London, April 22 : In a new research, scientists have determined that big volcanic eruptions don’t always fuel mass extinctions because the destructive potential of the blasts seems to depend upon carbon dioxide (CO2) spewing non-volcanic rocks in the region.

Earlier, geologists have found evidence of many huge ancient volcanic eruptions that seem to not be connected to mass extinctions at all.

Now, according to a report in Nature News, a team of researchers has analyzed just how much CO2 non-volcanic rocks around volcanoes might release if they are super-heated.

They have found that in some cases, the rocks might spew out much more CO2 than the volcano itself.

Clement Ganino and Nicholas Arndt at Joseph Fourier University in Grenoble, France, went to explore a volcanic site roughly 260 million years old in southwestern China that seems to have formed at the same time as a mass extinction wiped out 35 percent of all genera on the planet.

Ganino and Arndt looked closely at dolomite, one of the most common rocks in the region of the mid-Permian eruption.

Dolomite is composed of calcium, magnesium, and carbonate; when heated, it breaks down into magnesium oxide, calcium carbonate and CO2.

The researchers calculated that 1 kilogram of dolomite heated by a volcanic source would produce 240 grams of carbon dioxide.

They also found that impure marbles in the area would have released between 220 and 290 grams of CO2 per kilogram of rock when heated.

Based on the abundance of heated sedimentary rocks that would have released carbon dioxide, Ganino and Arndt estimate that between 61,600 and 145,600 gigatonnes of CO2 were released.

This would have overwhelmed the mere 16,800 gigatonnes of CO2 typically emitted by magma alone during eruptions, explained Ganino.

“The mass of CO2 released from sedimentary rock is 3.6 to 8.6 times larger than the mass of CO2 released from magma. We did not expect such a huge difference,” he said.

According to Henrik Svensen at the University of Oslo, Norway, “More than 99 percent of all carbon on the Earth’s surface is stored in sedimentary rocks, and heating those rocks with the high-temperature material that comes out of volcanoes is a good way to put a lot of carbon into the atmosphere quickly.”

“Destructive potential seems to depend upon the sedimentary rocks in the region,” said Svensen. (ANI)