Mars Rover Snaps Images Of Mysterious Rocks Caused By Violent Volcanic Eruptions On Red Planet

Researchers have determined that a type of rock on Mars may be the result of cataclysmic eruptions from colossal volcanic calderas. The team from Arizona State University have been scouring data collected over decades, covering several Mars missions.

A team of researchers led by Steve Ruff of Arizona State University's School of Earth and Space Exploration have resolved that ambiguous olivine-rich bedrock in Gusev crater and in and around Jezero crater may be "ignimbrite." This type of rock is typically the result of extremely hot volcanic calderas.

Results of the study conducted by the team has been published in Icarus, as they hope that the findings will lead to a better understanding of olivine-rich bedrock in other places on the Red Planet. They believe that the study may also indicate a style of volcanism more common on Mars' early history.

"There are lots of ideas for the origin of olivine-rich bedrock that covers large portions of a region called Nili Fossae, which includes Jezero crater," Ruff explained. "It's a debate that's been going on for nearly 20 years."

Data collected during NASA's Spirit rover mission has provided crucial information. As the team looked over images taken from Spirit's Microscopic Imager, which is similar to a geologist's hand lens, they noticed rocks with an unusual texture. When Ruff compared the images to an online library with images of rocks on Earth, he came across volcanic rocks with similar textures and that looked very similar to those in the mosaics from Mars.

"That was a eureka moment," Ruff stated. "I was seeing the same kind of textures in the rocks of Gusev crater as those in a very specific kind of volcanic rock found here on Earth."

The images being compared were a type of rock called "ignimbrite," which is actually both igneous and sedimentary at once. Ignimbrites are the result of flows of pyroclastic ash, pumice and blocks from the largest volcanic explosions known on Earth.

These ignimbrite deposits form over months or years as they slowly cool. The result is an intricate network of fractures known as cooling joints. It was notably similar fracture patterns in the olivine-rich bedrock deposits on Mars that Ruff recognized.

"No one had previously suggested ignimbrites as an explanation for olivine-rich bedrock on Mars," Ruff indicated. "And it's possible that this is the kind of rock that the Perseverance rover has been driving around on and sampling for the past year."

"Now with the strong evidence for ancient olivine-rich ignimbrites on Mars, maybe this points to a style of volcanism, cataclysmic explosive eruptions of olivine-rich magma, that happens in the early geologic evolution of a planet." Ruff added, "The answer in the case of Mars may come from rock samples collected by Perseverance and returned to Earth by future missions."

Top Image Courtesy of NASA