When wet meets dry: An Ivuna-like impactor triggered volatile loss on the angrite parent body

Angrite meteorites remain the “driest” known planetary materials in the Solar System. Recent mineralogical and oxygen (O) isotope data suggest that the angrite parent body (APB) experienced a major impact, raising questions about the identity of the impactor. We report high-precision mass-independent chromium (ε 54 Cr) isotope data for eight angrites and their components. Samples from deeper APB regions exhibit uniform ε 54 Cr values (−0.40 ± 0.03), representing the mantle composition, whereas matrix materials from quenched angrites show anomalous ε 54 Cr values (0.27 ± 0.06 and −0.15 ± 0.08), likely reflecting impactor contamination. Combined Cr-O isotope data point to a CI (Ivuna-type) chondritic impactor—the “wettest” known Solar System material. Although such an impact could introduce volatiles, high-energy conditions likely caused extensive volatile loss, preserving the angrites’ dry nature. CI contamination may also make quenched angrites unsuitable time anchors for siderophile short-lived chronometers, whereas the other “contamination-free” angrites yield a precise age of 4561.0 ± 0.9 million years, dating the formation of their mantle source.