Abstract: We present new results of geochronological, rock magnetic, paleomagnetic and paleointensity studies of the olivine gabbro dyke located at the northern part of the Murmansk craton, NE Fennoscandia (the Kola Peninsula). According to its geochemistry, petrographic and geochronology features, the dyke belongs to the 2.68 Ga dyke swarm, as confirmed by Sm-Nd mineral isochron. We find a significant difference in the rock magnetic and paleomagnetic characteristics of the central and marginal parts of the dyke, which is independently supported by petrography and geochemistry. It is shown that the rocks of the central part of the dyke retained not only their primary mineral composition, but also the primary component of the natural remanent magnetization. We use its direction to determine the 2.68 Ga virtual geomagnetic pole for the Murmansk craton: Slat = 68.64292° N, Slong = 37.7945° E, N = 41 specimens, Plat = –73.5°, Plong = 138.9°, dp/dm = 3.2°/3.4°, paleolat = –65.9°. We also obtain reliable estimates (17 samples) of the Earth’s magnetic field intensity at ca. 2.68 Ga: VDM value is found to be 1.85 × 1022 A m2 corresponding to the geomagnetic field several times weaker than the present-day field. © Pleiades Publishing, Ltd. 2024. ISSN 1069-3513, Izvestiya, Physics of the Solid Earth, 2024, Vol. 60, No. 4, pp. 772–794. Pleiades Publishing, Ltd., 2024.
Original languageEnglish
Pages (from-to)772-794
Number of pages23
JournalIzvestiya, Physics of the Solid Earth
Volume60
Issue number4
DOIs
StatePublished - 1 Aug 2024

    Research areas

  • dyke, Fennoscandian Shield, geochronology, Murmansk craton, Neoarchean, paleointensity, paleomagnetism, rock magnetism

ID: 126219970