Chemistry of abyssal and Horman peridotites

The concentrations of the platinum-group elements (PGE) Ir, Ru, Pt and Pd were determined in 11 abyssal peridotites from ODP Sites 895 and 920, as well in six ultramafic rocks from the Horoman peridotite body, Japan, which is generally thought to represent former asthenospheric mantle. Individual oceanic peridotites from ODP drill cores are characterized by variable absolute and relative PGE abundances, but the average PGE concentrations of both ODP suites are very similar. This indicates that the distribution of the noble metals in the mantle is characterized by small-scale heterogeneity and large-scale homogeneity. The mean Ru/Ir and Pt/Ir ratios of all ODP peridotites are within 15% and 3%, respectively, of CI-chondritic values. These results are consistent with models that advocate that a late veneer of chondritic material provided the present PGE budget of the silicate Earth. The data are not reconcilable with the addition of a significant amount of differentiated outer core material to the upper mantle. Furthermore, the results of petrogenetic model calculations indicate that the addition of sulfides derived from percolating magmas may be responsible for the variable and generally suprachondritic Pd/Ir ratios observed in abyssal peridotites. Ultramafic rocks from the Horoman peridotite have PGE signatures distinct from abyssal peridotites: Pt/Ir and Pd/Ir are correlated with lithophile element concentrations such that the most fertile lherzolites are characterized by non-primitive PGE ratios. This indicates that processes more complex than simple in-situ melt extraction are required to produce the geochemical systematics, if the Horoman peridotite formed from asthenospheric mantle with chondritic relative PGE abundances. In this case, the PGE results can be explained by melt depletion accompanied or followed by mixing of depleted residues with sulfides, with or without the addition of basaltic melt.

Data and Resources

This dataset has no data

Cite this as

Rehkämper, Mark, Halliday, Alex N, Alt, Jeffrey C, Fitton, J Godfrey, Zipfel, J, Takazawa, Eiichi (1999). Dataset: Chemistry of abyssal and Horman peridotites. https://doi.org/10.1594/PANGAEA.713715

DOI retrieved: 1999

Additional Info

Field Value
Imported on November 29, 2024
Last update November 29, 2024
License CC-BY-3.0
Source https://doi.org/10.1594/PANGAEA.713715
Author Rehkämper, Mark
Given Name Mark
Family Name Rehkämper
More Authors
Halliday, Alex N
Alt, Jeffrey C
Fitton, J Godfrey
Zipfel, J
Takazawa, Eiichi
Source Creation 1999
Publication Year 1999
Resource Type application/zip - filename: Rehkaemper_1999
Subject Areas
Name: Geophysics

Related Identifiers
Title: Non-chondritic platinum-group element ratios in oceanic mantle lithosphere: petrogenetic signature of melt percolation?
Identifier: https://doi.org/10.1016/S0012-821X(99)00193-4
Type: DOI
Relation: IsSupplementTo
Year: 1999
Source: Earth and Planetary Science Letters
Authors: Rehkämper Mark , Halliday Alex N , Alt Jeffrey C , Fitton J Godfrey , Zipfel J , Takazawa Eiichi .