The movement history and fault rock evolution of a reactivated crustal-scale strike-slip fault; the Walls Boundary fault zone, Shetland

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doi: 10.1144/0016-76492006-156
Authors:Watts, L. M.; Holdsworth, R. E.; Sleight, J. A.; Strachan, R. A.; Smith, S. A. F.
Author Affiliations:Primary:
University of Durham, Department of Earth Sciences, Durham, United Kingdom
University of Portsmouth, United Kingdom
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, 164(5), p.1037-1058. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:2007
Note:In English. 69 refs.; illus., incl. block diag., chart, sects., geol. sketch maps
Summary:The Walls Boundary Fault Zone is a crustal-scale strike-slip fault that cuts Precambrian-Caledonian basement terranes in Shetland and has been interpreted as the northern continuation of the Great Glen Fault Zone in Scotland. This paper presents the first detailed account of the kinematic history and fault rock assemblages associated with the onshore evolution of the Walls Boundary Fault Zone. These observations suggest that it initiated as a major late Caledonian (Silurian-Devonian) sinistral strike-slip fault associated with the successive development of mylonites and cataclasites. These fault rocks are preserved only locally, and elsewhere are obscured by the effects of later brittle overprinting and dismemberment of the fault zone during dextral strike-slip reactivation, probably during late Carboniferous inversion of the Orcadian Basin. This led to the development of extensive cataclasite and fault gouge assemblages, which are widely preserved along the Walls Boundary Fault. Narrow zones of post-Triassic dip-slip, and finally sinistral strike-slip, reactivation are localized within earlier-formed gouge-filled fault cores. There are some similarities to the kinematic history of the Great Glen Fault Zone, most notably the recognition of late Caledonian sinistral shear and post-Devonian dextral reactivation, but the post-Triassic reactivation histories appear to differ significantly.
Subjects:Blastomylonite; Brittle deformation; Caledonian Orogeny; Carboniferous; Cataclasites; Crust; Deformation; Fault zones; Faults; Gouge; Kinematics; Metamorphic rocks; Movement; Mylonites; Overprinting; Paleozoic; Reactivation; Stereographic projection; Strike-slip faults; Atlantic Ocean; Atlantic Ocean Islands; Europe; Great Britain; Great Glen Fault; North Atlantic; North Sea; Orcadian Basin; Scotland; Shetland Islands; United Kingdom; Western Europe; Walls Boundary fault zone
Coordinates:N601000 N605000 W0011000 W0013000
Abstract Numbers:07M/3461
Record ID:2007107320
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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