Palaeomagnetism of metacarbonates and fracture fills of Kongsfjorden islands (western Spitsbergen): Towards a better understanding of late- to post-Caledonian tectonic rotations

• Main Author: Krzysztof Michalski
• Format: Article in Journal/Newspaper
• Language: English
• Published: Polish Academy of Sciences 2018
• Subjects: arctic; svalbard; metamorphic caledonian basement; eurekan deformations; west spitsbergen thrust and fold belt; palaeomagnetism; Geology; QE1-996.5; Arctic; Blomstrandhalvøya; Lovénøyane; Svalbard; Kongsfjord*; Kongsfjorden; North Atlantic; Polar Research; Spitsbergen
• Online Access: https://doi.org/10.24425/118738; https://doaj.org/article/0c9b1dcb99d8402abadde0343f583746

A total number of 156 palaeomagnetic specimens of metacarbonates from 9 sites in Blomstrandhalvøya and Lovénøyane (Kongsfjorden, western Spitsbergen) and an additional 77 specimens of unmetamorphosed sediments infilling fractures (4 sites) within the Caledonian metamorphic basement of Blomstrandhalvøya were demagnetized. No relicts of pre-metamorphic magnetization were identified. The Natural Remanent Magnetization (NRM) pattern of metacarbonates is dominated by Caledonian (sensu lato) – Svalbardian and Late Mesozoic/Cenozoic secondary magnetic overprints carried by the pyrrhotite and magnetite/maghemite phases, respectively. The NRM of unmetamorphosed sediments infilling the karstic/tectonic fractures is dominated by hematite carrier. It revealed three stages of magnetization: Caledonian sensu lato, Carboniferous and Late Mesozoic/Cenozoic, which can be related to their initial fracturing, karstification and sedimentation or reactivation. As the majority of the palaeopoles calculated for the Kongsfjorden sites fit the 430 – 0 Ma sector of Laurussia reference path in an in situ orientation these results support the hypothesis that Blomstrandhalvøya and Lovénøyane escaped main Eurekan deformations. The potential rotation of the Kongsfjorden basement by any west dipping listric fault activity rotating the succession accompanying the opening of North Atlantic Ocean was not documented by the palaeomagnetic data presented here.