“Fingerprint” minerals to better understand how they are affected by meteorite impacts

Credit: SLAC National Accelerator Laboratory

When the rocks of the universe survive the passage of turbulence through the Earth’s atmosphere and collide with the surface, it produces shock waves that can compress and convert minerals in the planet’s crust. Because these changes depend on the pressure generated during a collision, experts can take advantage of the Earth’s mineral characteristics to learn about the life story of meteorites, from the moment of collision to the conditions under which celestial bodies occur.

“Comparing the averages mineral For those involved in the effects of meteorites, those who are shocked have some unique characteristics, “says Arianna Gleason, a scientist at the SLAC National Accelerator Laboratory at the Department of Energy. Although crystalline, it becomes chaotic internally and is filled with beautiful interlocking linear formations called lamellars. “

Plagioclase, the most abundant mineral in the Earth’s crust, is one of the most commonly used minerals to get a complete picture of the effects of meteorites. However, the pressure at which this mineral loses its crystalline form and becomes disordered, and how this process, called amorphization, works is the subject of ongoing debate.

In a new experiment, SLAC researchers mimic the effects of meteorites in the laboratory to investigate how plagioclase changes during impact compression. They found that amorphization started at a much lower pressure than previously expected. They also discovered that upon release, the material partially recrystallized and returned to its original shape. This shows the memory effect that may be available for materials science applications.Those results were published today Meteorology and planetary scienceMay lead to a more accurate model for learning the effects of meteorites, such as the speed of meteorite movement and the pressure generated during a collision.

“With the development of new tools and technologies, we can recreate these effects in the lab, get new information and see in more detail what’s happening,” said the SLAC scientist who co-led the study. Roberto Alonso-Mori says. “It really brings astronomy and planetary science to our fingertips.”

Fingerprint minerals

Using SLAC’s Linac Coherent Light Source (LCLS) X-ray Laser Matter in Extreme Conditions (MEC) instrument, researchers struck a sample of plagioclase with a high-power optical laser and transmitted a shock wave. As the shock wave passed through the sample, researchers hit the sample with an ultrafast X-ray laser pulse from LCLS at various points in time.Some of these X-rays are scattered and formed by the detector Diffraction pattern..

“The atomic structure of each mineral is unique, just as everyone has their own set of fingerprints,” says Gleason. “The diffraction pattern reveals the fingerprint and makes it possible to track how the sample’s atoms were rearranged in response to the pressure generated by the shock wave.”

Researchers can also adjust the optical laser to different energies to see how the diffraction pattern changes at different pressures.

“In our experiments, we were able to observe the actual amorphization that took place,” says Alon Somori. “We have found that it actually starts at a lower place. pressure more than I thought. We also found that the start and end “fingerprints” were very similar. This shows evidence of the memory effect of the material. This changes the way we think about the different shock stages of these processes and helps us improve the model we use to understand these effects. “

Beauty from destruction

In follow-up experiments, researchers plan to collect and analyze information about debris that bounces off during a collision. This allows them to get a more complete picture of the impact and compare it side-by-side with what experts have found in the field to further improve the model of meteorite impact. They are also planning to explore other minerals and use more powerful lasers and large amounts of materials. This may provide insights into large-scale processes such as planet formation.

Gleason adds that the study is excited about the light it shines on minerals found not only on Earth but also on other planets and extraterrestrial life forms. Further insights into how these minerals are affected by extreme impacts may unleash new information on astrophysical phenomena.

“I see mineralogy and petrology as an undergraduate and I remember seeing these minerals under a microscope. I changed the lights to illuminate all these beautiful details,” she says. “And now we can understand how some of these complex and gorgeous structures are formed at the atomic level, and in fact it correlates with this extreme, Earth-destroying process. It’s fascinating that something very destructive can produce something very delicate. “It’s beautiful.”

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For more information:
Arianna E. Gleason et al, ultrafast structural response of impact-compressed plagioclase, Meteorology and planetary science (2022). DOI: 10.1111 / maps.13785

Quote: “Fingerprint” minerals to better understand the effects of meteorite collisions (February 17, 2022) https: // Obtained from collisions on February 17, 2022. html

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“Fingerprint” minerals to better understand how they are affected by meteorite impacts

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