Partial thermal resetting of 40 Ar/ 39 Ar mineral ages in western Spitsbergen, Svalbard: possible evidence for Tertiary metamorphism
Abstract Hornblende and muscovite within high-grade Caledonian metamorphic rocks exposed in Albert I Land (northwest Spitsbergen) display internally concordant 40 Ar/ 39 Ar age spectra providing no record of any post-Silurian thermal history. Both minerals record 420−425 Ma plateau ages indicating t...
| Published in: | Geological Magazine |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
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Cambridge University Press (CUP)
1989
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| Online Access: | http://dx.doi.org/10.1017/s001675680002286x https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S001675680002286X |
| Summary: | Abstract Hornblende and muscovite within high-grade Caledonian metamorphic rocks exposed in Albert I Land (northwest Spitsbergen) display internally concordant 40 Ar/ 39 Ar age spectra providing no record of any post-Silurian thermal history. Both minerals record 420−425 Ma plateau ages indicating that relatively rapid cooling followed Silurian metamorphism. Muscovite within some metamorphic sequences exposed within the Tertiary tectonic zone of Oscar II Land (west-central Spitsbergen) displays a low-temperature 40 Ar/ 39 Ar age spectra discordance suggestive of a slight, post-Caledonian thermal disturbance. This is consistent with a post-Palaeozoic thermal overprint documented elsewhere in Oscar II Land and indicates that, at least locally, metamorphism may have accompanied the Tertiary orogeny. |
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