Tectonics of the Bude Formation, north Cornwall—the recognition of northerly directed décollement

Abstract

The Upper Carboniferous Bude Formation of North Cornwall and Devon underwent deformation, beginning shortly after its deposition, which resulted in a complex geometry of folding and thrusting. The deformation initially exploited slumped beds as dCcollement horizons and resulted in a significant northerly translation of thrust sheets. The development of chevron folds, for which the area is famous, commenced at this stage but continued, causing folding of thrust planes and cleavages. During the deformation the dominant sense of thrust movement switched from a northerly to a southerly direction and this is interpreted as the effect of backthrusting associated with the northwards migration of the deformation front.

The confrontation of structural styles and the evolution of a foreland basin in central SW England

“…18a). It may underlie only the foreland basin flysch deposits of the Culm Trough which experienced syn-sedimentary thrusting whilst still in an unconsolidated state during the Westphalian (Enfield et al 1985;Whalley & Lloyd 1986). Both of these models are compatible with offshore deep seismic profiles (BIRPS & ECORS 1986).…”

Return of `The Fan That Never Was': Westphalian turbidite systems in the Variscan Culm Basin: Bude Formation (south‐west England)

“…However, other examples of thick shelf deposits are the Jura Quartzite (> 5 km; Anderton, 1976) and the Lower Sandfjord Formation (1·5 km; Levell, 1980). Furthermore, recent recognition of thrusts in the strongly folded Bude Formation suggests that repetitions of the stratigraphy are likely ( Enfield et al ., 1985 ; p. 170; Whalley & Lloyd, 1986), such that the total thickness may have been overestimated.…”