Study reveals new clues about Great Dying, Earth's largest mass extinction

A new study sheds light on the potential cause of the End-Permian Extinction 250 million years ago.

Tyler MacDonald | Oct 22, 2019

A new study sheds light on the causes of the largest mass extinction in the Earth's history, also referred to as the End-Permian Extinction and the Great Dying.

The event took place approximately 250 million years ago when a giant volcanic eruption hit what is now Russia's province of Siberia. The eruption sent almost 90 percent of life into extinction. In geology, the eruption is referred to as the Siberian Flood Basalts, which ran for nearly one million years.

"The scale of this extinction was so incredible that scientists have often wondered what made the Siberian Flood Basalts so much more deadly than other similar eruptions," said Michael Broadley of the Centre for Petrographic and Geochemical Research in Vand?uvre-ls-Nancy, France, and lead author of the study.

The research was co-authored by the late Lawrence Taylor, who is the former director of the Planetary Geosciences Institute at the University of Tennessee, Knoxville.

"Taylor was instrumental in supplying samples of mantle xenoliths, rock sections of the lithosphere [a section of the planet located between the crust and the mantle] that get captured by the passing magma and erupted to the surface during the volcanic explosion," Broadley said. "Taylor also provided advice throughout the study."

The team analyzed samples to determine the lithosphere composition, which revealed that prior to the Siberian Basalt floods, it was loaded with bromine, iodine, and chlorine, all of which belong to the halogenchemical group. After the volcanic eruption, they disappeared.

"We concluded that the large reservoir of halogens that was stored in the Siberian lithosphere was sent into the earth's atmosphere during the volcanic explosion, effectively destroying the ozone layer at the time and contributing to the mass extinction," Broadley said.

The findings were published in Nature Geoscience.

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