Mafic tiers and transient mushes: evidence from Iceland
It is well established that magmatism is trans-crustal, with melt storage and processing occurring over a range of depths. Development of this conceptual model was based on observations of the products of magmatism at spreading ridges, including Iceland. Petrological barometry and tracking of the so...
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ftpubmed:oai:pubmedcentral.nih.gov:6335488 2023-05-15T16:46:52+02:00 Mafic tiers and transient mushes: evidence from Iceland Maclennan, J. 2019-02-25 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6335488/ http://www.ncbi.nlm.nih.gov/pubmed/30966937 https://doi.org/10.1098/rsta.2018.0021 en eng The Royal Society Publishing http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6335488/ http://www.ncbi.nlm.nih.gov/pubmed/30966937 http://dx.doi.org/10.1098/rsta.2018.0021 © 2019 The Author(s) http://royalsocietypublishing.org/licence Published by the Royal Society. All rights reserved. Articles Text 2019 ftpubmed https://doi.org/10.1098/rsta.2018.0021 2020-03-01T01:13:57Z It is well established that magmatism is trans-crustal, with melt storage and processing occurring over a range of depths. Development of this conceptual model was based on observations of the products of magmatism at spreading ridges, including Iceland. Petrological barometry and tracking of the solidification process has been used to show that the Icelandic crust is built by crystallization over a range of depths. The available petrological evidence indicates that most of the active rift zones are not underlain by extensive and pervasive crystal mush. Instead, the microanalytical observations from Iceland are consistent with a model where magmatic processing in the lower crust occurs in sills of decimetric vertical thickness. This stacked sills mode of crustal accretion corresponds to that proposed for the oceanic crust on the basis of ophiolite studies. A key feature of these models is that the country rock for the sills is hot but subsolidus. This condition can be met if the porosity in thin crystal mushes at the margins of the sills is occluded by primitive phases, a contention that is consistent with observations from cumulate nodules in Icelandic basalts. The conditions required for the stabilization of trans-crustal mushes may not be present in magmatic systems at spreading ridges. This article is part of the Theo Murphy meeting issue ‘Magma reservoir architecture and dynamics’. Text Iceland PubMed Central (PMC) Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377 2139 20180021 |
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Articles Maclennan, J. Mafic tiers and transient mushes: evidence from Iceland |
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It is well established that magmatism is trans-crustal, with melt storage and processing occurring over a range of depths. Development of this conceptual model was based on observations of the products of magmatism at spreading ridges, including Iceland. Petrological barometry and tracking of the solidification process has been used to show that the Icelandic crust is built by crystallization over a range of depths. The available petrological evidence indicates that most of the active rift zones are not underlain by extensive and pervasive crystal mush. Instead, the microanalytical observations from Iceland are consistent with a model where magmatic processing in the lower crust occurs in sills of decimetric vertical thickness. This stacked sills mode of crustal accretion corresponds to that proposed for the oceanic crust on the basis of ophiolite studies. A key feature of these models is that the country rock for the sills is hot but subsolidus. This condition can be met if the porosity in thin crystal mushes at the margins of the sills is occluded by primitive phases, a contention that is consistent with observations from cumulate nodules in Icelandic basalts. The conditions required for the stabilization of trans-crustal mushes may not be present in magmatic systems at spreading ridges. This article is part of the Theo Murphy meeting issue ‘Magma reservoir architecture and dynamics’. |
format |
Text |
author |
Maclennan, J. |
author_facet |
Maclennan, J. |
author_sort |
Maclennan, J. |
title |
Mafic tiers and transient mushes: evidence from Iceland |
title_short |
Mafic tiers and transient mushes: evidence from Iceland |
title_full |
Mafic tiers and transient mushes: evidence from Iceland |
title_fullStr |
Mafic tiers and transient mushes: evidence from Iceland |
title_full_unstemmed |
Mafic tiers and transient mushes: evidence from Iceland |
title_sort |
mafic tiers and transient mushes: evidence from iceland |
publisher |
The Royal Society Publishing |
publishDate |
2019 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6335488/ http://www.ncbi.nlm.nih.gov/pubmed/30966937 https://doi.org/10.1098/rsta.2018.0021 |
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Iceland |
genre_facet |
Iceland |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6335488/ http://www.ncbi.nlm.nih.gov/pubmed/30966937 http://dx.doi.org/10.1098/rsta.2018.0021 |
op_rights |
© 2019 The Author(s) http://royalsocietypublishing.org/licence Published by the Royal Society. All rights reserved. |
op_doi |
https://doi.org/10.1098/rsta.2018.0021 |
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Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |
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377 |
container_issue |
2139 |
container_start_page |
20180021 |
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1766036961740455936 |