Experimental determination of metal/silicate partition coefficients for P, Co, Ni, Cu, Ga, Ge, Mo, and W and some implications for the early evolution of the earth

Journal Article · Sun Jan 01 00:00:00 EST 1989 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(89)90284-6· OSTI ID:7242999

Schmitt, W; Palme, H; Waenke, H ^[1]

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1. Max-Planck-Institut fuer Chemie, Mainz (West Germany)

Metal/silicate partition coefficients were determined at 1600{degree}C for P, Ga, Ge and W and at 1300{degree}C for P, Fe, Co, Ni, Cu, Ga, Ge, Mo and W. Experiments span a range of two orders-of-magnitude in oxygen fugacity. Good correlations between log fO{sub 2} and the log of the partition coefficients were observed for all elements. The slopes of these correlations reflect the number of oxygen atoms associated with the metal oxides in the silicate phase. The composition of the silicates was basaltic, but variable with respect to FeO; from about 4% FeO at the most reducing experiments to 45% FeO at the most oxidizing experiments. Within these variations no dependence of the partition coefficients on silicate composition was observed, except for Ni and Co. The unusual slopes in the log D{sub Ni} and log D{sub Co} vs. log fO{sub 2} correlations can be explained by a strong dependence of the NiO and CoO activities on the liquid silicate composition. The distribution of siderophile elements in the upper mantle can be explained by accretion of increasingly oxidizing material. After accretion of some 80 to 90% of the Earth the oxygen fugacity is sufficiently high that Fe, Ni, Co and some other siderophile elements will be quantitatively retained in the upper mantle. The small amount of metal still segregating to the core will suffice to extract highly siderophile elements. The final 1% of accreting material is so oxidizing that metal segregation is completely inhibited. The pattern of siderophile elements observed in the upper mantle is broadly consistent with results from calculations based on this model and utilizing metal/silicate partition coefficients reported here.

• OSTI ID: 7242999
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 53:1; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
BASALT
CHEMICAL COMPOSITION
EARTH MANTLE
ELEMENT ABUNDANCE
EARTH PLANET
ORIGIN
METALS
THERMODYNAMIC ACTIVITY
SILICATES
COBALT COMPOUNDS
GALLIUM COMPOUNDS
GEOCHEMISTRY
GEOLOGIC HISTORY
GEOLOGIC MODELS
GERMANIUM COMPOUNDS
MOLYBDENUM COMPOUNDS
NICKEL COMPOUNDS
PARTITION
PETROGENESIS
PHOSPHORUS COMPOUNDS
TUNGSTEN COMPOUNDS
ABUNDANCE
CHEMISTRY
ELEMENTS
IGNEOUS ROCKS
OXYGEN COMPOUNDS
PLANETS
REFRACTORY METAL COMPOUNDS
ROCKS
SILICON COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
VOLCANIC ROCKS
580000* - Geosciences