Presolar Fe Oxide from the Acfer 094 Carbonaceous Chondrite
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Matrix and whole-rock fractionations in the Acfer 094 type 3.0 ungrouped carbonaceous chondrite
We used the electron microprobe to study matrix in the ungrouped type 3.0 carbonaceous chondrite Acfer 094 using 7 · 7-point, focused-beam arrays; data points attributable to mineral clasts were discarded. The grid areas show resolvable differences in composition, but differences are less pronounced than we observed in studies of CR2 LaPaz Icefield (LAP) 02342 (Wasson and Rubin [2009]) and CO3....
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Introduction: Fine-grained matrix is a major (and thermally the most primitive) component in chondrites. Analyses of chondrite matrix [1] reveal that it does not have a primordial CI-like composition, showing instead a consistent depletion compared to solar in all chondrite groups (except CI). This suggests that volatile depletion was an early event, possibly involving cooling of a hot inner di...
متن کاملContinued Characterization of Presolar Silicate Grains from the Acfer 094 Carbonaceous Chondrite
Introduction: Among circumstellar grains produced around O-rich evolved stars, silicate grains are the most abundant [1]. Until recently, the identification of presolar silicate grains in extraterrestrial materials proved difficult due in part to their destruction by parent body processes, requiring analysis of very primitive samples, and to the experimental challenge presented by their submicr...
متن کاملDiscovery of ancient silicate stardust in a meteorite.
We have discovered nine presolar silicate grains from the carbonaceous chondrite Acfer 094. Their anomalous oxygen isotopic compositions indicate formation in the atmospheres of evolved stars. Two grains are identified as pyroxene, two as olivine, one as a glass with embedded metal and sulfides (GEMS), and one as an Al-rich silicate. One grain is enriched in 26Mg, which is attributed to the rad...
متن کاملIdentification of an Extremely O-rich Presolar Silicate Grain in Acfer
Introduction: Presolar silicate grains have been abundantly identified since their first discovery less than a decade ago [1,2,3]. The O isotopic compositions of both silicate and oxide stardust indicate the vast majority (>90%) condensed around O-rich asymptotic giant branch (AGB) stars. Though both presolar phases have average sizes of ~300 nm, grains larger than 1 μm are extremely uncommon f...
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تاریخ انتشار 2007