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

Journal Article · Thu Nov 01 04:00:00 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), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 54:11; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

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