Major, trace element and Sr-Nd isotope evidence for a sublithospheric mantle source for the Umkondo large igneous province
The Mesoproterozoic (1.11 Ga) Umkondo large igneous province (LIP) in southern Africa and Antarctica was emplaced in < 5 Myr and is dominated by low-Ti tholeiitic doleritic-gabbroic sills. It is of particular interest because it is the least studied LIP in southern Africa with both sublithospheri...
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ftdoajarticles:oai:doaj.org/article:017782df184b497d9ee5bb36bf8c56a9 2024-01-14T10:02:27+01:00 Major, trace element and Sr-Nd isotope evidence for a sublithospheric mantle source for the Umkondo large igneous province Ben Hayes Lewis D. Ashwal Khulekani B. Khumalo Linda M. Iaccheri 2024-01-01T00:00:00Z https://doi.org/10.1016/j.gsf.2023.101719 https://doaj.org/article/017782df184b497d9ee5bb36bf8c56a9 EN eng Elsevier http://www.sciencedirect.com/science/article/pii/S167498712300186X https://doaj.org/toc/1674-9871 1674-9871 doi:10.1016/j.gsf.2023.101719 https://doaj.org/article/017782df184b497d9ee5bb36bf8c56a9 Geoscience Frontiers, Vol 15, Iss 1, Pp 101719- (2024) Umkondo large igneous province Low-Ti magma Continental tholeiites Sublithospheric mantle sources Kalahari craton Rodinia Geology QE1-996.5 article 1481 ftdoajarticles https://doi.org/10.1016/j.gsf.2023.101719 2023-12-17T01:37:53Z The Mesoproterozoic (1.11 Ga) Umkondo large igneous province (LIP) in southern Africa and Antarctica was emplaced in < 5 Myr and is dominated by low-Ti tholeiitic doleritic-gabbroic sills. It is of particular interest because it is the least studied LIP in southern Africa with both sublithospheric and lithospheric mantle sources proposed and it coincides with the early assembly of Rodinia, so it has importance in understanding the nature of magmatism and tectonics in and around the Kalahari craton during the Mesoproterozoic. In this study, we compiled a large database of existing (∼750) and new (∼100) major and trace element data for the Umkondo province, as well as 42 new Sr-Nd isotopic measurements, to provide constraints on its magma sources and geochemical evolution. Major element compositional variations in the low-Ti tholeiites are explained by low-pressure (1 kbar) three-phase fractional crystallisation (olivine, clinopyroxene and plagioclase) of a parent magma with ∼ 10 wt.% MgO in oxidising conditions (QFM + 1). Inverse models show that the low-Ti tholeiitic magmas were derived as residual melts after the crystallization of 12%–33% olivine from primary komatiitic-basaltic magmas (up to ∼ 20 wt.% MgO) in equilibrium with mantle olivine (Fo90). Low Sm/Yb and TiO2/Yb-Nb/Yb indicate that the primary magmas were derived by 2%–20% shallow (40–50 km) partial melting of spinel lherzolite. High Sm/Yb is restricted to dyke swarms and may imply limited magma production from deeper (up to ∼ 70 km) garnet lherzolite-like sources. The low-Ti tholeiites of the Umkondo province are enriched in large ion lithophile elements (Rb-Sr-Cs-K) and depleted in high-field strength elements (Zr-Hf-Nb-Ta), indicating the involvement of crustal material and/or the subcontinental lithospheric mantle. This is supported by covariations in Th/Nb, Nb/Yb, Nb/La and Ce/Sm with generally negative ΔNb. Sr-Nd isotopes lend support to the notion that the Umkondo magmas were derived from depleted and/or enriched sublithospheric mantle ... Article in Journal/Newspaper Antarc* Antarctica Directory of Open Access Journals: DOAJ Articles Geoscience Frontiers 15 1 101719 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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ftdoajarticles |
language |
English |
topic |
Umkondo large igneous province Low-Ti magma Continental tholeiites Sublithospheric mantle sources Kalahari craton Rodinia Geology QE1-996.5 |
spellingShingle |
Umkondo large igneous province Low-Ti magma Continental tholeiites Sublithospheric mantle sources Kalahari craton Rodinia Geology QE1-996.5 Ben Hayes Lewis D. Ashwal Khulekani B. Khumalo Linda M. Iaccheri Major, trace element and Sr-Nd isotope evidence for a sublithospheric mantle source for the Umkondo large igneous province |
