Mars is usually considered a geologically dead planet, but a new study challenges that idea. Multiple lines of evidence reveals a giant plume of magma is forcing its way up through the Red Planet’s mantle and producing seismic activity in one particular region of the surface.
After a volcanically active youth, Mars seems to have calmed down in middle age. But apparently it still knows how to party sometimes – NASA’s InSight lander has detected as many as 1,300 “marsquakes” in its four years of operation. Most of these seem to be coming from a region called Cerberus Fossae, which is made up of a network of fissures.
Exactly what’s causing the activity in this area remained unknown, but here on Earth there are usually two possibilities – plate tectonics, involving the movement of chunks of planetary crust rubbing against each other, and mantle plumes, which are big bubbles of magma rising from deep within the planet. And since Mars definitely doesn’t have plate tectonics, scientists at the University of Arizona investigated whether mantle plumes might be responsible.
“We have strong evidence for mantle plumes being active on Earth and Venus, but this isn't expected on a small and supposedly cold world like Mars,” said Jeff Andrews-Hanna, co-author of the study. “Mars was most active 3 to 4 billion years ago, and the prevailing view is that the planet is essentially dead today.”
To find out, the team examined the region around the fissures of Cerberus Fossae – a large plain called Elysium Planitia – for features that, on Earth, indicate the presence of mantle plumes. As the magma rises, the crust is uplifted and stretched, and eventually an eruption occurs that forms large, flat volcanic plains.
Elysium Planitia already seems to be a volcanic plain, so that’s one item ticked off the list immediately. The team found that the surface has already been raised by over a mile, and measurements of the gravity field in the area indicate that it’s driven by something deep within the planet. The floors of impact craters in the area are also tilted in one direction, suggesting the uplift has occurred since the craters formed.
The team applied a tectonic model to the region, and found it was unable to account for the features observed. The only explanation, they conclude, is a gigantic mantle plume measuring around 4,000 km (2,500 miles) wide.
“In terms of what you expect to see with an active mantle plume, Elysium Planitia is checking all the right boxes,” said Broquet. “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.”
Not only does the find raise questions about what we thought we knew about the Red Planet’s formation and evolution, but it could have major implications for life on Mars. The warmth of the magma could drive chemical reactions of the kind that can potentially sustain microbes deep underground.
The research was published in the journal Nature Astronomy.
Source: University of Arizona