Giant mantle plume under Martian surface suggests the planet is not dead
Mars is generally considered a dusty, dry, and inactive planet, or so we thought until now. In a new study conducted by the University of Arizona, researchers have found evidence that Mars may have a massive, active mantle plume below its surface, pushing the crust upward and causing marsquakes and volcanic eruptions.
Mars is more active than previously believed
Researchers Adrien Broquet and Jeff Andrews-Hanna from the Lunar and Planetary Laboratory of the University of Arizona analyzed data from several orbital probes and dozens of marsquakes captured by the NASA spacecraft, Insight.
The team developed geophysical models based on geological, terrain, and gravity data from Elysium Planitia, which is one of the largest Martian plains. Their results showed that Elysium Planitia sits over a giant mantle plume spanning a diameter of about 4,000 kilometers (2,485 miles) and is between 96 and 285 degrees Celsius (170 to 520 degrees Fahrenheit) hotter than the surrounding rock.
"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," Andrews-Hanna said. "Mars was most active 3 to 4 billion years ago, and the prevailing view is that the planet is essentially dead today."
A planet with an active volcanism
Mantle plumes are large blobs of warm and buoyant rock that rise from deep inside a planet and push through its intermediate layer – the mantle – to reach the base of its crust, causing earthquakes, faulting, and volcanic eruptions.
The region is also home to a system of fissures called Cerberus Fossae, where the most recent volcanic events on Mars are thought to have taken place 53,000 years ago. This explains the recent volcanism in the region, as well as the marsquakes registered by InSight.
The presence of an active plume will affect interpretations of the seismic data recorded by InSight, which must now take into account the fact that this region is far from normal for Mars.
The study notes that Mars has now become the third planet in the interior of the Solar System with known active volcanism, together with Earth and Venus.
The discovery of such a plume raises further questions about the geological development of our neighboring planet.
"Having an active mantle plume on Mars today is a paradigm shift for our understanding of the planet's geologic evolution," Broquet said, "similar to when analyses of seismic measurements recorded during the Apollo era demonstrated the moon's core to be molten."
Can there be life on Mars?
The study may also have implications in the search for life on Mars. The area where they discovered the plume also has the most recent evidence of liquid water flowing on the surface of the Red Planet. Since there is life virtually everywhere where there is water on Earth, scientists often focus the search for extraterrestrial life on sites that possess water.
"Microbes on Earth flourish in environments like this, and that could be true on Mars, as well," Andrews-Hanna said. "Knowing that there is an active giant mantle plume underneath the Martian surface raises important questions regarding how the planet has evolved over time. We're convinced that the future has more surprises in store."
The study was published in Nature Astronomy.
Although the majority of volcanic and tectonic activity on Mars occurred during the first 1.5 billion years of its geologic history, recent volcanism, tectonism and active seismicity in Elysium Planitia reveal ongoing activity. However, this recent pulse in volcanism and tectonics is unexpected on a cooling Mars. Here we present observational evidence and geophysical models demonstrating that Elysium Planitia is underlain by an ~4,000-km-diameter active mantle plume head. Plume activity provides an explanation for the regional gravity and topography highs, recent volcanism, transition from compressional to extensional tectonics and ongoing seismicity. The inferred plume head characteristics are comparable to terrestrial plumes that are linked to the formation of large igneous provinces. Our results demonstrate that the interior of Mars is geodynamically active today, and imply that volcanism has been driven by mantle plumes from the formation of the Hesperian volcanic provinces and Tharsis in the past to Elysium Planitia today.
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