Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geology
The Palaeoproterozoic Lapland granulite belt was juxtaposed between Archaean and Proterozoic terrains in the NE part of the Fennoscandian Shield concurrently with the accretion of Svecofennian arc complexes at ~1.9 Ga. The belt consists mainly of aluminous migmatitic metagreywackes. Abundant noritic...
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2006-06-01
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doaj-ad3e376baf9249eb91e962181364ac3a2020-11-25T00:02:24ZengGeological Society of FinlandBulletin of the Geological Society of Finland0367-52111799-46322006-06-017817110510.17741/bgsf/78.1.004Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geologyP. TuiskuP. MikkolaH. HuhmaThe Palaeoproterozoic Lapland granulite belt was juxtaposed between Archaean and Proterozoic terrains in the NE part of the Fennoscandian Shield concurrently with the accretion of Svecofennian arc complexes at ~1.9 Ga. The belt consists mainly of aluminous migmatitic metagreywackes. Abundant noritic to enderbitic magmas were intruded concordantly into the metasediments and were probably an important heat source for metamorphism, which took place during the crystallization of the magmas. This is supported by structural and contact relations of metasediments and igneous rocks, and by the lack progressive metamorphic reaction textures in the igneous rock series. The peak of metamorphism took place above the dehydration melting temperature of the biotite-sillimanite-plagioclase-quartz assemblage at 750 − 850 °C and 5 − 8.5 kbar which lead to formation of a restitic palaeosome and peraluminous granitic melt in metapelites. Subsequently, the rocks were decompressed and cooled below the wet melting temperature of pelitic rocks (650 °C) under the stability field of andalusite coexisting with potassium feldspar (2 − 3 kbar). Cooling was accompanied by the crystallization of the neosomes, often carrying aluminium-rich phases. Postmetamorphic duplexing of the LGB is clearly seen in the distribution of calculated PT conditions. http://www.geologinenseura.fi/bulletin/Volume78/tuisku.pdfgranulitesLapland Granulite Beltmigmatitesmetasedimentary rocksmetapeliteenderbitemineralogymetamorphismP-T conditionsPaleoproterozoicLapland ProvinceFinland |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
P. Tuisku P. Mikkola H. Huhma |
spellingShingle |
P. Tuisku P. Mikkola H. Huhma Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geology Bulletin of the Geological Society of Finland granulites Lapland Granulite Belt migmatites metasedimentary rocks metapelite enderbite mineralogy metamorphism P-T conditions Paleoproterozoic Lapland Province Finland |
author_facet |
P. Tuisku P. Mikkola H. Huhma |
author_sort |
P. Tuisku |
title |
Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geology |
title_short |
Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geology |
title_full |
Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geology |
title_fullStr |
Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geology |
title_full_unstemmed |
Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part I: Metamorphic geology |
title_sort |
evolution of migmatitic granulite complexes: implications from lapland granulite belt, part i: metamorphic geology |
publisher |
Geological Society of Finland |
series |
Bulletin of the Geological Society of Finland |
issn |
0367-5211 1799-4632 |
publishDate |
2006-06-01 |
description |
The Palaeoproterozoic Lapland granulite belt was juxtaposed between Archaean and Proterozoic terrains in the NE part of the Fennoscandian Shield concurrently with the accretion of Svecofennian arc complexes at ~1.9 Ga. The belt consists mainly of aluminous migmatitic metagreywackes. Abundant noritic to enderbitic magmas were intruded concordantly into the metasediments and were probably an important heat source for metamorphism, which took place during the crystallization of the magmas. This is supported by structural and contact relations of metasediments and igneous rocks, and by the lack progressive metamorphic reaction textures in the igneous rock series. The peak of metamorphism took place above the dehydration melting temperature of the biotite-sillimanite-plagioclase-quartz assemblage at 750 − 850 °C and 5 − 8.5 kbar which lead to formation of a restitic palaeosome and peraluminous granitic melt in metapelites. Subsequently, the rocks were decompressed and cooled below the wet melting temperature of pelitic rocks (650 °C) under the stability field of andalusite coexisting with potassium feldspar (2 − 3 kbar). Cooling was accompanied by the crystallization of the neosomes, often carrying aluminium-rich phases. Postmetamorphic duplexing of the LGB is clearly seen in the distribution of calculated PT conditions.
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topic |
granulites Lapland Granulite Belt migmatites metasedimentary rocks metapelite enderbite mineralogy metamorphism P-T conditions Paleoproterozoic Lapland Province Finland |
url |
http://www.geologinenseura.fi/bulletin/Volume78/tuisku.pdf |
work_keys_str_mv |
AT ptuisku evolutionofmigmatiticgranulitecomplexesimplicationsfromlaplandgranulitebeltpartimetamorphicgeology AT pmikkola evolutionofmigmatiticgranulitecomplexesimplicationsfromlaplandgranulitebeltpartimetamorphicgeology AT hhuhma evolutionofmigmatiticgranulitecomplexesimplicationsfromlaplandgranulitebeltpartimetamorphicgeology |
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