Oxygen- and Mg-isotope Compositions of Cais from Rumuruti

INVESTIGATIONS OF OXYGEN ISOTOPE COMPOSITIONS COMBINED WITH Be-B AND Al-Mg SYSTEMATICS IN CV3 CAIs

Si and Mg Isotope Fractionations in Melilite in Type B Cais

Introduction: Si and Mg isotopic compositions are indicators of evaporation processes experienced by CAIs [1]. Bulk Si and Mg isotopic compositions (up to ~5 permil/amu for Si and ~11 permil/amu for Mg) have been reported by [2]. Isotopic heterogeneity within CAIs is of interest because it may reveal how evaporation processes occurred. It may also reveal if secondary processes such as recondens...

Oxygen Isotope Measurements of a Rare Murchison Type a Cai and Its Rim

Introduction: Ca-, Al-rich inclusions (CAIs) from CV chondrites commonly show oxygen isotope heterogeneity among different mineral phases within individual inclusions reflecting the complex history of CAIs in both the solar nebula and/or parent bodies [1]. The degree of isotopic exchange is typically mineralspecific, yielding O-rich spinel, hibonite and pyroxene and O-depleted melilite and anor...

Oxygen isotope variations at the margin of a CAI records circulation within the solar nebula.

Micrometer-scale analyses of a calcium-, aluminum-rich inclusion (CAI) and the characteristic mineral bands mantling the CAI reveal that the outer parts of this primitive object have a large range of oxygen isotope compositions. The variations are systematic; the relative abundance of (16)O first decreases toward the CAI margin, approaching a planetary-like isotopic composition, then shifts to ...

Mean Oxygen-isotope Composition of the Protosolar Molecular Cloud Silicate Dust

Oxygen-isotope composition of the solar wind returned by GENESIS indicates that the Sun is 16 O-rich (Δ 17 O SMOW = −26±6‰) [1], supporting one of predictions of the CO self-shielding models [2−4]. The self-shielding models [3,4] assume that both the solids and gas were similarly 16 O-rich (Δ 17 O ~ −25‰), and solids subsequently evolved towards the terrestrial value as a result of CO self-shie...