Low melt viscosity enables melt doublets above the 410-km discontinuity
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.
Authors
- Laura Henry (ORCID: https://orcid.org/0000-0002-2531-620X)
- D. Andrault (ORCID: https://orcid.org/0000-0002-9921-4572)
- Yingwei Fei (ORCID: https://orcid.org/0000-0001-9955-5353)
- Noriyoshi Tsujino (ORCID: https://orcid.org/0000-0001-9242-2240)
- O. T. Lord (ORCID: https://orcid.org/0000-0003-0563-1293)
- Cunrui Han (ORCID: https://orcid.org/0000-0002-7886-8702)
- Takashi Yoshino (ORCID: https://orcid.org/0000-0002-5422-7396)
- J. O. S. Hammond (ORCID: https://orcid.org/0000-0001-9194-8689)
- Nicolas Guignot (ORCID: https://orcid.org/0000-0003-1105-6985)
- Sho Kakizawa (ORCID: https://orcid.org/0000-0001-7838-4065)
- Longjian Xie (ORCID: https://orcid.org/0000-0002-8956-4376)
- D. P. Dobson (ORCID: https://orcid.org/0000-0002-0890-0121)
- Fang Xu (ORCID: https://orcid.org/0000-0002-9537-662X)
- Simon Falvard
- Yuji Higo (ORCID: https://orcid.org/0000-0002-4221-8783)
- Bin Zhao (ORCID: https://orcid.org/0000-0001-7211-3280)
Institutions
- Centre National de la Recherche Scientifique (FR)
- Okayama University (JP)
- Carnegie Institution for Science (US)
- Université Clermont Auvergne (FR)
- Synchrotron soleil (FR)
- University of Bristol (GB)
- Japan Synchrotron Radiation Research Institute (JP)
- Laboratoire Magmas et Volcans (FR)
- Center for High Pressure Science and Technology Advanced Research (CN)
- Center for High Pressure Science & Technology Advanced Research (CN)
- The London College (GB)
- Institut de Recherche pour le Développement (FR)
- University College London (GB)
- Zhejiang University (CN)
- Birkbeck, University of London (GB)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-04-04
- DOI
- https://doi.org/10.1038/s41467-025-58518-7
- Citations
- 1
- Primary Topic
- High-pressure geophysics and materials
- Type
- article
- Field-Weighted Citation Impact
- 1.87
Funders
- Royal Society
- Research Councils UK
- Natural Environment Research Council
- Japan Society for the Promotion of Science