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In situ Os isotopes in abyssal peridotites bridge the isotopic gap between MORBs and their source mantle

Alard, Olivier; Luguet, Ambre; Pearson, Norman J.; Griffin, William L.; Lorand, Jean-Pierre; Gannoun, Abdelmouhcine; Burton, Kevin W. and O'Reilly, Suzanne Y. (2005). In situ Os isotopes in abyssal peridotites bridge the isotopic gap between MORBs and their source mantle. Nature, 346(7053) pp. 1005–1008.

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Abyssal peridotites are assumed to represent the mantle residue of mid-ocean-ridge basalts (MORBs). However, the osmium isotopic compositions of abyssal peridotites and MORB do not appear to be in equilibrium, raising questions about the cogenetic relationship between those two reservoirs. However, the cause of this isotopic mismatch is mainly due to a drastic filtering of the data based on the possibility of osmium contamination by sea water. Here we present a detailed study of magmatic sulphides (the main carrier of osmium) in abyssal peridotites and show that the 187Os/188Os ratio of these sulphides is of primary mantle origin and can reach radiogenic values suggesting equilibrium with MORB. Thus, the effect of sea water on the osmium systematics of abyssal peridotites has been overestimated and consequently there is no true osmium isotopic gap between MORBs and abyssal peridotites.

Item Type: Journal Article
ISSN: 0028-0836
Extra Information: Some of the symbols may not have transferred correctly into this bibliographic record and/or abstract.
Academic Unit/Department: Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 6646
Depositing User: Users 2315 not found.
Date Deposited: 02 Feb 2007
Last Modified: 14 Jan 2016 16:25
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