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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 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 • Towards continental collision and the Scandian orogeny • Late to post-orogenic tectonic processes • Late Palaeozoic continental rifting • Start of a new Wilson cycle

  2. The start: • Short overview of the main age provinces of Fennoscandia • (Baltic shield) • Super-continent cyclisity? • Main events of the Late Proterozoic: • Late Proterozoic Timanian (Baikalian/Cadomian) deformation • in Arctic Norway • Rifting along the future Caledonian margin of the Fennoscandian • shield, major igneous complexes, diatremes and dykes • The palaeocontinent of Baltica becomes an tectonic entity • The Vendian glaciation (before595 Ma, at ca 620 Ma?) • The Seve transitional continental - oceanic crust • The sedimentary basins and establishment of a rift margin • Sparagmites to the Cambro-Silurian foreland sequence

  3. The main geological layout of the Baltic Shield > 2.5 Ga 2.0-1.8 Ga 1.75-1.5 Ga 1.2 - 0.93 Ga

  4. Supercontinent cyclisity? From Rodinia to Pangea? Does the earth´s continental lithospheric plates assemble and rift apart in longer term cycles? Supercontinent PANGEA in the late Permian ca 255 Ma ≈ 500 myr. cycle? A speculative Rodinia reconstruction, ca 750 Ma

  5. TIME: 600-570 Ma The story is more complicated than a simple break-up of the supercontinent! F.example: In the Mid- to Late Vendian, we have the Timanian Orogeny; (prev. referred to as the Baikalian) in the now Arctic Norway. This reconstruction correlates the Timanian orogeny in time and space with the Cadomian of Europe, Eastern US and Canada NB! Notice uncertain position of Laurentia From: Roberts & Siedlecka 2002

  6. From Torsvik and Cox, for further explanation see: http://www.geodynamics.no/platemotions/500-400/ BALTICA CERTAINLY A SEPARATE CONTINENT AT 550 Ma Notice the Gondwana-wide Cadomian Pan-African deformation belts, also affecting the margin of Baltica (Timanian)

  7. MAGMATIC ROCKS ASSOCIATED WITH RIFTING OF BALTICA Northern Scandianvia: Seiland Igneous Province: Ultramafics, gabbros syenites etc Gabbros 570-560 Ma (Unpubl. data R.J. Roberts; pers com. 2003) Nefeline-syenite-pegmatite: 531 and 523 ± 2 Ma (Pedersen et al. 1989) Kalak nappe complex dyke complex(es) (not yet dated) Central Scandinavia: Sarek sheeted dykes: 608 ± 1 Ma (Svenningsen 1999) Ottfjellet dykes: 665 ± 10 Ma (Ar, Claesson & Roddick 1983) Southern Scandinavia: Lavas within the Hedemark “sparagmite” basin (not yet dated) Atløy dykes: (pre 450 Ma, not yet dated) Hunnedalen dykes: ~850 Ma (Ar, Walderhaug et al. 1999) Egersund dykes: 616 ± 3 Ma (Bingen et al. 1997) Fen complex: ~585 Ma (Ar, Meert et al. 1999)

  8. Egersund dykes 616Ma Fen 585 Ma Hedemark lava ? Atløy dykes ? Sarek dykes 608 Ma Ottfjallet dykes 665 Ma Seiland IC 570-560 Ma Fen complex ~585 Ma From Meert et al. 1999

  9. Second stage w nefeline- syenites U/Pb z. 531-523 Ma

  10. Varanger Glaciation older than 595 Ma, ~ 620 Ma? 600-570Ma VARIOUS VENDIANCAMBRIAN RECONSTRUCTIONS

  11. Southern hemisphere, major (~ 900) anticlockwise rotation Cambrian - Ordovician

  12. Late-Proterozoic to Cambrian stratigraphy in Scandinavia ~545 Ma older than 595 Ma ca 620 Ma?

  13. Traditional 2-D conseptual model From: Kumpulainen and Nystuen 1985

  14. ca 620 Ma ca 610-545 Ma, nb! remember Timanian def in the north From: Kumpulainen and Nystuen 1985

  15. First signs of collision: Eclogite facies metamorphism, Seve Nappe complex; arc-collision? From Torsvik and Cox, for further explanation see: http://www.geodynamics.no/platemotions/500-400/

  16. Transitional continental - oceanic crust preserved in the Seve nappe complex 608 ± 1 Ma Present day Norwegian Sea analogue to a Seve nappe complex

  17. 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

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