Highly refractory Archaean peridotite cumulates: Petrology and geochemistry of the Seqi Ultramafic Complex, SW Greenland
This paper investigates the petrogenesis of the Seqi Ultramafic Complex, which covers a total area of approximately 0.5 km2. The ultramafic rocks are hosted by tonalitic orthogneiss of the ca. 3000 Ma Akia terrane with crosscutting granitoid sheets providing an absolute minimum age of 2978 ± 8 Ma fo...
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ftunivderby:oai:derby.openrepository.com:10545/621658 2023-05-15T16:17:22+02:00 Highly refractory Archaean peridotite cumulates: Petrology and geochemistry of the Seqi Ultramafic Complex, SW Greenland Szilas, Kristoffer van Hinsberg, Vincent J. McDonald, Iain Næraa, Tomas Rollinson, Hugh Adetunji, Jacob Bird, Dennis Stanford University McGill University Lund University Cardiff University University of Derby 2017-06-06 http://hdl.handle.net/10545/621658 https://doi.org/10.1016/j.gsf.2017.05.003 en eng Elsevier http://linkinghub.elsevier.com/retrieve/pii/S1674987117300993 Szilas, K. et al (2017) 'Highly refractory Archaean peridotite cumulates: Petrology and geochemistry of the Seqi Ultramafic Complex, SW Greenland' Geoscience Frontiers, 9 (3), pp. 689-714. 16749871 doi:10.1016/j.gsf.2017.05.003 http://hdl.handle.net/10545/621658 Geoscience Frontiers Archived with thanks to Geoscience Frontiers Archaean Ultramafic North Atlantic craton Dunite Platinum-group elements Ultra-depleted mantle Fiskefjord Article 2017 ftunivderby https://doi.org/10.1016/j.gsf.2017.05.003 2020-09-04T06:43:19Z This paper investigates the petrogenesis of the Seqi Ultramafic Complex, which covers a total area of approximately 0.5 km2. The ultramafic rocks are hosted by tonalitic orthogneiss of the ca. 3000 Ma Akia terrane with crosscutting granitoid sheets providing an absolute minimum age of 2978 ± 8 Ma for the Seqi Ultramafic Complex. The Seqi rocks represent a broad range of olivine-dominated plutonic rocks with varying modal amounts of chromite, orthopyroxene and amphibole, i.e. various types of dunite (s.s.), peridotite (s.l.), as well as chromitite. The Seqi Ultramafic Complex is characterised primarily by refractory dunite, with highly forsteritic olivine with core compositions having Mg# ranging from about 91 to 93. The overall high modal contents, as well as the specific compositions, of chromite rule out that these rocks represent a fragment of Earth’s mantle. The occurrence of stratiform chromitite bands in peridotite, thin chromite layers in dunite and poikilitic orthopyroxene in peridotite instead supports the interpretation that the Seqi Ultramafic Complex represents the remnant of a fragmented layered complex or a magma conduit, which was subsequently broken up and entrained during the formation of the regional continental crust. Integrating all of the characteristics of the Seqi Ultramafic Complex points to formation of these highly refractory peridotites from an extremely magnesian (Mg# ~ 80), near-anhydrous magma, as olivine-dominated cumulates with high modal contents of chromite. It is noted that the Seqi cumulates were derived from a mantle source by extreme degrees of partial melting (>40%). This mantle source could potentially represent the precursor for the sub-continental lithospheric mantle (SCLM) in this region, which has previously been shown to be ultra-depleted. The Seqi Ultramafic Complex, as well as similar peridotite bodies in the Fiskefjord region, may thus constitute the earliest cumulates that formed during the large-scale melting event(s), which resulted in the ultra depleted cratonic keel under the North Atlantic Craton. Hence, a better understanding of such Archaean ultramafic complexes may provide constraints on the geodynamic setting of Earth’s first continents and the corresponding SCLM. Department of Geological Sciences, Stanford University, 450 Serra Mall, Stanford, CA 94305, USA Department of Earth & Planetary Sciences, McGill University, Quebec, Canada Department of Geology, Lund University, Sölvegatan 12, 223 62 Lund, Sweden School of Earth and Ocean Sciences, Cardiff University, Main Building, Cardiff CF10 3AT, United Kingdom College of Science, University of Derby, Derby, DE22 1GB, UK Article in Journal/Newspaper Fiskefjord Greenland North Atlantic UDORA - The University of Derby Online Research Archive Canada Greenland Geoscience Frontiers 9 3 689 714 |
institution |
Open Polar |
collection |
UDORA - The University of Derby Online Research Archive |
op_collection_id |
ftunivderby |
language |
English |
topic |
Archaean Ultramafic North Atlantic craton Dunite Platinum-group elements Ultra-depleted mantle Fiskefjord |
spellingShingle |
Archaean Ultramafic North Atlantic craton Dunite Platinum-group elements Ultra-depleted mantle Fiskefjord Szilas, Kristoffer van Hinsberg, Vincent J. McDonald, Iain Næraa, Tomas Rollinson, Hugh Adetunji, Jacob Bird, Dennis Highly refractory Archaean peridotite cumulates: Petrology and geochemistry of the Seqi Ultramafic Complex, SW Greenland |
topic_facet |
