Volcanoes on Mars exploded in ‘super eruptions’ that blotted out the sun

Mars is home to the solar system’s largest volcano, Olympus Mons, and volcanic activity has had a profound impact on shaping the planet into the state it is in today. Now, new evidence shows that volcanic eruptions on ancient Mars were incredibly dramatic, with thousands of “super eruptions” throwing huge quantities of dust and gases into the air and blocking out the sun.

Starting around 4 billion years ago, volcanic activity on Mars crescendoed into a period of around 500 million years when super eruptions spewed water vapor, carbon dioxide, and toxic sulfur dioxide into the atmosphere. These eruptions spread a thick blanket of ash for thousands of miles around the volcanoes, and according to NASA, they threw out the equivalent of 400 million Olympic-size swimming pools of molten rock and gas. This image shows several craters in Arabia Terra that are filled with layered rock, often exposed in rounded mounds. The bright layers are roughly the same thickness, giving a stair-step appearance. The process that formed these sedimentary rocks is not yet well understood. They could have formed from sand or volcanic ash that was blown into the crater, or in water if the crater hosted a lake. The image was taken by a camera, the High Resolution Imaging Experiment, on NASA’s Mars Reconnaissance Orbiter. NASA/JPL-Caltech/University of Arizona There was so much of this activity that it changed the entire planet’s climate, according to the study’s lead author Patrick Whelley, a geologist at NASA’s Goddard Space Flight Center. “Each one of these eruptions would have had a significant climate impact — maybe the released gas made the atmosphere thicker or blocked the sun and made the atmosphere colder,” Whelley said in a statement . “Modelers of the martian climate will have some work to do to try to understand the impact of the volcanoes.”

Whelley and his colleagues were investigating vast basins in the martian surface which were originally thought to be from asteroid impacts. But more recently, researchers realized that the craters could actually be the sites of ancient volcanoes which had collapsed in on themselves.

“We read that paper and were interested in following up, but instead of looking for volcanoes themselves, we looked for the ash, because you can’t hide that evidence,” Whelley said.

They investigated an area called Arabia Terra and looked for the way volcanic minerals were distributed across the surface using the Mars Reconnaissance Orbiter’s Compact Reconnaissance Imaging Spectrometer for Mars instrument. They found these volcanic minerals even thousands of miles from the craters and used 3D topographical maps to see that the ash had been laid down in consistent layers, suggesting it was deposited around the same time. Not only that, but the layers were so thick that the ash must have been created from thousands of super eruptions.

Currently, the Arabia Terra region is the only place on Mars with evidence of these huge explosive volcanic eruptions has been found, making this a special place on the planet.

“People are going to read our paper and […]

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