Major tectonic processes illustrated with examples from the Geology of Norway
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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
description
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 - PowerPoint PPT Presentation
Transcript of Major tectonic processes illustrated with examples from the Geology of Norway
Major tectonic processesillustrated 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
The telescopedCaledonian margin of Baltica
WHERE DO WE FIND EVIDENCE FOREARLY-CALEDONIAN (PRE-SCANDIAN)
TECTONIC EVENTS ALONG THE CALEDONIAN MARGIN OF BALTICA?
11) W- Finnmark/E-Troms (pre-490 Ma)
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2) Central Sweden-Nordland (pre-490 Ma)
3
3) Otta-Foldal-Røros (pre-470 Ma)
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4) Atløy (pre 450 Ma)
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5) Jæren (?)
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6) Cromite in Seds in foreland ca 470
608 ± 1 Ma
QuickTime™ and aTIFF (LZW) decompressorare needed to see this picture.
From: Modified from Rehnström et al. 2002 From Svenningsen et al. 1993
Atløy
Otta
Seiland Igneous Province 650Ma + 525Ma
Well documented pre-Silurian orogenic event at ca 450 Ma W-Norway
From: Andersen et al. 1990
MAJOR EVENTSDOCUMENTED FROM BALTIC TERRANES
(deformation/metamorphismin rocks belonging to the
Caledonian margin ofBaltica)
From: Andersen et al. 1998
OUTBOARD ACTIVITY:From the Ægir Sea to the
Iapetus and Tornquist Oceans
The oldest supra-subduction zoneophiolites and island-arc complexesin the Scandinavian Caledonides(`Group 1´) formed in this time-spanin the Early to MiddleOrdovician (495 to 465 Ma) whileBaltica started to drift northwardswith velocities up to ~10 cm/yr
QuickTime™ and aTIFF (LZW) decompressorare needed to see this picture.
QuickTime™ and aTIFF (LZW) decompressorare needed to see this picture.
From: Torsvik & Rehnström 2002
Timanian
Plate-tectonic velocitiesof Baltica quantified by pal-mag. data (Torsvik & coworkers)
`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
Karmøy
Bømlo/Stord
Bergen
Trondheim area
Otta-Foldal
Leka
Narvik
Lyngen
Gjersvik
Roberts et al. 2002
Subduction polarityaway from Baltica, eventuallybuild-up of mature arcs
From: Roberts et al. 2002
From: Pedersen 1992
AGE OF GROUP-1 OPHIOLITES/ISLAND -ARCS
Arc
-rel
ated
plu
ton
s
“Soft docking” of Avaloniabefore the Late Ordovician ?
Closure of the Tornquist Ocean
MATURE ISLAND-ARCVOLCANIC AND COMPOSITEPLUTONIC COMPLEXESBUILD DURING THE MIDDLETO LATE ORDOVICIAN
Smøla-Hitra
Up Hovind Gp.
Sunnhordland
Bindal-Helgeland
INTRA-ARC INCONFORMITIESBELOW MID-LATE SILURIAN
OR DEVONIAN CONGLOMERATES(UCF-3) IN SUNNHORDLAND
IAPETUS IS CLOSING AND CONTINENTALCOLLISION TAKES OVER FROM THE WENLOCK
THE LATE-SILURIANFULL SCALE COLLISON
BETWEEN BALTICA AND LAURENTIA