Archaean Ultramafic North Atlantic craton Dunite Platinum-group elements Ultra-depleted mantle Fiskefjord |
description |
This paper investigates the petrogenesis of the Seqi Ultramafic Complex, which covers a total area of approximately 0.5 km2. The ultramafic rocks are hosted by tonalitic orthogneiss of the ca. 3000 Ma Akia terrane with crosscutting granitoid sheets providing an absolute minimum age of 2978 ± 8 Ma for the Seqi Ultramafic Complex. The Seqi rocks represent a broad range of olivine-dominated plutonic rocks with varying modal amounts of chromite, orthopyroxene and amphibole, i.e. various types of dunite (s.s.), peridotite (s.l.), as well as chromitite. The Seqi Ultramafic Complex is characterised primarily by refractory dunite, with highly forsteritic olivine with core compositions having Mg# ranging from about 91 to 93. The overall high modal contents, as well as the specific compositions, of chromite rule out that these rocks represent a fragment of Earth’s mantle. The occurrence of stratiform chromitite bands in peridotite, thin chromite layers in dunite and poikilitic orthopyroxene in peridotite instead supports the interpretation that the Seqi Ultramafic Complex represents the remnant of a fragmented layered complex or a magma conduit, which was subsequently broken up and entrained during the formation of the regional continental crust. Integrating all of the characteristics of the Seqi Ultramafic Complex points to formation of these highly refractory peridotites from an extremely magnesian (Mg# ~ 80), near-anhydrous magma, as olivine-dominated cumulates with high modal contents of chromite. It is noted that the Seqi cumulates were derived from a mantle source by extreme degrees of partial melting (>40%). This mantle source could potentially represent the precursor for the sub-continental lithospheric mantle (SCLM) in this region, which has previously been shown to be ultra-depleted. The Seqi Ultramafic Complex, as well as similar peridotite bodies in the Fiskefjord region, may thus constitute the earliest cumulates that formed during the large-scale melting event(s), which resulted in the ultra depleted cratonic keel under the North Atlantic Craton. Hence, a better understanding of such Archaean ultramafic complexes may provide constraints on the geodynamic setting of Earth’s first continents and the corresponding SCLM. Department of Geological Sciences, Stanford University, 450 Serra Mall, Stanford, CA 94305, USA Department of Earth & Planetary Sciences, McGill University, Quebec, Canada Department of Geology, Lund University, Sölvegatan 12, 223 62 Lund, Sweden School of Earth and Ocean Sciences, Cardiff University, Main Building, Cardiff CF10 3AT, United Kingdom College of Science, University of Derby, Derby, DE22 1GB, UK |
author2 |
Stanford University McGill University Lund University Cardiff University University of Derby |
format |
Article in Journal/Newspaper |
author |
Szilas, Kristoffer van Hinsberg, Vincent J. McDonald, Iain Næraa, Tomas Rollinson, Hugh Adetunji, Jacob Bird, Dennis |
author_facet |
Szilas, Kristoffer van Hinsberg, Vincent J. McDonald, Iain Næraa, Tomas Rollinson, Hugh Adetunji, Jacob Bird, Dennis |
author_sort |
Szilas, Kristoffer |
title |
Highly refractory Archaean peridotite cumulates: Petrology and geochemistry of the Seqi Ultramafic Complex, SW Greenland |
title_short |
Highly refractory Archaean peridotite cumulates: Petrology and geochemistry of the Seqi Ultramafic Complex, SW Greenland |
title_full |
Highly refractory Archaean peridotite cumulates: Petrology and geochemistry of the Seqi Ultramafic Complex, SW Greenland |
title_fullStr |
Highly refractory Archaean peridotite cumulates: Petrology and geochemistry of the Seqi Ultramafic Complex, SW Greenland |
title_full_unstemmed |
Highly refractory Archaean peridotite cumulates: Petrology and geochemistry of the Seqi Ultramafic Complex, SW Greenland |
title_sort |
highly refractory archaean peridotite cumulates: petrology and geochemistry of the seqi ultramafic complex, sw greenland |
publisher |
Elsevier |
publishDate |
2017 |
url |
http://hdl.handle.net/10545/621658 https://doi.org/10.1016/j.gsf.2017.05.003 |
geographic |
Canada Greenland |
geographic_facet |
Canada Greenland |
genre |
Fiskefjord Greenland North Atlantic |
genre_facet |
Fiskefjord Greenland North Atlantic |
op_relation |
http://linkinghub.elsevier.com/retrieve/pii/S1674987117300993 Szilas, K. et al (2017) 'Highly refractory Archaean peridotite cumulates: Petrology and geochemistry of the Seqi Ultramafic Complex, SW Greenland' Geoscience Frontiers, 9 (3), pp. 689-714. 16749871 doi:10.1016/j.gsf.2017.05.003 http://hdl.handle.net/10545/621658 Geoscience Frontiers |
op_rights |
Archived with thanks to Geoscience Frontiers |
op_doi |
https://doi.org/10.1016/j.gsf.2017.05.003 |
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Geoscience Frontiers |
container_volume |
9 |
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3 |
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689 |
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714 |
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