¹⁶O poor cosmic spherules from near-Earth CY chondrite asteroids
File(s)
Published version
Author(s)
Genge, Matthew
Matthias, van Ginneken
Genge, Matthew
Type
Journal Article
Abstract
Approximately 10% of cosmic spherules—microscopic extraterrestrial particles that melt upon atmospheric entry and dominate the influx of astromaterials to Earth—exhibit anomalous oxygen isotopic compositions, suggesting an asteroidal source not represented in current meteorite collections. We introduce a new subset of micrometeorites, the sulphur-rich cumulate olivine (SCumPo) cosmic spherules, characterized by cumulate textures evidencing the settling of olivine crystals, and 16O-poor bulk signatures. The systematically Ni-poor olivine phenocrysts, frequent Fe-Ni-S droplets, unusually S-rich mesostasis and a virtual absence of magnetite, all point to unusually highly reducing conditions during atmospheric entry, which may reflect unusual precursor mineralogy. Numerical modeling of olivine settling under deceleration speeds of ~14–17 km s-1 suggests high-eccentricity precursor orbits (e > 0.2), incompatible with typical main-belt asteroid sources. These findings point to a previously unsampled, primitive, sulphide-rich CY-like Near-Earth Asteroid, which represents a “missing” meteorite parent body that contributes distinctive 16O-poor cosmic dust to Earth.
Date Issued
2026-06-26
Date Acceptance
2026-05-12
Citation
Science Advances, 2026, 12 (26)
ISSN
2375-2548
Publisher
American Association for the Advancement of Science (AAAS)
Journal / Book Title
Science Advances
Volume
12
Issue
26
Copyright Statement
Copyright This paper is embargoed until publication. Once published the Version of Record (VoR) will be available on immediate open access.
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Publication Status
Published