An early carboniferous river-dominated regressive facies in southern Ireland

Abstract

The Early Carboniferous Kinsale Formation contains a distinctive sand dominant unit in western County Waterford known as the Crows Point Member. This is built up by epsilon cross-stratified grey sandstones with minor thin claystone and heterolithic intercalations. Six rhythmically diminishing lithofacies, organised-into four sequential facies associations, are distinguished. Facies analysis shows it to be the record of high-energy pulses of fluvial sediment influx via distributary channels from the ESE. These were modelled by fluctuations in river stage; an overall allocyclic mechanism may have been responsible for the interpreted progressive shallowing of the distributaries. through time, accompanied by an increased tidal influence in response to a north-easterly regional transgression. The member provides additional support for a positive source area lying off the southeastern margin of the Munster Basin during the Early carboniferous. This together with its relationship to adjacent facies, indicates a NE-SW axial drainage pattern within-this basin at this time.