Upper Cretaceous tectonic phases and end Cretaceous inversion in the Chalk of the Anglo-Paris Basin

Abstract

Three intra-Upper Cretaceous tectonic phases, Stille's Ilsede (Late Turonian-Early Coniacian), Wernigerode (Late Santonian-Early Campanian) and Riedel's Peine (latest Lower Campanian) are investigated in the Anglo-Paris Basin. Criteria for recognizing these events include field evidence of slumping, allochthonous chalks; lateral changes in thickness and lithology; seismic evidence for slump horizons; and lacunae closely related to tectonic axes. Further evidence from seismic sections indicates large-scale channel development during these phases but the spatial relationship with tectonic lineaments is more difficult to determine. Each phase rejuvenates the tectonic topography which is subsequently buried by post-tectonic facies changes, for example from Lewes to Seaford Chalk following the Ilsede tectonic phase and Culver to Portsdown Chalk, following the Peine tectonic phase. The tectonic phases are recognized along local tectonic lineaments in contrast to more widespread sea-level fluctuations. New information on the end Cretaceous inversion in the London and Anglo-Paris basins supports the recognition of a London axis of uplift where the chalk at subcrop was more deeply eroded than at outcrop. Maximum inversion in the Weald-Wessex area occurred in East Sussex along the southern margin of the Weald where the thickest chalks had previously been deposited.