Not an asteroid but massive volcanic eruptions in India might have set off mass extinction 66 million years ago

(Representative image) An active volcano erruptionUnsplash
  • New evidence has been found the support the theory that a series of volcanic eruptions in the Deccan Traps might have triggered Earth’s mass extinction 66 million years ago.
  • Volcanoes, like the Deccan Traps, are the largest source of mercury in the atmosphere.
  • Fossils find that at the time of the eruptions — tens of thousands of years before the asteroid impact — had a profound and long-lasting impact on the world.
Theories around how the dinosaurs met their untimely end aren’t restricted to an earth-killing asteroid. New evidence says has found that massive volcanic eruptions in India might have contaminated the atmosphere with mercury long before any asteroid even flew close.

These eruptions began tens of thousands of years before the asteroid impact. They form what is now known as the Deccan Traps in southwestern India. The lava flowing from them covered nearly 1.5 million kilometres — approximately half the size of the peninsula.

Location of Deccan Traps on the Indian peninsular continentUniversity of California - Berkeley


Marine mossulk shell fossils from 66 million years ago found by the University of Michigan indicate that the eruption had a ‘profound, long-lasting and global’ impact on the world — enough to light the match of mass extinction.

"For the first time, we can provide insights into the distinct climatic and environmental impacts of Deccan Traps volcanism by analysing a single material," said Kyle Meyer, lead author of the study.

How can volcanoes set off mass extinctions?

Volcanoes are the largest source of mercury in the atmosphere — a toxic trace metal that poses a grave threat to human health, and wildlife in general — in addition to the substantial amount of carbon dioxide and sulfur dioxide they spew.

Sulphur dioxide fumes from an active volcanoUnsplash

So, theoretically, when the Deccan Traps erupted, they filled the atmosphere with a host of lethal gases. The sulfur fumes were enough to turn the oceans to acid and kill three-quarters of the Earth’s population.

And, new fossils found by researchers, indicates that to be true. The shells act as pre-historic record of temperature and mercury.

And, they signal two things. There was an abrupt ocean warming at the time and, the mercury concentration in the atmosphere was elevated. It was so high that it matched levels of ‘significant modern industrial mercury contamination’.

Studying the shells

Before researchers fold marine mollusk shell fossils from 66 million years ago, records of environmental mercury have largely been based on marine sediments. But, they have never been able to establish changes in the mercury levels as a response to changes in the climate.


This is the first time that the indicator for both events has been found in the same specimen.

The new fossils gave them an opportunity to assemble the first-ever deep-time record of mercury preserved in fossilized remains, while also determining marine temperature using a technique called carbonate clumped isotope paleothermometry.

According to their results, an abrupt global warming event took place 250 thousand years before the dinosaur-ending asteroid hit Earth. Other studies have found that volcanic activity during that same time period was so intense that it created a carpet of lava 100 feet thick.


The Deccan Trap eruptions were also what reportedly broke up the Gondwana supercontinent and brought the western Indian Ocean into existence.

See also:
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