Paleomagnetic results from the Cambrian and Ordovician sediments of Bornholm (Denmark) and Southern Sweden and paleogeographical implications for Baltica

Abstract

[1] If apparent polar wander paths (APWP) cross, the question arises how to prove the older magnetization to be primary and not just a younger overprint. This problem is typically met in areas affected by percolating mineralizing fluids and/or heating due to a younger regional igneous activity. The Permian magnetic overprint is the classical example. Earlier paleomagnetic studies over the Lowermost Cambrian Nekso Sandstone Fm (NSF) of Bornholm (Denmark) yielded a characteristic remanent magnetization (ChRM) similar to the Permian directions for Baltica. Since a possible reason could be a chemical overprint, we checked whether this phenomenon did take place on a regional scale. Some samples therefore were collected from other Lower Cambrian clastics of Bornholm and Southern Scandinavia. In result we show that the well-grouped and stable ChRM of the NSF contrasts with fairly chaotic, soft, and badly preserved magnetizations of the Balka, Hardeberga, Mickwitzia, and Lingulid sandstones of Bornholm and Southern Sweden, thus not indicating widespread paleomagnetic overprint. We demonstrate that the ChRM of the NSF is most probably of syndepositional/early diagenetic origin and its similarity to the Permian direction for Baltica is only casual. We propose a normal polarity and a near-equatorial position on the Southern Hemisphere for Baltica in the early Cambrian time, as well as a more complicated trend of the APWP for this paleocontinent than envisaged by other authors. Paleomagnetic results from the Arenigian limestones of the Laesaa Formation (Bornholm) that yield excellently defined but most probably only secondary components are also presented.

Ediacaran–Cambrian paleogeography of Baltica: A paleomagnetic view from a diamond pit on the White Sea east coast

“…A pole from the early Cambrian Nexø Sandstone in Denmark (ca. 540 Ma; Lewandowski and Abrahamsen, 2003) yields a lower latitude position (~20°) for Baltica, albeit higher than our results. Our new datum places the study location near the equator (2° ± 3°, S or N).…”

“…6), whereas the Brusov pole is unique. If the assumption of the secondary origin of the Cambrian Andrarum and Tornetrask and Nexø results (Torsvik and Rehnström, 2001;Lewandowski and Abrahamsen, 2003) is accepted, the Ediacaran-Cambrian paleogeographic evolution of the circum-North Atlantic region needs to be substantially revised. The high-latitude position of Baltica in the early Ediacaran (616 Ma) is based on a single pole from the Egersund dikes .…”

Chapter 6 Phanerozoic palaeoenvironment and palaeolithofacies maps of the Arctic region

“…Stratified argillaceous and calcareous sediments up to 180 m thick were accumulated in the central part of the basin. Carbonates dominated in the deposits of the Baltic republics and Scandinavia (Jaanusson 1973;Kaljo et al 1988;Zdanavi˘ciuté & Bojesen-Koefoed 1997;Puura et al 1999;Tuuling & Flodén 2000;Lewandowski & Abrahamsen 2002;Ainsaar et al 2004;Modliński et al 2007;Pedersen et al 2007;Raudsep 2008). Subsidence of the Peri-Urals zone continued along the entire eastern margin of the craton.…”

Fifty Years of Palaeomagnetic Studies in the Institute of Geophysics, Polish Academy of Sciences

“…performed together with the French group from the University of Lille (France) were presented in several articles Lamarche et al 2003;Lamarche et al 2002;Lacquement et al 2005). In the same years together with scientist from Denmark he studied origin of natural magnetic remanence of Cambrian sandstones from Nexø (Lewandowski and Abrahamsen 2003). His scientific interests were focused on Pangaea applying palaeomagnetic and palaeoclimatic data for revealing its history (Lewandowski 2003, Fig.…”