The structural development of the Wessex Basin

Abstract

The Mesozoic and Cenozoic structures of southern England form part of a system of disturbances which extends across the Channel into northern France. They are reviewed in the light of published data from south Dorset. Basin development started with Permo-Triassic rifting, and is believed to have continued through the Jurassic and early Cretaceous with intermittent growth on deep-seated listric normal faults, probably associated with roll-over anticlines. This regime had ceased by the Aptian and the basin passed through a period of relative stability in the late Cretaceous, followed by tectonic inversion and, in the Miocene, by northwards compressive movement along the former normal faults. This partially restored the earlier separative displacement at depth, and probably accentuated pre-existing roll-over anticlines: it was expressed in the surficial Upper Cretaceous-Palaeogene sequence as monoclinal flexuring. The early rifting and the change from overall N-S crustal stretching to compression may reflect plate tectonic events in the North Atlantic region.