The geometry of ductile conjugate fold systems in the Ardnamurchan Moine,Scotland |
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| Authors: | Brian H O'Brien |
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| Abstract: | Four ductile phases of superimposed deformation are regionally mappable in the Ardnamurchan Moine in the Western Highlands of Scotland. These deformations are recognized on the basis of their individual geometrical characteristics and are named, in ascending order, the Kentra phase (D1), the Ardtoe phase (D2), the Glenmore phase (D3), and the Claish phase (D4). Non-systematic earlier structures (pre-D1), possibly coeval with the climactic metamorphism, are locally observable. Folds and fabrics produced by the D2, D1, and D4 deformations, however, developed as conjugate sets. There is a significant spatial variation in the distribution and intensity of each of the D1-D4 phases. The regional deformation of the Moine schists is notably inhomogeneous due to the nature of the D1-D4 incremental strains. In the areas affected by large finite strains, pervasive, normally composite LS-fabrics are developed. In the areas that persistently suffered negligible strain increments, right-way-up rocks commonly display several mineral foliations lying at various angles to bedding. The conjugate systems of folds and fabrics appear to be related to the evolution of a ductile shear belt in Ardnamurchan. |
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| Keywords: | Moine Ardnamurchan Conjugate folds Deformation |
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