Scientists have often considered Mars to be a dead planet due to the lack of the geological activity that rocks Earth and Venus. However, a new study shows evidence of what could be an active mantle plume beneath the surface of the red planet.
Published in Nature Astronomy, the study suggests a more dynamic interior of Mars than previously thought.
“Our study presents multiple lines of evidence that reveal the presence of a giant active mantle plume on present-day Mars,” said Dr. Adrien Broquet, co-author of the paper and a postdoctoral research associate in the Lunar and Planetary Laboratory at University of Arizona, in a press release.
According to the evidence found by the scientists, the mantle plume is situated underneath a low-lying area called Elysium Planitia that lies north to the equator. Though an otherwise indistinctive area, scientists found unexpected evidence of geological activities in Elysium in the recent past.
Mantle plumes are large blobs of molten rock that rise towards the surface from the interiors of a planet. They pushthrough the intermediate or mantle layers and accumulate at the base of the crust. This geological phenomenon can be witnessed on Earth in Hawaii where the warm materials from the plume ooze out of fissures to create great volcanic plains.
Associate professor and study co-author Dr. Jeff Andrews-Hanna noted that the predominant view is that Mars is essentially dead today as most of its geological activity, which created some of the tallest volcanoes in the solar system, happened three to four billion years ago. Though there is little activity in the form of quakes (marsquakes) or volcanic eruptions now, these have mostly been attributed to the ‘passive processes on a cooling planet.’
As compared to the otherwise silent planet, Elysium Planitia has experienced large eruptions in the last 200 million years. It holds evidence of the youngest volcanic eruption on Mars. “It created a small explosion of volcanic ash around 53,000 years ago, which in geologic time is essentially yesterday,” Dr Andrews-Hanna added.
Studying the data from NASA’s InSight lander, scientists found that the volcanic eruptions at Elysium Planitia originate from a set of fissures called Cerberus Fossae that stretch for more than 1278 kilometres (800 miles) across the planet’s surface. They also found that most marsquakes emanate from this region.
“We know that Mars does not have plate tectonics, so we investigated whether the activity we see in the Cerberus Fossae region could be the result of a mantle plume,” Broquet said.
According to the data from Elysium Planitia, the force of the mantle plume is thought to have raised the surface by more than a mile, making it one of the highest points in the lowlands of Mars’ northern hemisphere. They also applied a tectonic model to the region and discovered that the creation of the Cerebrus Fossae could only be explained by the existence of a massive mantle plume that was 4,023 km (2,500 miles) wide.
The floor of impact craters being tilted in the direction of the plume also supported the hypothesis that something pushed the craters to the surface well after their formation.
“In terms of what you expect to see with an active mantle plume, Elysium Planitia is checking all the right boxes,” Dr. Broquet said. He also noted that the discovery challenges the theories that planetary scientists use to research the thermal development of planets. “This mantle plume has affected an area of Mars roughly equivalent to that of the continental United States. Future studies will have to find a way to account for a very large mantle plume that wasn’t expected to be there.”