Geology of the southern part of the Kautokeino Greenstone Belt: Rb-Sr geochronology and geochemistry of associated gneisses and late intrusions.
The southern part of the Kautokeino Greenstone Belt is divided into four volcanic formations separated by sedimentary units. The formation represent a development from Archaean komatiitic sequences to Middle Proterozoic possible rift-forming environemnts. The earliest volcanism is represented by bas...
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ftnorgesgu:oai:openarchive.ngu.no:11250/2674243 2023-05-15T17:01:46+02:00 Geology of the southern part of the Kautokeino Greenstone Belt: Rb-Sr geochronology and geochemistry of associated gneisses and late intrusions. Olsen, Karl Inge Nilsen, Kjell S. 1985 application/pdf https://hdl.handle.net/11250/2674243 eng eng NGU Bulletin (403) https://hdl.handle.net/11250/2674243 Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no CC-BY 131-160 DATERING GRANITT GRØNNSTEIN OMDANNING PREKAMBRIUM Journal article 1985 ftnorgesgu 2022-07-03T15:26:48Z The southern part of the Kautokeino Greenstone Belt is divided into four volcanic formations separated by sedimentary units. The formation represent a development from Archaean komatiitic sequences to Middle Proterozoic possible rift-forming environemnts. The earliest volcanism is represented by basaltic komatiitic enclaves within the eastern gneiss complex, and may be equivalent to parts of the lowermost formation within the greenstone belt. The latter consists of up to 50% basaltic to peridotitic komatiites (12-30% MgO) and was probably deposited after the formation of the gneiss complex. The tonalitic-trondhjemitic gneisses arc dated to 3.0+-0.2 b.y. and represent primary magmas reulting from the crust-forming events at that time. They are similar in age and composition to gneisses in East and North Finland. The late plutonic complexes are ca. 1700 m.y.old and may be the Middle Proterozoic counterparts to the Archaean gneisses. Regional metamorphism within the belt reached middle to high amphibolite facies and occurred ca. 1950 m.y. ago on the basis of Rb-Sr radiometric dating on metasediments and amphibolites. Granitic gneisses southwest of the main greenstone belt are very uniform geochemically and represent products of differentiation. Widespread and intensive brecciation, shearing and carbonatization are later than the main deformation and metamorphism, and may be associated with faulting and block movements in connection with possible rift tectonics. 36186 Article in Journal/Newspaper Kautokeino North Finland NGU Open Archive (Geological Survey of Norway) Kautokeino ENVELOPE(23.048,23.048,69.003,69.003) |
institution |
Open Polar |
collection |
NGU Open Archive (Geological Survey of Norway) |
op_collection_id |
ftnorgesgu |
language |
English |
topic |
DATERING GRANITT GRØNNSTEIN OMDANNING PREKAMBRIUM |
spellingShingle |
DATERING GRANITT GRØNNSTEIN OMDANNING PREKAMBRIUM Olsen, Karl Inge Nilsen, Kjell S. Geology of the southern part of the Kautokeino Greenstone Belt: Rb-Sr geochronology and geochemistry of associated gneisses and late intrusions. |
topic_facet |
DATERING GRANITT GRØNNSTEIN OMDANNING PREKAMBRIUM |
description |
The southern part of the Kautokeino Greenstone Belt is divided into four volcanic formations separated by sedimentary units. The formation represent a development from Archaean komatiitic sequences to Middle Proterozoic possible rift-forming environemnts. The earliest volcanism is represented by basaltic komatiitic enclaves within the eastern gneiss complex, and may be equivalent to parts of the lowermost formation within the greenstone belt. The latter consists of up to 50% basaltic to peridotitic komatiites (12-30% MgO) and was probably deposited after the formation of the gneiss complex. The tonalitic-trondhjemitic gneisses arc dated to 3.0+-0.2 b.y. and represent primary magmas reulting from the crust-forming events at that time. They are similar in age and composition to gneisses in East and North Finland. The late plutonic complexes are ca. 1700 m.y.old and may be the Middle Proterozoic counterparts to the Archaean gneisses. Regional metamorphism within the belt reached middle to high amphibolite facies and occurred ca. 1950 m.y. ago on the basis of Rb-Sr radiometric dating on metasediments and amphibolites. Granitic gneisses southwest of the main greenstone belt are very uniform geochemically and represent products of differentiation. Widespread and intensive brecciation, shearing and carbonatization are later than the main deformation and metamorphism, and may be associated with faulting and block movements in connection with possible rift tectonics. 36186 |
format |
Article in Journal/Newspaper |
author |
Olsen, Karl Inge Nilsen, Kjell S. |
author_facet |
Olsen, Karl Inge Nilsen, Kjell S. |
author_sort |
Olsen, Karl Inge |
title |
Geology of the southern part of the Kautokeino Greenstone Belt: Rb-Sr geochronology and geochemistry of associated gneisses and late intrusions. |
title_short |
Geology of the southern part of the Kautokeino Greenstone Belt: Rb-Sr geochronology and geochemistry of associated gneisses and late intrusions. |
title_full |
Geology of the southern part of the Kautokeino Greenstone Belt: Rb-Sr geochronology and geochemistry of associated gneisses and late intrusions. |
title_fullStr |
Geology of the southern part of the Kautokeino Greenstone Belt: Rb-Sr geochronology and geochemistry of associated gneisses and late intrusions. |
title_full_unstemmed |
Geology of the southern part of the Kautokeino Greenstone Belt: Rb-Sr geochronology and geochemistry of associated gneisses and late intrusions. |
title_sort |
geology of the southern part of the kautokeino greenstone belt: rb-sr geochronology and geochemistry of associated gneisses and late intrusions. |
publishDate |
1985 |
url |
https://hdl.handle.net/11250/2674243 |
long_lat |
ENVELOPE(23.048,23.048,69.003,69.003) |
geographic |
Kautokeino |
geographic_facet |
Kautokeino |
genre |
Kautokeino North Finland |
genre_facet |
Kautokeino North Finland |
op_source |
131-160 |
op_relation |
NGU Bulletin (403) https://hdl.handle.net/11250/2674243 |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no |
op_rightsnorm |
CC-BY |
_version_ |
1766054908159590400 |