topic_facet |
Umkondo large igneous province Low-Ti magma Continental tholeiites Sublithospheric mantle sources Kalahari craton Rodinia Geology QE1-996.5 |
description |
The Mesoproterozoic (1.11 Ga) Umkondo large igneous province (LIP) in southern Africa and Antarctica was emplaced in < 5 Myr and is dominated by low-Ti tholeiitic doleritic-gabbroic sills. It is of particular interest because it is the least studied LIP in southern Africa with both sublithospheric and lithospheric mantle sources proposed and it coincides with the early assembly of Rodinia, so it has importance in understanding the nature of magmatism and tectonics in and around the Kalahari craton during the Mesoproterozoic. In this study, we compiled a large database of existing (∼750) and new (∼100) major and trace element data for the Umkondo province, as well as 42 new Sr-Nd isotopic measurements, to provide constraints on its magma sources and geochemical evolution. Major element compositional variations in the low-Ti tholeiites are explained by low-pressure (1 kbar) three-phase fractional crystallisation (olivine, clinopyroxene and plagioclase) of a parent magma with ∼ 10 wt.% MgO in oxidising conditions (QFM + 1). Inverse models show that the low-Ti tholeiitic magmas were derived as residual melts after the crystallization of 12%–33% olivine from primary komatiitic-basaltic magmas (up to ∼ 20 wt.% MgO) in equilibrium with mantle olivine (Fo90). Low Sm/Yb and TiO2/Yb-Nb/Yb indicate that the primary magmas were derived by 2%–20% shallow (40–50 km) partial melting of spinel lherzolite. High Sm/Yb is restricted to dyke swarms and may imply limited magma production from deeper (up to ∼ 70 km) garnet lherzolite-like sources. The low-Ti tholeiites of the Umkondo province are enriched in large ion lithophile elements (Rb-Sr-Cs-K) and depleted in high-field strength elements (Zr-Hf-Nb-Ta), indicating the involvement of crustal material and/or the subcontinental lithospheric mantle. This is supported by covariations in Th/Nb, Nb/Yb, Nb/La and Ce/Sm with generally negative ΔNb. Sr-Nd isotopes lend support to the notion that the Umkondo magmas were derived from depleted and/or enriched sublithospheric mantle ... |
format |
Article in Journal/Newspaper |
author |
Ben Hayes Lewis D. Ashwal Khulekani B. Khumalo Linda M. Iaccheri |
author_facet |
Ben Hayes Lewis D. Ashwal Khulekani B. Khumalo Linda M. Iaccheri |
author_sort |
Ben Hayes |
title |
Major, trace element and Sr-Nd isotope evidence for a sublithospheric mantle source for the Umkondo large igneous province |
title_short |
Major, trace element and Sr-Nd isotope evidence for a sublithospheric mantle source for the Umkondo large igneous province |
title_full |
Major, trace element and Sr-Nd isotope evidence for a sublithospheric mantle source for the Umkondo large igneous province |
title_fullStr |
Major, trace element and Sr-Nd isotope evidence for a sublithospheric mantle source for the Umkondo large igneous province |
title_full_unstemmed |
Major, trace element and Sr-Nd isotope evidence for a sublithospheric mantle source for the Umkondo large igneous province |
title_sort |
major, trace element and sr-nd isotope evidence for a sublithospheric mantle source for the umkondo large igneous province |
publisher |
Elsevier |
publishDate |
1481 |
url |
https://doi.org/10.1016/j.gsf.2023.101719 https://doaj.org/article/017782df184b497d9ee5bb36bf8c56a9 |
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Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
Geoscience Frontiers, Vol 15, Iss 1, Pp 101719- (2024) |
op_relation |
http://www.sciencedirect.com/science/article/pii/S167498712300186X https://doaj.org/toc/1674-9871 1674-9871 doi:10.1016/j.gsf.2023.101719 https://doaj.org/article/017782df184b497d9ee5bb36bf8c56a9 |
op_doi |
https://doi.org/10.1016/j.gsf.2023.101719 |
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Geoscience Frontiers |
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