Meinhold, G ORCID: https://orcid.org/0000-0001-8375-8375, Wemmer, K, Högström, AES, Ebbestad, JOR, Jensen, S, Palacios, T, Høyberget, M, Agić, H and Taylor, WL (2019) A late Caledonian tectono-thermal event in the Gaissa Nappe Complex, Arctic Norway: evidence from fine-fraction K‒Ar dating and illite crystallinity from the Digermulen Peninsula. GFF. (In Press)

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Abstract

Fine-fraction K‒Ar dating and illite crystallinity determination were applied on a peculiar pale olive green shale sample from the upper Ediacaran Indreelva Member (Stáhpogieddi Formation, Vestertana Group, Gaissa Nappe Complex) of the Digermulen Peninsula in Finnmark, Arctic Norway, to constrain the age and metamorphic conditions of tectono-thermal overprint. The <2 µm and <0.2 µm grain-size fractions are almost purely illite and yielded an illite crystallinity (expressed as the Kübler index) of 0.215 Δ° 2Θ and 0.228 Δ° 2Θ and K‒Ar ages of 403.9 ± 4.2 Ma and 391.5 ± 4.0 Ma, respectively. The K‒Ar ages are interpreted to present late-stage thermal overprint under low epizonal conditions along a localized shear zone, likely post-dating the peak of metamorphism and cleavage generation on the Digermulen Peninsula. Thus, a later tectono-metamorphic event related to the late stage of the Scandian orogeny is locally recorded in the Gaissa Nappe Complex of the Caledonides of Finnmark. This late Scandian event was probably caused by orogenic extensional collapse and appears to have extended at least into Mid-Devonian time.

Item Type: Article
Additional Information: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Taylor & Francis at http://doi.org/10.1080/11035897.2019.1583685 - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: Caledonides, Scandian orogeny, Finnmark, K‒Ar geochronology, Ediacaran, Devonian
Subjects: G Geography. Anthropology. Recreation > G Geography (General)
Divisions: Faculty of Natural Sciences > School of Geography, Geology and the Environment
Depositing User: Symplectic
Date Deposited: 14 Feb 2019 15:49
Last Modified: 14 Feb 2019 15:49
URI: http://eprints.keele.ac.uk/id/eprint/5841

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