Contrasting Ultra-Slow Ridges near the Bouvet Triple Junction in the South Atlantic
Two ultraslow mid ocean ridges, i.e., the westernmost portion of the Southwest Indian Ridge (SWIR) and the easternmost portion of the American-Antarctic Ridge (AAR), meet the southernmost portion of the Mid Atlantic Ridge (MAR) at the Bouvet Triple Junction. Although both the SWIR and the AAR have v...
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ftunivmodena:oai:iris.unimore.it:11380/856289 2024-02-04T09:55:04+01:00 Contrasting Ultra-Slow Ridges near the Bouvet Triple Junction in the South Atlantic Ligi M. Bonatti E. Brueckner H.K. Fabretti P. Ottolini L. BRUNELLI, Daniele CIPRIANI, Anna AGU Ligi, M. Bonatti, E. Brueckner, H. K. Brunelli, Daniele Cipriani, Anna Fabretti, P. Ottolini, L. 1998 ELETTRONICO http://hdl.handle.net/11380/856289 eng eng AGU country:USA place:Washington ispartofbook:EOS Trans. AGU AGU Fall Meeting volume:1 firstpage:Abstract T31F-08 lastpage:Abstract T31F-08 journal:EOS http://hdl.handle.net/11380/856289 ridge/hot spot thermal swell triple junction Bouvet info:eu-repo/semantics/article 1998 ftunivmodena 2024-01-09T23:14:38Z Two ultraslow mid ocean ridges, i.e., the westernmost portion of the Southwest Indian Ridge (SWIR) and the easternmost portion of the American-Antarctic Ridge (AAR), meet the southernmost portion of the Mid Atlantic Ridge (MAR) at the Bouvet Triple Junction. Although both the SWIR and the AAR have very slow spreading rates, i.e., 7.5 mm/y and 10 mm/y, respectively, they display strongly contrasting morphostructural and petrological characteristics. The AAR axial zone is deeper than normal (>4000m); some of its segments are oblique, being oriented roughly 45 degrees from the direction of spreading; basalt and peridotite chemistry suggests a relatively low degree of melting of the mantle below the AAR. In contrast, the SWIR axial zone is shallower than normal ($<$2500m); the last segment (Spiess Ridge) is particularly anomalous, reaching ~400 m below sea level. Basalt and peridotite chemistry of this portion of SWIR suggests high extents of melting of the upper mantle. The H2O content of the SWIR basaltic glasses ranges between 0.6% and 1.0% and is significantly higher than in normal MORB. The high extent of melting at the SWIR segments is probably related not only to a mantle thermal anomaly, but also to its high volatiles content. Mantle thermal structure and composition, rather than spreading rate, are the main factors determing the structure of these ridges. Article in Journal/Newspaper Antarc* Antarctic Archivio della ricerca dell'Università di Modena e Reggio Emilia (Unimore: IRIS) Antarctic Indian Mid-Atlantic Ridge Bouvet ENVELOPE(3.358,3.358,-54.422,-54.422) |
institution |
Open Polar |
collection |
Archivio della ricerca dell'Università di Modena e Reggio Emilia (Unimore: IRIS) |
op_collection_id |
ftunivmodena |
language |
English |
topic |
ridge/hot spot thermal swell triple junction Bouvet |
spellingShingle |
ridge/hot spot thermal swell triple junction Bouvet Ligi M. Bonatti E. Brueckner H.K. Fabretti P. Ottolini L. BRUNELLI, Daniele CIPRIANI, Anna Contrasting Ultra-Slow Ridges near the Bouvet Triple Junction in the South Atlantic |
topic_facet |
ridge/hot spot thermal swell triple junction Bouvet |
description |
Two ultraslow mid ocean ridges, i.e., the westernmost portion of the Southwest Indian Ridge (SWIR) and the easternmost portion of the American-Antarctic Ridge (AAR), meet the southernmost portion of the Mid Atlantic Ridge (MAR) at the Bouvet Triple Junction. Although both the SWIR and the AAR have very slow spreading rates, i.e., 7.5 mm/y and 10 mm/y, respectively, they display strongly contrasting morphostructural and petrological characteristics. The AAR axial zone is deeper than normal (>4000m); some of its segments are oblique, being oriented roughly 45 degrees from the direction of spreading; basalt and peridotite chemistry suggests a relatively low degree of melting of the mantle below the AAR. In contrast, the SWIR axial zone is shallower than normal ($<$2500m); the last segment (Spiess Ridge) is particularly anomalous, reaching ~400 m below sea level. Basalt and peridotite chemistry of this portion of SWIR suggests high extents of melting of the upper mantle. The H2O content of the SWIR basaltic glasses ranges between 0.6% and 1.0% and is significantly higher than in normal MORB. The high extent of melting at the SWIR segments is probably related not only to a mantle thermal anomaly, but also to its high volatiles content. Mantle thermal structure and composition, rather than spreading rate, are the main factors determing the structure of these ridges. |
author2 |
AGU Ligi, M. Bonatti, E. Brueckner, H. K. Brunelli, Daniele Cipriani, Anna Fabretti, P. Ottolini, L. |
format |
Article in Journal/Newspaper |
author |
Ligi M. Bonatti E. Brueckner H.K. Fabretti P. Ottolini L. BRUNELLI, Daniele CIPRIANI, Anna |
author_facet |
Ligi M. Bonatti E. Brueckner H.K. Fabretti P. Ottolini L. BRUNELLI, Daniele CIPRIANI, Anna |
author_sort |
Ligi M. |
title |
Contrasting Ultra-Slow Ridges near the Bouvet Triple Junction in the South Atlantic |
title_short |
Contrasting Ultra-Slow Ridges near the Bouvet Triple Junction in the South Atlantic |
title_full |
Contrasting Ultra-Slow Ridges near the Bouvet Triple Junction in the South Atlantic |
title_fullStr |
Contrasting Ultra-Slow Ridges near the Bouvet Triple Junction in the South Atlantic |
title_full_unstemmed |
Contrasting Ultra-Slow Ridges near the Bouvet Triple Junction in the South Atlantic |
title_sort |
contrasting ultra-slow ridges near the bouvet triple junction in the south atlantic |
publisher |
AGU |
publishDate |
1998 |
url |
http://hdl.handle.net/11380/856289 |
long_lat |
ENVELOPE(3.358,3.358,-54.422,-54.422) |
geographic |
Antarctic Indian Mid-Atlantic Ridge Bouvet |
geographic_facet |
Antarctic Indian Mid-Atlantic Ridge Bouvet |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
ispartofbook:EOS Trans. AGU AGU Fall Meeting volume:1 firstpage:Abstract T31F-08 lastpage:Abstract T31F-08 journal:EOS http://hdl.handle.net/11380/856289 |
_version_ |
1789958947923296256 |