Cracks crossing land formations on Mars indicate that Mars is a much more active planet than previously thought
Orbital observations reveal the presence of a huge mantle plume that pushes the Martian surface upwards and causes intense volcanic and seismic activity.
On Earth, shifts of the tectonic plates change the Earth's surface and cause dynamism in the interior. Because of the lack of such processes on Mars, many thought that it was a dead planet, that not much had happened to it in the last three billion years.
University of Arizona scientists are casting doubt on current beliefs about the geodynamic evolution of Mars with a report of the discovery of an active mantle plume that pushes the Martian surface upward, causing earthquakes and volcanic eruptions. The findings show that the calmness of the Martian surface is deceiving and perhaps they hide an inner part that is more turbulent than previously thought.
"Our study presents ample evidence that reveals the presence of a vast active mantle plume on present-day Mars," said Adrian Brockett, a postdoctoral research fellow in the university's Lunar and Planetary Laboratory and co-author of the study with Jeff Andrews-Hannah, associate professor of planetary sciences at the laboratory.
Mantle plumes are hot, icy blocks of rock that rise from deep within the star's interior and are pushed through the middle layer - the mantle - and reach the base of the crust and cause earthquakes, aftershocks and volcanic eruptions. The Hawaiian island chain, for example, was formed as the Pacific Plate drifted slowly across a mantle plume.
"We have strong evidence that mantle plumes are active on Earth and Venus, but this is not expected on a small and probably cold world like Mars," Andrews-Hannah said. "Mars was most active 3-4 billion years ago, and the popular opinion is that the planet is actually dead today."
"An enormous amount of volcanic activity in the early history of the planet created the tallest volcanoes in the Solar System and covered most of the northern hemisphere in volcanic deposits," Brockett said. "The little activity that has occurred in recent times is usually attributed to passive processes in a cooling star."
The researchers were drawn to a surprising amount of activity in another featureless region of Mars called the Elysium Plain, in the northern lowlands near the equator. Unlike other volcanic regions on Mars, which have not been active for billions of years, the Elysium Plain has had major eruptions in the last 200 million years.
"Our previous research found evidence on the Elysium Plain for the youngest known volcanic eruption on Mars," said Andrews-Hannah. "It created a small explosion of volcanic ash about 53,000 years ago, and in geological time this is actually yesterday."
The volcanism on the Elysium plain originates from Cerberus Fossae, a group of young fissures that extend across the surface of Mars for more than 1300 km. Recently, NASA's InSight team found that almost all earthquakes on Mars originate from this region. Although this young volcanic and tectonic activity has been documented, its cause is still unknown.
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