Petrography and facies of some upper Visean (Mississippian) limestones in north Wales

The succession studied marks the transition from marine carbonate deposition of the Carboniferous Limestone to the marine mud and sand deposition of the Millstone Grit, and includes a deep shelf or upper slope facies consisting mainly of bioclastic and subordinate crinoidal calcarenites, a lagoonal facies of coquina-lutites with shelly calcite mudstones and calcite siltstones and clay shales, and a shallow shelf facies of quartzose sandstones with varying amounts of bioclastic debris and interbedded silty shales.

This record provided courtesy of AGI/GeoRef.