Study Shows How Volcanism Might Have Affected Earth's Worst Mass Extinctions

More than 90 percent of Earth's marine species and 75 percent of terrestrial species became extinct during the most catastrophic mass extinction event in the previous 540 million years. Although scientists previously hypothesized that the end-Permian mass extinction, which occurred 251 million years ago, was caused by massive volcanic eruptions in what is now Siberia, they could not explain how the eruptions caused the extinction of so many different species, both in the oceans and on land.

In collaboration with Chinese, Canadian, and Swiss scientists, associate professor Laura Wasylenki of Northern Arizona University's School of Earth and Sustainability and Department of Chemistry and Biochemistry co-authored a new paper in Nature Communications titled "Nickel isotopes link Siberian Traps aerosol particles to the end-Permian mass extinction." The findings of nickel isotope studies done at Wasylenki's lab on Late Permian sedimentary rocks obtained in Arctic Canada are presented in this study.

Nickel Isotope

The nickel isotope ratio in the samples isn't found in sedimentary rocks, so the only plausible explanation is that it came from a volcanic source, was carried by aerosol particles, and deposited in the ocean, where it drastically changed the chemistry of seawater and severely disrupted the marine ecosystem.

"The study results show that nickel-rich particles were aerosolized and distributed far, both through the atmosphere and into the water," stated Wasylenki in a statement released by Northern Arizona University.

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Creating Siberian Traps

According to the study, flood-basalt eruptions, such as those that created the Siberian Traps, endure millennia and send huge amounts of nickel-rich ash into the sky. As evidenced by the finding of nickel-rich deposits in Canada, atmospheric currents will disperse the ash around the globe, harming land and sea.

Although nickel is an essential trace element for many organisms, a rise in nickel abundance would have resulted in an unexpected increase in methanogen productivity, producing methane gas by microbes. Increased methane levels would have been extremely detrimental to all oxygen-dependent species, producing severe heat and ocean acidification (as gases are carried into the sea by rain). Extreme droughts, widespread deoxygenation, and sulfide poisoning of the oceans would create an environmental collapse in a warmer world, the research finds, wiping out a broad range of animal and plant groupings.

According to geologists, long-term volcanism related to magma plumes rising up in Earth's mantle is thought to be the cause of such cataclysmic catastrophes, which occur every 25 to 30 million years.

Volcanism

Volcanism is defined as the eruption of molten rock (magma) onto a planet's surface. The vent through which magma and gases are expelled is known as a volcano. Lava refers to magma that has reached the surface. Vulcan, the Roman god of fire, is the name given to volcanoes.

Volcanism occurs when a planet's interior heat is lost. When rock near the surface becomes hot enough to melt, a volcano can develop. This frequently occurs on Earth in conjunction with plate boundaries (check out the section on tectonism). Material from Earth's core progressively rises up, melts when it reaches lower pressures, and fills in space where two plates move apart, such as at mid-ocean volcanic ridges. Magma chambers can occur when one plate is subducted beneath another. The volcanic islands that indicate subduction zones are fed by these magma masses.

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