The Lower Carboniferous Waulsortian Facies

Abstract

Massive lime mudstone containing scattered crinoid and bryozoan fragments and forming lens-like buildups and mounds, constitutes a distinctive and ubiquitous facies in Lower Carboniferous (Tournaisian-Visean) strata throughout the northern hemisphere. The rock of such buildups takes the name Waulsortian, from a village in the Dinant basin, south of Namur in Belgium. Mounds and massive sheet limestone of the same age and type are well known in Pembroke, Derbyshire, and the Pennines of England and in Ireland; they also occur in central France. In the regional paleotectonic patterns of all these areas, the Waulsortian mounds and lenses appear chiefly as an intermediate (shelf margin) facies between geosynclinal basins and shelf deposits which were formed in conditions of open marine circulation (Fig. V-1).