A regional 1.92Ga tectonothermal episode in Ostrobothnia, Finland: Implications for models of Svecofennian accretion

Trans-Baltic Palaeoproterozoic correlations towards the reconstruction of supercontinent Columbia/Nuna

“…Seismically, Bergslagen has also been traced in the middle and lower crust beneath the Ljusdal domain farther north (Korja and Heikkinen, 2005). Andersson (1997), Andersson et al (2004), Bergman et al (2008), Beunk and Page (2001), Hermansson et al (2007Hermansson et al ( , 2008, Högdahl and Sjöström (2001), Högdahl et al (2004), Johansson et al (2006, Krzeminska et al (2009), Lahtinen andNironen (2010), Lahtinen et al (2002Lahtinen et al ( , 2009a, Mansfeld et al (2005), Rutland et al (2001Rutland et al ( , 2004, Stephens et al (2009), Sultan et al (2005, Wikström and Andersson (2004), Williams et al (2008Williams et al ( , 2009). Fe-S-Si indicates the presence of various iron-and sulfide ore deposits.…”

“…In order to explain the "equidimensional" patterns of the continental crust in the Svecofennian orogen, this model has recently been modified by involving orocline tectonics (Beunk and Kuipers, 2012), as well as rotations of primarily linear terranes and their "tectonic wrecks" (Lahtinen et al, 2014). (b) The other group of interpretations, which proposes marginal basin accretion governed by a master subduction zone, has been employed to explain, among other things, the wide distribution of similar populations of detrital zircon and basin formation in the northern and central parts of the Svecofennian orogen in Sweden and Finland at 2.1-1.98, 1.97-1.92, and 1.91-1.86 Ga, while short events of accretion and compression interrupted basin formation at 1.98, 1.92 and 1.88-1.86 Ga (Rutland et al, 2001(Rutland et al, , 2004Williams et al, 2008). A related model, named the "migratory tectonic switching", emphasizes the existence of cycles of alternating extension and compression during the development of the Svecofennian orogen in central Sweden and also elsewhere (Hermansson et al, 2008).…”

Synthesis of the Geological Evolution and Metallogeny of Finland

“…Based on in situ zircon analyses, the former concluded that there is a major unconformity in the Vammala area, where a migmatite complex metamorphosed at around 1920 Ma is overlain by rocks of the Tampere belt (refer to Fig. A similar unconformity was later established by Williams et al (2008) in the Himanka area, Pohjanmaa belt ( Fig. The supracrustal rocks of the migmatite complex contain partly Archean detritus and were likely deposited as far back as around 1970 Ma, being thus older than any of the PA rocks.…”

“…The oldest dated rocks are ~1930-1920 Ma gneissic tonalites and associated volcanic rocks in the PA, but based on isotopic studies, it has been proposed that there are still older, 2100-2000 Ma, buried microcontinents (e.g., Keitele) in the Svecofennian domain (Lahtinen et al, 2005). The age relationships have become more complex after publication of the dating results obtained by Rutland et al (2004) and Williams et al (2008). Based on in situ zircon analyses, the former concluded that there is a major unconformity in the Vammala area, where a migmatite complex metamorphosed at around 1920 Ma is overlain by rocks of the Tampere belt (refer to Fig.…”

Danopolonian migmatization of Mesoproterozoic sedimentary rocks in southernmost Sweden: a SIMS zircon study

“…Recently, secondary ion mass spectrometry (SIMS) methods have been applied extensively to Paleoproterozoic metasedimentary and metavolcanic sequences in the Svecofennian domain of the Baltic/Fennoscandian Shield in Finland (Kähkönen, 2005;Lahtinen et al 2010) and central Sweden (Claesson et al 1993;Andersson et al 2006;Sultan & Plink-Bjorklund 2006;Bergman et al 2008;Williams et al 2008). The results indicate that sedimentation was related to the overall accretionary evolution of the Svecofennian domain between c. 1.95 and 1.8 Ga, which involved the formation of continental margin, forearc and backarc basins.…”