Early Mars may have been more tectonically and volcanically active than previously thought. Evidence for tectonic activity about 4 billion years ago was provided by 63 new examples of several volcanoes found in a strange region of Mars with strange properties that distinguish it from the rest of the Martian highlands.
A team of planetary scientists has discovered that the landscape of the Eridania region of Mars, located in the planet’s southern hemisphere, appears to have been shaped in response to changes occurring within Mars’ crust, not forces originating from above. or below it. The discovery could influence the search for signs of ancient life on the Red Planet, currently being carried out by NASA’s Curiosity and Perseverance rovers.
“The large basins of this region once hosted a lake system known as paleolake Eridania, which was about a mile deep when the lake was at its greatest extent,” team member and planetary geologist Aster Cowart told Space. from the Institute of Planetary Sciences. .com. “Long-lived volcanic vents coupled with abundant water may have fueled hydrothermal systems that could have nourished life.
“At the very least, these findings give us a greater number of places where we can look for evidence of life.”
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Unlike today’s Earth, today’s Mars has little to no volcanic or tectonic activity. Furthermore, since about half of the Red Planet’s surface appears to be more than 3.5 billion years old, this suggests that recycling of the Earth’s crust has not occurred extensively on Mars.
On Earth, recycling of the Earth’s crust is driven by plate tectonics when one tectonic plate slides beneath another, causing surface material to be recycled in the mantle between the Earth’s crust and its 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 around the Red Planet, including the Mars Global Surveyor, Mars Odyssey and the Mars Reconnaissance Orbiter.
“Several attributes of the Eridania region have attracted special attention for some time,” Cowart added. “Gamma-ray spectroscopy shows that this is a region of the crust with an especially distinctive composition, gravity data have shown that it is generally less dense and thicker than the rest of the Martian crust, and magnetic data show that it is an intensely magnetized region. crust.”
They identified 63 examples of volcanism so far discovered in four different types of volcanoes: volcanic domes, stratovolcanoes, pyroclastic shields and caldera complexes.
The team suspects that the Eridania region alone contains hundreds of other examples of volcanic activity that are the remnants of episodes of extreme geological activity on Mars about 3.5 billion years ago. They also believe that the volcanic variety observed in this region could be replicated in other regions of the Martian surface.
Tectonic activity powered early Mars
The type of geological activity observed on Mars through these observations is vertical tectonics, in which the Earth moves 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 the 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 more rigid, and it floated relative to the mantle,” Cowart continued. “However, the slow incorporation of water into the deeper levels of the crust began to cause mineral transformations that caused the deep crust to become denser.”
Cowart explained that once enough of the Earth’s lower crust had undergone these mineral transformations, it began to sink toward the mantle, a process known as “sagduction.” This pushed water-rich minerals that had formed near the Earth’s surface deeper into its crust, where they helped form floating magmas. The buoyancy of these magmas caused other regions of the crust to rise upward.
This resulted in a landscape dominated by large basins where the crust subsided, mountain ranges where the crust rose upward, and volcanic rocks with a composition richer in silica than the mantle rocks.
“This is exactly what we see in the Eridania region,” Cowart said. “It’s really exciting to see a landscape so shaped by pre-plate tectonic processes. Much of what we know about these processes on Earth has been obtained from heavily eroded ancient rocks that have some degree of superimposition of plate tectonic activity. later plates. or from where they occur in modern environments and are influenced by plate tectonic dynamics.”
This newly discovered geology of Mars could not only offer an opportunity to study a period of Earth’s past that is not accessible in our planet’s geological record, but it could also help determine how life emerged on our planet.
This is because the processes behind these features could be very analogous to scenarios related to the origins of life in which living things emerge around porous hydrothermal vents, sites where heated, mineral-laden seawater collects. pours from the cracks in the oceanic crust.
“It’s simply amazing to think about the scale of activity in this region. Mars has a tendency to do everything big, and to see a landscape almost the size of Europe or Arabia made up of an interrelated set of tectonic processes in this amount of detail.” It’s amazing,” Cowart concluded. “See a Martian landscape
shaped by these processes and preserved in stasis provides us with a great opportunity to investigate the evolution of the planetary landscape in more
The team’s research was published Monday (February 12) in the journal Nature.