Komatiitic explosive volcanism and its tectonic setting in Finland, the Fennoscandian (Baltic) Shield
The variously explosive komatiitic volcanism in Finland was virtually confined to the Archaean continental segment, where it occurred in the Lapland and Kuhmo‒ Suomussalmi greenstone belts between 3.0 Ga and 2.5 Ga, in the continental borderland at 1.97 Ga, and in the continental shelf break 1.91‒1....
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Geological Society of Finland
1990
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ftdoajarticles:oai:doaj.org/article:dc6238d6b1974af884a10ffbb72ff3f4 2023-05-15T16:12:56+02:00 Komatiitic explosive volcanism and its tectonic setting in Finland, the Fennoscandian (Baltic) Shield M. Saverikko 1990-06-01T00:00:00Z https://doi.org/10.17741/bgsf/62.1.001 https://doaj.org/article/dc6238d6b1974af884a10ffbb72ff3f4 EN eng Geological Society of Finland http://www.geologinenseura.fi/bulletin/Volume62/sgs_bt_062_1_pages_003_038.pdf https://doaj.org/toc/0367-5211 https://doaj.org/toc/1799-4632 doi:10.17741/bgsf/62.1.001 0367-5211 1799-4632 https://doaj.org/article/dc6238d6b1974af884a10ffbb72ff3f4 Bulletin of the Geological Society of Finland, Vol 62, Iss 1, Pp 3-38 (1990) komatiite volcanism pyroclastics greenstone belts lithostratigraphy plate tectonics rifting aulacogens Baltic Shield Precambrian Finland Geology QE1-996.5 article 1990 ftdoajarticles https://doi.org/10.17741/bgsf/62.1.001 2022-12-31T13:10:20Z The variously explosive komatiitic volcanism in Finland was virtually confined to the Archaean continental segment, where it occurred in the Lapland and Kuhmo‒ Suomussalmi greenstone belts between 3.0 Ga and 2.5 Ga, in the continental borderland at 1.97 Ga, and in the continental shelf break 1.91‒1.88 Ga ago. The Archaean continent comprised the Saamian craton, which stabilized at 3.1‒3.0 Ga before splitting into an array of sialic megablocks. Except for the NW-trending rifts, the linear crustal openings of the Fennoscandian greenstone belts constituted a radial swarm of aulacogens caused by domal uplift in connection with shield-wide mantle upwelling. Diapirism resulted in the Lapponian pyroclastic komatiite zone of mantle-activated rifting and in the large Solovetski mantle plume in the USSR, along which continental breakup reached no more than an embryonic stage of divergence. The Finnish greenstone belts underwent three periods of supracrustal evolution from cratonic deposition and/or continental rifting to oceanic or mantle-activated rifting. The extensional stage of the greenstone-belt genesis is recognizable in Lapland but not in the Kuhmo‒Suomussalmi area, in the ductile? periphery of the continental plate, where sagduction obscured the geological history. In Lapland, the komatiitic central-vents opened at rift‒aulacogen intersections. Some signs of volcanic bursting, albeit obscure, can be traced in the earlier ultramafics, namely in the initial komatiitic greenstones beneath the cratonic metasediments and in those associated with bimodal metavolcanics. Pyroclastics formed in all the komatiitic rock types but the pyroxene peridotitic komatiite (MgO 18‒30 wt%, anhydrous basis) was the predominant substance to extrude in enormous magmatic explosions during the terminal stage of mantle upwelling. After the Karelian anorogenic period, mantle activity produced two ophiolitic suites from the mantle plumes 1.97‒1.96 Ga ago. The one at Outokumpu brought about volcaniclastic komatiites under shallow-water to ... Article in Journal/Newspaper Fennoscandian karelia* karelian Lapland Directory of Open Access Journals: DOAJ Articles Bulletin of the Geological Society of Finland 62 1 3 38 |
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Directory of Open Access Journals: DOAJ Articles |
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ftdoajarticles |
language |
English |
topic |
komatiite volcanism pyroclastics greenstone belts lithostratigraphy plate tectonics rifting aulacogens Baltic Shield Precambrian Finland Geology QE1-996.5 |
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komatiite volcanism pyroclastics greenstone belts lithostratigraphy plate tectonics rifting aulacogens Baltic Shield Precambrian Finland Geology QE1-996.5 M. Saverikko Komatiitic explosive volcanism and its tectonic setting in Finland, the Fennoscandian (Baltic) Shield |
