Dinosaur Extinction Affected By Large Eruption of Underwater Magma

This was one hell of a mass extinction event.

Earth was not a fun place to be 66 million years ago. The end of Cretaceous period was a time of mass extinction: Approximately 75 percent of the planet’s plants and animals died off, an event arguably spurred by an unholy ripple effect ignited by an asteroid pummeling into the Yucatán Peninsula. Scientist increasingly agree that this impact accelerated catastrophic volcanic activity in India’s Deccan Traps, prompting massive eruptions for thousands of years, and ultimately ended the reign of the dinosaurs.

While those global events may seem terrifying enough, scientists announced Wednesday that another factor may have contributed to the mass extinction. In a study published in Science Advances, Earth science researchers from the Universities of Oregon and Minnesota show that one powerful factor may have exacerbated the extreme environmental changes at the end of the Cretaceous period, contributing to the major die-offs: a massive pulse of magma.

Illustration of the shallow portion of a fast-spreading ocean ridge. Octopi live in lava flow ridges today.

E. Paul Oberlander/WHOI Graphic Services/Joseph Byrnes

To determine what events happened within one million years of the Chicxulub impact, authors Joseph Byrnes, Ph.D., and Leif Karlstrom, Ph.D., analyzed gravity anomalies on the seafloor crust, showing that the asteroid’s impact triggered large seismic waves that traveled to mid-ocean ridges. The crash was so powerful that it ultimately separated the tectonic plates at the bottom of the sea.

Tearing apart the plates generated a pulse of global submarine volcanism as that separation released a “massive but short-lived pulse of marine magmatism,” they write. As the magma burst through the seafloor crust, it generated enormous underwater volcanic eruptions and intrusions across tens of thousands kilometers of volcanic ridges that span the ocean basins. In total, they estimate that approximately 23,000 to 230,000 cubic miles of magma erupted out of the ocean ridges.

Colored and black points mark seafloor with ages of 66 million years. The colors indicate the maximum gravity anomaly within two degrees.

Byrnes and Karlstrom

This marine volcanism likely contributed to the Cretaceous period’s extinctions because the magma released large volumes of basalt and released volcanic gases like methane, which, in a self-review of their work published in the Conversation, they said would be “presumably be more bad news for the dinosaurs and other flora and fauna of the time.”

They estimate that around the time of the Chicuxulub impact, They noted in the Conversation piece, however, that they’re still working out the exact ways the underwater activity affected this period of extinction.

“Was there enough mid-ocean ridge activity to contribute to the mass extinction, or was the triggered submarine volcanism merely a symptom of some significant planetary ailment?” they write. “What is clear is that this new research points to global-scale connections between catastrophes, a good reminder that events happening on the other side of the planet can have effects felt everywhere.”