Mars might be geologically quiet today, but it once teemed with tectonic and volcanic movement. New research shows that Mars’ ancient surface was studded with 63 volcanoes, each responsible for morphing the Red Planet’s rocky geography. The discovery ultimately transforms researchers’ understanding of Mars’ mysterious past and offers a rare peek into early planetary evolution.
According to a paper published Monday in Nature Astronomy, geoscientists and astronomers from the United States and China used data from the old Mars Global Surveyor, the Mars Odyssey Orbiter, and the ultra-powerful Mars Reconnaissance Orbiter to map Mars’ ancient volcanic landscape. The “diverse volcanism” they discovered consisted of four feature types: caldera complexes, pyroclastic shields, stratovolcanoes, and volcanic domes. While caldera complexes are known as destructional volcanic features due to their hallmark surface collapse and the absence of raised rims, volcanic domes meanwhile possess a tell-tale convex shape. Pyroclastic shields and stratovolcanoes possess a more classic “volcano shape,” with valleys etched into their flanks by erosion.
Most of these features belonged to what we now call the Eridania region on Mars’ southern hemisphere. Because of their proximity to Eridania’s wide basins—which deviate from the region’s patterns of deeply seated remnant crustal magnetism—the researchers believe the volcanoes played a role in crustal recycling, in which the planet’s outermost layer, or crust, was drawn into the mantle underneath. When the crust melted, it became a component of Mars’ magmatic evolution, which the researchers say is similar to Earth’s pre-plate tectonic processes during the watery Archean Eon.
Building upon the Mars canon in this way allows scientists to improve their understanding of early planetary evolution, even when looking at other celestial bodies. As the researchers point out, Mars provides “a natural window” into planetary development that we simply don’t get here on Earth, as our planet has undergone sustained tectonic recycling and erosion throughout its 4.54 billion-year life. While Earth’s tectonic movements can inform scientists’ understanding of the Red Planet’s geological processes, Mars can serve as a jumping-off point for research into planetary geology across the solar system and beyond.
The discovery of ancient Martian volcanoes might also boost researchers’ efforts to find signs of bygone extraterrestrial life. Earth’s earliest microbial life is believed to have burst from our planet’s crust or deep sea via hydrothermal vents roughly 4 billion years ago. If the Red Planet’s volcanic features really did cycle material between Mars’ surface and mantle, ancient life could have come about in a similar way.
