Late Aqueous Activity on Vesta

Abstract Fluid‐assisted metasomatism was prevalent on Vesta, but the timing and source(s) of aqueous activities remain elusive. Here, we report an absolute 207 Pb/ 206 Pb isochron age (4,169 ± 85 Ma) of apatites from a plagioclase‐rich eucrite clast within the Jikharra 001 eucrite. Petrographic, mineralogical, and geochemical characteristics demonstrate that apatite veins in the clast formed during fluid‐assisted metasomatism on Vesta. The elevated 87 Sr/ 86 Sr ratios observed in the bulk clast and plagioclase grains suggest the incorporation of fluid from primitive sources, probably carbonaceous chondrites. The slightly negative oxygen isotopic composition (Δ 17 O = −0.275 ± 0.013‰) of the clast further indicates a largely carbonaceous chondrite source. Impacts from carbonaceous chondrites are the probable origin of Veneneia. Evidence from apatite veins in the Jikharra 001 is consistent with a carbonaceous fluid source and may constrain the age of Veneneia to the late heavy bombardment, approximately 4.1–4.2 Ga.