The meta-igneous granulite xenoliths from Kerguelen Archipelago: Evidence of a continent nucleation in an oceanic setting
Xenoliths of meta-igneous origin occur as one of the two main types of ultramafic and mafic xenoliths entrained by alkaline lavas of the Kerguelen islands. These are designated type II xenoliths and are subdivided into three mineralogical groups. Subtype IIa and IIc xenoliths are interpreted as crys...
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ftunivbruxelles:oai:dipot.ulb.ac.be:2013/165587 2023-08-27T04:10:23+02:00 The meta-igneous granulite xenoliths from Kerguelen Archipelago: Evidence of a continent nucleation in an oceanic setting Grégoire, Michel Cottin, Jean-Yves Giret, André Mattielli, Nadine Weis, Dominique 1998 No full-text files http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/165587 en eng uri/info:scp/19444371530 http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/165587 Contributions to Mineralogy and Petrology, 133 (3 Géographie physique Pétrologie Géochimie info:eu-repo/semantics/article info:ulb-repo/semantics/articlePeerReview info:ulb-repo/semantics/openurl/article 1998 ftunivbruxelles 2023-08-09T22:23:08Z Xenoliths of meta-igneous origin occur as one of the two main types of ultramafic and mafic xenoliths entrained by alkaline lavas of the Kerguelen islands. These are designated type II xenoliths and are subdivided into three mineralogical groups. Subtype IIa and IIc xenoliths are interpreted as crystallisation products of basaltic melts that were emplaced near the crust-mantle boundary during the early tholeiitic-transitional magmatic activity of the Kerguelen islands. Younger magmatism became more alkaline and subtype lib xenoliths were formed as high-pressure alkaline cumulates related to the last alkaline volcanic stage. Subsequently, the plagioclase-bearing type II rocks have been re-equilibrated under granulite facies conditions. This addition of mafic material around the crust-mantle boundary is consistent with seismic evidence for crustal thickening to 14-20 km. Calculated compressional seismic velocities (Vp) for the basic granulites are consistent with the range of observed Vp in the low-velocity region underlying the oceanic crust. Such growth in the thickness of the oceanic crust may be caused by intrusion of basalts at different levels in the lithosphere and may provide the heat responsible for granulitic metamorphism in the oceanic setting. This study suggests that basic granulites can account for the observed seismic characteristics of oceanic plateaux and can be important components of Kerguelen oceanic lithosphere where there has been large-scale magma production. Moreover we speculate that the Kerguelen islands and perhaps the surrounding plateau represent a continental nucleation process. © Springer-Verlag 1998. SCOPUS: ar.j info:eu-repo/semantics/published Article in Journal/Newspaper Kerguelen Islands DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) Kerguelen Kerguelen Islands |
institution |
Open Polar |
collection |
DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) |
op_collection_id |
ftunivbruxelles |
language |
English |
topic |
Géographie physique Pétrologie Géochimie |
spellingShingle |
Géographie physique Pétrologie Géochimie Grégoire, Michel Cottin, Jean-Yves Giret, André Mattielli, Nadine Weis, Dominique The meta-igneous granulite xenoliths from Kerguelen Archipelago: Evidence of a continent nucleation in an oceanic setting |
topic_facet |
Géographie physique Pétrologie Géochimie |
description |
Xenoliths of meta-igneous origin occur as one of the two main types of ultramafic and mafic xenoliths entrained by alkaline lavas of the Kerguelen islands. These are designated type II xenoliths and are subdivided into three mineralogical groups. Subtype IIa and IIc xenoliths are interpreted as crystallisation products of basaltic melts that were emplaced near the crust-mantle boundary during the early tholeiitic-transitional magmatic activity of the Kerguelen islands. Younger magmatism became more alkaline and subtype lib xenoliths were formed as high-pressure alkaline cumulates related to the last alkaline volcanic stage. Subsequently, the plagioclase-bearing type II rocks have been re-equilibrated under granulite facies conditions. This addition of mafic material around the crust-mantle boundary is consistent with seismic evidence for crustal thickening to 14-20 km. Calculated compressional seismic velocities (Vp) for the basic granulites are consistent with the range of observed Vp in the low-velocity region underlying the oceanic crust. Such growth in the thickness of the oceanic crust may be caused by intrusion of basalts at different levels in the lithosphere and may provide the heat responsible for granulitic metamorphism in the oceanic setting. This study suggests that basic granulites can account for the observed seismic characteristics of oceanic plateaux and can be important components of Kerguelen oceanic lithosphere where there has been large-scale magma production. Moreover we speculate that the Kerguelen islands and perhaps the surrounding plateau represent a continental nucleation process. © Springer-Verlag 1998. SCOPUS: ar.j info:eu-repo/semantics/published |
format |
Article in Journal/Newspaper |
author |
Grégoire, Michel Cottin, Jean-Yves Giret, André Mattielli, Nadine Weis, Dominique |
author_facet |
Grégoire, Michel Cottin, Jean-Yves Giret, André Mattielli, Nadine Weis, Dominique |
author_sort |
Grégoire, Michel |
title |
The meta-igneous granulite xenoliths from Kerguelen Archipelago: Evidence of a continent nucleation in an oceanic setting |
title_short |
The meta-igneous granulite xenoliths from Kerguelen Archipelago: Evidence of a continent nucleation in an oceanic setting |
title_full |
The meta-igneous granulite xenoliths from Kerguelen Archipelago: Evidence of a continent nucleation in an oceanic setting |
title_fullStr |
The meta-igneous granulite xenoliths from Kerguelen Archipelago: Evidence of a continent nucleation in an oceanic setting |
title_full_unstemmed |
The meta-igneous granulite xenoliths from Kerguelen Archipelago: Evidence of a continent nucleation in an oceanic setting |
title_sort |
meta-igneous granulite xenoliths from kerguelen archipelago: evidence of a continent nucleation in an oceanic setting |
publishDate |
1998 |
url |
http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/165587 |
geographic |
Kerguelen Kerguelen Islands |
geographic_facet |
Kerguelen Kerguelen Islands |
genre |
Kerguelen Islands |
genre_facet |
Kerguelen Islands |
op_source |
Contributions to Mineralogy and Petrology, 133 (3 |
op_relation |
uri/info:scp/19444371530 http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/165587 |
_version_ |
1775352358769786880 |