ALH85085: A unique volatile-poor carbonaceous chondrite with possible implications for nebular fractionation processes
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Abstract
Allan Hills 85085 is a unique chondrite with affinities to the Al Rais-Renazzo clan of carbonaceous chondrites. Its constituents are less than 50 μm in mean size. Chondrules and microchondrules of all textures are present; nonporphyritic chondrules are unusually abundant. The mean compositions of porphyritic, nonporphyritic and barred olivine chondrules resemble those in ordinary chondrites except that they are depleted in volatile elements. Ca-, Al-rich inclusions are abundant and largely free of nebular alteration; they comprise types similar to those in CM and CO chondrites, as well as unique types. Calcium dialuminate occurs in several inclusions. Metal, silicate and sulfide compositions are close to those in CM-CO chondrites and Al Rais and Renazzo. C1-chondrite clasts and metal-rich “reduced” clasts are present, but opaque matrix is absent. Siderophile abundances in ALH85085 are extremely high (e.g., Fe/Si= 1.7 × solar), and volatiles are depleted (e.g., Na/Si= 0.25 × solar, S/Si= 0.03 × solar). Nonvolatile lithophile abundances are similar to those in Al Rais, Renazzo, and CM and CO chondrites.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | ALH85085: A unique volatile-poor carbonaceous chondrite with possible implications for nebular fractionation processes |
| Series title | Earth and Planetary Science Letters |
| DOI | 10.1016/0012-821X(88)90149-5 |
| Volume | 91 |
| Issue | 1-2 |
| Year Published | 1988 |
| Language | English |
| Publisher | Elsevier |
| Description | 22 p. |
| First page | 33 |
| Last page | 54 |
| Google Analytic Metrics | Metrics page |