Affiliation:
1. Department of Earth Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA, UK.
Abstract
Mantle peridotites drilled from the Izu-Bonin-Mariana forearc have unradiogenic
187
Os/
188
Os 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.
Publisher
American Association for the Advancement of Science (AAAS)
Reference40 articles.
1. Re-Os Ages of Group IIA, IIIA, IVA, and IVB Iron Meteorites
2. Pearson D. G., Carlson R. W., Shirey S. B., Boyd F. R., Nixon P. H., Earth Planet. Sci. Lett. 134, 341 (1995);
3. Pearson D. G., et al., Geochim. Cosmochim. Acta 59, 959 (1995).
4. Reisberg L., Lorand J.-P., Nature 376, 159 (1995).
5. Handler M. R., Bennett V. C., Esat T. M., Earth Planet. Sci. Lett. 151, 61 (1997).
Cited by
178 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献