For decades, it has been thought that Marte was a geologically dead planet: its interior would be made up mostly of solid and immobile rock, very different from our stratified world, with a molten iron core that drives its activity towards the outside, creating volcanism or the displacement of the tectonic plates. However, in recent years, some findings have shaken this theory: on the Red Planet, everything from ‘recent’ magma to prolific and continuous seismic activity has been discovered. Is our neighbor also alive?
This hypothesis is now added to a new study published in ‘Nature Communications’ in which it is stated that under the great Martian plain baptized as The Plains of Elysium there is a colossal convection plume some 4,000 kilometers wide, something like Western Europe, which is driving molten magma from the Martian interior to its surface, making it a geologically active world. And it could also erupt before our eyes.
“Although most of the volcanic and tectonic activity on Mars occurred during the first 1.5 billion years of its geological history, recent volcanism, tectonism, and active seismicity on Elysium Planitia reveal continued activity,” the authors write. Adrien Broquet y Jeffrey Andrews-Hanna, from the University of Arizona. “Plume activity provides an explanation for regional topographic and gravity maxima, recent volcanism and seismicity, as well as the formation of the Elysium Planitia volcanic zones.”
conflicting evidence
Mars has shown very convincing signs of being geologically dead, both inside and out: its relatively old surface, with no plate tectonics or areas of apparent recent volcanic activity; The current absence of a global magnetic field does not help either (ours is created from our molten iron core), although there are studies that indicate that it did have one in the past. All this seemed to indicate that the Red Planet was all solid and immobile rock from the surface to its deepest interior.
However, in recent times there have been disconcerting findings that refute this theory. For example, a meteorite of Martian origin that reached Earth showed signs of mantle convection (that is, that currents of hotter material had been produced in the Martian interior) about 500 million years ago, 1 billion years later than its geological peak.
Soon after, satellite photos showed evidence of volcanic surface deposits (ie, solidified magma) in a fissure system called Cerberus Fossae, which runs about 1,000 kilometers within Elysium Planitia. The most curious thing about this finding is that scientists dated the formation of this material to only 50,000 years ago, which would be a cosmic ‘sigh’ in terms of planet formation.
Part of the Cerberus Fossae system in the Elysium Plain, near the Martian equator
In 2018, the Mars InSight probe landed precisely on Elysium Planitia, literally drilling into the Martian soil to listen to what was happening inside. Their instruments discovered significant seismic activity that would in turn explain volcanic activity such as the one indicated by previous findings. And it does not stop there: it has also been seen that the local gravity in Elysium Planitia is unusually strong, which would be consistent with some type of underground activity.
Recently, a study published in ‘Science’, analyzed a set of more than 20 recent Martian earthquakes, all of them originating from Cerberus Fossae. The conclusion of the study indicated that these low-frequency earthquakes indicate a warm source that could be explained by the current molten lava.
With all these clues, Broquet and Andrew-Hanna searched for a theory that could explain each and every one of these phenomena, which fits with a kind of magma deposit some 4,000 kilometers wide called a plume, which would have bombed the area and that, furthermore, would be ready to erupt in a relatively short time (at planetary scales).
Map showing mantle plume location in context with InSight seismic detections
To match the observed data, including the epicenters of the seismic activity detected by InSight, the plume would be at least 3,500 kilometers wide – although they estimate that it is surely as much as 4,000 kilometers – and would be between 95 and 285 degrees hotter than the rest of the planet. This is very similar to mantle plumes on Earth that fueled prehistoric volcanic activity that created, for example, the Trap the Dean (one of the largest volcanic formations on our planet that is located on the Deccan Plateau, in the center-west of India) or the Brito-Arctic igneous province. The Canary Islands would also have been created by a similar model.
“Although Mars is smaller than Earth, plumes of a similar size could form inside it due to the lower gravity and higher viscosity of the Martian mantle,” the researchers write in their paper. The best-fit center of the plume head, based solely on gravity and topography data, lies precisely in the center of Cerberus Fossae, where both recent volcanism and most marsquakes have been located.”
This, the researchers say, means that Mars would be the third planet in the Solar System with mantle plume activity, joining Earth and Venus.
The implications of this finding
This does not mean that Mars is a world with huge volcanoes that are constantly spewing magma from their craters; but it has heat inside that could prevent lakes under the Martian surface from freezing. This, in turn, has implications for the search for Martian life in the form of microbes peacefully existing on them.
“The continued activity of the plume demonstrates that Mars is not only seismically and volcanically active at present, but also possesses a geodynamically active interior,” Broquet and Andrews-Hanna write. “A plume under Elysium Planitia also indicates that surface volcanic flows and seismic activity are not isolated events, but part of a long-lived and actively sustained regional system, with implications for the longevity and astrobiological potential of subsurface habitable environments.”