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The structure of the Glenelg-Attadale Lewisianoid Inlier and its relationship to the Moine thrust zone

A. J. Barber
The structure of the Glenelg-Attadale Lewisianoid Inlier and its relationship to the Moine thrust zone
Scottish Journal of Geology (November 2011) 47 (2): 113-132

Abstract

The Glenelg-Attadale Lewisianoid Inlier lies adjacent to the Moine Thrust Zone. The inlier is surrounded and divided into Eastern and Western units by Moinian metasediments. The Eastern Unit was emplaced against the Western Unit in the Grenvillian Orogeny. Moinian sediments were deposited unconformably on both units in the Neoproterozoic. During the Late Neoproterozoic Knoydartian and Lower Palaeozoic Caledonian orogenies, both the inlier and the overlying Moinian rocks were deformed and metamorphosed in the amphibolite facies. Deformation affected particularly the western and eastern margins of the inlier and a strip of infolded Moinian rocks between Eastern and Western units, with the formation of blastomylonites and isoclinal folding (F1). Above a major decollement in the Moine strip and along the western margin of the inlier, the rocks were folded by easterly plunging reclined (F2) folds. This phase of folding affected mainly the Lewisianoid rocks of the Eastern Unit and the adjacent Moine sediments of the Mountain Belt. Deformation was associated with the formation of a large-scale mushroom interference structure and the extrusion of the inlier northwestward, toward the foreland, marked by a dominant ESE stretching lineation. In Avernish, reclined F2 folds are cut by randomly oriented hornblende porphyroblasts, which are altered to biotite and smeared out in localized mylonitic shear zones similar to the mylonites in the Moine Thrust Zone. If these mylonitic shear zones were formed contemporaneously with the mylonites in the Thrust Zone, folding and thrusting events superimposed on the mylonites, must have occurred later than events in the Mountain Belt.


ISSN: 0036-9276
EISSN: 2041-4951
Coden: SJGEAX
Serial Title: Scottish Journal of Geology
Serial Volume: 47
Serial Issue: 2
Title: The structure of the Glenelg-Attadale Lewisianoid Inlier and its relationship to the Moine thrust zone
Author(s): Barber, A. J.
Affiliation: Royal Holloway University of London, Department of Earth Sciences, Egham, United Kingdom
Pages: 113-132
Published: 201111
Text Language: English
Publisher: Geological Society Publishing House for the Geological Societies of Edinburgh and Glasgow, Bath, United Kingdom
References: 43
Accession Number: 2012-007689
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch maps
N54°40'00" - N61°00'00", W08°30'00" - W00°45'00"
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 201204
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