Millennia of magmatism recorded in crustal xenoliths from alkaline provinces in Southwest Greenland
Mantle-derived CO2-rich magma ascends rapidly through the lithospheric column, supporting upward transport of large mantle-xenoliths and xenocryst (>30vol%) loads to the (sub-)surface within days. The regional magmatism during which such pulses occur is typically well characterized in terms of ge...
Published in: | Earth and Planetary Science Letters |
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2016
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Online Access: | https://curis.ku.dk/portal/da/publications/millennia-of-magmatism-recorded-in-crustal-xenoliths-from-alkaline-provinces-in-southwest-greenland(023cd5c1-4568-4d9a-9e6e-620ffcb70a5c).html https://doi.org/10.1016/j.epsl.2016.06.047 |
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ftcopenhagenunip:oai:pure.atira.dk:publications/023cd5c1-4568-4d9a-9e6e-620ffcb70a5c 2023-05-15T16:28:39+02:00 Millennia of magmatism recorded in crustal xenoliths from alkaline provinces in Southwest Greenland Smit, Matthijs Waight, Tod Earle Nielsen, Troels 2016 https://curis.ku.dk/portal/da/publications/millennia-of-magmatism-recorded-in-crustal-xenoliths-from-alkaline-provinces-in-southwest-greenland(023cd5c1-4568-4d9a-9e6e-620ffcb70a5c).html https://doi.org/10.1016/j.epsl.2016.06.047 eng eng info:eu-repo/semantics/closedAccess Smit , M , Waight , T E & Nielsen , T 2016 , ' Millennia of magmatism recorded in crustal xenoliths from alkaline provinces in Southwest Greenland ' , Earth and Planetary Science Letters , vol. 451 , pp. 241-250 . https://doi.org/10.1016/j.epsl.2016.06.047 article 2016 ftcopenhagenunip https://doi.org/10.1016/j.epsl.2016.06.047 2022-02-24T00:22:05Z Mantle-derived CO2-rich magma ascends rapidly through the lithospheric column, supporting upward transport of large mantle-xenoliths and xenocryst (>30vol%) loads to the (sub-)surface within days. The regional magmatism during which such pulses occur is typically well characterized in terms of general duration and regional compositional trends. In contrast, the time-resolved evolution of individual ultramafic dyke and pipe systems is largely unknown. To investigate this evolution, we performed a geochemical and speedometric analysis of xenoliths from ultramafic (aillikite) dykes in two Neoproterozoic alkaline provinces in West Greenland: 1)Sarfartôq, which overlies Archean ultra-depleted SCLM and yielded ultra-deep mineral indicators, and 2)Sisimiut, where the SCLM is refertilized and deep xenoliths (>120km) are lacking. We focused on the rare and understudied crustal xenoliths, which preserve a rich record of melt injection. The xenoliths are derived from 25–36km depth and were transported to the sub-surface within 4 ±1 h(Fe-in-rutile speedometry), during which they were exposed to the magmatic temperature of 1,015 ±50 ◦C(Zr-in-rutile thermometry). Garnet major-element speedometry shows that before the xenolith-ascent stage the lower crust had already been exposed to a variety of magmas for 700 (Sarfartôq) and 7,100 (Sisimiut) years. The Sisimiut samples contain exotic carbonate-and sulfide-rich assemblages, which occurred during the early stages of melt infiltration. Absence of such exotic assemblages and the faster magmatic development at Sarfartôq are tentatively linked to higher decarbonation kinetics in the more depleted SCLM at this location. The data reveal the so far unrecognized pre-eruptive development of ultramafic systems. This stage involves non-steady state melt-silicate interaction between ascending magmas and the immediate SCLM wall-rock, during which the composition of both is modified. The progress and duration of this interaction is strongly influenced by the composition of the SCLM. Kinetics factors describing this interaction could thus be used to model the chemistry of aillikite and similar ultramafic magmas. Article in Journal/Newspaper Greenland Sisimiut University of Copenhagen: Research Greenland Sisimiut ENVELOPE(-53.674,-53.674,66.939,66.939) Earth and Planetary Science Letters 451 241 250 |
institution |
Open Polar |
collection |
University of Copenhagen: Research |
op_collection_id |
ftcopenhagenunip |
language |
