A Martian meteorite fragment containing unexpected grains of mineral could hold clues to the Red Planet’s geological history, according to an international team of researchers.

Prior to the team’s new paper, which was published in Geochemical Perspectives Letters, the red mineral garnet had never been observed in any martian rock sample. Now, the meteorite discovery provides scientists with new clues to Mars‘ extreme past conditions, over its 4.5 billion-year history, which could include hidden magma sources or ancient impact events.

Garnet and Geology

Although the gemstone garnet can come in many colors, it is best known for its dark red varieties, which were historically popular in ancient Egypt, Rome, and Victorian England. Beyond its beauty, the rock is important for the record it keeps of its birth, providing Earth’s geologists with information on our planet’s tectonic forces, ore-forming processes, and the fluid-rock interactions of the crust and mantle.

Similarly, the small grains of garnet discovered in the meteorite sample contain important data for reconstructing the forces that forged the Red Planet long ago.

“The findings add a striking new dimension to our understanding of the geology of Mars and open an exciting new window into the evolution of our planetary neighbour,” said co-author Professor James Darling.

“This discovery is going to expand our knowledge of the geologic processes that are possible on this planet,” said lead author Tanya Kizovski, Assistant Professor of Earth Sciences, from Brock University in Canada. “This new garnet-bearing rock type could give us clues to how Mars has changed throughout its history and new insights into the ancient environments that could have formed the garnet and related minerals.”

Mars Meteorite NWA 8171

The garnet fragments were discovered in a tiny Martian meteorite sample held in the Royal Ontario Museum’s collection, designated NWA 8171, discovered in northwest Africa. Kizovski led the team in analyzing the sample’s mineral and chemical composition after identifying it as a unique piece within the collection.

“This little section of the meteorite looked really interesting, and the chemistry was a bit odd,” Kizovski said. “At first, we assumed it was a mineral called pyroxene, which is very common, but then we decided to take a second look.”

The international effort brought in researchers from Italy’s University di Trieste and the UK’s Open University, utilizing the Royal Ontario Museum’s laser equipment and the University of Portsmouth’s Electron Microscopy and Microanalysis Unit.

Having never been observed in any previous Martian sample, the researchers were surprised to identify garnet in the meteorite’s composition. From their analysis of the sample’s chemistry and mineralogy, the researchers began to consider how the unexpected garnet could have formed.

“Garnet is a classic example of a mineral often found in metamorphic rocks on Earth,” Kizovski said. “The process of metamorphism transforms igneous or sedimentary rocks into a new form through exposure to extreme heat, high pressure, or hot fluids.”

“On Mars, the heat and pressure needed to produce garnet through metamorphism could have come from the impact of a meteorite hitting the surface of Mars, magma rising up into the Martian crust, or both,” Kizovski continued.

Explaining Martian Garnet

While garnet provided geologists with some data about how it formed, this is not like the point of origin stamped on a manufactured good. It is possible that the garnet was deposited on Mars during an earlier meteorite impact, only to later travel through the solar system again, or that it was created by a heretofore unknown magma source on Mars.

Only further analysis of the garnet’s isotopic signatures will allow the researchers to determine whether the mineral formed on Mars or elsewhere. Unfortunately, to do so, the team would have to destroy a portion of this rare and precious sample, which measures only 0.8 by 0.5 millimeters to begin with.

“Measuring oxygen isotopes from the garnet-bearing rock type itself would help to confirm if it is Martian in origin or from an exotic meteorite impactor,” Kizovski said.

“Isotopes are a collection of atoms with equal numbers of protons and electrons, but different numbers of neutrons,” she added, “which was avoided thus far due to its rarity, as it may be the only garnet-bearing Martian rock we have for study.”

A few members of the team are continuing their study of the sample by comparing their findings to Martian data collected by rovers and orbital platforms. Further insights, they hope, may help them discover more about how the garnet could have formed, and what its presence means for the deeper history of the Red Planet.

The paper, “Expanding Mars’ Lithologic Diversity: Discovery of a Garnet-Bearing Clast in NWA 8171,” appeared in Geochemical Perspectives Letters on June 16, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.

