Patterns of folding within nappes and thrust sheets: examples from the Variscan of southwest England

Rattey, P.R. and Sanderson, D.J. (1982) Patterns of folding within nappes and thrust sheets: examples from the Variscan of southwest England. [in special issue: Strain Within Thrust Belts] Tectonophysics, 88 (3-4), 247-267. (doi:10.1016/0040-1951(82)90239-6).

Record type: Article

Abstract

Folding is a common response to deformation within nappes and thrust sheets and a wide variety of attitudes of folds can result. Two examples of patterns of variably oriented folds from southwest England are analysed in terms of thrust tectonics.

In northern Cornwall, the Millook nappe contains a downward progression from upright to recumbent folding with a zone of oblique or sheath folds at its base. These changes are related to an increasing simple shear component towards the base of the nappe.

In southwestern Cornwall, D1 and D2 deformations are related to the thrust emplacement of the Lizard complex. F1 folds in rocks below and to the north of the Lizard complex have variable axial orientations. Alternating zones of folds trending normal and oblique to the transport direction have been mapped. The oblique folds are interpreted as initiating in zones of differential movement within thrust sheets. Later D2 shear zones cut up-section ahead of the advancing Lizard complex, in which case they result in refolding of F1 folds. Beneath the Lizard complex these D2 shear zones cut down-section, extending, but rarely refolding, the D1 structures.

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