Kinematics of the Hoybakken detachment zone and the More-Trondelag fault complex, central Norway

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doi: 10.1144/0016-764904-129
Authors:Osmundsen, Per T.; Eide, E. A.; Haabesland, N. E.; Roberts, D.; Andersen, T. B.; Kendrick, M.; Bingen, B.; Braathen, A.; Redfield, T. F.
Author Affiliations:Primary:
Geological Survey of Norway, Trondheim, Norway
University of Oslo, Norway
University of Bergen, Norway
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, 163(2), p.303-318. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:2006
Note:In English. 87 refs.; illus., incl. geol. sketch maps, block diags., sect.
Summary:The tectonic disintegration of the Caledonian orogen through combined extension, contraction and strike-slip was characterized by spatial and temporal strain partitioning through a period of at least 30 Ma. Early to Mid-Devonian exhumation of the Central Norway basement window was associated with retrograde, top-to-the-SW extensional shearing in the Hoybakken detachment zone, sinistral shearing along the More-Trondelag Fault Complex, and formation of extension-parallel folds. Progressive exhumation led to increasing strain localization and to the transition from ductile to brittle deformation. In the interval between c. 370 and 320 Ma, the Hoybakken detachment fault cut previously folded detachment mylonites, capturing mylonites in its hanging wall. 40Ar/39Ar mica and K-feldspar ages indicate a Late Devonian or younger age for the uppermost parts of the adjacent "Old Red" basin. Gentle folding of this stratigraphic level attests to the continuation of shortening and orogen-oblique extension into Late Devonian-Carboniferous time. Shortening was intensified along strands of the More-Trondelag Fault Complex, as shown by mutually cross-cutting reverse and strike-slip faults. "Flower structures" may be particularly common in constrictional strain systems where strike-slip faults develop parallel to the principal elongation trend, but normal to the principal axis of shortening.
Subjects:Absolute age; Alkali feldspar; Ar/Ar; Basement; Brittle deformation; Caledonian Orogeny; Cataclasites; Crustal shortening; Dates; Deformation; Detachment faults; Devonian; Ductile deformation; Exhumation; Extension; Fault zones; Faults; Feldspar group; Framework silicates; Hanging wall; K-feldspar; Kinematics; Metamorphic rocks; Mica group; Mylonites; Normal faults; Oblique-slip faults; Paleozoic; Reverse faults; Shear zones; Sheet silicates; Silicates; Strike-slip faults; Tectonics; Thrust faults; Windows; Europe; Norway; Scandinavia; Western Europe; Western Gneiss region; Hoybakken Detachment; More-Trondelag Fault
Coordinates:N630000 N660000 E0150000 E0070000
Abstract Numbers:06M/1107
Record ID:2006024995
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States, Reference includes data from The Geological Society, London
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