Evidence for structural controls on the deposition of the late Jurassic-early Cretaceous Purbeck Limestone Group, Dorset, southern England

Integration of field studies with subsurface data demonstrate that deposition of the late Jurassic-early Cretaceous Purbeck Limestone Group occurred under semi-arid conditions during an important phase of synsedimentary extensional activity in the Wessex Basin. Use of structural restorations and neotectonic analogue-studies support the introduction of a new model to account for the regional and local along-strike variability in deposition of the Purbeck Limestone Group. It is proposed that the segmented nature of the episodically-active, basin-bounding Purbeck Fault explains observed thickness and sedimentological variations, including lateral facies changes and clast reworking. In addition to affording a tectonic framework in which to understand the rich palaeontological assemblages, the new depositional model also provides a mechanism for explaining the rapid death and unusual preservation of conifer forests through rapid submergence following co-seismic activity on the normal fault system.