Evolution of the English Channel Basin

Abstract

The Mesozoic Channel Basin is structurally linked to the main Wessex Basin (to the north), the Paris Basin (to the south) and Western Approaches Trough to the west. The Mesozoic (and Cenozoic) history of the English Channel area shows the complex interplay between crustal extension–subsidence and later inversion associated with intra-plate tectonics of the European area and the opening of the North Atlantic. Similar structural and sedimentological features are found in the Paris, Wessex, Western Approaches Trough and Channel basins, thus making the latter area the geographic focus for the development of this model of basin evolution. The development of the Channel Basin is similar to the onshore Paris Basin and Wessex Basin. A syn-rift succession of Permian–Triassic non-marine sediments is succeeded by widespread marine Jurassic sediments of the thermal relaxation phase. Uplift of the basin margins and intra-basinal ‘highs’ occurred during the earliest Cretaceous, and was facilitated by reactivation of Variscan basement thrusts at depth. Consequently, a common structural/stratigraphic pattern can be observed across the Channel Basin: this comprises a prominent Aptian–Albian unconformity on faulted and folded Jurassic footwall highs, adjacent to thick early Cretaceous successions (Wealden) preserved in the hangingwall. The two successions are separated by Cretaceous–Tertiary inversion axes such as the Isle of Wight–Purbeck Monocline and northern margin of the Brittany Basin. The final movement on such axes was Oligo-Miocene. The timing of late Jurassic–early Cretaceous uplift is not absolute: as no sediments of this age are preserved on the footwall of uplifted blocks, the successions on the . . .