Palaeomagnetic investigations across Hinlopenstretet border zone: from Caledonian metamorphosed rocks of Ny Friesland to foreland facies of Nordaustlandet (NE Svalbard)
Posted on 04.08.2022 - 14:54
Abstract: New demagnetization results of 286 palaeomagnetic specimens from 15 sites in Neoproterozoic – Lower Palaeozoic sequences of Ny Friesland - Nordaustlandet (the Caledonian Eastern Svalbard Terrane) are presented. New in situ 40Ar/39Ar Uv-MS age determinations on amphibolites and mylonites from the Ny Friesland cluster in the 340–460 Ma interval correspond broadly to the Caledonian thermal event. Older ages are observed but are more scattered and likely reflect partial resetting/argon gain of Proterozoic micas. Palaeomagnetic, petrological and structural data confirm a west to east decrease in the degree of the Caledonian metamorphism and remagnetization across Hinlopenstretet, which is interpreted here to coincide with the limit of Caledonian east-directed over-thrusting. No pre-Caledonian palaeomagnetic record was identified in investigated amphibolites and metacarbonates of Ny Friesland. Pre-folding pre-Caledonian, potentially Neoproterozoic (primary ?) magnetization was recognized only in non-metamorphosed Murchisonfjorden (Nordaustlandet) carbonates. However, selective palaeomagnetic palaeopoles from Murchisonfjorden also fall into Caledonian sensu lato and Mesozoic sectors of Laurussia reference path. This also indicates that regions east of Hinlopenstretet and east of the Caledonian front could be partially subjected to Caledonian remagnetization. Mesozoic palaeomagnetic overprints are potentially related to the injection of Mesozoic dolerites in Eastern Svalbard. Here, we discuss two concepts of post-Caledonian rotations that could affect the palaeomagnetic record of the Eastern Svalbard Terrane - rotations around vertical axes related to strike-slip faults and rotations around horizontal axes related to normal listric faults that originated during the extension in Devonian Basin and the opening of Atlantic and Arctic Oceans.
CITE THIS COLLECTION
Michalski, Krzysztof; Manby, Geoffrey M.; Nejbert, Krzysztof; Domańska-Siuda, Justyna; Burzyński, Mariusz (2022): Palaeomagnetic investigations across Hinlopenstretet border zone: from Caledonian metamorphosed rocks of Ny Friesland to foreland facies of Nordaustlandet (NE Svalbard). Geological Society of London. Collection. https://doi.org/10.6084/m9.figshare.c.6132018.v2
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ORCID FOR SUBMITTING AUTHOR(s)
Geoffrey M. Manby
structural data confirmms age determinationslaurussia reference pathinterval correspond broadlydiscuss two concepts340 – 460sensu lato </selective palaeomagnetic palaeopolesnormal listric faults286 palaeomagnetic specimenscaledonian thermal event40 </ sup39 </ supny friesland clusternew demagnetization resultsmurchisonfjorden also fallar /< supmesozoic palaeomagnetic overprintseastern svalbard terranecaledonian metamorphosed rockscaledonian front couldremagnetization across hinlopenstretetcaledonian palaeomagnetic recordpalaeomagnetic recordny frieslandmetamorphosed murchisonfjordeneastern svalbardcaledonian remagnetizationsitu </slip faultscould affectar uvalso indicatesne svalbardmesozoic sectorsmesozoic doleritescaledonian rotationscaledonian metamorphismcaledonian eastproterozoic micasprimary ?)potentially relatedpotentially neoproterozoicpartially subjectedolder agesforeland faciesdevonian basinargon gainarctic oceans15 sites