A seismic shockwave traveling within the Earth moved the entire Japanese archipelago by 5 to 6 millimeters, posing a previously unknown Earthquake danger, according to a University of Chicago researcher.

Revealed in a recent paper published in the journal Science, Sunyoung Park and colleagues identified a shear wave bouncing off the Earth’s core after the Tohoku-Oki earthquake in 2011. According to the researchers, this specific type of rebound effect in the mainshock area after an earthquake has never been recognized before, offering new insights into the residual dangers of seismic events and how the layers of our planet interact.

Japan Shifts

As the best-recorded megathrust event in history, the 2011 Tohoku-Oki earthquake has already been well characterized in past studies. However, the team decided to take another look at the event, as monitoring stations throughout Japan detected the ScS shear wave’s return after hitting the core, as well as the archipelago’s eastward movement.

“When we examined the GPS time series in detail, we noticed a small, coherent eastward motion across much of Japan that followed seismic waves reflected from the core (the ScS phase) return to Japan,” Park told The Debrief. “This motion was puzzling because there was no known earthquake (aftershocks) associated with it at that timing, and so we wanted to understand what was really happening.”

According to the team, a previously unknown phenomenon produced the notable ground shift. In just those 13 minutes, a shear wave from the Tohoku-Oki earthquake raced through the planet, bounced off the core, and reactivated the tectonic plate beneath Japan. 

Analyzing the Earthquake Data

In their analysis, they found the rebound shear wave aligned with the tectonic plate boundaries, which, combined with weakened frictional forces after the mainshock, produced the shear wave reflection.

“We only gradually became convinced that this returning wave could actually trigger slip on multiple plate boundaries,” Park said. “It was particularly surprising that such a long-traveling wave (traveling ~5800 km, comparable to the radius of the Earth) could both trigger an event and do so over such a broad region, comparable to the length of Japan, involving several different plate interfaces.”

The movement is described as “steplike,” due to the small but sudden nature of the shift. In the data, the movement resembles a staircase: a flat position, followed by a sudden shift, then another flattening at a different level. Resolving that tiny step proved a challenge.

“In this case, the steplike motion is only a few to several millimeters, so it is relatively small compared to the noise and various processing artifacts that can appear in GPS records,” Park explained. “We did not process the GPS data ourselves; instead, we relied on a carefully processed data product. Even so, we had to be very cautious, because subtle signals can sometimes be introduced by the way the data are processed.”

The research reexamined the main shock source for any evidence of large underwater landslides to rule out other potential causes and found no other correlations.

A New Type of Earthquake Events

According to the team, it is no surprise that such events have previously gone unrecognized. For this rebound effect to occur, an extremely powerful earthquake is required to produce a noticeable effect, and dense, high-precision monitoring networks are needed to detect tiny motions over a large area. Additionally, most seismic studies focus on localized effects rather than viewing the aftermath on such a broad scale.

The slip is six to seven times that of the main shock rupture, making it the broadest single event rupture area ever recorded, doubling that of the great Sumatra Earthquake in 2004. According to the researchers, the Sumatra earthquake may be another example of this behavior, although no work has yet been done to investigate this.

From their work, the team says they cannot predict the exact amount of slip from such an event in the future, similar to the inability to predict normal earthquakes; yet, they can predict when the rebound effect will occur after the main thrust.

“I want to understand more generally how processes deep inside the Earth interact with shallow parts of the Earth,” Park concluded. “I am interested in why deep earthquakes happen and how they may be linked to the whole subduction system and the dynamics, from shallow to deep depth ranges.”

Park added that he is also finding “that these deep events can produce measurable deformation at the Earth’s surface, just like the step-like motions we see in this study,” all of which is helping researchers like him “better understand both these earthquakes and the structure of the Earth.”

The paper, “ScS-Triggered Slip on Megathrust Interfaces after the 2011 Mw 9.0 Tohoku-Oki Earthquake,” appeared in Science on June 18, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.