Ancient Mars was volcanic

Young Mars had a period of active volcanism and crust recycling according to new research based on data from satellites orbiting the planet.

Remote sensing found 63 sites showing ancient volcanic activity dating to 3.5–4 billion years ago. These correspond to 4 different types of volcano – volcanic domes, stratovolcanoes, pyroclastic shields and caldera complexes.

The results are published in Nature Astronomy.

Unlike Earth, Mars today is geologically inactive. But, also unlike Earth, the fact that more than half of its surface is 3.5 billion years old allows astronomers to peer back in time to a period when the Red Planet was much more alive.

Having such an ancient surface suggests that, for 3.5 billion years, Mars hasn’t had extensive “crust recycling” – a tectonic process which sees the upper layer of the planet fall into mantle underneath.

“The relatively well-preserved ancient crust of Mars provides a natural window into early planetary evolution not available on Earth due to sustained tectonic recycling and erosion on this planet,” the authors of the new paper write.

Astronomers have known for a while that Mars wasn’t always so geologically inactive. But understanding the first billion years of the planet’s tectonic and volcanic past has remained elusive.

This latest study used remote sensing data from various satellites including the Mars Global Surveyor, Mars Odyssey and the Mars Reconnaissance Orbiter.

Data from these orbiters was focused on the planet’s Eridania region in the southern hemisphere.

Eridania has the strongest remnants of Mars’s ancient magnetic fields and signatures of volcanism in its crust.

Not only did the analysis of the data reveal ancient volcanoes, it showed crustal recycling on early Mars. This process would have been driven by vertical tectonics – a kind of precursor to the full plate tectonics which, on Earth, drives continental drift and other geological processes.

It suggests that volcanism could have been more widespread on early Mars.

The researchers believe their findings could aid in the search for ancient life on the Red Planet. It is believed that underwater hydrothermal vents could have sparked the first organisms on Earth. A volcanically active ancient Mars could have seen similar processes lead to the emergence of life.

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