Coexisting silicate and carbonatitic magmas in the Qassiarsuk Complex, Gardar Rift, southwest Greenland
The Mesoproterozoic Qassiarsuk complex in the Gardar Rift in southwestern Greenland comprises lavas, pyroclastic rocks and subvolcanic intrusions of alkaline silicate rocks and carbonatites. The volcanic rocks are interlayered with sandstones and basalts belonging to the lower part of the Eriksfjord...
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ftmacquarieunicr:oai:https://researchers.mq.edu.au:publications/c898294c-5d97-41fc-be03-b01145a3409c 2024-10-13T14:07:40+00:00 Coexisting silicate and carbonatitic magmas in the Qassiarsuk Complex, Gardar Rift, southwest Greenland Andersen, Tom 2008-08 https://researchers.mq.edu.au/en/publications/c898294c-5d97-41fc-be03-b01145a3409c https://doi.org/10.3749/canmin.46.4.933 http://www.scopus.com/inward/record.url?scp=56749132449&partnerID=8YFLogxK eng eng info:eu-repo/semantics/restrictedAccess Andersen , T 2008 , ' Coexisting silicate and carbonatitic magmas in the Qassiarsuk Complex, Gardar Rift, southwest Greenland ' , Canadian Mineralogist , vol. 46 , no. 4 , pp. 933-950 . https://doi.org/10.3749/canmin.46.4.933 Carbonatite Gardar rift Greenland Liquid immiscibility Qassiarsuk Complex article 2008 ftmacquarieunicr https://doi.org/10.3749/canmin.46.4.933 2024-10-03T00:23:11Z The Mesoproterozoic Qassiarsuk complex in the Gardar Rift in southwestern Greenland comprises lavas, pyroclastic rocks and subvolcanic intrusions of alkaline silicate rocks and carbonatites. The volcanic rocks are interlayered with sandstones and basalts belonging to the lower part of the Eriksfjord Formation (Mussartat member). The carbonatites at Qassiarsuk are mainly dolomite carbonatite, with subordinate calcite carbonatite. Reconstruction of the composition of heterogeneous, devitrified silicate glass found in lavas, pyroclastic rocks and as lapilli by raster analysis with the electron microprobe indicates that silicate magmas with K-poor, ultramafic and K-rich, basic to intermediate compositions were present during eruption. Samples of the latter today show extreme K 2 O/Na 2 O at (Na + K) /Al well below 1.0, reflecting selective loss of Na from a potassic to mildly ultrapotassic magmatic glass during postmagmatic alteration. The presence of coexisting lapilli of silicate rocks and carbonatite suggest that a magnesiocarbonatitic liquid was present together with both of the silicate magmas during eruption. These coexisting magmas were ultimately derived from a common source in the upper mantle, but they probably do not represent pairs of immiscible liquids separated from a single precursor in the shallow crust. It is most likely that the carbonatitic magma at Qassiarsuk arose by immiscible separation from a carbonated mafic or ultramalic silicate parental magma evolving by fractional crystallization at some depth in the magmatic plumbing system, the magnesiocarbonatitic liquid remaining immiscible with silicate magmas during ascent and eruption. Article in Journal/Newspaper Greenland Qassiarsuk Macquarie University Research Portal Greenland The Canadian Mineralogist 46 4 933 950 |
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Open Polar |
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Macquarie University Research Portal |
op_collection_id |
ftmacquarieunicr |
language |
English |
topic |
Carbonatite Gardar rift Greenland Liquid immiscibility Qassiarsuk Complex |
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Carbonatite Gardar rift Greenland Liquid immiscibility Qassiarsuk Complex Andersen, Tom Coexisting silicate and carbonatitic magmas in the Qassiarsuk Complex, Gardar Rift, southwest Greenland |
topic_facet |
Carbonatite Gardar rift Greenland Liquid immiscibility Qassiarsuk Complex |
description |
The Mesoproterozoic Qassiarsuk complex in the Gardar Rift in southwestern Greenland comprises lavas, pyroclastic rocks and subvolcanic intrusions of alkaline silicate rocks and carbonatites. The volcanic rocks are interlayered with sandstones and basalts belonging to the lower part of the Eriksfjord Formation (Mussartat member). The carbonatites at Qassiarsuk are mainly dolomite carbonatite, with subordinate calcite carbonatite. Reconstruction of the composition of heterogeneous, devitrified silicate glass found in lavas, pyroclastic rocks and as lapilli by raster analysis with the electron microprobe indicates that silicate magmas with K-poor, ultramafic and K-rich, basic to intermediate compositions were present during eruption. Samples of the latter today show extreme K 2 O/Na 2 O at (Na + K) /Al well below 1.0, reflecting selective loss of Na from a potassic to mildly ultrapotassic magmatic glass during postmagmatic alteration. The presence of coexisting lapilli of silicate rocks and carbonatite suggest that a magnesiocarbonatitic liquid was present together with both of the silicate magmas during eruption. These coexisting magmas were ultimately derived from a common source in the upper mantle, but they probably do not represent pairs of immiscible liquids separated from a single precursor in the shallow crust. It is most likely that the carbonatitic magma at Qassiarsuk arose by immiscible separation from a carbonated mafic or ultramalic silicate parental magma evolving by fractional crystallization at some depth in the magmatic plumbing system, the magnesiocarbonatitic liquid remaining immiscible with silicate magmas during ascent and eruption. |
format |
Article in Journal/Newspaper |
author |
Andersen, Tom |
author_facet |
Andersen, Tom |
author_sort |
Andersen, Tom |
title |
Coexisting silicate and carbonatitic magmas in the Qassiarsuk Complex, Gardar Rift, southwest Greenland |
title_short |
Coexisting silicate and carbonatitic magmas in the Qassiarsuk Complex, Gardar Rift, southwest Greenland |
title_full |
Coexisting silicate and carbonatitic magmas in the Qassiarsuk Complex, Gardar Rift, southwest Greenland |
title_fullStr |
Coexisting silicate and carbonatitic magmas in the Qassiarsuk Complex, Gardar Rift, southwest Greenland |
title_full_unstemmed |
Coexisting silicate and carbonatitic magmas in the Qassiarsuk Complex, Gardar Rift, southwest Greenland |
title_sort |
coexisting silicate and carbonatitic magmas in the qassiarsuk complex, gardar rift, southwest greenland |
publishDate |
2008 |
url |
https://researchers.mq.edu.au/en/publications/c898294c-5d97-41fc-be03-b01145a3409c https://doi.org/10.3749/canmin.46.4.933 http://www.scopus.com/inward/record.url?scp=56749132449&partnerID=8YFLogxK |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Qassiarsuk |
genre_facet |
Greenland Qassiarsuk |
op_source |
Andersen , T 2008 , ' Coexisting silicate and carbonatitic magmas in the Qassiarsuk Complex, Gardar Rift, southwest Greenland ' , Canadian Mineralogist , vol. 46 , no. 4 , pp. 933-950 . https://doi.org/10.3749/canmin.46.4.933 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.3749/canmin.46.4.933 |
container_title |
The Canadian Mineralogist |
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46 |
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4 |
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933 |
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950 |
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1812814173820682240 |