topic_facet |
komatiite volcanism pyroclastics greenstone belts lithostratigraphy plate tectonics rifting aulacogens Baltic Shield Precambrian Finland Geology QE1-996.5 |
description |
The variously explosive komatiitic volcanism in Finland was virtually confined to the Archaean continental segment, where it occurred in the Lapland and Kuhmo‒ Suomussalmi greenstone belts between 3.0 Ga and 2.5 Ga, in the continental borderland at 1.97 Ga, and in the continental shelf break 1.91‒1.88 Ga ago. The Archaean continent comprised the Saamian craton, which stabilized at 3.1‒3.0 Ga before splitting into an array of sialic megablocks. Except for the NW-trending rifts, the linear crustal openings of the Fennoscandian greenstone belts constituted a radial swarm of aulacogens caused by domal uplift in connection with shield-wide mantle upwelling. Diapirism resulted in the Lapponian pyroclastic komatiite zone of mantle-activated rifting and in the large Solovetski mantle plume in the USSR, along which continental breakup reached no more than an embryonic stage of divergence. The Finnish greenstone belts underwent three periods of supracrustal evolution from cratonic deposition and/or continental rifting to oceanic or mantle-activated rifting. The extensional stage of the greenstone-belt genesis is recognizable in Lapland but not in the Kuhmo‒Suomussalmi area, in the ductile? periphery of the continental plate, where sagduction obscured the geological history. In Lapland, the komatiitic central-vents opened at rift‒aulacogen intersections. Some signs of volcanic bursting, albeit obscure, can be traced in the earlier ultramafics, namely in the initial komatiitic greenstones beneath the cratonic metasediments and in those associated with bimodal metavolcanics. Pyroclastics formed in all the komatiitic rock types but the pyroxene peridotitic komatiite (MgO 18‒30 wt%, anhydrous basis) was the predominant substance to extrude in enormous magmatic explosions during the terminal stage of mantle upwelling. After the Karelian anorogenic period, mantle activity produced two ophiolitic suites from the mantle plumes 1.97‒1.96 Ga ago. The one at Outokumpu brought about volcaniclastic komatiites under shallow-water to ... |
format |
Article in Journal/Newspaper |
author |
M. Saverikko |
author_facet |
M. Saverikko |
author_sort |
M. Saverikko |
title |
Komatiitic explosive volcanism and its tectonic setting in Finland, the Fennoscandian (Baltic) Shield |
title_short |
Komatiitic explosive volcanism and its tectonic setting in Finland, the Fennoscandian (Baltic) Shield |
title_full |
Komatiitic explosive volcanism and its tectonic setting in Finland, the Fennoscandian (Baltic) Shield |
title_fullStr |
Komatiitic explosive volcanism and its tectonic setting in Finland, the Fennoscandian (Baltic) Shield |
title_full_unstemmed |
Komatiitic explosive volcanism and its tectonic setting in Finland, the Fennoscandian (Baltic) Shield |
title_sort |
komatiitic explosive volcanism and its tectonic setting in finland, the fennoscandian (baltic) shield |
publisher |
Geological Society of Finland |
publishDate |
1990 |
url |
https://doi.org/10.17741/bgsf/62.1.001 https://doaj.org/article/dc6238d6b1974af884a10ffbb72ff3f4 |
genre |
Fennoscandian karelia* karelian Lapland |
genre_facet |
Fennoscandian karelia* karelian Lapland |
op_source |
Bulletin of the Geological Society of Finland, Vol 62, Iss 1, Pp 3-38 (1990) |
op_relation |
http://www.geologinenseura.fi/bulletin/Volume62/sgs_bt_062_1_pages_003_038.pdf https://doaj.org/toc/0367-5211 https://doaj.org/toc/1799-4632 doi:10.17741/bgsf/62.1.001 0367-5211 1799-4632 https://doaj.org/article/dc6238d6b1974af884a10ffbb72ff3f4 |
op_doi |
https://doi.org/10.17741/bgsf/62.1.001 |
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Bulletin of the Geological Society of Finland |
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62 |
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1 |
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3 |
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38 |
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1765998546428887040 |