Spreading rate, spreading obliquity, and melt supply at the ultra-slow 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...
Published in: | Geochemistry, Geophysics, Geosystems |
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American Geophysical Union
2008
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Online Access: | http://hdl.handle.net/11577/154420 https://doi.org/10.1029/2007GC001676 http://www.agu.org/pubs/crossref/2008/2007GC001676.shtml |
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ftunivpadovairis:oai:www.research.unipd.it:11577/154420 2024-04-14T08:08:35+00:00 Spreading rate, spreading obliquity, and melt supply at the ultra-slow spreading Southwest Indian Ridge CANNAT C SAUTER D BEZOS A E. HUMLER M. LE RIGOLEUR MEYZEN, CHRISTINE MARIE Cannat, C Sauter, D Bezos, A Meyzen, CHRISTINE MARIE E., Humler M., LE RIGOLEUR 2008 ELETTRONICO http://hdl.handle.net/11577/154420 https://doi.org/10.1029/2007GC001676 http://www.agu.org/pubs/crossref/2008/2007GC001676.shtml eng eng American Geophysical Union info:eu-repo/semantics/altIdentifier/wos/WOS:000254715700002 volume:9 issue:4 journal:GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS http://hdl.handle.net/11577/154420 doi:10.1029/2007GC001676 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-60649118959 http://www.agu.org/pubs/crossref/2008/2007GC001676.shtml info:eu-repo/semantics/article 2008 ftunivpadovairis https://doi.org/10.1029/2007GC001676 2024-03-28T01:28:15Z 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 Padua Research Archive (IRIS - Università degli Studi di Padova) Arctic Indian Gakkel Ridge ENVELOPE(90.000,90.000,87.000,87.000) Geochemistry, Geophysics, Geosystems 9 4 n/a n/a |
institution |
Open Polar |
collection |
Padua Research Archive (IRIS - Università degli Studi di Padova) |
op_collection_id |
ftunivpadovairis |
language |
English |
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. |
author2 |
Cannat, C Sauter, D Bezos, A Meyzen, CHRISTINE MARIE E., Humler M., LE RIGOLEUR |
format |
Article in Journal/Newspaper |
author |
CANNAT C SAUTER D BEZOS A E. HUMLER M. LE RIGOLEUR MEYZEN, CHRISTINE MARIE |
spellingShingle |
CANNAT C SAUTER D BEZOS A E. HUMLER M. LE RIGOLEUR MEYZEN, CHRISTINE MARIE Spreading rate, spreading obliquity, and melt supply at the ultra-slow spreading Southwest Indian Ridge |
author_facet |
CANNAT C SAUTER D BEZOS A E. HUMLER M. LE RIGOLEUR MEYZEN, CHRISTINE MARIE |
author_sort |
CANNAT C |
title |
Spreading rate, spreading obliquity, and melt supply at the ultra-slow spreading Southwest Indian Ridge |
title_short |
Spreading rate, spreading obliquity, and melt supply at the ultra-slow spreading Southwest Indian Ridge |
title_full |
Spreading rate, spreading obliquity, and melt supply at the ultra-slow spreading Southwest Indian Ridge |
title_fullStr |
Spreading rate, spreading obliquity, and melt supply at the ultra-slow spreading Southwest Indian Ridge |
title_full_unstemmed |
Spreading rate, spreading obliquity, and melt supply at the ultra-slow spreading Southwest Indian Ridge |
title_sort |
spreading rate, spreading obliquity, and melt supply at the ultra-slow spreading southwest indian ridge |
publisher |
American Geophysical Union |
publishDate |
2008 |
url |
http://hdl.handle.net/11577/154420 https://doi.org/10.1029/2007GC001676 http://www.agu.org/pubs/crossref/2008/2007GC001676.shtml |
long_lat |
ENVELOPE(90.000,90.000,87.000,87.000) |
geographic |
Arctic Indian Gakkel Ridge |
geographic_facet |
Arctic Indian Gakkel Ridge |
genre |
Arctic |
genre_facet |
Arctic |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:000254715700002 volume:9 issue:4 journal:GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS http://hdl.handle.net/11577/154420 doi:10.1029/2007GC001676 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-60649118959 http://www.agu.org/pubs/crossref/2008/2007GC001676.shtml |
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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1796306010542964736 |