Demonstration of REE fractionation among individual chondrules from the allende (CV3) chondrite

Journal Article · Wed Jun 01 04:00:00 EDT 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90238-4· OSTI ID:5557689

Misawa, K; Nakamura, N ^[1]

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1. Kobe Univ. (Japan)

Abundances of REE, Ba, Sr, Rb, K, Mg and Ca were determined by precise mass spectrometric isotope dilution techniques for 24 chondrules from the Allende (CV3) chondrite. The REE abundances are 2.5-10 {times} CI for barred olivine chondrules, 2-8 {times} CI for porphyritic and nonporphyritic pyroxene chondrules, 0.15-4 {times} CI for porphyritic olivine and porphyritic olivine-pyroxene chondrules and are more or less similarly fractionated. General REE fractionations and large (up to 170%) anomalies of Ce, Eu and Yb occur in all chondrule types, particularly for barred olivine and pyroxene-rich chondrules. Positive correlations of REE with the moderately volatile elements, K and Rb, as well as other refractory elements, Ca, Sr and Ba, are independent of textural type and major chemical compositions. Each type of chondrule has large and systematic abundance variations of K and Rb, but shows a constant K/Rb ratio close to that of CIs. From the these results, the following constraints on the chemical characteristics of precursors and chondrule-forming events are suggested: (1) vaporization loss of alkalis accompanied by K/Rb fractionation did not occur during chondrule-formation melting events, (2) elemental abundances were basically established prior to melting events by accretion of alkali-free component(s) and alkali-bearing refractory precursors with fractionated REE, (3) gas/solid (or liquid) processes yielding REE fractionations took place during the formation of refractory precursors.

• OSTI ID: 5557689
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 52:6; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580400* -- Geochemistry-- (-1989)
ALKALI METALS
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
ANTARCTIC REGIONS
ANTARCTICA
BARIUM
CALCIUM
CHEMICAL COMPOSITION
CHEMISTRY
CHONDRITES
ELEMENTS
FRACTIONATION
GEOCHEMISTRY
INCLUSIONS
IRON COMPOUNDS
IRON SILICATES
MAGNESIUM
MAGNESIUM COMPOUNDS
MAGNESIUM SILICATES
MASS SPECTROSCOPY
METALS
METEORITES
MINERALS
OLIVINE
OXYGEN COMPOUNDS
POLAR REGIONS
POTASSIUM
RARE EARTHS
RUBIDIUM
SEPARATION PROCESSES
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SPECTROSCOPY
STONE METEORITES
STRONTIUM
TRANSITION ELEMENT COMPOUNDS