Depositional environment and sequence architecture of the Silurian Coralliferous Group,Southern Pembrokeshire,UK

The Lower Silurian siliciclastic Coralliferous Group is shown to have been deposited in an intra‐shelf position 10–15 km south of the palaeogeographic shelf‐break of the Welsh Basin. After a phase of thermal subsidence related to the development of the predominantly Llandovery Skomer Volcanic Group, the shelf basin was transgressed. This transgression was punctuated by an episode of tectonic uplift in southern Pembrokeshire, resulting in subaerial exposure of the shelf and a significant basinward shift in sedimentary environments. Erosion and sediment bypass ensued, with coarse‐grained low‐sinuosity fluvial channels transporting sediment to the northerly Welsh Basin, where significant submarine fans developed. During the early Telychian, renewed transgression took place, with lowstand gravels being ravined and reworked into parasequences of the transgressive systems tract. These thin, coarse‐grained parasequences record deposition within high‐energy wave‐dominated shoreface/inner shelf environments. Further coastal onlap resulted in the closing down of significant coarse‐grained sediment supply, with the remaining Coralliferous Group being dominated by wave‐influenced silts, mud‐shales and thin sandstones comprising the highstand systems tract. Copyright © 2002 John Wiley & Sons, Ltd.