Early Mars may have been more tectonically and volcanically active than previously thought. Evidence of tectonic activity some 4 billion years ago was provided by 63 new examples of several volcanoes found in a strange region of Mars with strange features that set it apart from the rest of the Martian highlands.
A team of planetary scientists has discovered that the landscape of Mars’ Eridania region, located in the planet’s southern hemisphere, appears to have been formed in response to changes taking place in Mars’ crust, and not by forces coming from above or get under the crust. The discovery could impact the hunt for signs of ancient life on the Red Planet, currently underway by NASA’s Curiosity and Perseverance rovers.
“The large basins in this region once housed a lake system known as Lake Eridania Paleola, which was up to about a mile deep when the lake was at its largest extent,” team member and Planetary Science Institute planetary geologist Aster Cowart told Space. .com. “Long-lived volcanic springs alongside abundant water could have fueled hydrothermal systems that could have nourished life.
“At the very least, these findings give us a greater number of places to look for evidence of life.”
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Unlike today’s Earth, modern Mars has little to no volcanic or tectonic activity. Furthermore, because about half of the Red Planet’s surface appears to be older than 3.5 billion years, this suggests that crustal recycling has not occurred on a large scale on Mars.
On Earth, crustal recycling is driven by plate tectonics when one tectonic plate slides beneath another, recycling surface material in the mantle between the Earth’s crust and the molten core.
The team behind this new research studied the morphology and mineralogy of the Eridania region of Mars in the Southern Hemisphere using data from spacecraft orbiting the Red Planet, including the Mars Global Surveyor, Mars Odyssey and the Mars Reconnaissance Orbiter.
“Several features of the Eridania region have been attracting special attention for some time,” Cowart added. ‘Gamma-ray spectroscopy shows that this is an area of the crust with a particularly distinctive composition; gravity data have shown that it is generally less dense and thicker than the rest of Mars’ crust, and magnetic data show that it is an intensely magnetized core. crust.”
They identified 63 examples of so far exposed volcanism in four different volcano types: volcanic domes, stratovolcanoes, pyroclastic shield and caldera complexes.
The team suspects that the Eridania region alone contains hundreds of other examples of volcanic activity, left over from periods of extreme geological activity on Mars some 3.5 billion years ago. They also think that the volcanic variation observed in this region could be replicated in other regions of Mars’ surface.
Tectonic activity boosted early Mars
The type of geological activity observed on Mars through these observations is vertical tectonics, where land shifts upward, causing uplift and subsidence. This was a precursor to the full plate tectonics we see on Earth today.
Cowart said the crustal changes behind these newly discovered volcanic features are analogous to a step Earth took on its own evolutionary path toward plate tectonics more than 2.5 billion years ago.
“Before the development of plate tectonics, it was difficult to recycle the crust back into the mantle because the composition of the crust was more uniform, the crust was stiffer, and it was buoyant relative to the mantle,” Cowart continued. “However, the slow absorption of water into the deeper layers of the crust began to cause mineral transformations that made the deep crust denser.”
Cowart explained that once enough of the Earth’s lower crust had undergone these mineral transformations, it began to sink down into the mantle, a process called “sagduction.” This pushed water-rich minerals that had formed near the Earth’s surface deeper into the crust, where they helped form floating magmas. The buoyancy of these magmas caused other parts of the crust to rise.
This resulted in a landscape dominated by large basins at points where the crust subducted, mountain ranges where the crust rose, and volcanic rocks with a more silica-rich composition than rocks from mantle sources.
“This is exactly what we are seeing in the Eridania region,” Cowart said. “It’s really exciting to see a landscape so heavily shaped by pre-plate tectonic processes. Much of what we know about these processes on Earth has been pieced together from heavily eroded ancient rocks that have been overprinted to some extent by later plate tectonics .or where they occur in modern environments and are affected by plate tectonics.”
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This newly discovered geology of Mars could not only provide the opportunity to study a period in Earth’s past that is not accessible in our planet’s geological record, but it could also help determine how life evolved on our planet. planet was created.
This is because the processes behind these features could be closely analogous to origin-of-life scenarios in which living things emerge around porous hydrothermal vents, locations where heated, mineral-laden seawater flows from cracks in the ocean crust.
‘It’s just astonishing to think about the scale of activity in this region. Mars tends to do everything on a grand scale, and seeing a landscape almost the size of Europe or Arabia, shaped by an interconnected series of tectonic processes in this amount of detail is astonishing,” concludes Cowart. “A Martian landscape to see
shaped by these processes and preserved in stasis, offers us a great opportunity to further investigate the evolution of the planetary landscape
detail.”
The team’s research was published Monday (Feb. 12) in the journal Nature.