Meteorites often contain small grains of iron–nickel metal that formed billions of years ago inside asteroids. These metal grains can preserve microscopic structures created during collisions between asteroids early in the Solar System’s history. By studying these structures, scientists can learn how meteorites were heated, deformed, and cooled during impact events.
In this research, scientists analyzed iron–nickel metal from L-group ordinary chondrite meteorites using a technique called electron backscattered diffraction (EBSD). This method allows researchers to map the crystal orientation of metals in very fine detail, revealing how the metal structure changed during past shock events.
The researchers focused on a group of metal textures known as plessite, which form when high-temperature metal cools and separates into different phases. The study identified several types of plessite structures, including net plessite, acicular plessite, duplex plessite, and pearlitic plessite. Each structure reflects a different cooling pathway after the metal was heated during an impact event.
The results suggest that many of these structures formed when the metal was briefly heated to high temperatures during asteroid collisions and then cooled rapidly as the surrounding rock solidified. In some cases, the metal transformed into a high-temperature phase and later broke down into complex microstructures as it cooled.
By analyzing these structures, scientists can better understand the thermal history and impact conditions experienced by meteorites and their parent asteroids. These microscopic metal patterns serve as valuable records of the violent processes that shaped the early Solar System.
The findings also complement earlier studies of shock structures in meteorites, providing a more complete picture of how impacts influence both silicate minerals and metallic components inside asteroids.
Reference
Y. Luo et al., “EBSD analysis of iron-nickel metal in L type ordinary chondrites: 2. Formation of net, acicular, duplex, and pearlitic plessite,” Journal of Geophysical Research: Planets, vol. 129, 2024, doi: 10.1029/2023JE007940
