Study: Explosive volcanic eruption produces rare minerals on Mars

Planetary scientists from Rice University, NASA’s Johnson Space Center and the California Institute of Technology have answers to a mystery that has baffled the Mars research community since NASA’s Curiosity rover discovered a mineral called tridymite in Gale Crater in 2016.

NASA’s Curiosity Mars rover took this low-angle self-portrait at the location where it drilled rock on July 30, 2015, producing a powder (seen in the foreground) that was later confirmed to contain the rare mineral tridymite. (Image courtesy of NASA/JPL-Caltech/MSSS)

Tridymite is a very rare form of high-temperature, low-pressure quartz on Earth, and it’s not immediately clear how the concentrated chunks ended up in craters. Gale Crater was chosen as Curiosity’s landing site because of the possibility that it once harbored liquid water, and Curiosity found evidence confirming Gale Crater was a lake as recently as 1 billion years ago.

“The discovery of tridymite in mudstone at Gale Crater is one of the most surprising observations the Curiosity rover has made in its 10 years of exploring Mars,” said Kirsten Siebach of Rice, co-author of the study published online in Earth and Planetary Science. Letter. “Tridymite is usually associated with the formation of quartz, explosive, volcanic systems that evolved on Earth, but we found it at the bottom of ancient lakes on Mars, where most volcanoes were very primitive.”

Siebach, an assistant professor in Rice’s Department of Earth, Environmental and Planetary Sciences, is a mission specialist on NASA’s Curiosity team. To find the answer to the mystery, she partnered with two postdoctoral researchers in her Rice research group, Valerie Payré and Michael Thorpe, Elizabeth Rampe of NASA and Paula Antoshechkina of Caltech. Payré, lead author of the study, is now at Northern Arizona University and preparing to join the faculty at the University of Iowa in the fall.

Siebach and his colleagues began by re-evaluating data from every reported tridymite find on Earth. They also reviewed volcanic material from the Martian model of volcanism and re-examined evidence of sediment from the Gale Crater lake. They then came up with a new scenario that fits all the evidence: Martian magma sits longer than usual in the space beneath the volcano, undergoing a partial cooling process called fractional crystallization until extra silicon is available. In a violent eruption, the volcano spewed ash containing extra silicon in the form of tridymite into the Gale Crater lake and surrounding rivers. Water helps break down ash through the natural process of chemical weathering, and it also helps to break down the minerals produced by weathering.

The scenario would concentrate tridymite, resulting in a mineral consistent with the 2016 findings. It would also account for other geochemical evidence of Curiosity found in the sample, including opaline silicates and reduced concentrations of aluminum oxide.

NASA’s Curiosity Mars Rover drilled this hole to collect sample material from a rock target called “Buckskin” on July 30, 2015. The diameter of the hole is slightly smaller than a US dime. Rock powder from the drilling site was then sent to a laboratory inside the rover and was found to contain the rare mineral tridymite. (Image courtesy of NASA/JPL-Caltech/MSSS)

“This is actually a direct evolution of other volcanic rocks that we found in the crater,” Siebach said. “We think that because we only saw this mineral once, and it was so concentrated in one layer, the volcano probably erupted at the same time as the lake there. Although the specific sample we analyzed wasn’t just volcanic ash, it was ash that had been weathered and sorted by water.”

If a volcanic eruption like the one in the scenario did occur when Gale Crater contained a lake, it would mean that the volcanic eruption occurred more than 3 billion years ago, when Mars was in transition from a wetter and possibly warmer world to a drier and drier planet. barren. is today.

“There is a lot of evidence of basaltic volcanic eruptions on Mars, but this is a more developed chemistry,” he said. “This work suggests that Mars may have had a more complex and interesting volcanic history than we imagined before Curiosity.”

The Curiosity rover is still active, and NASA is preparing to celebrate the 10th anniversary of its landing next month.

This research was funded by NASA (15-MSLPSP15_2-0051, 15-MSLPSP15_0015, 80NSSC22K0732), the National Science Foundation (1947616) and Rice’s Department of Earth, Environmental and Planetary Sciences.

Peer-reviewed papers

“Tridymite in lacustrine mudstone in Gale Crater, Mars: Evidence of explosive silica eruptions during the Hesperian” | Earth and Planetary Science Letter | DOI: 10.1016/j.epsl.2022.117694

Authors: Valerie Payré, Kirsten Siebach, Michael Thorpe, Paula Antoshechkina and Elizabeth Rampe

Image download

CAPTION: NASA’s Curiosity Mars rover took this low-angle self-portrait at a rock drilling site on July 30, 2015, producing a powder (seen in the foreground) that was later confirmed to contain the rare mineral tridymite. (Image courtesy of NASA/JPL-Caltech/MSSS)

CAPTION: NASA’s Curiosity Mars Rover drilled this hole to collect sample material from a rock target called “Buckskin” on July 30, 2015. The diameter of the hole is slightly smaller than a US dime. Rock powder from the drilling site was then sent to a laboratory inside the rover and was found to contain the rare mineral tridymite. (Image courtesy of NASA/JPL-Caltech/MSSS)

CAPTION: Kirsten Siebach (Photo courtesy of Rice University)

/ Public Release. Material from this original organization/author may be timely, edited for clarity, style and length. The views and opinions expressed are those of the author. See more here.

#Study #Explosive #volcanic #eruption #produces #rare #minerals #Mars