An asteroid that hit the Earth about 66 million years ago and is believed to have wiped dinosaurs off the face of the planet has also caused huge amounts of magma to be ejected from the ocean floor, a new study of the seabed has revealed.
For decades, scientists have pointed out that the cataclysmic asteroid that crashed into the planet is the cause of the extinction of dinosaurs and many other species on Earth. This event is known as the Cretaceous-Tertiary, or K-T extinction.
The impact, which scientists think left a 180-kilometer-wide Chicksulub crater in the Gulf of Mexico, would destroy all life in the area and raise huge clouds of waste into the air, blocking out the sun.
But scientists have pointed to another clue – Dean’s openings in present-day India, one of the largest volcanic provinces in the world, which happened to be very active at the time of the K-T extinction.
Ash and gases from the Dean’s openings, on the plateau of the same name, are the real cause of dinosaur deaths, some scientists say, diminishing the role of asteroids.
“People are still debating the real cause of the changes that led to the extinction of the dinosaurs,” Leaf Carlstrom, a scientist at the University of Oregon in Eugene, told the Los Angeles Times.
Researchers have also suggested that two factors may have been linked – the asteroid may have caused the volcano to activate, leading to one or two brutal strikes that wiped out plant and animal species from three-quarters of the Earth’s surface.
“But recent work has shown that openings began to eject magma about a quarter of a million years before the asteroid struck,” says Karlstrom.
However, scientists are wondering if there is a connection between the two events. Study leader Joseph Burns, a geophysicist at the University of Minnesota in Minneapolis, realized that if an asteroid impact had a major impact on volcanism at the time, the effects should be seen in activity along the mid-ocean ridge.
The mid-ocean ridge is an underwater mountain range, formed by the movement of tectonic plates. It is made up of long cracks in the Earth’s crust on the ocean floor, where tectonic plates meet. As the plates separate, hot magma rises between them, protruding on one of the plates, and then cooling, creating a new seabed. This network, with about 65,000 km of continuous ridge, is the longest mountain range on Earth.
The youngest rock is always to the right of the ridge, where fresh magma continues to form new rocks, which age as they move away from the ridge on both sides.
Taking into account the data on the Earth’s magnetic field, scientists were able to determine the age of the sea floor.
They then combined these data with those of the gravitational field of the surface beneath the ocean. This gave them an insight into the topography of the ocean floor, most of which is still a mystery.
“We have the topography of the Earth’s surface, Mars and Venus, but we don’t have the topography of the ocean floor,” Burns said, adding that it would take about 900 years to explore the entire ocean floor.
It was discovered that at the time of the asteroid impact, there was a sudden eruption of magma from the crack, which deposited hundreds of thousands to a million cubic kilometers of volcanic material.
That is not far from the estimated seven million cubic kilometers of magma produced by the Dean’s openings.
“It is possible that the powerful seismic waves produced by the impact caused the release of magma reservoirs below the surface,” says Karlstrom.
And if it affected the mid-ocean ridge in this way, it may have played a similar role in the Dean’s openings, causing even more volcanic activity.
This means that the mid-ocean ridge would be the forerunner of similar phenomena in the already active area of the Dean’s traps.
Although it is not known whether the release of sea magma caused any damage, ie whether the additional ejection of magma on the ocean floor worsened the K-T extinction, it could have played a role in further acidification of the ocean.