Tracing arclogites in the Paleoproterozoic Era - A shift from 1.88 Ga calc-alkaline to 1.86 Ga high-Nb and adakite-like magmatism in central Fennoscandian Shield
Arclogites, i.e., lower crustal gamet-pyroxenite cumulates, are suggested to play an important role in controlling magma differentiation in modem continental arcs. Until now, arclogite-related magmatism has only been described from the Phanerozoic Era. The Svecofennian orogen in the central Fennosca...
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ftunivturku:oai:www.utupub.fi:10024/171515 2023-05-15T16:12:57+02:00 Tracing arclogites in the Paleoproterozoic Era - A shift from 1.88 Ga calc-alkaline to 1.86 Ga high-Nb and adakite-like magmatism in central Fennoscandian Shield Lahaye Yann Heinonen Jussi S. Huhma Hannu O'Brien Hugh Väisänen Markku Kara Jaakko geologia, Geology 2606902 2022-10-28T14:27:53Z https://www.utupub.fi/handle/10024/171515 en eng ELSEVIER Netherlands Alankomaat NL 372 ARTN 105663 10.1016/j.lithos.2020.105663 Lithos https://www.utupub.fi/handle/10024/171515 URN:NBN:fi-fe2021042826671 1872-6143 0024-4937 2022 ftunivturku 2022-11-03T00:02:42Z Arclogites, i.e., lower crustal gamet-pyroxenite cumulates, are suggested to play an important role in controlling magma differentiation in modem continental arcs. Until now, arclogite-related magmatism has only been described from the Phanerozoic Era. The Svecofennian orogen in the central Fennoscandian Shield hosts a rare association of 1.86 Ga igneous rocks geochemically distinct from the surrounding and much more abundant 1.90-1.87 Ga subduction-related talc-alkaline magmatism. The 1.86 Ga magmatic rocks are divided into three groups: 1) high-Nb gabbros (HNB) which are enriched in Fe 2 O 3 T , TiO 2 , P2O 5 , F. LILE, and HFSE (especially Nb: 18.9-44 ppm), show positive initial ε Nd value, and near-chondritic but variable initial zircon ε Hf values; 2) high-Mg gabbros (HMG) which are characterised by high MgO, CaO, Cr and Ni contents, slight enrichment in LILE, positive ε Hf , and positive but variable zircon ε Hf values; 3) adakite-like rocks showing high Al 2 O 3 and Na 2 O contents, slight enrichment in LILE, relative depletion in some HFSE, positive CNd value, and chondritic to negative zircon ε Nd values. The three groups yield zircon U-Pb ages of similar to 1.86 Ga and exhibit undeformed textures in contrast to the surrounding supracrustal rocks metamorphosed at similar to 1.88 Ga. The ages and compositions are dearly different from the adjacent 1.90-1.87 Ga arc-related igneous rocks suggesting a distinct origin. Despite similar ages and close spatial relationship, separate sources are required for each of the different 1.86 Ga rock groups. Trace element modelling of partial melting suggests that arclogites, with compositions similar to pyroxenite xenoliths found in the kimberlite pipes of eastern Finland, are the source for the HNB rocks. In contrast, subduction-modified mantle peridotite is the source for the HMG rocks, and a mafic lower crustal source is suggested for the adakite-like rocks. The following geodynamic model is suggested: (rutile-bearing) arclogite formation at 1.90-1.87 Ga followed by ... Other/Unknown Material Fennoscandian University of Turku: UTUPub |
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University of Turku: UTUPub |
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English |
