Spreading rate, spreading obliquity, and melt supply at the ultraslow spreading Southwest Indian Ridge
We use bathymetry, gravimetry, and basalt composition to examine the relationship between spreading rate, spreading obliquity, and the melt supply at the ultraslow spreading Southwest Indian Ridge (SWIR). We find that at regional scales (more than 200 km), melt supply reflects variations in mantle m...
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Language: | English |
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Amer Geophysical Union
2008
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Online Access: | https://archimer.ifremer.fr/doc/00237/34860/33204.pdf https://doi.org/10.1029/2007GC001676 https://archimer.ifremer.fr/doc/00237/34860/ |
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ftarchimer:oai:archimer.ifremer.fr:34860 2023-05-15T15:15:33+02:00 Spreading rate, spreading obliquity, and melt supply at the ultraslow spreading Southwest Indian Ridge Cannat, Mathilde Sauter, Daniel Bezos, Antoine Meyzen, Christine Humler, Eric Le Rigoleur, Marion 2008-04 application/pdf https://archimer.ifremer.fr/doc/00237/34860/33204.pdf https://doi.org/10.1029/2007GC001676 https://archimer.ifremer.fr/doc/00237/34860/ eng eng Amer Geophysical Union https://archimer.ifremer.fr/doc/00237/34860/33204.pdf doi:10.1029/2007GC001676 https://archimer.ifremer.fr/doc/00237/34860/ Copyright 2008 by the American Geophysical Union. info:eu-repo/semantics/openAccess restricted use Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2008-04 , Vol. 9 , N. 4 / Q04002 , P. 1-26 mid-ocean ridges melt supply mantle melting magmatic segmentation text Publication info:eu-repo/semantics/article 2008 ftarchimer https://doi.org/10.1029/2007GC001676 2021-09-23T20:25:26Z We use bathymetry, gravimetry, and basalt composition to examine the relationship between spreading rate, spreading obliquity, and the melt supply at the ultraslow spreading Southwest Indian Ridge (SWIR). We find that at regional scales (more than 200 km), melt supply reflects variations in mantle melting that are primarily controlled by large-scale heterogeneities in mantle temperature and/or composition. Focusing on adjacent SWIR regions with contrasted obliquity, we find that the effect of obliquity on melt production is significant (about 1.5 km less melt produced for a decrease of 7 mm/a to 4 mm/a in effective spreading rates, ESR) but not enough to produce near-amagmatic spreading in the most oblique regions of the ridge, unless associated with an anomalously cold and/or depleted mantle source. Our observations lead us to support models in which mantle upwelling beneath slow and ultraslow ridges is somewhat focused and accelerated, thereby reducing the effect of spreading rate and obliquity on upper mantle cooling and melt supply. To explain why very oblique SWIR regions nonetheless have large outcrops of mantle-derived ultramafic rocks and, in many cases, no evidence for axial volcanism [Cannat et al., 2006; Dick et al., 2003], we develop a model which combines melt migration along axis to more volcanically robust areas, melt trapping in the lithospheric mantle, and melt transport in dikes that may only form where enough melt has gathered to build sufficient overpressure. These dikes would open perpendicularly to the direction of the least compressive stress and favor the formation of orthogonal ridge sections. The resulting segmentation pattern, with prominent orthogonal volcanic centers and long intervening avolcanic or nearly avolcanic ridge sections, is not specific to oblique ridge regions. It is also observed along the SWIR and the arctic Gakkel Ridge in orthogonal regions underlain by cold and/or depleted mantle. Article in Journal/Newspaper Arctic Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) Arctic Gakkel Ridge ENVELOPE(90.000,90.000,87.000,87.000) Indian Geochemistry, Geophysics, Geosystems 9 4 n/a n/a |
institution |
Open Polar |
collection |
Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) |
op_collection_id |
ftarchimer |
language |
English |
topic |
mid-ocean ridges melt supply mantle melting magmatic segmentation |
spellingShingle |
