Thrust tectonics of S Devon

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Abstract
The tectonics of the area from Start Point to Chudleigh, SW England, are shown to be dominated by northward-verging thrust nappes. Two major thrusts are postulated. The ‘Dartmouth antiform’ is considered to be a major thrust structure, not a fold structure as previously interpreted. The Torquay limestones are allochthonous and part of a klippe of a major thrust nappe with a minimum displacement of 13 km northwards. A progressive and diachronous sequence of deformation has been established with deformation starting in the S and moving N. Many of the folds and cleavages are probably related to the strains developed locally in thrust tips and may have no regional correlation. More intense and complex deformation is found in the S compared to the N. The diachroneity is also reflected in the K-Ar mineral ages. In the S, at Start Point, southward-verging backfolding is the last significant Hercynian deformation phase folding the thrust nappes.