Distribution of s-, r-, and p-process nuclides in the early Solar System inferred from Sr isotope anomalies in meteorites

Abstract

Nucleosynthetic isotope anomalies in meteorites allow distinguishing between the non-carbonaceous (NC) and carbonaceous (CC) meteorite reservoirs and show that correlated isotope anomalies exist in both reservoirs. It is debated, however, whether these anomalies reflect thermal processing of presolar dust in the disk or are primordial heterogeneities inherited from the Solar System's parental molecular cloud. Here, using new high-precision 84Sr isotope data, we show that NC meteorites, Mars, and the Earth and Moon are characterized by the same 84Sr isotopic composition. This 84Sr homogeneity of the inner Solar System contrasts with the well-resolved and correlated isotope anomalies among NC meteorites observed for other elements, and most likely reflects correlated s- and (r-, p-)-process heterogeneities leading to 84Sr excess and deficits of similar magnitude which cancel each other. For the same reason there is no clearly resolved 84Sr difference between NC and CC meteorites, because in some carbonaceous chondrites the characteristic 84Sr excess of the CC reservoir is counterbalanced by an 84Sr deficit resulting from s-process variations. Nevertheless, most carbonaceous chondrites exhibit 84Sr excesses, which reflect admixture of refractory inclusions and more pronounced s-process heterogeneities in these samples. Together, the correlated variations of s-, (r-, p-)-process nuclides revealed by the 84Sr data of this study refute an origin of these isotope anomalies solely by processing of presolar dust grains, but points to primordial mixing of isotopically distinct dust reservoirs as the dominant process producing the isotopic heterogeneity of the Solar System.

18 pages 4 Figures

References in corpus (8)

• Nucleosynthesis and Remnants in Massive Stars of Solar Metallicity
• Galactic Chemical Evolution and solar s-process abundances: dependence on the 13C-pocket structure
• Contemporary formation of early solar system planetesimals at two distinct radial locations
• Terrestrial planet formation from lost inner solar system material
• Early evolution of the solar accretion disk inferred from Cr-Ti-O isotopes in individual chondrules
• Isotopic evolution of the inner Solar System inferred from molybdenum isotopes in meteorites
• Origin of isotopic diversity among carbonaceous chondrites
• Fingerprints of the protosolar cloud collapse in the Solar System II: Nucleosynthetic anomalies in meteorites

Cited by in corpus (3)

• Infall and Disk Processes - the Message from Meteorites
• Physicochemical Controls on the Compositions of the Earth and Planets
• Origin of nucleosynthetic isotope variability in the NC reservoir: Evidence from Ti, Cr, and Mo isotopes