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A silicate dynamo in the early Earth

The Earth’s magnetic field has operated for at least 3.4 billion years, yet how the ancient field was produced is still unknown. The core in the early Earth was surrounded by a molten silicate layer, a basal magma ocean that may have survived for more than one billion years. Here we use density func...

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Autores principales: Stixrude, Lars, Scipioni, Roberto, Desjarlais, Michael P.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7042358/
https://www.ncbi.nlm.nih.gov/pubmed/32098945
http://dx.doi.org/10.1038/s41467-020-14773-4
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author Stixrude, Lars
Scipioni, Roberto
Desjarlais, Michael P.
author_facet Stixrude, Lars
Scipioni, Roberto
Desjarlais, Michael P.
author_sort Stixrude, Lars
collection PubMed
description The Earth’s magnetic field has operated for at least 3.4 billion years, yet how the ancient field was produced is still unknown. The core in the early Earth was surrounded by a molten silicate layer, a basal magma ocean that may have survived for more than one billion years. Here we use density functional theory-based molecular dynamics simulations to predict the electrical conductivity of silicate liquid at the conditions of the basal magma ocean: 100–140 GPa, and 4000–6000 K. We find that the electrical conductivity exceeds 10,000 S/m, more than 100 times that measured in silicate liquids at low pressure and temperature. The magnetic Reynolds number computed from our results exceeds the threshold for dynamo activity and the magnetic field strength is similar to that observed in the Archean paleomagnetic record. We therefore conclude that the Archean field was produced by the basal magma ocean.
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spelling pubmed-70423582020-03-04 A silicate dynamo in the early Earth Stixrude, Lars Scipioni, Roberto Desjarlais, Michael P. Nat Commun Article The Earth’s magnetic field has operated for at least 3.4 billion years, yet how the ancient field was produced is still unknown. The core in the early Earth was surrounded by a molten silicate layer, a basal magma ocean that may have survived for more than one billion years. Here we use density functional theory-based molecular dynamics simulations to predict the electrical conductivity of silicate liquid at the conditions of the basal magma ocean: 100–140 GPa, and 4000–6000 K. We find that the electrical conductivity exceeds 10,000 S/m, more than 100 times that measured in silicate liquids at low pressure and temperature. The magnetic Reynolds number computed from our results exceeds the threshold for dynamo activity and the magnetic field strength is similar to that observed in the Archean paleomagnetic record. We therefore conclude that the Archean field was produced by the basal magma ocean. Nature Publishing Group UK 2020-02-25 /pmc/articles/PMC7042358/ /pubmed/32098945 http://dx.doi.org/10.1038/s41467-020-14773-4 Text en © The Author(s) 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Stixrude, Lars
Scipioni, Roberto
Desjarlais, Michael P.
A silicate dynamo in the early Earth
title A silicate dynamo in the early Earth
title_full A silicate dynamo in the early Earth
title_fullStr A silicate dynamo in the early Earth
title_full_unstemmed A silicate dynamo in the early Earth
title_short A silicate dynamo in the early Earth
title_sort silicate dynamo in the early earth
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7042358/
https://www.ncbi.nlm.nih.gov/pubmed/32098945
http://dx.doi.org/10.1038/s41467-020-14773-4
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