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Enhanced mantle-to-crust rhenium transfer in undegassed arc magmas
journal contribution
posted on 2023-05-16, 14:38 authored by Sun, W, Bennett, VC, Eggins, SM, Vadim Kamenetsky, Arculus, RJVariations in the 187Os/188Os isotopic signature of mantle and mantle-derived rocks have been thought to provide a powerful chemical tracer of deep Earth structure. Many studies have inferred from such data that a long-lived, high-rhenium component exists in the deep mantle (187Re is the parent isotope decaying to 187Os, with a half-life of ~42 billion years), and that this reservoir probably consists of subducted oceanic crust. The interpretation of these isotopic signatures is, however, dependent on accurate estimates of rhenium and osmium concentrations in all of the main geochemical reservoirs, and the crust has generally been considered to be a minor contributor to such global budgets. In contrast, we here present observations of high rhenium concentrations and low Yb/Re ratios in arc-type melt inclusions. These results indicate strong enrichment of rhenium in undegassed arc rocks, and consequently the continental crust, which results in a crustal estimate of ~2 p.p.b. rhenium, as compared to previous estimates of 0.4–0.2 p.p.b. Previous determinations of rhenium in arc materials, which were largely measured on subaerially erupted samples, are likely to be in error owing to rhenium loss during degassing. High mantle-to-crust rhenium fluxes, as observed here, require a revaluation of geochemical models based on the 187Re-187Os decay system.
History
Publication title
NatureVolume
422Issue
6929Pagination
294-297ISSN
0028-0836Department/School
School of Natural SciencesPublisher
Nature Publishing GroupPlace of publication
London UKRights statement
Copyright 2003 Nature Publishing GroupRepository Status
- Restricted