The Sgurr Beag Slide–a major tectonic break within the Moinian of the Western Highlands of Scotland

Publisher Website
Google Scholar
Abstract
Detailed mapping of an area at the head of Loch Hourn, Inverness-shire, has shown that major facies changes occur within the Glenelg–Knoydart succession (Ramsay & Spring 1962) as it is traced north-eastwards from the type area. A slide, here recognized as a tectonic break of major importance within the Moine Nappe, separates members of this succession at Kinloch Hourn from rocks of a different stratigraphical sequence farther east. Lewisian-type rocks rest upon the slide plane and together with an overlying sequence of Moinian rocks have been slid against upper members of the Glenelg–Knoydart succession. It is suggested that the Scardroy Lewisian, which forms a sheet-like body in central Ross-shire, has been brought to its present position by this slide movement and not thrust wedge-like into an unbroken Moinian succession as suggested by Sutton & Watson (1962). Three phases of folding are recognized and the geometry of the major folds and their structural relationship to the slide plane is described in detail. Slide movement occurred during the second folding and before the peak of the regional metamorphism.