Did you know that some meteorites preserve water locked within their minerals? These space rocks, fragments of asteroids, likely played a key role in delivering water to the inner solar system and therefore in making Earth habitable. But certain meteorites reveal even more – offering direct evidence of how water once moved within these ancient rocky bodies.
A remarkable example is the newly discovered meteorite Reckling Peak (RKP) 17085, found in Antarctica in 2017 by the Italian National Antarctic Program (PNRA). This meteorite provides a rare glimpse into water-driven processes that shaped asteroids billions of years ago. New research published in Meteoritics and Planetary Science: “Early fluid migration and alteration fronts in the CM chondrite Reckling Peak 17085” by Musolino et al. (2024) details these findings, with key analyses conducted using the Scanning Electron Microscope (SEM) at the Centre for Instrument Sharing of the University of Pisa (CISUP).
This meteorite (RKP 17085) belongs to a group called the “CM chondrites”. They are known for having high-water contents and abundant organic matter. As a result they have astrological significance. Unlike most CM chondrite meteorites, which show extensive interaction with liquid water, RKP 17085 contains only subtle, localized evidence of water-induced alteration. This occurs in the form of “alteration fronts”, bands rich in iron. They mark “tide lines” showing transient water flow on the parent asteroid. These structures were observed in unprecedented detail. The team used CISUP’s high-resolution SEM (a FEI Quanta 450 field emission gun SEM, equipped with a Bruker QUANTAX 400 XFlash detector) to map the distribution of minerals and trace the chemical fingerprints of ancient hydrothermal activity.
Lead author Anna Musolino, currently a PhD student at Aix-Marseille University, but formerly a master’s student at the Dipartimento di Scienze della Terra (DST) explains: “RKP 17085 reveals evidence of water flow that was suddenly halted, leaving behind thin iron-rich bands. These ‘fossilized’ flows are essentially a snapshot of water activity billions of years ago, offering us insights into where water first accreted in these primitive materials, and it later migrated outwards during hydrothermal alteration”.
Co-author Martin D. Suttle from the Open University (UK) emphasizes the broader implications: “Meteorites like RKP 17085, with their abundance of hydrated minerals and organics, may have delivered crucial ingredients to the inner Solar System, including Earth. Understanding their geological context is vital to exploring the origins of habitable environments.”
URL for the article: https://onlinelibrary.wiley.com/doi/10.1111/maps.14261
The cover image of Meteoritics & Planetary Science (Volume 59, Issue 11) features a full thin section of RKP 17085 alongside a close-up of its alteration fronts. These brighter, irregular bands surrounding a chondrule were captured using backscattered electron imaging (FEG-SEM), highlighting the intricate structures that provide evidence of ancient water flow within the meteorite.