caa a22 4500 386401837 CHVBK 20180307112202.0 cr unu---uuuuu 161130e198909 xx s 000 0 eng 10.1017/S001675680002286X doi S001675680002286X pii (NATIONALLICENCE)cambridge-10.1017/S001675680002286X Dallmeyer R. D. Department of Geology, University of Georgia, Athens, Georgia 30602, U.S.A. Partial thermal resetting of 40Ar/39Ar mineral ages in western Spitsbergen, Svalbard: possible evidence for Tertiary metamorphism [Elektronische Daten] [R. D. Dallmeyer] Hornblende and muscovite within high-grade Caledonian metamorphic rocks exposed in Albert I Land (northwest Spitsbergen) display internally concordant 40Ar/39Ar 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 40Ar/39Ar 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. Copyright © Cambridge University Press 1989 Geological Magazine Cambridge University Press 126/5(1989-09), 587-593 0016-7568 126:5<587 1989 126 GEO https://doi.org/10.1017/S001675680002286X text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S001675680002286X text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Dallmeyer R. D. Department of Geology, University of Georgia, Athens, Georgia 30602, U.S.A NATIONALLICENCE 773 0- Geological Magazine Cambridge University Press 126/5(1989-09), 587-593 0016-7568 126:5<587 1989 126 GEO CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge