The Palaeoproterozoic Gallujavri Ultramafic Intrusion, Karasjok Greenstone Belt; Petrogenesis of a Trans-Crustal Magma System
Abstract The modern concepts of magmatic plumbing systems have evolved from simple models of melt-dominated crustal magma chambers to magmatic systems that span the continental crust. The geochemistry of these systems is challenging to model numerically because of a complex polybaric and multiphase...
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Oxford University Press (OUP)
2022
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Online Access: | http://dx.doi.org/10.1093/petrology/egac008 https://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egac008/42514754/egac008.pdf https://academic.oup.com/petrology/article-pdf/63/3/egac008/43548045/egac008.pdf |
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croxfordunivpr:10.1093/petrology/egac008 2024-09-15T18:06:08+00:00 The Palaeoproterozoic Gallujavri Ultramafic Intrusion, Karasjok Greenstone Belt; Petrogenesis of a Trans-Crustal Magma System Orvik, Alf Andre Slagstad, Trond Hansen, Harald Nilsson, Lars Petter Sørensen, Bjørn Eske Department of Geoscience and Petroleum, Faculty of Engineering, at the NTNU and the Geological Survey of Norway 2022 http://dx.doi.org/10.1093/petrology/egac008 https://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egac008/42514754/egac008.pdf https://academic.oup.com/petrology/article-pdf/63/3/egac008/43548045/egac008.pdf en eng Oxford University Press (OUP) http://creativecommons.org/licenses/by/4.0/ Journal of Petrology volume 63, issue 3 ISSN 0022-3530 1460-2415 journal-article 2022 croxfordunivpr https://doi.org/10.1093/petrology/egac008 2024-07-22T04:26:47Z Abstract The modern concepts of magmatic plumbing systems have evolved from simple models of melt-dominated crustal magma chambers to magmatic systems that span the continental crust. The geochemistry of these systems is challenging to model numerically because of a complex polybaric and multiphase evolution, which is not well described by mathematic end-member formulas. We propose that a recent modelling tool, the Magma Chamber Simulator (MCS), can reveal part of the petrological complexities of such systems. The MCS numerically models phase equilibria, mineral chemistry and major and trace elements in multicomponent–multiphase systems by finding the extremes of the appropriate state functions. This study presents new petrographical and geochemical data from the Palaeoproterozoic Gallujavri ultramafic intrusion in the Karasjok Greenstone Belt, Arctic Norway. Our data indicate that (1) the intrusion is affected by crustal assimilation, (2) phase equilibria require polybaric crystallisation and (3) spinel compositions are similar to sub-volcanic intrusions of continental flood basalt provinces. We utilise the MCS to simulate the petrogenesis of the intrusion and test the model by comparing it against our reported petrological and geochemical data. Our modelling shows that the parental magma of the intrusion is consistent with coeval Karasjok-type komatiites observed at various places throughout the greenstone belt. First, the komatiitic primary magma intruded Archaean lower crust (c. 700 MPa), where fractionation and assimilation resulted in a hybrid melt. Second, the hybrid melt migrated and accumulated in a mid-crustal magma chamber (c. 400 MPa), where it continued to fractionate and assimilate while remaining open to recharge of mantle-derived komatiitic melts, forming the Gallujavri intrusion. We interpret the Gallujavri intrusion as part of a Palaeoproterozoic trans-crustal magma plumbing system, with many similarities to other Fennoscandian ultramafic-mafic layered intrusions. Article in Journal/Newspaper Fennoscandian Karasjok Oxford University Press Journal of Petrology 63 3 |
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Oxford University Press |
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croxfordunivpr |
language |
English |
description |
Abstract The modern concepts of magmatic plumbing systems have evolved from simple models of melt-dominated crustal magma chambers to magmatic systems that span the continental crust. The geochemistry of these systems is challenging to model numerically because of a complex polybaric and multiphase evolution, which is not well described by mathematic end-member formulas. We propose that a recent modelling tool, the Magma Chamber Simulator (MCS), can reveal part of the petrological complexities of such systems. The MCS numerically models phase equilibria, mineral chemistry and major and trace elements in multicomponent–multiphase systems by finding the extremes of the appropriate state functions. This study presents new petrographical and geochemical data from the Palaeoproterozoic Gallujavri ultramafic intrusion in the Karasjok Greenstone Belt, Arctic Norway. Our data indicate that (1) the intrusion is affected by crustal assimilation, (2) phase equilibria require polybaric crystallisation and (3) spinel compositions are similar to sub-volcanic intrusions of continental flood basalt provinces. We utilise the MCS to simulate the petrogenesis of the intrusion and test the model by comparing it against our reported petrological and geochemical data. Our modelling shows that the parental magma of the intrusion is consistent with coeval Karasjok-type komatiites observed at various places throughout the greenstone belt. First, the komatiitic primary magma intruded Archaean lower crust (c. 700 MPa), where fractionation and assimilation resulted in a hybrid melt. Second, the hybrid melt migrated and accumulated in a mid-crustal magma chamber (c. 400 MPa), where it continued to fractionate and assimilate while remaining open to recharge of mantle-derived komatiitic melts, forming the Gallujavri intrusion. We interpret the Gallujavri intrusion as part of a Palaeoproterozoic trans-crustal magma plumbing system, with many similarities to other Fennoscandian ultramafic-mafic layered intrusions. |
author2 |
Department of Geoscience and Petroleum, Faculty of Engineering, at the NTNU and the Geological Survey of Norway |
format |
Article in Journal/Newspaper |
author |
Orvik, Alf Andre Slagstad, Trond Hansen, Harald Nilsson, Lars Petter Sørensen, Bjørn Eske |
spellingShingle |
Orvik, Alf Andre Slagstad, Trond Hansen, Harald Nilsson, Lars Petter Sørensen, Bjørn Eske The Palaeoproterozoic Gallujavri Ultramafic Intrusion, Karasjok Greenstone Belt; Petrogenesis of a Trans-Crustal Magma System |
author_facet |
Orvik, Alf Andre Slagstad, Trond Hansen, Harald Nilsson, Lars Petter Sørensen, Bjørn Eske |
author_sort |
Orvik, Alf Andre |
title |
The Palaeoproterozoic Gallujavri Ultramafic Intrusion, Karasjok Greenstone Belt; Petrogenesis of a Trans-Crustal Magma System |
title_short |
The Palaeoproterozoic Gallujavri Ultramafic Intrusion, Karasjok Greenstone Belt; Petrogenesis of a Trans-Crustal Magma System |
title_full |
The Palaeoproterozoic Gallujavri Ultramafic Intrusion, Karasjok Greenstone Belt; Petrogenesis of a Trans-Crustal Magma System |
title_fullStr |
The Palaeoproterozoic Gallujavri Ultramafic Intrusion, Karasjok Greenstone Belt; Petrogenesis of a Trans-Crustal Magma System |
title_full_unstemmed |
The Palaeoproterozoic Gallujavri Ultramafic Intrusion, Karasjok Greenstone Belt; Petrogenesis of a Trans-Crustal Magma System |
title_sort |
palaeoproterozoic gallujavri ultramafic intrusion, karasjok greenstone belt; petrogenesis of a trans-crustal magma system |
publisher |
Oxford University Press (OUP) |
publishDate |
2022 |
url |
http://dx.doi.org/10.1093/petrology/egac008 https://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egac008/42514754/egac008.pdf https://academic.oup.com/petrology/article-pdf/63/3/egac008/43548045/egac008.pdf |
genre |
Fennoscandian Karasjok |
genre_facet |
Fennoscandian Karasjok |
op_source |
Journal of Petrology volume 63, issue 3 ISSN 0022-3530 1460-2415 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1093/petrology/egac008 |
container_title |
Journal of Petrology |
container_volume |
63 |
container_issue |
3 |
_version_ |
1810443628005294080 |