182W evidence for core-mantle interaction in the source of mantle plumes

Abstract : Tungsten isotopes are the ideal tracers of core-mantle chemical interaction. Given that W is moderately siderophile, it preferentially partitioned into the Earth’s core during its segregation, leaving the mantle depleted in this element. In contrast, Hf is lithophile, and its short-lived radioactive isotope 182Hf decayed entirely to 182W in the mantle after metal-silicate segregation. Therefore, the 182W isotopic composition of the Earth’s mantle and its core are expected to differ by about 200 ppm. Here, we report new high precision W isotope data for mantle-derived rock samples from the Paleoarchean Pilbara Craton, and the Réunion Island and the Kerguelen Archipelago hotspots. Together with other available data, they reveal a temporal shift in the 182W isotopic composition of the mantle that is best explained by core-mantle chemical interaction. Core-mantle exchange might be facilitated by diffusive isotope exchange at the core-mantle boundary, or the exsolution of W-rich, Si-Mg-Fe oxides from the core into the mantle. Tung-sten-182 isotope compositions of mantle-derived magmas are similar from 4.3 to 2.7 Ga and decrease afterwards. This change could be related to the onset of the crystallisation of the inner core or to the initiation of post-Archean deep slab subduction that more efficiently mixed the mantle.
Document type :
Journal articles
Complete list of metadatas

https://hal.uca.fr/hal-02283763
Contributor : Sylvaine Jouhannel <>
Submitted on : Wednesday, September 11, 2019 - 10:58:12 AM
Last modification on : Thursday, September 12, 2019 - 1:21:41 AM

Identifiers

  • HAL Id : hal-02283763, version 1

Collections

Citation

Hanika Rizo, Denis Andrault, N.R. Bennett, M. Humayun, A. Brandon, et al.. 182W evidence for core-mantle interaction in the source of mantle plumes. Geochemical Perspectives Letters, European Assoication of Geochemistry, 2019, 11, pp.6-11. ⟨hal-02283763⟩

Share

Metrics

Record views

18