Massive amounts of lava spewed from a volcanic region roughly half the size of France about 3.5 billion years ago caused the outer layers of Mars to become displaced, and the Red Planet’s original north and south poles to change position, according to a new study.
As Sylvain Bouley, a geoscientist at the University of Paris-Sud, and his colleagues, reported Wednesday in the journal Nature, the discovery explains why dry river beds and underground regions of water ice are found in unexpected places, and could solve other Martian mysteries.
Credit: Sylvain Bouley et. al.
“If a similar shift happened on Earth, Paris would be in the Polar Circle,” Bouley told the AFP news agency, adding that the period of volcanic activity likely lasted for a few hundred million years and would have tilted the surface of the planet by 20 to 25 degrees.
The lava flow would have also created the Tharsis dome, a 2,000 square mile (5,000 square kilometer) wide, 7.5 mile (12 kilometer) thick plateau. The formation of this “aberration” would have caused the crust and layer of Mars to shift drastically , the study author noted.
Findings may explain positioning of riverbeds, underground ice
Bouley’s team compared their findings with a 2010 theoretical study that showed if the massive Tharsis dome was to be removed from Mars, it would cause the planet to shift on its axis, as well as other computer models and observations. Their analysis lead to a lightbulb moment.
“Scientists couldn’t figure out why the rivers,” which today are dry riverbeds today, “were where they are. The positioning seemed arbitrary,” he said to the AFP. “But if you take into account the shift in the surface, they all line up on the same tropical band.”
Similarly, the location of the Red Planet’s extensive frozen underground water ice has long been a source of confusion for scientists, who realized that they should be closer to the poles. Because of the new study, they now know that, at one time, they were. Furthermore, the findings also help explain why Tharsis dome is located on the “new” equator – it was necessary for planet to regain its equilibrium following the shift, Bouley told the news organization.
The study also challenges the notion that the rivers formed after the Tharsis dome, as the authors concluded that most of these waterways would have flowed from south to north whether the lava fields were there or not. However, Bouley cautioned that there were still questions that needed to be answered, such as whether or not the tilt caused Mars’ magnetic fields to stop working, and if it played any role in the planet losing its atmosphere.
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Image credit: NASA / JPL-Caltech / Arizona State University
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