Lagoonal sedimentation and fluctuating salinities in the Vectis Formation (Wealden Group, Lower Cretaceous) of the Isles of Wight, southern England

Sedimentation in the Shepherd's Chine Member of the Vectis Formation is characterised by a cyclicity of four principal facies on which a strong asymmetry has been imprinted by erosional events. The four lithofacies are: (1) very fine to fine sandstones; (2) heterolithic sand/silt and mudstones; (3) parallel-laminated (pinstripe) mudstones; and (4) black mudstones. Lithofacies and biotas indicate deposition in a lagoon that was shallow and temporarily emergent. The cyclicity is thought to represent the more distal phases of the advance and retreat of deltaic sand bodies, derived from a westerly direction, into the lagoon.