Single-zircon Pb-evaporation and 40Ar/39Ar dating of the metamorphic and granitic rocks in north-west Spitsbergen
North-west Spitsbergen consists of a complex of Caledonian and Grenvillian crystalline rocks, situated at the north-west corner of the Barents Shelf. The aim of this study is to understand the extent of pre-Caledonian basement rocks and their protoliths. Micas and zircon grains from six rocks from n...
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Norwegian Polar Institute
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ftjpolarres:oai:journals.openacademia.net:article/2131 2023-05-15T18:02:40+02:00 Single-zircon Pb-evaporation and 40Ar/39Ar dating of the metamorphic and granitic rocks in north-west Spitsbergen Ohta, Yoshihide Larionov, Alexander N. Tebenkov, Alexander M. Lepvrier, Claude Maluski, Henri Lange, Michael Hellebrandt, Barbara 2002-01-06 application/pdf https://polarresearch.net/index.php/polar/article/view/2131 https://doi.org/10.3402/polar.v21i1.6475 eng eng Norwegian Polar Institute https://polarresearch.net/index.php/polar/article/view/2131/5382 https://polarresearch.net/index.php/polar/article/view/2131 doi:10.3402/polar.v21i1.6475 Copyright (c) 2018 Polar Research Polar Research; Vol. 21 No. 1 (2002); 73-89 1751-8369 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2002 ftjpolarres https://doi.org/10.3402/polar.v21i1.6475 2021-11-11T19:12:09Z North-west Spitsbergen consists of a complex of Caledonian and Grenvillian crystalline rocks, situated at the north-west corner of the Barents Shelf. The aim of this study is to understand the extent of pre-Caledonian basement rocks and their protoliths. Micas and zircon grains from six rocks from north-west Spitsbergen have been dated by the 40Ar/39Ar and single-zircon Pb-evaporation methods. Two grey granites yielded Late Caledonian mica 40Ar/39Ar and zircon ages of ca. 420-430 My, with inherited zircon grains as old as 1725 My. Zircon grains from a gneissose granite xenolith in a grey granites gave crystallization ages of ca. 960 My; some grains from a migmatite neosome show similar ages. Zircon grains yielding Archean and late Palaeoproterozoic ages (1600-1800 My) are interpreted as xenocrysts of detrital origin. The youngest ages obtained from detrital zircon grains from a greenschist facies quartzite of the Signehamna unit are ca. 1800 My. Similar schists are included as xenoliths in the 960 My old gneissose granite; therefore, the sedimentary protoliths of the unit are Mesoproterozoic. The dating results suggest a significant tectonothermal event during Grenvillian time; subsequent Caledonian events had less extensive thermal effects. However, it is still a matter of debate whether Grenvillian or Caledonian metamorphism produced the majority of the migmatites. A large population of zircon grains with Late Palaeoproterozoic ages suggests a wide surface exposure of rocks of this age in the source area, with some Archean zircons. Article in Journal/Newspaper Polar Research Spitsbergen Polar Research (E-Journal) Signehamna ENVELOPE(11.533,11.533,79.283,79.283) Polar Research 21 1 73 89 |
institution |
Open Polar |
collection |
Polar Research (E-Journal) |
op_collection_id |
ftjpolarres |
language |
English |
description |
North-west Spitsbergen consists of a complex of Caledonian and Grenvillian crystalline rocks, situated at the north-west corner of the Barents Shelf. The aim of this study is to understand the extent of pre-Caledonian basement rocks and their protoliths. Micas and zircon grains from six rocks from north-west Spitsbergen have been dated by the 40Ar/39Ar and single-zircon Pb-evaporation methods. Two grey granites yielded Late Caledonian mica 40Ar/39Ar and zircon ages of ca. 420-430 My, with inherited zircon grains as old as 1725 My. Zircon grains from a gneissose granite xenolith in a grey granites gave crystallization ages of ca. 960 My; some grains from a migmatite neosome show similar ages. Zircon grains yielding Archean and late Palaeoproterozoic ages (1600-1800 My) are interpreted as xenocrysts of detrital origin. The youngest ages obtained from detrital zircon grains from a greenschist facies quartzite of the Signehamna unit are ca. 1800 My. Similar schists are included as xenoliths in the 960 My old gneissose granite; therefore, the sedimentary protoliths of the unit are Mesoproterozoic. The dating results suggest a significant tectonothermal event during Grenvillian time; subsequent Caledonian events had less extensive thermal effects. However, it is still a matter of debate whether Grenvillian or Caledonian metamorphism produced the majority of the migmatites. A large population of zircon grains with Late Palaeoproterozoic ages suggests a wide surface exposure of rocks of this age in the source area, with some Archean zircons. |
format |
Article in Journal/Newspaper |
author |
Ohta, Yoshihide Larionov, Alexander N. Tebenkov, Alexander M. Lepvrier, Claude Maluski, Henri Lange, Michael Hellebrandt, Barbara |
spellingShingle |
Ohta, Yoshihide Larionov, Alexander N. Tebenkov, Alexander M. Lepvrier, Claude Maluski, Henri Lange, Michael Hellebrandt, Barbara Single-zircon Pb-evaporation and 40Ar/39Ar dating of the metamorphic and granitic rocks in north-west Spitsbergen |
author_facet |
Ohta, Yoshihide Larionov, Alexander N. Tebenkov, Alexander M. Lepvrier, Claude Maluski, Henri Lange, Michael Hellebrandt, Barbara |
author_sort |
Ohta, Yoshihide |
title |
Single-zircon Pb-evaporation and 40Ar/39Ar dating of the metamorphic and granitic rocks in north-west Spitsbergen |
title_short |
Single-zircon Pb-evaporation and 40Ar/39Ar dating of the metamorphic and granitic rocks in north-west Spitsbergen |
title_full |
Single-zircon Pb-evaporation and 40Ar/39Ar dating of the metamorphic and granitic rocks in north-west Spitsbergen |
title_fullStr |
Single-zircon Pb-evaporation and 40Ar/39Ar dating of the metamorphic and granitic rocks in north-west Spitsbergen |
title_full_unstemmed |
Single-zircon Pb-evaporation and 40Ar/39Ar dating of the metamorphic and granitic rocks in north-west Spitsbergen |
title_sort |
single-zircon pb-evaporation and 40ar/39ar dating of the metamorphic and granitic rocks in north-west spitsbergen |
publisher |
Norwegian Polar Institute |
publishDate |
2002 |
url |
https://polarresearch.net/index.php/polar/article/view/2131 https://doi.org/10.3402/polar.v21i1.6475 |
long_lat |
ENVELOPE(11.533,11.533,79.283,79.283) |
geographic |
Signehamna |
geographic_facet |
Signehamna |
genre |
Polar Research Spitsbergen |
genre_facet |
Polar Research Spitsbergen |
op_source |
Polar Research; Vol. 21 No. 1 (2002); 73-89 1751-8369 |
op_relation |
https://polarresearch.net/index.php/polar/article/view/2131/5382 https://polarresearch.net/index.php/polar/article/view/2131 doi:10.3402/polar.v21i1.6475 |
op_rights |
Copyright (c) 2018 Polar Research |
op_doi |
https://doi.org/10.3402/polar.v21i1.6475 |
container_title |
Polar Research |
container_volume |
21 |
container_issue |
1 |
container_start_page |
73 |
op_container_end_page |
89 |
_version_ |
1766173098330030080 |