Aluminum depletion in komatiites and garnet fractionation in the early Archean mantle: Hafnium isotopic constraints

Journal Article · Thu Nov 01 00:00:00 EST 1990 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(90)90125-5· OSTI ID:6106143

Gruau, G ^[1]; Chauvel, C; Arndt, N T ^[2]; Cornichet, J ^[3]

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1. Max Planck Institut fuer Chemie, Mainz (West Germany) Universite de Rennes (France)
2. Max Planck Institut fuer Chemie, Mainz (West Germany)
3. Universite de Rennes (France)

Hafnium isotopic compositions were measured in Al-depleted and Al-enriched komatiites from the 3,450 Ma old Barberton greenstone belt, southern Africa. All samples have initial {var epsilon}{sub Hf} values close to zero. Such values are at variance with the strongly negative or positive values that should be observed if these rocks came from old garnet-depleted or garnet-enriched layers, such as may have formed during the solidification of an ancient terrestrial magma ocean. The garnet fractionation observed in komatiites probably took place during the melting event.

• OSTI ID: 6106143
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 54:11; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
VOLCANIC ROCKS
CHEMICAL COMPOSITION
PETROGENESIS
COMPARATIVE EVALUATIONS
EARTH MANTLE
GARNETS
GEOCHEMISTRY
GEOLOGIC HISTORY
HAFNIUM ISOTOPES
ISOTOPE RATIO
PETROCHEMISTRY
PRECAMBRIAN ERA
CHEMISTRY
GEOLOGIC AGES
IGNEOUS ROCKS
ISOTOPES
MINERALS
OXYGEN COMPOUNDS
ROCKS
SILICATES
SILICON COMPOUNDS
580000* - Geosciences