Palaeomagnetism and magnetostratigraphy of the Permian and Triassic of Spitsbergen: a review of progress and challenges
AbstractPermian and Triassic sediments from Svalbard provide a testing ground for evaluating concepts about the polarity and configuration of the geomagnetic field during the Palaeozoic–Mesozoic transition. This review examines existing palaeomagnetic and magnetostratigraphic data, and also re-examines the issue of partial remagnetization of these sediments. Permian and Triassic palaeomagnetic poles from Spitsbergen demonstrate a close similarity to the stable Europe apparent polar wander path. Magnetostratigraphy from the Gipsdalen and Tempelfjorden groups demonstrates the dominance of reverse polarity (the Permo-Carboniferous Reverse Superchron), with evidence for three normal magnetozones of short duration, one of which may provide a useful marker near the base of the Permian. The other two normal magnetozones in the middle and lower parts of the Kapp Starostin Formation are most likely to represent equivalent magnetozones in the Wordian and Capitanian (mid- Permian). Magnetostratigraphy of the Lower Triassic up to the lowest parts of the Upper Triassic in central and western Spitsbergen provides greater chronostratigraphic detail than has been available hitherto from biostratigraphy alone. This demonstrates the scale of a number of suspected hiatuses, and also hints at improved chronostratigraphic correlations between east and west Spitsbergen. Upper Triassic sediments provide the best palaeomagnetic properties, indicating that future magnetostratigraphic studies in this interval may improve chronostratigraphic understanding of this poorly dated interval. A persistent partial remagnetization affecting both Permian and Triassic sediments is not of a single origin. It may be both a Brunhes-age viscous remanence and a Palaeogene heating/burial-induced magnetization, or a fluid flow related remagnetization locally in western Spitsbergen. The remagnetization is often composite (Cenozoic plus older) in nature.
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