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Arclogites, i.e., lower crustal gamet-pyroxenite cumulates, are suggested to play an important role in controlling magma differentiation in modem continental arcs. Until now, arclogite-related magmatism has only been described from the Phanerozoic Era. The Svecofennian orogen in the central Fennoscandian Shield hosts a rare association of 1.86 Ga igneous rocks geochemically distinct from the surrounding and much more abundant 1.90-1.87 Ga subduction-related talc-alkaline magmatism. The 1.86 Ga magmatic rocks are divided into three groups: 1) high-Nb gabbros (HNB) which are enriched in Fe 2 O 3 T , TiO 2 , P2O 5 , F. LILE, and HFSE (especially Nb: 18.9-44 ppm), show positive initial ε Nd value, and near-chondritic but variable initial zircon ε Hf values; 2) high-Mg gabbros (HMG) which are characterised by high MgO, CaO, Cr and Ni contents, slight enrichment in LILE, positive ε Hf , and positive but variable zircon ε Hf values; 3) adakite-like rocks showing high Al 2 O 3 and Na 2 O contents, slight enrichment in LILE, relative depletion in some HFSE, positive CNd value, and chondritic to negative zircon ε Nd values. The three groups yield zircon U-Pb ages of similar to 1.86 Ga and exhibit undeformed textures in contrast to the surrounding supracrustal rocks metamorphosed at similar to 1.88 Ga. The ages and compositions are dearly different from the adjacent 1.90-1.87 Ga arc-related igneous rocks suggesting a distinct origin. Despite similar ages and close spatial relationship, separate sources are required for each of the different 1.86 Ga rock groups. Trace element modelling of partial melting suggests that arclogites, with compositions similar to pyroxenite xenoliths found in the kimberlite pipes of eastern Finland, are the source for the HNB rocks. In contrast, subduction-modified mantle peridotite is the source for the HMG rocks, and a mafic lower crustal source is suggested for the adakite-like rocks. The following geodynamic model is suggested: (rutile-bearing) arclogite formation at 1.90-1.87 Ga followed by ... |
author2 |
geologia, Geology 2606902 |
author |
Lahaye Yann Heinonen Jussi S. Huhma Hannu O'Brien Hugh Väisänen Markku Kara Jaakko |
spellingShingle |
Lahaye Yann Heinonen Jussi S. Huhma Hannu O'Brien Hugh Väisänen Markku Kara Jaakko Tracing arclogites in the Paleoproterozoic Era - A shift from 1.88 Ga calc-alkaline to 1.86 Ga high-Nb and adakite-like magmatism in central Fennoscandian Shield |
author_facet |
Lahaye Yann Heinonen Jussi S. Huhma Hannu O'Brien Hugh Väisänen Markku Kara Jaakko |
author_sort |
Lahaye Yann |
title |
Tracing arclogites in the Paleoproterozoic Era - A shift from 1.88 Ga calc-alkaline to 1.86 Ga high-Nb and adakite-like magmatism in central Fennoscandian Shield |
title_short |
Tracing arclogites in the Paleoproterozoic Era - A shift from 1.88 Ga calc-alkaline to 1.86 Ga high-Nb and adakite-like magmatism in central Fennoscandian Shield |
title_full |
Tracing arclogites in the Paleoproterozoic Era - A shift from 1.88 Ga calc-alkaline to 1.86 Ga high-Nb and adakite-like magmatism in central Fennoscandian Shield |
title_fullStr |
Tracing arclogites in the Paleoproterozoic Era - A shift from 1.88 Ga calc-alkaline to 1.86 Ga high-Nb and adakite-like magmatism in central Fennoscandian Shield |
title_full_unstemmed |
Tracing arclogites in the Paleoproterozoic Era - A shift from 1.88 Ga calc-alkaline to 1.86 Ga high-Nb and adakite-like magmatism in central Fennoscandian Shield |
title_sort |
tracing arclogites in the paleoproterozoic era - a shift from 1.88 ga calc-alkaline to 1.86 ga high-nb and adakite-like magmatism in central fennoscandian shield |
publisher |
ELSEVIER |
publishDate |
2022 |
url |
https://www.utupub.fi/handle/10024/171515 |
genre |
Fennoscandian |
genre_facet |
Fennoscandian |
op_relation |
372 ARTN 105663 10.1016/j.lithos.2020.105663 Lithos https://www.utupub.fi/handle/10024/171515 URN:NBN:fi-fe2021042826671 1872-6143 0024-4937 |
_version_ |
1765998564872290304 |