Petrogenesis of a Hybrid Cluster of Evolved Kimberlites and Ultramafic Lamprophyres in the Kuusamo Area, Finland
Abstract Kimberlites are often closely associated, both in time and space, with a wide variety of alkaline ultramafic rock types, yet the question of a genetic relationship between these rock types remains uncertain. One locality where these relationships can be studied within the same cluster is th...
Published in: | Journal of Petrology |
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Oxford University Press (OUP)
2019
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Online Access: | http://dx.doi.org/10.1093/petrology/egz062 http://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egz062/33017340/egz062.pdf http://academic.oup.com/petrology/article-pdf/60/10/2025/33138454/egz062.pdf |
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croxfordunivpr:10.1093/petrology/egz062 2024-09-15T18:16:14+00:00 Petrogenesis of a Hybrid Cluster of Evolved Kimberlites and Ultramafic Lamprophyres in the Kuusamo Area, Finland Dalton, Hayden Giuliani, Andrea O’Brien, Hugh Phillips, David Hergt, Janet Maas, Roland Australian Research Training Program Australian Research Council ARC Discovery Early Career Researcher Award DECRA 2019 http://dx.doi.org/10.1093/petrology/egz062 http://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egz062/33017340/egz062.pdf http://academic.oup.com/petrology/article-pdf/60/10/2025/33138454/egz062.pdf en eng Oxford University Press (OUP) https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model Journal of Petrology volume 60, issue 10, page 2025-2050 ISSN 0022-3530 1460-2415 journal-article 2019 croxfordunivpr https://doi.org/10.1093/petrology/egz062 2024-07-29T04:20:23Z Abstract Kimberlites are often closely associated, both in time and space, with a wide variety of alkaline ultramafic rock types, yet the question of a genetic relationship between these rock types remains uncertain. One locality where these relationships can be studied within the same cluster is the Karelian craton in Finland. In this study we present the first petrographic, mineral and whole-rock geochemical results for the most recently discovered kimberlite cluster on this craton, which represents an example of the close spatial overlap of kimberlites with ultramafic lamprophyres. The Kuusamo cluster incorporates seven bodies [Kasma 45, Kasma 45 south, Kasma 47, Kalettomanpuro (KP), Kattaisenvaara (KV), Dike 15 and Lampi] distributed along a 60 km NE–SW corridor. Hypabyssal samples from KV, KP, Kasma 45 and Kasma 47 consist of altered olivine macrocrysts and microcrysts and phlogopite phenocrysts in a groundmass of perovskite, apatite, spinel, ilmenite, serpentine, and calcite. These petrographic features combined with mineral (e.g. Mg-rich ilmenite, Al–Ba-rich, Ti–Fe-poor mica) and whole-rock incompatible trace element compositions (La/Nb = 0·8 ± 0·1; Th/Nb = 0·07 ± 0·01; Nb/U = 66 ± 9) are consistent with these rocks being classified as archetypal kimberlites. These Kuusamo kimberlites are enriched in CaO and poor in MgO, which, combined with the absence of chromite and paucity of olivine macrocrysts and mantle-derived xenocrysts (including diamonds), suggests derivation from differentiated magmas after crystal fractionation. Samples from Lampi share similar petrographic features, but contain mica with compositions ranging from kimberlitic (Ba–Al-rich cores) to those more typical of orangeites–lamproites (increasing Si–Fe, decreasing Al–Ti–Ba), and have higher bulk-rock SiO2 contents than the Kuusamo kimberlites. These features, combined with the occurrence of quartz and titanite in the groundmass, indicate derivation from a kimberlite magma that underwent considerable crustal contamination. This study ... Article in Journal/Newspaper karelia* karelian Oxford University Press Journal of Petrology 60 10 2025 2050 |
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Open Polar |
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Oxford University Press |
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croxfordunivpr |
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English |
description |
