by Early Mars may have been more tectonically and volcanically active than previously thought. Evidence of tectonic activity around 4 billion years ago has been provided with 63 new samples of different volcanoes found in a strange region of Mars with unusual properties that set it apart from the rest of the Martian highlands.
A team of planetary scientists discovered that the landscape of the Eridania region of Mars, located in the southern hemisphere of the planet, appears to have been formed in response to changes that occurred within the crust of Mars, not from forces that came from above or below. The discovery could have implications for the search for signs of ancient life on the Red Planet, currently being conducted by NASA’s Curiosity and Endurance rovers.
“The large basins in this region hosted a lake system known as paleolake Eridania, which was up to a mile deep at its largest,” said staff member and planetary geologist at the Planetary Science Institute Aster Cowart with Space .com. “Long-lived volcanic sources near abundant water could have fueled hydrothermal systems that could support life.
“At the very least, these results give us a larger number of places we can look for evidence of life.”
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Unlike Earth today, Mars has very little volcanic or tectonic activity today. Furthermore, since about half of the Red Planet’s surface appears to be older than 3.5 billion years, this suggests that crust on Mars has not been recycled much.
On Earth, crustal recycling is driven by plate tectonics when one tectonic plate slides under another, allowing surface material to be recycled into the mantle between the Earth’s crust and its molten core.
The team behind this new research studied the morphology and mineralogy of the Mars Eridania region 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 characteristics of the Eridania region have attracted particular attention for some time,” said Cowart. “Gamma-ray spectroscopy shows that this is a region of the crust with a very specific composition, gravity data showed that it is generally denser and thicker than the rest of the Martian crust, and magnetic data shows that it is strongly magnetized. crust.”
They identified 63 examples of volcanism exposed so far across 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 left over from extreme geological events on Mars around 3.5 billion years ago. They also think that the volcanic diversity seen in this region could be replicated in other regions of the Martian surface.
Tectonic activity gave rise to early Mars
The type of geological activity seen on Mars through these observations is vertical tectonics, in which the ground moves upwards, creating 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 match the stage Earth took on its own evolutionary path toward plate tectonics more than 2.5 billion years ago.
“Before plate tectonics developed, it was difficult to recycle crust back into the mantle because the composition of the crust was more uniform, the crust was more rigid, and it was buoyant 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 made the deep crust denser.”
Cowart explained that after much of the Earth’s lower crust had undergone these mineral transformations, it began to flow down into the mantle, a process known as ‘sagduction.’ This pushed water-rich minerals that formed near the Earth’s surface deeper into its crust, where they helped create buoyant magmas. Because of the buoyancy of these magmas, other regions of the crust rose up.
This resulted in a landscape dominated by large basins at points where the crust was flowing, mountain chains where the crust was rising, and volcanic rocks with a richer composition of silica than source rocks mantle.
“This is exactly what we see in the Eridania region,” said Cowart. “It’s very exciting to see a landscape so shaped by pre-plate tectonic processes. Much of what we know about these processes on Earth has been assembled from ancient rocks that have been heavily eroded and have some overprints from later plate tectonic activity. or from where they occur in modern settings and are influenced by plate tectonic dynamics.”
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The newly discovered geology of Mars may not only provide an opportunity to study a period of Earth’s past that is inaccessible in our planet’s geological record, but it may also help determine how life evolved. on our planet.
This is because the processes behind these features may be very similar to situations related to the origin of life where life appears to have evolved around porous hydrothermal vents, sites where seawater has been spilled. heated, mineral-laden from cracks in the ocean crust.
“It’s amazing to think about the scale of activity in this region. Mars tends to do everything in a big way, and to see a landscape almost the size of Europe or Arabia shaped by an interrelated series of tectonic processes in this of the data is amazing,” said Cowart. “Seeing the Martian landscape
shaped by these processes and preserved in stasis gives us a great opportunity to explore the evolution of planetary landscapes in more
minor.”
The team’s research was published on Monday (February 12) in the journal Nature.
