1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield
At least 14 small (1-11 km across) 1.8 Ga Svecofennian post-collisional bimodal intrusions occur in southern Finland and Russian Karelia in a 600-km-long belt from the Aland Islands to the NW Lake Ladoga region. The rocks range from ultramafic, calc-alkaline, apatite-rich potassium lamprophyres to p...
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1998
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Online Access: | https://research.abo.fi/en/publications/9ce80214-b9f7-4bce-a610-58d78388a5fe https://doi.org/10.1016/S0024-4937(98)00027-9 |
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ftaboakademicris:oai:pure.atira.dk:publications/9ce80214-b9f7-4bce-a610-58d78388a5fe 2024-04-28T08:18:41+00:00 1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield Eklund, Olav Konopelko, D Rutanen, H Fröjdö, Sören Shebanov, AD 1998 https://research.abo.fi/en/publications/9ce80214-b9f7-4bce-a610-58d78388a5fe https://doi.org/10.1016/S0024-4937(98)00027-9 und unknown https://research.abo.fi/en/publications/9ce80214-b9f7-4bce-a610-58d78388a5fe info:eu-repo/semantics/restrictedAccess Eklund , O , Konopelko , D , Rutanen , H , Fröjdö , S & Shebanov , AD 1998 , ' 1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield ' , Lithos , vol. 45 , no. 1-4 , pp. 87–108 . https://doi.org/10.1016/S0024-4937(98)00027-9 apatite Fennoscandian shield lamprophyres post-collisional magmatism shoshonitic rocks trace elements article 1998 ftaboakademicris https://doi.org/10.1016/S0024-4937(98)00027-9 2024-04-02T16:55:37Z At least 14 small (1-11 km across) 1.8 Ga Svecofennian post-collisional bimodal intrusions occur in southern Finland and Russian Karelia in a 600-km-long belt from the Aland Islands to the NW Lake Ladoga region. The rocks range from ultramafic, calc-alkaline, apatite-rich potassium lamprophyres to peraluminous HiBaSr granites, and form a shoshonitic series with K2O + Na2O > 5%, K2O/Na2O > 0.5, Al2O3 > 9% over a wide spectrum of SiO2 (32-78%). Although strongly enriched in all rocks, the LILE Ba and Sr and the LREE generally define a decreasing trend with increasing SiO2. Depletion is noted for HFSE Ti, Nb and Ta. Available isotopic data show overlapping values for lamprophyres and granites within separate intrusions and a cogenetic origin is thus not precluded. Initial magmas (Mg# > 65) in this shoshonitic association are considered to be generated in an enriched lithospheric mantle during post-collisional uplift some 30 Ma after the regional Svecofennian metamorphic peak. However, prior to the melting episode, the lithospheric mantle was affected by carbonatite metasomatism; more extensively in the east than in the west. The melts generated in the more carbonate-rich mantle are extremely enriched in P2O5 similar to 4%, F similar to 12,000 ppm, LILE: Ba similar to 9000 ppm, Sr similar to 7000 ppm, LREE: La similar to 600 ppm and Ce similar to 1000 ppm. The parental magma underwent 55-60% fractionation of biotite + clinopyroxene + apatite + magnetite + sphene whereupon intermediate varieties were produced. After further fractionation, 60-80%, of K-feldspar + amphibole + plagioclase + (minor magnetite, sphene and apatite), leucosyenites and quartz-monzonites were formed. In the west, where the source was less affected by carbonatite metasomatism, calc-alkaline lamprophyres (vogesites, minettes and spessartites) and equivalent plutonic rocks (monzonites) were formed. Removal of about 50% of biotite, amphibole, plagioclase, magnetite, apatite and sphene produced peraluminous HiBaSr granites. The impact ... Article in Journal/Newspaper Fennoscandian karelia* Åbo Akademi University Research Portal Lithos 45 1-4 87 108 |
institution |
Open Polar |
collection |
Åbo Akademi University Research Portal |
op_collection_id |
ftaboakademicris |
language |
unknown |
topic |
