Xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the Kerguelen archipelago
Alkali basalts from the Kerguelen islands have entrained many mantle peridotites (harzburgites and dunites) in addition to various other ultramafic and mafic xenoliths. The harzburgites and the dunites were equilibrated in the spinel peridotite stability field (T = 850-1150°C). They attest to the ex...
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ftmacquarieunicr:oai:https://researchers.mq.edu.au:publications/15a41d24-bd82-4c0a-81e3-0db1a50b2288 2024-09-15T18:16:26+00:00 Xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the Kerguelen archipelago Grégoire, Michel Lorand, Jean Pierre Cottin, Jean Yves Giret, André Mattielli, Nadine Weis, Dominique 1997-09 https://researchers.mq.edu.au/en/publications/15a41d24-bd82-4c0a-81e3-0db1a50b2288 http://www.scopus.com/inward/record.url?scp=0031414613&partnerID=8YFLogxK eng eng info:eu-repo/semantics/restrictedAccess Grégoire , M , Lorand , J P , Cottin , J Y , Giret , A , Mattielli , N & Weis , D 1997 , ' Xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the Kerguelen archipelago ' , European Journal of Mineralogy , vol. 9 , no. 5 , pp. 1085-1100 . Dunites Harzburgites Kerguelen islands Mantle xenoliths Mantle/melt reactions Partial melting article 1997 ftmacquarieunicr 2024-07-31T23:49:40Z Alkali basalts from the Kerguelen islands have entrained many mantle peridotites (harzburgites and dunites) in addition to various other ultramafic and mafic xenoliths. The harzburgites and the dunites were equilibrated in the spinel peridotite stability field (T = 850-1150°C). They attest to the existence of a metasomatized refractory upper mantle beneath the southeastern province of the Kerguelen islands. To date no fertile mantle Iherzolite has been found in this area. The harzburgites can be divided into protogranular Cr-diopside-bearing harzburgites and poikilitic harzburgites which contain an interstitial magnesian-augite. They bear the imprint of two main processes: (1) high degree of partial melting, and (2) interactions with basaltic magmas. The partial melting event is well established by the high refractory indices of both whole rocks and minerals (Fo up to 92, Cr-rich spinel, high MgO and low CaO, Al 2 O 3 , Na 2 O and total Fe 2 O 3 contents in bulk-rock analyses). Evidence of the interaction with basaltic melts is apparent in the development of coarse granular to poikilitic textures, U-shaped REE patterns in both types of harzburgites and in the presence of Cr-Na-rich magnesian-augite sometimes associated with phlogopite in the poikilitic harzburgites. Moreover, the mg* numbers of minerals and bulk rocks in the poikilitic harzburgites and dunites are systematically lower than those predicted by partial-melting models. These characteristics suggest an interaction between previously depleted harzburgites and LREE-enriched alkali basaltic melts. The dunites are the wall-rocks of magmatic dykes of websterites, clinopyroxenites and hornblendites. They show the same textural (coarse granular to poikilitic textures), chemical (low mg* number of mafic phases) and REE patterns as the harzburgites. All these features are consistent with a model whereby the dunites were formed by interactions between formerly depleted harzburgites and basaltic melts of transitional to alkaline affinities propagating within ... Article in Journal/Newspaper Kerguelen Islands Macquarie University Research Portal |
institution |
Open Polar |
collection |
Macquarie University Research Portal |
op_collection_id |
ftmacquarieunicr |
language |
English |
topic |
Dunites Harzburgites Kerguelen islands Mantle xenoliths Mantle/melt reactions Partial melting |
spellingShingle |
Dunites Harzburgites Kerguelen islands Mantle xenoliths Mantle/melt reactions Partial melting Grégoire, Michel Lorand, Jean Pierre Cottin, Jean Yves Giret, André Mattielli, Nadine Weis, Dominique Xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the Kerguelen archipelago |
topic_facet |
Dunites Harzburgites Kerguelen islands Mantle xenoliths Mantle/melt reactions Partial melting |
description |
Alkali basalts from the Kerguelen islands have entrained many mantle peridotites (harzburgites and dunites) in addition to various other ultramafic and mafic xenoliths. The harzburgites and the dunites were equilibrated in the spinel peridotite stability field (T = 850-1150°C). They attest to the existence of a metasomatized refractory upper mantle beneath the southeastern province of the Kerguelen islands. To date no fertile mantle Iherzolite has been found in this area. The harzburgites can be divided into protogranular Cr-diopside-bearing harzburgites and poikilitic harzburgites which contain an interstitial magnesian-augite. They bear the imprint of two main processes: (1) high degree of partial melting, and (2) interactions with basaltic magmas. The partial melting event is well established by the high refractory indices of both whole rocks and minerals (Fo up to 92, Cr-rich spinel, high MgO and low CaO, Al 2 O 3 , Na 2 O and total Fe 2 O 3 contents in bulk-rock analyses). Evidence of the interaction with basaltic melts is apparent in the development of coarse granular to poikilitic textures, U-shaped REE patterns in both types of harzburgites and in the presence of Cr-Na-rich magnesian-augite sometimes associated with phlogopite in the poikilitic harzburgites. Moreover, the mg* numbers of minerals and bulk rocks in the poikilitic harzburgites and dunites are systematically lower than those predicted by partial-melting models. These characteristics suggest an interaction between previously depleted harzburgites and LREE-enriched alkali basaltic melts. The dunites are the wall-rocks of magmatic dykes of websterites, clinopyroxenites and hornblendites. They show the same textural (coarse granular to poikilitic textures), chemical (low mg* number of mafic phases) and REE patterns as the harzburgites. All these features are consistent with a model whereby the dunites were formed by interactions between formerly depleted harzburgites and basaltic melts of transitional to alkaline affinities propagating within ... |
format |
Article in Journal/Newspaper |
author |
Grégoire, Michel Lorand, Jean Pierre Cottin, Jean Yves Giret, André Mattielli, Nadine Weis, Dominique |
author_facet |
Grégoire, Michel Lorand, Jean Pierre Cottin, Jean Yves Giret, André Mattielli, Nadine Weis, Dominique |
author_sort |
Grégoire, Michel |
title |
Xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the Kerguelen archipelago |
title_short |
Xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the Kerguelen archipelago |
title_full |
Xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the Kerguelen archipelago |
title_fullStr |
Xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the Kerguelen archipelago |
title_full_unstemmed |
Xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the Kerguelen archipelago |
title_sort |
xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the kerguelen archipelago |
publishDate |
1997 |
url |
https://researchers.mq.edu.au/en/publications/15a41d24-bd82-4c0a-81e3-0db1a50b2288 http://www.scopus.com/inward/record.url?scp=0031414613&partnerID=8YFLogxK |
genre |
Kerguelen Islands |
genre_facet |
Kerguelen Islands |
op_source |
Grégoire , M , Lorand , J P , Cottin , J Y , Giret , A , Mattielli , N & Weis , D 1997 , ' Xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the Kerguelen archipelago ' , European Journal of Mineralogy , vol. 9 , no. 5 , pp. 1085-1100 . |
op_rights |
info:eu-repo/semantics/restrictedAccess |
_version_ |
1810454441862627328 |