A new study published in Planet reveals a Micro-XRD method to quantitatively measure the ancient collision histories of meteorites. Researchers from China, Canada, and Japan have developed a quantitative technique to determine peak shock pressures in enstatite chondrites—rare meteorites chemically linked to Earth's building blocks—using micro-X-ray diffraction (micro-XRD) method.
Why It Matters
Enstatite chondrites (ECs) formed under extreme reducing (oxygen-poor) conditions in the early Solar System. Their mineralogy provides critical clues about planet formation near the Sun and even offers analogs for Mercury's surface. Though these meteorites preserve collision histories from ancient asteroid impacts, previous methods to gauge impact intensity relied solely on qualitative visual estimates (e.g., microscopic shock features).
The Innovation
Led by Dr. Matthew Izawa (from Okayama University), the team analyzed 11 ECs across all known shock stages (S1–S5). Using 2D micro-XRD, they measured strain-related mosaicity (SRM) in the mineral enstatite (MgSiO₃), a common planetary mineral. By correlating SRM—quantified as ΣFWHMχ (sum of X-ray peak widths along Debye rings)—with both established shock stages and shock pressure estimates from Rubin et al. (1997), they established a robust linear calibration:
Peak Pressure (GPa) = 4.62 × ΣFWHMχ + 0.57 (R² = 0.92, valid for 4–30 GPa).
Key Discoveries
- ΣFWHMχ data of enstatite (020), (610) and (131) lattice planes at each shock level shows that shock deformation is isotropic across all three enstatite crystal axes. Higher shock pressure produces bigger ΣFWHMχ value for these three lattice planes.
- The pressure model applies broadly to enstatite-rich planetary materials, enabling shock quantification in Martian meteorites and lunar samples.
Future Impact
This non-destructive micro-XRD technique unlocks transformative applications:
• High-throughput shock screening: Rapid pressure estimation for meteorite collections and future sample-return missions (e.g., Mars, asteroids).
• Asteroid collision forensics: Reconstructing impact histories of parent bodies to decode early Solar System dynamics.
Dr. Fengke Cao, co-author at Chengdu University of Technology, notes: "This work transforms shock quantification from art to science. We can now extract precise impact pressures from enstatite grains in any rock, from Earth's craters to asteroid fragments."
The study was funded by Natural Sciences and Engineering Research Council ofCanada (NSERC) Discovery Grants and Open Project for Innovative Platform of Meteoritical Research, Shanghai Science and Technology Museum.
