Alkali (Rb/K) abundances in Allende barred-olivine chondrules - Implications for the melting conditions of chondrules

Journal Article · Fri Jun 01 04:00:00 EDT 1990 · Meteoritics; (USA)

DOI:https://doi.org/10.1111/j.1945-5100.1990.tb00985.x· OSTI ID:6576428

Matsuda, Hitoshi; Nakamura, Noboru; Noda, Shinji ^[1]

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1. Kobe Univ. (Japan)

Twenty five petrographically characterized chondrules, including 18 barred olivine (BO) chondrules from the Allende (CV3) meteorite, were analyzed for alkalis (K and Rb) and alkaline earths (Sr, Ba, Ca and Mg) by mass spectrometric isotope dilution. Most BO chondrules with higher alkalis (greater than the CI level) have nearly CI-chondritic Rb/K ratios, while those with lower alkalis clearly show higher Rb/K ratios than the CI-chondritic. In general, BO chondrules with higher Rb/K exhibit more depletion of alkalis relative to Ca. The mean olivine Fa for individual chondrules positively correlates with bulk alkali concentrations in BO type but not in porphyritic type chondrules. These observations suggest that some BO chondrules formed from more reducing assemblages of precursor minerals, which experienced more intensive vaporization losses of alkalis, accompanied by Rb/K fractionation, during the chondrule-formation melting. 30 refs.

• OSTI ID: 6576428
• Journal Information: Meteoritics; (USA), Journal Name: Meteoritics; (USA) Vol. 25; ISSN 0026-1114; ISSN MERTA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
CHEMICAL COMPOSITION
CHONDRITES
CRYSTAL GROWTH
ELEMENT ABUNDANCE
ELEMENTS
IRON COMPOUNDS
IRON SILICATES
ISOTOPES
MAGNESIUM COMPOUNDS
MAGNESIUM SILICATES
MASS SPECTROMETERS
MEASURING INSTRUMENTS
METALS
METEORITES
MINERALS
OLIVINE
OXYGEN COMPOUNDS
PETROGRAPHY
POTASSIUM COMPOUNDS
RUBIDIUM COMPOUNDS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SPECTROMETERS
STONE METEORITES
TRANSITION ELEMENT COMPOUNDS