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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ftmacquarieunicr:oai:https://researchers.mq.edu.au:publications/44a3e08d-c684-4e05-93b3-0d529bfa96d3 2023-05-15T17:02:01+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 https://researchers.mq.edu.au/en/publications/44a3e08d-c684-4e05-93b3-0d529bfa96d3 http://www.scopus.com/inward/record.url?scp=19444371530&partnerID=8YFLogxK eng eng info:eu-repo/semantics/restrictedAccess Grégoire , M , Cottin , J Y , Giret , A , Mattielli , N & Weis , D 1998 , ' The meta-igneous granulite xenoliths from Kerguelen Archipelago : Evidence of a continent nucleation in an oceanic setting ' , Contributions to Mineralogy and Petrology , vol. 133 , no. 3 , pp. 259-283 . article 1998 ftmacquarieunicr 2022-11-06T06:40:45Z 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. Article in Journal/Newspaper Kerguelen Islands Macquarie University Research Portal Kerguelen Kerguelen Islands |
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Open Polar |
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Macquarie University Research Portal |
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ftmacquarieunicr |
language |
English |
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. |
format |
Article in Journal/Newspaper |
author |
Grégoire, Michel Cottin, Jean Yves Giret, André Mattielli, Nadine Weis, Dominique |
spellingShingle |
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 |
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 |
https://researchers.mq.edu.au/en/publications/44a3e08d-c684-4e05-93b3-0d529bfa96d3 http://www.scopus.com/inward/record.url?scp=19444371530&partnerID=8YFLogxK |
geographic |
Kerguelen Kerguelen Islands |
geographic_facet |
Kerguelen Kerguelen Islands |
genre |
Kerguelen Islands |
genre_facet |
Kerguelen Islands |
op_source |
Grégoire , M , Cottin , J Y , Giret , A , Mattielli , N & Weis , D 1998 , ' The meta-igneous granulite xenoliths from Kerguelen Archipelago : Evidence of a continent nucleation in an oceanic setting ' , Contributions to Mineralogy and Petrology , vol. 133 , no. 3 , pp. 259-283 . |
op_rights |
info:eu-repo/semantics/restrictedAccess |
_version_ |
1766055249237245952 |