Ancient mantle in a modern arc: Osmium isotopes in Izu-Bonin-Mariana forearc peridotites

Ian J. Parkinson*, Chris J. Hawkesworth, Anthony S. Cohen

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

150 Citations (Scopus)

Abstract

Mantle peridotites drilled from the Izu-Bonin-Mariana forearc have unradiogenic 187Os/188Os ratios (0.1193 to 0.1273), which give Proterozoic model ages of 820 to 1230 million years ago. If these peridotites are residues from magmatism during the initiation of subduction 40 to 48 million years ago, then the mantle that melted was much more depleted in incompatible elements than the source of mid-ocean ridge basalts (MORB). This result indicates that osmium isotopes record information about ancient melting events in the convecting upper mantle not recorded by incompatible lithophile isotope tracers. Subduction zones may be a graveyard for ancient depleted mantle material, and portions of the convecting upper mantle may be less radiogenic in osmium isotopes than previously recognized.

Original languageEnglish
Pages (from-to)2011-2013
Number of pages3
JournalScience
Volume281
Issue number5385
DOIs
Publication statusPublished - 25 Sep 1998

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