Xie, L. and Andrault, D. and Yoshino, T. and Han, C. and Hammond, James O.S. and Xu, F. and Zhao, B. and Lord, O.T. and Fei, Y. and Falvard, S. and Kakizawa, S. and Tsujino, N. and Higo, Y. and Henry, L. and Guignot, N. and Dobson, D.P. (2025) Low melt viscosity enables melt doublets above the 410-km discontinuity. Nature Communications 16 (1), ISSN 2041-1723.
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Abstract
Seismic and magnetotelluric studies suggest hydrous silicate melts atop the 410 km discontinuity form 30–100 km thick layers. Importantly, in some regions, two layers are observed. These stagnant layers are related to their comparable density to the surrounding mantle, but their formation mechanisms and detailed structures remain unclear. Here we report a large decrease of silicate melt viscosity at ~14 GPa, from 96(5) to 11.7(6) mPa⋅s, as water content increases from 15.5 to 31.8 mol% H₂O. Such low viscosities facilitate rapid segregation of melt, which would typically prevent thick layer accumulation. Our 1D finite element simulations show that continuous dehydration melting of upwelling mantle material produces a primary melt layer above 410 km and a secondary layer at the depth of equal mantle-melt densities. These layers can merge into a single thick layer under low density contrasts or high upwelling rates, explaining both melt doublets and thick single layers.
Metadata
| Item Type: | Article |
|---|---|
| School: | Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences |
| Research Centres and Institutes: | Earth and Planetary Sciences, Institute of |
| Depositing User: | James Hammond |
| Date Deposited: | 23 Apr 2025 12:54 |
| Last Modified: | 02 May 2025 23:21 |
| URI: | https://eprints.bbk.ac.uk/id/eprint/55417 |
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