New palaeomagnetic results from the Oslo Graben, a Permian Superchron lava province

• Published in: Geophysical Journal International
• Main Authors: Haldan, M.M., Meijers, M.J.M., Langereis, C.G., Larsen, B.T., Heyer, H.
• Other Authors: Paleomagnetic Laboratory Fort Hoofddijk, Universiteit Utrecht / Utrecht University Utrecht, Department of Earth Sciences Minneapolis, University of Minnesota Twin Cities (UMN), University of Minnesota System (UMN)-University of Minnesota System (UMN), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UniCA)-Université Côte d'Azur (UniCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud ), Det Norske Oljeselskap, Fjordveien 27
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Geomagnetic Pole
• Online Access: https://hal.science/hal-01854921; https://hal.science/hal-01854921/document; https://hal.science/hal-01854921/file/ggu351.pdf; https://doi.org/10.1093/gji/ggu351

International audience We have performed an extended palaeomagnetic study of the Oslo Graben volcanics, compared to the study of half a century ago by van Everdingen, using modern techniques and a four times larger amount of sites, plus additional rock magnetic experiments. We conclude that the average direction (D = 204.0, I = −37.9, k = 46.9, α95 = 2.0) and associated palaeomagnetic pole (λ = 48.3, ϕ = 155.5, K = 52.2, A95 = 1.9) of the Krokskogen and Vestfold volcanics together are statistically identical to those of the earlier study. This gives confidence in the fact that older palaeomagnetic studies can be reliable and robust, even though methods have improved. Our larger number of samples, and better age constraints, enable us to separate the data into two major intervals: the younger, on average, Krokskogen area and the older Vestfold area. The results show firstly that palaeolatitudes are slightly higher than predicted by the latest apparent polar wander path (APWP) for Eurasia by Torsvik et al. These data support an early Permian Pangaea A configuration and do not necessitate a Pangaea B configuration.The larger data set also allows us to assess the distribution of the characteristic remanent magnetization directions of the Oslo Graben in terms of geomagnetic field behaviour, which were acquired during a long period of dominantly single polarity the Permo-Carboniferous Reversed Superchron (PCRS). The distributions show a significantly lower virtual geomagnetic pole (VGP) scatter at the observed (low) latitudes than expected from a compilation from lavas of the last 5 Myr. The data do however show excellent agreement with the scatter observed both during the Cretaceous Normal Superchron and the PCRS. A comparison of the directional distributions in terms of elongation is less discriminating, since the large errors in all cases allow a fit to the predicted elongation/inclination behaviour of the TK03.GAD model.