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Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden

Magma transport through the Earth’s crust occurs dominantly via sheet intrusions, such as dykes and cone-sheets, and is fundamental to crustal evolution, volcanic eruptions and geochemical element cycling. However, reliable methods to reconstruct flow direction in solidified sheet intrusions have pr...

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Autores principales: Andersson, Magnus, Almqvist, Bjarne S. G., Burchardt, Steffi, Troll, Valentin R., Malehmir, Alireza, Snowball, Ian, Kübler, Lutz
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4901264/
https://www.ncbi.nlm.nih.gov/pubmed/27282420
http://dx.doi.org/10.1038/srep27635
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author Andersson, Magnus
Almqvist, Bjarne S. G.
Burchardt, Steffi
Troll, Valentin R.
Malehmir, Alireza
Snowball, Ian
Kübler, Lutz
author_facet Andersson, Magnus
Almqvist, Bjarne S. G.
Burchardt, Steffi
Troll, Valentin R.
Malehmir, Alireza
Snowball, Ian
Kübler, Lutz
author_sort Andersson, Magnus
collection PubMed
description Magma transport through the Earth’s crust occurs dominantly via sheet intrusions, such as dykes and cone-sheets, and is fundamental to crustal evolution, volcanic eruptions and geochemical element cycling. However, reliable methods to reconstruct flow direction in solidified sheet intrusions have proved elusive. Anisotropy of magnetic susceptibility (AMS) in magmatic sheets is often interpreted as primary magma flow, but magnetic fabrics can be modified by post-emplacement processes, making interpretation of AMS data ambiguous. Here we present AMS data from cone-sheets in the Alnö carbonatite complex, central Sweden. We discuss six scenarios of syn- and post-emplacement processes that can modify AMS fabrics and offer a conceptual framework for systematic interpretation of magma movements in sheet intrusions. The AMS fabrics in the Alnö cone-sheets are dominantly oblate with magnetic foliations parallel to sheet orientations. These fabrics may result from primary lateral flow or from sheet closure at the terminal stage of magma transport. As the cone-sheets are discontinuous along their strike direction, sheet closure is the most probable process to explain the observed AMS fabrics. We argue that these fabrics may be common to cone-sheets and an integrated geology, petrology and AMS approach can be used to distinguish them from primary flow fabrics.
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spelling pubmed-49012642016-06-13 Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden Andersson, Magnus Almqvist, Bjarne S. G. Burchardt, Steffi Troll, Valentin R. Malehmir, Alireza Snowball, Ian Kübler, Lutz Sci Rep Article Magma transport through the Earth’s crust occurs dominantly via sheet intrusions, such as dykes and cone-sheets, and is fundamental to crustal evolution, volcanic eruptions and geochemical element cycling. However, reliable methods to reconstruct flow direction in solidified sheet intrusions have proved elusive. Anisotropy of magnetic susceptibility (AMS) in magmatic sheets is often interpreted as primary magma flow, but magnetic fabrics can be modified by post-emplacement processes, making interpretation of AMS data ambiguous. Here we present AMS data from cone-sheets in the Alnö carbonatite complex, central Sweden. We discuss six scenarios of syn- and post-emplacement processes that can modify AMS fabrics and offer a conceptual framework for systematic interpretation of magma movements in sheet intrusions. The AMS fabrics in the Alnö cone-sheets are dominantly oblate with magnetic foliations parallel to sheet orientations. These fabrics may result from primary lateral flow or from sheet closure at the terminal stage of magma transport. As the cone-sheets are discontinuous along their strike direction, sheet closure is the most probable process to explain the observed AMS fabrics. We argue that these fabrics may be common to cone-sheets and an integrated geology, petrology and AMS approach can be used to distinguish them from primary flow fabrics. Nature Publishing Group 2016-06-10 /pmc/articles/PMC4901264/ /pubmed/27282420 http://dx.doi.org/10.1038/srep27635 Text en Copyright © 2016, Macmillan Publishers Limited http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
spellingShingle Article
Andersson, Magnus
Almqvist, Bjarne S. G.
Burchardt, Steffi
Troll, Valentin R.
Malehmir, Alireza
Snowball, Ian
Kübler, Lutz
Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden
title Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden
title_full Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden
title_fullStr Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden
title_full_unstemmed Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden
title_short Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden
title_sort magma transport in sheet intrusions of the alnö carbonatite complex, central sweden
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4901264/
https://www.ncbi.nlm.nih.gov/pubmed/27282420
http://dx.doi.org/10.1038/srep27635
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