Wenlock carbonate, level bottom, brachiopod-dominated communities from Wales and the Welsh Borderland

Abstract

Four marine level bottom communities are described from Wenlock carbonate rocks (i.e. the Wenlock and Woolhope limestones) of Wales and the Welsh Borderland. The communities are: (1) Sphaerirhynchia wilsoni, (2) Isorthis clivosa, (3) Eoplectodonta duvalii, and (4) Visbyella trewerna. The Sphaerirhynchia wilsoni community is divided into: (a) an argillaceous micrite phase, and (b) a biomicrite phase. The communities and the phases are defined on the basis of consistent and recurrent numerical species combinations. The community spectrum from Sphaerirhynchia wilsoni to Visbyella trewerna is broadly correlated with an increase in water depth. The communities show no correlation with major limestone facies types. It is suggested that turbulence, rates of sedimentation and substrate type are some of the environmental parameters, in the shallow near-shore regime, which determine the distribution of brachiopods.