying began. It continued, sporadically, for another 700,000.

Such a profound upheaval causes substantial environmental disruption - including long-lasting spikes in carbon dioxide and sulphur combinations that have been regularly and reliably associated with high levels of animal and plant deaths.

Now, however, scientists led by Sofie Lindström of the Geological Survey of Denmark and Greenland have identified another nasty: pulsed elevated concentrations of mercury in the ocean and the soil.

Mercury, write the researchers, is "the most genotoxic element on Earth". That means it doesn't just eventually kill whatever plants or animals it comes into contact with. It also causes mutations within their genomes, resulting in offspring that do not survive.

To test the contribution of mercury to the end-Triassic mass die-off, Lindström and colleagues examined fossilised fern spores from the period and looked for irregular shapes.

A proportion of mutation within any species is expected - it is, after all, one of the main drivers of evolution. In the fern species this natural rate of genetic change runs between 3% and 5%.

The scientists discovered that in spores and pollen collected from some areas in the highly volcanic period leading up to the mass extinction as many as 56% appeared deformed, suggesting very high rates of mutation.

"As one of the most toxic elements on the planet, mercury can cause both visible injuries and physiological disorders in plants," the researchers write.

They add that that today "mercury pollution from anthropogenic sources is known to seriously disturb growth and reproductive cycles in plants, causing long-term effects on soil fertility and subsequent severe health issues to animals and human population".

Around 200 million years ago, of course, there were no anthropogenic sources of mercury - but there is ample evidence that volcanoes pumped out enormous amounts of it.

Its effect on life on Earth would have been to deliver a double blow. First, plant species would have been severely depleted, with many becoming extinct. Second, the loss of plant matter would have resulted in a very short time in an upstream decrease in the numbers of animals who normally dined on them.

If lava or atmospheric poisons didn't kill them, it seems, hunger would.

The research (https://advances.sciencemag.org/content/5/10/eaaw4018) is published in the journal Science Advances.


https://www.sott.net/image/s27/542813/large/191023_mercury.jpg (https://www.sott.net/image/s27/542813/full/191023_mercury.jpg)
A normal fern spore compared with mutated ones from the end-Triassic mass extinction event. © S LINDSTRÖM, GEUS