Abstract Kimberlites are often closely associated, both in time and space, with a wide variety of alkaline ultramafic rock types, yet the question of a genetic relationship between these rock types remains uncertain. One locality where these relationships can be studied within the same cluster is the Karelian craton in Finland. In this study we present the first petrographic, mineral and whole-rock geochemical results for the most recently discovered kimberlite cluster on this craton, which represents an example of the close spatial overlap of kimberlites with ultramafic lamprophyres. The Kuusamo cluster incorporates seven bodies [Kasma 45, Kasma 45 south, Kasma 47, Kalettomanpuro (KP), Kattaisenvaara (KV), Dike 15 and Lampi] distributed along a 60 km NE–SW corridor. Hypabyssal samples from KV, KP, Kasma 45 and Kasma 47 consist of altered olivine macrocrysts and microcrysts and phlogopite phenocrysts in a groundmass of perovskite, apatite, spinel, ilmenite, serpentine, and calcite. These petrographic features combined with mineral (e.g. Mg-rich ilmenite, Al–Ba-rich, Ti–Fe-poor mica) and whole-rock incompatible trace element compositions (La/Nb = 0·8 ± 0·1; Th/Nb = 0·07 ± 0·01; Nb/U = 66 ± 9) are consistent with these rocks being classified as archetypal kimberlites. These Kuusamo kimberlites are enriched in CaO and poor in MgO, which, combined with the absence of chromite and paucity of olivine macrocrysts and mantle-derived xenocrysts (including diamonds), suggests derivation from differentiated magmas after crystal fractionation. Samples from Lampi share similar petrographic features, but contain mica with compositions ranging from kimberlitic (Ba–Al-rich cores) to those more typical of orangeites–lamproites (increasing Si–Fe, decreasing Al–Ti–Ba), and have higher bulk-rock SiO2 contents than the Kuusamo kimberlites. These features, combined with the occurrence of quartz and titanite in the groundmass, indicate derivation from a kimberlite magma that underwent considerable crustal contamination. This study ... |
author2 |
Australian Research Training Program Australian Research Council ARC Discovery Early Career Researcher Award DECRA |
format |
Article in Journal/Newspaper |
author |
Dalton, Hayden Giuliani, Andrea O’Brien, Hugh Phillips, David Hergt, Janet Maas, Roland |
spellingShingle |
Dalton, Hayden Giuliani, Andrea O’Brien, Hugh Phillips, David Hergt, Janet Maas, Roland Petrogenesis of a Hybrid Cluster of Evolved Kimberlites and Ultramafic Lamprophyres in the Kuusamo Area, Finland |
author_facet |
Dalton, Hayden Giuliani, Andrea O’Brien, Hugh Phillips, David Hergt, Janet Maas, Roland |
author_sort |
Dalton, Hayden |
title |
Petrogenesis of a Hybrid Cluster of Evolved Kimberlites and Ultramafic Lamprophyres in the Kuusamo Area, Finland |
title_short |
Petrogenesis of a Hybrid Cluster of Evolved Kimberlites and Ultramafic Lamprophyres in the Kuusamo Area, Finland |
title_full |
Petrogenesis of a Hybrid Cluster of Evolved Kimberlites and Ultramafic Lamprophyres in the Kuusamo Area, Finland |
title_fullStr |
Petrogenesis of a Hybrid Cluster of Evolved Kimberlites and Ultramafic Lamprophyres in the Kuusamo Area, Finland |
title_full_unstemmed |
Petrogenesis of a Hybrid Cluster of Evolved Kimberlites and Ultramafic Lamprophyres in the Kuusamo Area, Finland |
title_sort |
petrogenesis of a hybrid cluster of evolved kimberlites and ultramafic lamprophyres in the kuusamo area, finland |
publisher |
Oxford University Press (OUP) |
publishDate |
2019 |
url |
http://dx.doi.org/10.1093/petrology/egz062 http://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egz062/33017340/egz062.pdf http://academic.oup.com/petrology/article-pdf/60/10/2025/33138454/egz062.pdf |
genre |
karelia* karelian |
genre_facet |
karelia* karelian |
op_source |
Journal of Petrology volume 60, issue 10, page 2025-2050 ISSN 0022-3530 1460-2415 |
op_rights |
https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model |
op_doi |
https://doi.org/10.1093/petrology/egz062 |
container_title |
Journal of Petrology |
container_volume |
60 |
container_issue |
10 |
container_start_page |
2025 |
op_container_end_page |
2050 |
_version_ |
1810454253653721088 |