SALMINEN, Johanna1, MERTANEN, Satu
2, EVANS, David A.D.
3, and KLEIN, Robert
1, (1) Physical Sciences, Division of Geophysics, University of Helsinki, PO Box 64, 00014 University of Helsinki, Helsinki, 00014, Finland, johanna.m.salminen@helsinki.fi, (2) Geological Survey of Finland, P.O. Box 96, Espoo, FI-02151, Finland, (3) Department of Geology and Geophysics, Yale University, New Haven CT 06520-8109, USA, New Haven, CT 06520
Paleoproterozoic supercontinent Nuna (Columbia, Hudsonland) has been proposed by several authors [e.g. 1, 2, 3]. Many recent reconstructions of this supercontinent support, within the analytical uncertainties, that the core of Nuna was formed by a single NENA (Northern Europe – North America) juxtaposition between Baltica and Laurentia between ca. 1.75 Ga and ca. 1.27 Ga [4, 5, 6]. However, recent paleomagnetic data from ca. 1.63 Ga Melville Bugt dykes in Greenland does not support that fit [7]. To address these concerns, we present new paleomagnetic data from Late Mesoproterozoic diabase dyke swarms (Satakunta: 1565 Ma and Åland: 1577-1540 Ma) and from Mesoproterozoic Satakunta sandstone located in SW Finland. A dual-polarity, high-stability remanence component from the dated 1565 Ma Satakunta dyke swarm with the paleopole of Plat=29.3°N, Plon=188.1°E (A95 = 6.6°), is confirmed to be primary by positive baked-contact tests, and suggests that NENA was valid also at 1.63-1.54 Ga [8, 9]. Comparable paleopole (Plat=26.8°N, Plon=173.5°E; A95 = 5.7°) from the ca. 1.6 Ga Satakunta sandstone gives support to this result.
[1] Williams et al. 1991. Tectonophysics 187, 117–134. [2] Hoffman 1996. In: Van der Pluijm, B. A. & Marshak, S. (eds.) Earth Structure: an Introduction to Structural Geology and Tectonics. McGraw-Hill, New York, 459–464. [3] Pesonen et al. 2003. Tectonophysics 375, 289-324. [4] Salminen & Pesonen 2007. Precambrian Res. 159, 212-230. [5] Pisarevsky & Bylund 2010. Am. J. Sci. 310, 1168-1186. [6] Evans & Mitchell 2011. Geology 39, 443-446. [10] Salminen et al. 2009. In: Reddy et al (eds.), Palaeoproterozoic Supercontinents and Global Evolution. Geol. Soc. Lond. Spec. Publ. 323, 199-217. [7] Halls et al. 2011. In Dyke Swarms: Keys for Geodynamic Interpretation. Ed. R.K. Srivastava, Pub. Springer-Verlag, Berlin, p.605, Chapter 27, pp. 509-535. [8] Salminen et al. 2013. Precambrian Res. submitted. [19] Klein et al. 2013. Precambrian Res. submitted.
Tectonics, Geophysics/Tectonophysics/Seismology, Structural Geology
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