Scientists have estimated the last eruption of one of Mars’ largest volcanoes.
New research from NASA shows that the huge Martian shield volcano Arsia Mons last erupted around 50 million years ago, right after the time when the dinosaurs went extinct. The research shows that during its last active period, the 20 km tall mountain was producing lava flows once ever million to two million years.
Mars’ geology is dominated by volcanoes which dot the surface. This is something researchers have known since 1972 when the Mariner 9 space mission flew a drone past the red planet and took several pictures of it. Mars features everything from small lava flows (some evidence even suggests there may be active flows today) to huge shield volcanoes of immense scale. The largest mountain in the solar system, Olympus Mons, is one of these shield volcanoes. It’s roughly the same surface area as the US state of Arizona and more than twice the height of Mount Everest. Not far from it lies three other shield volcanoes known as the Tharsis Montes. The southernmost of these volcanoes is Arsia Mons.
“We estimate that the peak activity for the volcanic field at the summit of Arsia Mons probably occurred approximately 150 million years ago—the late Jurassic period on Earth—and then died out around the same time as Earth’s dinosaurs,” said Jacob Richardson, a postdoctoral researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s possible, though, that the last volcanic vent or two might have been active in the past 50 million years, which is very recent in geological terms.”
The volcano’s caldera is 110 km wide, and deep enough to fit Lake Victoria inside it. The researchers studied the volcano using high resolution imagery from the Mars Reconnaissance Orbiter, mapping lava flows and layers from each of Arsia Mons’ 29 volcanic vents, as well as counted the number of craters of at least 100 m diameter. This allowed the scientists to estimate the volcano’s history. Their conclusion found that the oldest lava flows likely occurred some 200 million years ago, with the most recent being somewhere between 10 to 90 million years old.
“A major goal of the Mars volcanology community is to understand the anatomy and lifecycle of the planet’s volcanoes. Mars’ volcanoes show evidence for activity over a larger time span than those on Earth, but their histories of magma production might be quite different,” said Jacob Bleacher, a planetary geologist at Goddard and a co-author on the study. “This study gives us another clue about how activity at Arsia Mons tailed off and the huge volcano became quiet.”