Scientists say a column of hot, burning rock as wide as the continental United States is rising near the Martian core and may help explain recent volcanism and earthquakes seen on the Red Planet.
Most volcanoes on Mars It occurred during the first 1.5 billion years of its history, leaving behind gigantic monuments such as Olympus Mons, the highest mountain in the solar system. However, scientists have largely believed that Mars has since cooled, essentially dead over the past three billion years or so. But in recent years, scientists have seen hints of geological activity after all, and now scientists have found a mushroom-shaped plume of scorching rock floating below an area called Elysium Planitia that may explain the latest findings.
“Our study shows that Mars is not dead,” study lead author Adrien Broquet, a planetary scientist at the University of Arizona in Tucson, told Space.com.
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The narrative about modern Martian geology is beginning to change, with a 2021 study finding evidence of this Mars may still be volcanically active, with signs of a volcanic eruption in the last 53,000 years or so. Using data from satellites orbiting Mars, this research discovered a previously unknown, dark soft presence volcanic The deposits cover an area slightly larger than Washington, D.C. The sediment surrounds a crack that forms an 800-mile-wide (1,300-kilometer) system of small cracks known as the Cerberus Fossae. This region lies within the relatively empty plains known as Elysium Planitia, located in the northern lowlands near the Martian equator.
In addition, NASA InSight lander Discover hundreds of Earthquakes on the red planet, with most of the largest of those bogs originating from Cerberus Fossae. In general, the results of the probe indicate that the level of seismic activity on Mars is between levels the moon Based on a land.
In the new research, scientists developed geophysical models based on geological, terrain and gravity data from Elysium Planitia. They found evidence that the entire region sits atop a mantle plume – a column of hot rock rising from the depths of Mars to burn the material above it like a blowtorch. This mantle plume, Broquet said, forms about 930 miles (1,500 kilometers) below the surface, at the interface between the Martian core and the mantle layer, which itself lies between the Martian core and crust.
“We found that this giant plume is about the size of the American continent, about 2,500 miles (4,000 kilometers) across – which is much larger for a planet smaller than Earth,” Broquet said.
Although this is the first plume discovered by scientists on Mars, geologists have long known about mantle plumes on Earth. For example, the Hawaiian Islands chain formed when the Pacific Ocean tectonic plate slowly drifted up the mantle plume.
The material in the mantle plume is buoyant compared to the surrounding rock. “It’s lighter, so it floats and migrates upward, similar to what can be seen in a lava lamp, where hot oil rises,” Broquet said.
The researchers suggested that the center of the newly discovered Martian mantle plume lies exactly below Cerberus Fossae. They estimated that the plume was about 170 to 520 degrees Fahrenheit (95 to 285 degrees Celsius) hotter than its surroundings.
Researchers found that the mantle plume pushed the Martian crust up more than a mile (1.6 km), sending hot magma to the surface of the Red Planet and driving the earthquakes detected by InSight.
“Not only is there recent volcanic activity in this area, but we see this volcanism as part of a recent resurgence of activity,” Broquet said. “About 100 million years ago, the last significant activity in this region was about 3 billion years ago. So again, something must have happened to cause this eruption, and that something is the mantle plume.”
Broquet said he suspects that Elysium Planitia was the only region on Mars with an active mantle plume, although another plume may be hiding under Tharsis. He noted that Tharsis is a 3,000-mile-wide (4,800 km) region near the equator in the western hemisphere of Mars that contains the largest volcanoes in the solar system and where scientists have detected recent and ongoing volcanic activity.
However, there may be explanations for the volcanic activity at Tharsis other than mantle plume. For example, the crust there is very thick and so may trap heat, which helps keep the rocks there molten. By contrast, “in the Elysium Planitia region, where we found the plume, the crust is known to be significantly thinner, and so we had to invoke another mechanism — the plume — to induce volcanic activity,” he said.
Overall, these results indicate that Mars is the third body in the inner solar system, after Earth and Venuswhere mantle plumes are currently active.
“We used to think InSight landed in one of the most geologically boring regions on Mars — a nice flat surface that should roughly represent the planet’s lowlands,” Brockett said. “Instead, our study shows that InSight landed directly on top of an active plume.”
The researchers said the new findings may also have implications for the search for life on Mars. The area where they discovered the plume also contains the latest evidence of liquid water flowing on the surface of the Red Planet. Because there is life almost everywhere there is water on Earth, scientists often focus the search for extraterrestrial life in locations that contain water.
“Water ice is still thought to be present in the subsurface of Mars, and so, if the plume is still providing heat, which we think is the case, then pockets of liquid water or aquifers could be located next to magma chambers in the crust of the Helixium region,” Broquet said. planitia.” “On Earth, microbes thrive in environments like this. Therefore, I would say that the plume has implications for the astrobiological potential of Mars at present. The next step could be to estimate if aquifers exist and where they might be.”
It remains unclear how the mantle plume formed so recently on cold Mars.
“It usually takes a few hundred million years for a plume to rise from the primary mantle boundary to the surface,” Broquet said. “Once it reaches the surface, our experience on Earth tells us that the plume remains active for a few tens to a few hundred million years. So geologically speaking, this plume formed and reached the base of the crust very recently, which is amazing. It’s not an ancient plume that survived the history of Mars. “.
Broquet noted that scientists once thought the moon was geologically dead. “Because of its small size, it would have been expected to cool faster than Earth,” he said. “However, seismic data recorded during the Apollo era was used to show that the moon’s core was molten, which was a huge surprise. The moon isn’t cold and dead — there’s still some heat inside.”
Similar to these findings on the Moon, “our discovery is a paradigm shift in our understanding of how Mars evolved,” Broquet said. “Such a massive mantle plume is not expected by the current model of the thermal evolution of Mars. Future studies will need to invoke a new mechanism and new geological history to find a way to account for the huge mantle plume that was not expected to be there.”
Overall, “there’s a lot of fundamental physics in the interior of a planet that we obviously don’t understand,” Brockett said. “Like when we thought the moon was dead.”
The research is described in a paper (Opens in a new tab) Published Monday (December 5) in the journal Nature Astronomy.
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