Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle
Mantle xenoliths sampled by kimberlite and alkali basalt magmas show a range of metasomatic styles, but direct evidence for the nature of the metasomatising fluids is often elusive. It has been suggested that carbonate-rich melts produced by partial melting of carbonated peridotites and eclogites pl...
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ftunivtasecite:oai:ecite.utas.edu.au:80015 2023-05-15T18:45:07+02:00 Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle Giuliani, A Kamenetsky, VS Phillips, D Kendrick, MA Wyatt, BA Goemann, K 2012 https://doi.org/10.1130/G33221.1 http://ecite.utas.edu.au/80015 en eng Geological Soc America http://dx.doi.org/10.1130/G33221.1 Giuliani, A and Kamenetsky, VS and Phillips, D and Kendrick, MA and Wyatt, BA and Goemann, K, Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle, Geology, 40, (11) pp. 967-970. ISSN 0091-7613 (2012) [Refereed Article] http://ecite.utas.edu.au/80015 Earth Sciences Geology Igneous and Metamorphic Petrology Refereed Article PeerReviewed 2012 ftunivtasecite https://doi.org/10.1130/G33221.1 2019-12-13T21:45:21Z Mantle xenoliths sampled by kimberlite and alkali basalt magmas show a range of metasomatic styles, but direct evidence for the nature of the metasomatising fluids is often elusive. It has been suggested that carbonate-rich melts produced by partial melting of carbonated peridotites and eclogites play an important role in modifying the composition of the lithospheric mantle. These mantle-derived carbonate melts are often inferred to be enriched in alkali elements; however, alkali-rich carbonate fluids have only been reported as micro-inclusions in diamonds and as unique melts involved in the formation of the Udachnaya-East kimberlite (Yakutia, Russia). In this paper we present the first direct evidence for alkali-carbonate melts in the shallow lithospheric mantle (∼110115 km), above the diamond stability field. These alkali-carbonate melts are preserved in primary multiphase inclusions hosted by large metasomatic ilmenite grains contained in a polymict mantle xenolith from the Bultfontein kimberlite (Kimberley, South Africa). The inclusions host abundant carbonates (magnesite, dolomite, and K-Na-Ca carbonates), kalsilite, phlogopite, K-Na titanates, and phosphates, with lesser amounts of olivine, chlorides, and alkali sulfates. Textural and chemical observations indicate that the alkali-carbonate melt likely derived from primary or precursor kimberlite magmas. Our findings extend the evidence for alkali-carbonate melts/fluids permeating the Earth mantle outside the diamond stability field and provide new insights into the chemical features of previously hypothesized melts. As metasomatism by alkali-rich carbonate melts is often reported to affect mantle xenoliths, and predicted from experimental studies, the fluid type documented here likely represent a major metasomatising agent in the Earths lithospheric mantle. Article in Journal/Newspaper Yakutia eCite UTAS (University of Tasmania) Geology 40 11 967 970 |
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Open Polar |
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eCite UTAS (University of Tasmania) |
op_collection_id |
ftunivtasecite |
language |
English |
topic |
Earth Sciences Geology Igneous and Metamorphic Petrology |
spellingShingle |
Earth Sciences Geology Igneous and Metamorphic Petrology Giuliani, A Kamenetsky, VS Phillips, D Kendrick, MA Wyatt, BA Goemann, K Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle |
topic_facet |
Earth Sciences Geology Igneous and Metamorphic Petrology |
description |
Mantle xenoliths sampled by kimberlite and alkali basalt magmas show a range of metasomatic styles, but direct evidence for the nature of the metasomatising fluids is often elusive. It has been suggested that carbonate-rich melts produced by partial melting of carbonated peridotites and eclogites play an important role in modifying the composition of the lithospheric mantle. These mantle-derived carbonate melts are often inferred to be enriched in alkali elements; however, alkali-rich carbonate fluids have only been reported as micro-inclusions in diamonds and as unique melts involved in the formation of the Udachnaya-East kimberlite (Yakutia, Russia). In this paper we present the first direct evidence for alkali-carbonate melts in the shallow lithospheric mantle (∼110115 km), above the diamond stability field. These alkali-carbonate melts are preserved in primary multiphase inclusions hosted by large metasomatic ilmenite grains contained in a polymict mantle xenolith from the Bultfontein kimberlite (Kimberley, South Africa). The inclusions host abundant carbonates (magnesite, dolomite, and K-Na-Ca carbonates), kalsilite, phlogopite, K-Na titanates, and phosphates, with lesser amounts of olivine, chlorides, and alkali sulfates. Textural and chemical observations indicate that the alkali-carbonate melt likely derived from primary or precursor kimberlite magmas. Our findings extend the evidence for alkali-carbonate melts/fluids permeating the Earth mantle outside the diamond stability field and provide new insights into the chemical features of previously hypothesized melts. As metasomatism by alkali-rich carbonate melts is often reported to affect mantle xenoliths, and predicted from experimental studies, the fluid type documented here likely represent a major metasomatising agent in the Earths lithospheric mantle. |
format |
Article in Journal/Newspaper |
author |
Giuliani, A Kamenetsky, VS Phillips, D Kendrick, MA Wyatt, BA Goemann, K |
author_facet |
Giuliani, A Kamenetsky, VS Phillips, D Kendrick, MA Wyatt, BA Goemann, K |
author_sort |
Giuliani, A |
title |
Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle |
title_short |
Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle |
title_full |
Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle |
title_fullStr |
Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle |
title_full_unstemmed |
Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle |
title_sort |
nature of alkali-carbonate fluids in the sub-continental lithospheric mantle |
publisher |
Geological Soc America |
publishDate |
2012 |
url |
https://doi.org/10.1130/G33221.1 http://ecite.utas.edu.au/80015 |
genre |
Yakutia |
genre_facet |
Yakutia |
op_relation |
http://dx.doi.org/10.1130/G33221.1 Giuliani, A and Kamenetsky, VS and Phillips, D and Kendrick, MA and Wyatt, BA and Goemann, K, Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle, Geology, 40, (11) pp. 967-970. ISSN 0091-7613 (2012) [Refereed Article] http://ecite.utas.edu.au/80015 |
op_doi |
https://doi.org/10.1130/G33221.1 |
container_title |
Geology |
container_volume |
40 |
container_issue |
11 |
container_start_page |
967 |
op_container_end_page |
970 |
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