Evidence of recent volcanic activity on Mars shows that eruptions could have taken place within the last 50,000 years, according to a new study by researchers from the Lunar and Planetary Laboratory and the Planetary Science Institute at the University of Arizona.
Most volcanism on the Red Planet occurred between 3 and 4 billion years ago, with smaller eruptions in isolated locations continuing perhaps as recently as 3 million years ago. . But, until now, there was no evidence that Mars might still be volcanically active.
Using data from satellites orbiting Mars, researchers have discovered a previously unknown volcanic deposit. They detail their findings in the article “Evidence for geologically recent explosive volcanism at Elysium Planitia, Mars”, published in the journal Icarus.
“This may be the youngest volcanic deposit ever documented on Mars,” said study lead author David Horvath, who carried out the research as a postdoctoral researcher at UArizona and is now researcher at the Planetary Science Institute. “If we were to compress the geologic history of Mars into a single day, it would have happened in the very last second.”
The volcanic eruption produced a smooth, dark deposit 8 miles wide surrounding a 20 mile long volcanic fissure.
“When we first noticed this deposit, we knew it was something special,” said study co-author Jeff Andrews-Hanna, associate professor at UArizona Lunar and Planetary. Laboratory and lead author of the study. “The deposit was unlike anything else found in the region, or even on all of Mars, and was more like features created by older volcanic eruptions on the Moon and Mercury.”
Further investigation showed that the properties, composition and distribution of the materials are consistent with what one would expect for a pyroclastic eruption – an explosive eruption of magma driven by expanding gases, much like the opening of a shaken soda can.
The majority of volcanism in the Elysium Planitia region and elsewhere on Mars consists of lava flowing over the surface, similar to recent eruptions in Iceland studied by co-author Christopher Hamilton, associate professor of lunar and planetary sciences at the ‘UArizona. Although there are many examples of explosive volcanism on Mars, they happened a long time ago. However, this repository appears to be different.
“This feature overlies the surrounding lava flows and appears to be a relatively cool, thin deposit of ash and rock, representing a different style of eruption from previously identified pyroclastic features,” Horvath said. “This eruption could have spewed ash up to 10 km into the Martian atmosphere. It is possible that these types of deposits were more common but were eroded or buried.”
The site of the recent eruption is about 1,000 miles (1,600 kilometers) from NASA’s InSight lander, which has been studying seismic activity on Mars since 2018. Two Marsquakes, the Martian equivalent of Earthquakes earth, were found to originate from the region around the Cerberus Fossae, and recent work has suggested the possibility that these may be due to the movement of magma deep underground.
“The young age of this deposit absolutely raises the possibility that there could still be volcanic activity on Mars, and it’s intriguing that the recent Mars tremors detected by the InSight mission are from the Cerberus Fossae,” Horvath said. In fact, the research team predicted this would be a likely location for Marsquakes several months before NASA’s InSight lander touched down on Mars.
A volcanic deposit such as this also raises the possibility of habitable conditions below the surface of Mars in recent history, Horvath said.
“The interaction of rising magma and icy substrate in this region could have provided favorable conditions for microbial life quite recently and raises the possibility of extant life in this region,” he said.
Similar volcanic fissures in this area were the source of massive flooding perhaps as recently as 20 million years ago when groundwater erupted to the surface.
Andrews-Hanna’s research group continues to investigate the causes of the eruption. Pranabendu Moitra, a researcher with the Arizona Department of Geosciences, probed the mechanism behind the eruption.
An expert in similar explosive eruptions on Earth, Moitra developed models to examine the possible cause of the Martian eruption. In an article to be published in the journal Earth and Planetary Science Letters, he suggests that the explosion could have been the result of gases already present in the Martian magma, or that it could have occurred when the magma came into contact with Martian permafrost.
“The ice melts into water, mixes with the magma and vaporizes, forcing a violent explosion of the mixture,” Moitra said. “When water mixes with magma, it’s like pouring gasoline on a fire.”
He also points out that the youngest volcanic eruption on Mars occurred just 10 kilometers from the planet’s youngest high-impact crater – a 6-mile-wide crater named Zunil.
“The ages of the eruption and the impact are indistinguishable, raising the possibility, even speculative, that the impact actually triggered the volcanic eruption,” Moitra said.
Several studies have found evidence that large earthquakes on Earth can cause magma stored below the surface to erupt. The impact that formed the Zunil crater on Mars would have rocked the red planet like an earthquake, Moitra explained.
While the most spectacular giant volcanoes elsewhere on Mars – like Olympus Mons, the tallest mountain in the solar system – tell the story of the planet’s ancient dynamics, the current hotspot of Martian activity appears to be in the relatively featureless plains of the Elysée region of the planet.
Andrews-Hanna said it was remarkable that an area had the epicenters of current earthquakes, the most recent floods, the most recent lava flows and now an even more recent explosive volcanic eruption.
“This may be the most recent volcanic eruption on Mars,” he said, “but I think we can be sure it won’t be the last.”
The volcanic deposit described in this study, together with the ongoing seismic rumble inside the planet detected by InSight and possible evidence of atmospheric methane plume releases detected by NASA’s MAVEN orbiter, suggest that Mars is far from a cold, inactive world, Andrews-Hanna said.
“All of this data seems to be telling the same story,” he said. “Mars is not dead.”