Paleomagnetic and rock magnetic study of the Mesoproterozoic sill, Valaam island, Russian Karelia

A paleomagnetic study of the Mesoproterozoic Valaam monzodioritic sill (U-Pb age ∼1458 Ma) was undertaken in an attempt to provide a new well dated paleomagnetic pole for Baltica and to test the proposed joint drift history of Baltica and Laurentia from 1.83 to ca. 1.26 Ga. Two components of natural remanent magnetization (NRM) were isolated in the sill with alternating field and thermal treatments. The first component is a low coercivity component of viscous origin with a direction similar to that of the Earth's present field at the sampling site. The second one (component A) with a high unblocking temperature/coercivity has a remanent magnetization direction of D = 43.4°, I = −14.3°, α95 = 3.3°, corresponding to a paleomagnetic pole of Plat. = 13.8°, Plong. = 166.4°, A95 = 2.4°.Rock magnetic and scanning electron microscopy (SEM) studies revealed that the main carrier of the magnetization A is medium sized primary titanomagnetite, with varying Ti-content. This component is interpreted to be of primary origin and it provides a new well dated (1458 +4/−3 Ma) pole for Baltica. This result supports the idea that Baltica and Laurentia drifted together during the interval from 1.76 to 1.26 Ga forming the core of the supercontinent Hudsonland (Columbia, Nuna).