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Styles of basement involvement in the Moine thrust belt, NW Scotland

Robert W. H. Butler, R. E. Holdsworth and S. J. Matthews
Styles of basement involvement in the Moine thrust belt, NW Scotland (in Styles of continental contraction, Stefano Mazzoli (editor) and Robert W. H. Butler (editor))
Special Paper - Geological Society of America (2006) 414: 133-151

Abstract

The Moine Thrust Belt contains imbricate systems derived from Cambro-Ordovician sediments together with thrust sheets of their Lewisian basement. Correlation of Precambrian structures between these thrust sheets and the adjacent foreland demonstrates displacements >25 km, values confirmed and exceeded by restored cross sections constructed through the imbricated sedimentary cover. The basement-carrying thrust sheets display a wide variety of structural styles even though they have deformed under essentially the same metamorphic pressure and temperature conditions (lower greenschist facies). These include the translation of crystalline basement as sheets with no appreciable internal deformation apart from sparse quartz-epidote-filled fractures and approximately 1 m of mylonites and related fault rocks along the basal thrusts. Thrust trajectories can run parallel to the regional, near-horizontal datum (the sub-Cambrian unconformity) even though there are no apparent preexisting surfaces that might have localized slip on these horizons within the basement. In other examples, however, parts of basement thrust trajectories appear to have located preferentially on preexisting faults. These features have been underemphasized in previous studies and can be inferred by the preservation of Precambrian Torridonian strata beneath the sub-Cambrian unconformity within thrust sheets. Basin faults that controlled deposition and preservation of Torridonian strata may have promoted large-scale folding at the basement-cover interface that is manifest as the large-scale recumbent structures of the southern part of the thrust belt. These different styles are compared and discussed in terms of the propensity of the Lewisian basement to localize deformation at greenschist facies through reactivation and retrogression-enhanced weakening.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 414
Title: Styles of basement involvement in the Moine thrust belt, NW Scotland
Title: Styles of continental contraction
Author(s): Butler, Robert W. H.Holdsworth, R. E.Matthews, S. J.
Author(s): Mazzoli, Stefanoeditor
Author(s): Butler, Robert W. H.editor
Affiliation: University of Leeds, Institute of Geophysics and Tectonics, Leeds, United Kingdom
Affiliation: Universita di Napoli "Federico II", Dipartimento di Scienze della Terra, Naples, Italy
Pages: 133-151
Published: 2006
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
Meeting name: 32nd international geological congress, symposium on Styles of continental compression
Meeting location: Florence, ITA, Italy
Meeting date: 20040820Aug. 20-28, 2004
References: 66
Accession Number: 2007-022913
Categories: Structural geology
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., geol. sketch maps
N57°00'00" - N58°40'00", W06°30'00" - W04°00'00"
Secondary Affiliation: University of Leeds, GBR, United KingdomUniversity of Durham, GBR, United KingdomBP Exploration, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200713
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