While scouring Gale Crater, NASA’s Mars Curiosity rover found a sedimentary rock rich in silica which may suggest that the Red Planet once hosted volcanoes with explosive eruptions not just non-explosive volcanoes as previously thought.
NASA scientists reported that the rock had high concentrations of SiO2 also known as tridymite. This mineral needs high pressures and tremendous temperatures to form, researchers explained.
Silica-rich magmas however are tied to explosive eruptions, while basaltic magmas are associated with non-explosive volcanic eruptions such as those seen in Hawaiian volcanoes. Scientists had previously believed that the Red Planet was home only to non-explosive volcanoes.
NASA team found that tridymite is present in Martian rocks without having to look at the sample themselves. Curiosity X-rayed a mudstone, and scientists concluded that the mineral was present from the patterns left by the scattered rays.
Richard V. Morris, senior researcher with the NASA’s Johnson Space Center and one of the scientists who proposed the new theory about Mars’ volcanism, said that scientists have been aware for decades that the planet hosted basaltic volcanoes.
Silicic volcanoes often have explosive eruptions just like the U.S.’s Mount St. Helens had. The magma within these volcanoes is very viscous, has high concentrations of silica, and gets melted at higher temperatures than basaltic magma.
Morris explained that because the magma is so viscous, i.e. it is very thick, it slowly accumulates inside the volcano and so does the pressure. When a critical point is reached an explosive eruption takes place.
Morris and his team believed that all Martian volcanoes were fed by basaltic magma. Though researchers are not sure whether the silica-rich rock originated from a volcano, they do know that if it did, it came from an explosive one.
On our planet, silicic volcanism occurs where plates meet. For instance, this is the case with the volcanoes on the west coast. But Mars does not have plate tectonics or at least scientists have so far failed to find any proof of it.
This is why the team is puzzled by the new finding. Scientists speculate that Martian volcanism may be different from the Earth’s so they admitted that they haven’t fully understood it.
Still, the team cautions that the newly found rock is not absolute proof that Mars once had explosive volcanism. The Red Planet might as well have geological processes that are not common on our planet.
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