Xie, Longjian;
Andrault, Denis;
Yoshino, Takashi;
Cunrui, Han;
Hammond, James OS;
Xu, Fang;
Lord, Oliver T;
... Dobson, David P; + view all
(2025)
Low melt viscosity enables melt doublets above the 410-km discontinuity.
Nature Communications
, Article 3239. 10.1038/s41467-025-58518-7.
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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.
| Type: | Article |
|---|---|
| Title: | Low melt viscosity enables melt doublets above the 410-km discontinuity |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1038/s41467-025-58518-7 |
| Publisher version: | https://doi.org/10.1038/s41467-025-58518-7 |
| Language: | English |
| Additional information: | © The Author(s), 2025. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. https://creativecommons.org/licenses/by/4.0/ |
| Keywords: | Geodynamics, Geophysics, Mineralogy, Seismology, Volcanology |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10207035 |
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