apatite Fennoscandian shield lamprophyres post-collisional magmatism shoshonitic rocks trace elements |
spellingShingle |
apatite Fennoscandian shield lamprophyres post-collisional magmatism shoshonitic rocks trace elements Eklund, Olav Konopelko, D Rutanen, H Fröjdö, Sören Shebanov, AD 1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield |
topic_facet |
apatite Fennoscandian shield lamprophyres post-collisional magmatism shoshonitic rocks trace elements |
description |
At least 14 small (1-11 km across) 1.8 Ga Svecofennian post-collisional bimodal intrusions occur in southern Finland and Russian Karelia in a 600-km-long belt from the Aland Islands to the NW Lake Ladoga region. The rocks range from ultramafic, calc-alkaline, apatite-rich potassium lamprophyres to peraluminous HiBaSr granites, and form a shoshonitic series with K2O + Na2O > 5%, K2O/Na2O > 0.5, Al2O3 > 9% over a wide spectrum of SiO2 (32-78%). Although strongly enriched in all rocks, the LILE Ba and Sr and the LREE generally define a decreasing trend with increasing SiO2. Depletion is noted for HFSE Ti, Nb and Ta. Available isotopic data show overlapping values for lamprophyres and granites within separate intrusions and a cogenetic origin is thus not precluded. Initial magmas (Mg# > 65) in this shoshonitic association are considered to be generated in an enriched lithospheric mantle during post-collisional uplift some 30 Ma after the regional Svecofennian metamorphic peak. However, prior to the melting episode, the lithospheric mantle was affected by carbonatite metasomatism; more extensively in the east than in the west. The melts generated in the more carbonate-rich mantle are extremely enriched in P2O5 similar to 4%, F similar to 12,000 ppm, LILE: Ba similar to 9000 ppm, Sr similar to 7000 ppm, LREE: La similar to 600 ppm and Ce similar to 1000 ppm. The parental magma underwent 55-60% fractionation of biotite + clinopyroxene + apatite + magnetite + sphene whereupon intermediate varieties were produced. After further fractionation, 60-80%, of K-feldspar + amphibole + plagioclase + (minor magnetite, sphene and apatite), leucosyenites and quartz-monzonites were formed. In the west, where the source was less affected by carbonatite metasomatism, calc-alkaline lamprophyres (vogesites, minettes and spessartites) and equivalent plutonic rocks (monzonites) were formed. Removal of about 50% of biotite, amphibole, plagioclase, magnetite, apatite and sphene produced peraluminous HiBaSr granites. The impact ... |
format |
Article in Journal/Newspaper |
author |
Eklund, Olav Konopelko, D Rutanen, H Fröjdö, Sören Shebanov, AD |
author_facet |
Eklund, Olav Konopelko, D Rutanen, H Fröjdö, Sören Shebanov, AD |
author_sort |
Eklund, Olav |
title |
1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield |
title_short |
1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield |
title_full |
1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield |
title_fullStr |
1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield |
title_full_unstemmed |
1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield |
title_sort |
1.8 ga svecofennian post-collisional shoshonitic magmatism in the fennoscandian shield |
publishDate |
1998 |
url |
https://research.abo.fi/en/publications/9ce80214-b9f7-4bce-a610-58d78388a5fe https://doi.org/10.1016/S0024-4937(98)00027-9 |
genre |
Fennoscandian karelia* |
genre_facet |
Fennoscandian karelia* |
op_source |
Eklund , O , Konopelko , D , Rutanen , H , Fröjdö , S & Shebanov , AD 1998 , ' 1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield ' , Lithos , vol. 45 , no. 1-4 , pp. 87–108 . https://doi.org/10.1016/S0024-4937(98)00027-9 |
op_relation |
https://research.abo.fi/en/publications/9ce80214-b9f7-4bce-a610-58d78388a5fe |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1016/S0024-4937(98)00027-9 |
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