Prehistoric volcanoes created much of the world's oil

A new study by the University of Alberta suggests that a massive undersea volcano eruption 93 million years ago was the source of much of the world’s oil.

Researchers Steven Turgeon and Robert Creaser were alerted to the prehistoric blast when they found specific levels of osmium isotopes (indicators of volcanic activity in sea water) in black shale rocks off the coast of South America and in the mountains of central Italy.

Two theories, which are not mutually exclusive, emerge to explain the chemistry of what happened next.

    One is that the volcanoes spewed out metal-rich fluids that provided food for the phytoplankton in the upper level of the ocean. The phytoplankton stored up carbon and then sank to the sea floor and decayed, stripping the ocean of oxygen.

    The other is that the volcanoes disgorged clouds of carbon dioxide to the atmosphere, which made the ocean suddenly starved of oxygen, wiping out swathes of marine life.

    Figuring out the post-volcanism scenario could help scientists wrestling with unknowns about global warming today, said Tim Bralower, a geologist at Pennsylvania State University, who reviewed the paper.

After 10,000-50,000 years, the carbon dioxide levels rose again. "Business as usual," said Turgeon, adding that this might hold a warning for organic life on the planet today, he said.

"There's a bit of an analogy for what's going on today," he said. "What happens if we pump more CO2 into the atmosphere? This tells me that the oceans maybe have limited buffering capacity for CO2 ."

The research appears on Thursday in the weekly science journal Nature.