mid-ocean ridges melt supply mantle melting magmatic segmentation Cannat, Mathilde Sauter, Daniel Bezos, Antoine Meyzen, Christine Humler, Eric Le Rigoleur, Marion Spreading rate, spreading obliquity, and melt supply at the ultraslow spreading Southwest Indian Ridge |
topic_facet |
mid-ocean ridges melt supply mantle melting magmatic segmentation |
description |
We use bathymetry, gravimetry, and basalt composition to examine the relationship between spreading rate, spreading obliquity, and the melt supply at the ultraslow spreading Southwest Indian Ridge (SWIR). We find that at regional scales (more than 200 km), melt supply reflects variations in mantle melting that are primarily controlled by large-scale heterogeneities in mantle temperature and/or composition. Focusing on adjacent SWIR regions with contrasted obliquity, we find that the effect of obliquity on melt production is significant (about 1.5 km less melt produced for a decrease of 7 mm/a to 4 mm/a in effective spreading rates, ESR) but not enough to produce near-amagmatic spreading in the most oblique regions of the ridge, unless associated with an anomalously cold and/or depleted mantle source. Our observations lead us to support models in which mantle upwelling beneath slow and ultraslow ridges is somewhat focused and accelerated, thereby reducing the effect of spreading rate and obliquity on upper mantle cooling and melt supply. To explain why very oblique SWIR regions nonetheless have large outcrops of mantle-derived ultramafic rocks and, in many cases, no evidence for axial volcanism [Cannat et al., 2006; Dick et al., 2003], we develop a model which combines melt migration along axis to more volcanically robust areas, melt trapping in the lithospheric mantle, and melt transport in dikes that may only form where enough melt has gathered to build sufficient overpressure. These dikes would open perpendicularly to the direction of the least compressive stress and favor the formation of orthogonal ridge sections. The resulting segmentation pattern, with prominent orthogonal volcanic centers and long intervening avolcanic or nearly avolcanic ridge sections, is not specific to oblique ridge regions. It is also observed along the SWIR and the arctic Gakkel Ridge in orthogonal regions underlain by cold and/or depleted mantle. |
format |
Article in Journal/Newspaper |
author |
Cannat, Mathilde Sauter, Daniel Bezos, Antoine Meyzen, Christine Humler, Eric Le Rigoleur, Marion |
author_facet |
Cannat, Mathilde Sauter, Daniel Bezos, Antoine Meyzen, Christine Humler, Eric Le Rigoleur, Marion |
author_sort |
Cannat, Mathilde |
title |
Spreading rate, spreading obliquity, and melt supply at the ultraslow spreading Southwest Indian Ridge |
title_short |
Spreading rate, spreading obliquity, and melt supply at the ultraslow spreading Southwest Indian Ridge |
title_full |
Spreading rate, spreading obliquity, and melt supply at the ultraslow spreading Southwest Indian Ridge |
title_fullStr |
Spreading rate, spreading obliquity, and melt supply at the ultraslow spreading Southwest Indian Ridge |
title_full_unstemmed |
Spreading rate, spreading obliquity, and melt supply at the ultraslow spreading Southwest Indian Ridge |
title_sort |
spreading rate, spreading obliquity, and melt supply at the ultraslow spreading southwest indian ridge |
publisher |
Amer Geophysical Union |
publishDate |
2008 |
url |
https://archimer.ifremer.fr/doc/00237/34860/33204.pdf https://doi.org/10.1029/2007GC001676 https://archimer.ifremer.fr/doc/00237/34860/ |
long_lat |
ENVELOPE(90.000,90.000,87.000,87.000) |
geographic |
Arctic Gakkel Ridge Indian |
geographic_facet |
Arctic Gakkel Ridge Indian |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2008-04 , Vol. 9 , N. 4 / Q04002 , P. 1-26 |
op_relation |
https://archimer.ifremer.fr/doc/00237/34860/33204.pdf doi:10.1029/2007GC001676 https://archimer.ifremer.fr/doc/00237/34860/ |
op_rights |
Copyright 2008 by the American Geophysical Union. info:eu-repo/semantics/openAccess restricted use |
op_doi |
https://doi.org/10.1029/2007GC001676 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
9 |
container_issue |
4 |
container_start_page |
n/a |
op_container_end_page |
n/a |
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1766345916834381824 |