Contrasting modes of reactivation in the Outer Hebrides fault zone, northern Barra, Scotland

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doi: 10.1144/jgs.157.5.1009
Authors:Macinnes, E. A.; Alsop, G. I.; Oliver, G. J. H.
Author Affiliations:Primary:
University of St. Andrews, School of Geography & Geosciences, St. Andrews, United Kingdom
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, Vol.157(Part 5), p.1009-1017. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:2000
Note:In English. 16 refs.; illus., incl. sects., 1 table, geol. sketch map
Summary:The gently ESE-dipping Outer Hebrides Fault Zone may be traced for c. 170 km through the Lewisian gneisses of northwestern Scotland and defines broad, arcuate swings in strike from NE-SW to almost north-south. This study evaluates the kinematic evolution of the fault zone within the hinge region of such a strike swing exposed in the small isles north of Barra. New structural mapping of this area has concentrated on the geometry, kinematic significance and the relative age of different structural elements of the fault zone, and provides a comparison with the better known tectonics of the northern portions of the Outer Hebrides Fault Zone. Hitherto unrecognized top-to-the-NW ductile thrusting in this southern portion of the fault zone, coupled with abundant evidence of extensional reactivation and lack of sinistral strike-slip in phyllonites as reported further north, suggests that the present segmented and arcuate geometry is a primary feature of the fault system. The original thrust template governed the subsequent reactivation and relative importance of both late Caledonian strike-slip and extensional collapse components. Inherited structural architectures may thus provide geometric constraints on the nature and patterns of subsequent reactivation and tectonism.
Sections:Petrology
Subsections:General
Subjects:Continental shelf; Deformation; Extension tectonics; Fault zones; Faults; Lewisian; Precambrian; Proterozoic; Reactivation; Tectonics; Upper Precambrian; Arctic Ocean; Europe; Great Britain; Hebrides; Norwegian Sea; Outer Hebrides; Scotland; United Kingdom; Western Europe; Barra Island; Northwestern Scotland; Outer Hebrides fault zone
Coordinates:N570000 N570000 W0073000 W0073000
Abstract Numbers:01M/761
Record ID:2001001980
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
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