Apparent partial loss age spectra of Neoarchean hornblende (Murmansk Terrane, Kola Peninsula, Russia): the role of biotite inclusions revealed by 40 Ar/ 39 Ar laserprobe analysis
Abstract Metamorphic hornblende frequently yields spectra with progressively increasing 40 Ar/ 39 Ar age steps, often interpreted as caused by partial resetting due to thermally activated radiogenic argon loss by solid‐state diffusion. Yet, in many cases rising Ca/K ratio spectra for such samples im...
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crwiley:10.1111/j.1365-3121.2006.00699.x 2024-06-02T08:09:56+00:00 Apparent partial loss age spectra of Neoarchean hornblende (Murmansk Terrane, Kola Peninsula, Russia): the role of biotite inclusions revealed by 40 Ar/ 39 Ar laserprobe analysis De Jong, Koen Wijbrans, Jan R. 2006 http://dx.doi.org/10.1111/j.1365-3121.2006.00699.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-3121.2006.00699.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3121.2006.00699.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Terra Nova volume 18, issue 5, page 353-364 ISSN 0954-4879 1365-3121 journal-article 2006 crwiley https://doi.org/10.1111/j.1365-3121.2006.00699.x 2024-05-03T11:11:39Z Abstract Metamorphic hornblende frequently yields spectra with progressively increasing 40 Ar/ 39 Ar age steps, often interpreted as caused by partial resetting due to thermally activated radiogenic argon loss by solid‐state diffusion. Yet, in many cases rising Ca/K ratio spectra for such samples imply the presence of minor inclusions of K‐contaminant minerals. To avoid parts of grains with mineral inclusions or compositional zoning we drilled tiny discs from thin sections under a petrographic microscope. Laser step‐heating of drilled biotite‐free hornblende discs yielded flat age and ratio spectra. In contrast, furnace step‐heated hornblende separates from the same samples produced apparent loss age spectra. Moreover, biotite‐free samples yielded flat spectra by laser and furnace dating. Consequently, apparent loss spectra result from degassing of included substantially younger biotite before its hornblende host during laboratory step‐heating; c. 2640 Ma hornblende ages constrain the Murmansk Terrane's cooling. Article in Journal/Newspaper kola peninsula Wiley Online Library Kola Peninsula Murmansk Terra Nova 18 5 353 364 |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract Metamorphic hornblende frequently yields spectra with progressively increasing 40 Ar/ 39 Ar age steps, often interpreted as caused by partial resetting due to thermally activated radiogenic argon loss by solid‐state diffusion. Yet, in many cases rising Ca/K ratio spectra for such samples imply the presence of minor inclusions of K‐contaminant minerals. To avoid parts of grains with mineral inclusions or compositional zoning we drilled tiny discs from thin sections under a petrographic microscope. Laser step‐heating of drilled biotite‐free hornblende discs yielded flat age and ratio spectra. In contrast, furnace step‐heated hornblende separates from the same samples produced apparent loss age spectra. Moreover, biotite‐free samples yielded flat spectra by laser and furnace dating. Consequently, apparent loss spectra result from degassing of included substantially younger biotite before its hornblende host during laboratory step‐heating; c. 2640 Ma hornblende ages constrain the Murmansk Terrane's cooling. |
format |
Article in Journal/Newspaper |
author |
De Jong, Koen Wijbrans, Jan R. |
spellingShingle |
De Jong, Koen Wijbrans, Jan R. Apparent partial loss age spectra of Neoarchean hornblende (Murmansk Terrane, Kola Peninsula, Russia): the role of biotite inclusions revealed by 40 Ar/ 39 Ar laserprobe analysis |
author_facet |
De Jong, Koen Wijbrans, Jan R. |
author_sort |
De Jong, Koen |
title |
Apparent partial loss age spectra of Neoarchean hornblende (Murmansk Terrane, Kola Peninsula, Russia): the role of biotite inclusions revealed by 40 Ar/ 39 Ar laserprobe analysis |
title_short |
Apparent partial loss age spectra of Neoarchean hornblende (Murmansk Terrane, Kola Peninsula, Russia): the role of biotite inclusions revealed by 40 Ar/ 39 Ar laserprobe analysis |
title_full |
Apparent partial loss age spectra of Neoarchean hornblende (Murmansk Terrane, Kola Peninsula, Russia): the role of biotite inclusions revealed by 40 Ar/ 39 Ar laserprobe analysis |
title_fullStr |
Apparent partial loss age spectra of Neoarchean hornblende (Murmansk Terrane, Kola Peninsula, Russia): the role of biotite inclusions revealed by 40 Ar/ 39 Ar laserprobe analysis |
title_full_unstemmed |
Apparent partial loss age spectra of Neoarchean hornblende (Murmansk Terrane, Kola Peninsula, Russia): the role of biotite inclusions revealed by 40 Ar/ 39 Ar laserprobe analysis |
title_sort |
apparent partial loss age spectra of neoarchean hornblende (murmansk terrane, kola peninsula, russia): the role of biotite inclusions revealed by 40 ar/ 39 ar laserprobe analysis |
publisher |
Wiley |
publishDate |
2006 |
url |
http://dx.doi.org/10.1111/j.1365-3121.2006.00699.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-3121.2006.00699.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3121.2006.00699.x |
geographic |
Kola Peninsula Murmansk |
geographic_facet |
Kola Peninsula Murmansk |
genre |
kola peninsula |
genre_facet |
kola peninsula |
op_source |
Terra Nova volume 18, issue 5, page 353-364 ISSN 0954-4879 1365-3121 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/j.1365-3121.2006.00699.x |
container_title |
Terra Nova |
container_volume |
18 |
container_issue |
5 |
container_start_page |
353 |
op_container_end_page |
364 |
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1800755721958064128 |