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Major tectonic processes illustrated with examples from the Geology of Norway

Major tectonic processes illustrated with examples from the Geology of Norway. Intro and overview of the Late Proterozoic to Permian tectonic evolution Baltica becomes a tectonic entity The margins of Baltica Early deformation along the Caledonian margin Ophiolites and island arcs

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Major tectonic processes illustrated with examples from the Geology of Norway

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  1. Major tectonic processesillustrated with examples fromthe Geology of Norway Intro and overview of the Late Proterozoic to Permian tectonic evolution Baltica becomes a tectonic entity The margins of Baltica Early deformation along the Caledonian margin Ophiolites and island arcs Towards continental collision and the Scandian orogeny Late to post-orogenic tectonic processes Late Palaeozoic continental rifting Start of a new Wilson cycle

  2. WHERE DO WE FIND EVIDENCE FOR EARLY-CALEDONIAN (PRE-SCANDIAN) TECTONIC EVENTS ALONG THE CALEDONIAN MARGIN OF BALTICA? 1 1) W- Finnmark/E-Troms (pre-490 Ma) 2) Central Sweden-Nordland (pre-490 Ma) 2 3) Otta-Foldal-Røros (pre-470 Ma) 4) Atløy (pre 450 Ma) 5) Jæren (?) 4 5 3 6) Cromite in Seds in foreland ca 470 6 The telescoped Caledonian margin of Baltica

  3. 608 ± 1 Ma Seiland Igneous Province 650Ma + 525Ma Otta Atløy From: Modified from Rehnström et al. 2002 From Svenningsen et al. 1993

  4. Well documented pre-Silurian orogenic event at ca 450 Ma W-Norway From: Andersen et al. 1990

  5. MAJOR EVENTS DOCUMENTED FROM BALTIC TERRANES (deformation/metamorphism in rocks belonging to the Caledonian margin of Baltica) From: Andersen et al. 1998

  6. OUTBOARD ACTIVITY: From the Ægir Sea to the Iapetus and Tornquist Oceans The oldest supra-subduction zone ophiolites and island-arc complexes in the Scandinavian Caledonides (`Group 1´) formed in this time-span in the Early to Middle Ordovician (495 to 465 Ma) while Baltica started to drift northwards with velocities up to ~10 cm/yr

  7. Plate-tectonic velocities of Baltica quantified by pal-mag. data (Torsvik & coworkers) Timanian From: Torsvik & Rehnström 2002

  8. `Group 1´ type ophiolites and island-arc complexes: • Situated within the Upper Allochton between Karmøy • in the south and Lyngen in the north • Ages spanning 495 to 465 Ma (within uncertainty) • with the Leka, Karmøy ophiolites as the oldest and • arc-plutons and volcancs as the youngest • Both spreding axis and arc-magmatism • have geochemical subduction zone signatures Lyngen Narvik Leka Gjersvik Trondheim area Otta-Foldal Roberts et al. 2002 Subduction polarity away from Baltica, eventually build-up of mature arcs Bergen Bømlo/Stord Karmøy

  9. AGE OF GROUP-1 OPHIOLITES/ISLAND -ARCS Arc-related plutons From: Pedersen 1992 From: Roberts et al. 2002

  10. Closure of the Tornquist Ocean “Soft docking” of Avalonia before the Late Ordovician ?

  11. MATURE ISLAND-ARC VOLCANIC AND COMPOSITE PLUTONIC COMPLEXES BUILD DURING THE MIDDLE TO LATE ORDOVICIAN Bindal-Helgeland Smøla-Hitra Up Hovind Gp. Sunnhordland

  12. INTRA-ARC INCONFORMITIES BELOW MID-LATE SILURIAN OR DEVONIAN CONGLOMERATES (UCF-3) IN SUNNHORDLAND

  13. IAPETUS IS CLOSING AND CONTINENTAL COLLISION TAKES OVER FROM THE WENLOCK

  14. THE LATE-SILURIAN FULL SCALE COLLISON BETWEEN BALTICA AND LAURENTIA

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