English |
description |
Mantle-derived CO2-rich magma ascends rapidly through the lithospheric column, supporting upward transport of large mantle-xenoliths and xenocryst (>30vol%) loads to the (sub-)surface within days. The regional magmatism during which such pulses occur is typically well characterized in terms of general duration and regional compositional trends. In contrast, the time-resolved evolution of individual ultramafic dyke and pipe systems is largely unknown. To investigate this evolution, we performed a geochemical and speedometric analysis of xenoliths from ultramafic (aillikite) dykes in two Neoproterozoic alkaline provinces in West Greenland: 1)Sarfartôq, which overlies Archean ultra-depleted SCLM and yielded ultra-deep mineral indicators, and 2)Sisimiut, where the SCLM is refertilized and deep xenoliths (>120km) are lacking. We focused on the rare and understudied crustal xenoliths, which preserve a rich record of melt injection. The xenoliths are derived from 25–36km depth and were transported to the sub-surface within 4 ±1 h(Fe-in-rutile speedometry), during which they were exposed to the magmatic temperature of 1,015 ±50 ◦C(Zr-in-rutile thermometry). Garnet major-element speedometry shows that before the xenolith-ascent stage the lower crust had already been exposed to a variety of magmas for 700 (Sarfartôq) and 7,100 (Sisimiut) years. The Sisimiut samples contain exotic carbonate-and sulfide-rich assemblages, which occurred during the early stages of melt infiltration. Absence of such exotic assemblages and the faster magmatic development at Sarfartôq are tentatively linked to higher decarbonation kinetics in the more depleted SCLM at this location. The data reveal the so far unrecognized pre-eruptive development of ultramafic systems. This stage involves non-steady state melt-silicate interaction between ascending magmas and the immediate SCLM wall-rock, during which the composition of both is modified. The progress and duration of this interaction is strongly influenced by the composition of the SCLM. Kinetics factors describing this interaction could thus be used to model the chemistry of aillikite and similar ultramafic magmas. |
format |
Article in Journal/Newspaper |
author |
Smit, Matthijs Waight, Tod Earle Nielsen, Troels |
spellingShingle |
Smit, Matthijs Waight, Tod Earle Nielsen, Troels Millennia of magmatism recorded in crustal xenoliths from alkaline provinces in Southwest Greenland |
author_facet |
Smit, Matthijs Waight, Tod Earle Nielsen, Troels |
author_sort |
Smit, Matthijs |
title |
Millennia of magmatism recorded in crustal xenoliths from alkaline provinces in Southwest Greenland |
title_short |
Millennia of magmatism recorded in crustal xenoliths from alkaline provinces in Southwest Greenland |
title_full |
Millennia of magmatism recorded in crustal xenoliths from alkaline provinces in Southwest Greenland |
title_fullStr |
Millennia of magmatism recorded in crustal xenoliths from alkaline provinces in Southwest Greenland |
title_full_unstemmed |
Millennia of magmatism recorded in crustal xenoliths from alkaline provinces in Southwest Greenland |
title_sort |
millennia of magmatism recorded in crustal xenoliths from alkaline provinces in southwest greenland |
publishDate |
2016 |
url |
https://curis.ku.dk/portal/da/publications/millennia-of-magmatism-recorded-in-crustal-xenoliths-from-alkaline-provinces-in-southwest-greenland(023cd5c1-4568-4d9a-9e6e-620ffcb70a5c).html https://doi.org/10.1016/j.epsl.2016.06.047 |
long_lat |
ENVELOPE(-53.674,-53.674,66.939,66.939) |
geographic |
Greenland Sisimiut |
geographic_facet |
Greenland Sisimiut |
genre |
Greenland Sisimiut |
genre_facet |
Greenland Sisimiut |
op_source |
Smit , M , Waight , T E & Nielsen , T 2016 , ' Millennia of magmatism recorded in crustal xenoliths from alkaline provinces in Southwest Greenland ' , Earth and Planetary Science Letters , vol. 451 , pp. 241-250 . https://doi.org/10.1016/j.epsl.2016.06.047 |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/10.1016/j.epsl.2016.06.047 |
container_title |
Earth and Planetary Science Letters |
container_volume |
451 |
container_start_page |
241 |
op_container_end_page |
250 |
_version_ |
1766018323310444544 |