title: Oxygen isotope ratios in eclogites from kimberlites.
abstract: The oxygen isotope compositions (delta(18)O) of eclogitic xenoliths from the Roberts Victor kimberlite range from 2 to 8 per mil relative to SMOW (standard mean ocean water). This surprising variation appears to be due to fractional crystallization: the eclogites rich in oxygen-18 represent early crystal accumulates; the eclogites poor in oxygen-18 represent residual liquids. Crystal-melt partitioning probably exceeded 3 per mil and is interpreted to be pressure-dependent. Anomalous enrichment of oxygen-18 in cumulate eclogites relative to ultramafic xenoliths suggests that crystal-melt partitioning increased after melt-formation but prior to crystallization.
authors.forename: G D
authors.initials: GD
authors.lastname: Garlick
authors.forename: I D
authors.initials: ID
authors.lastname: Macgregor
authors.forename: D E
authors.initials: DE
authors.lastname: Vogel