The spatial distributions of faults and deep sea carbonate mounds in the Porcupine Basin, offshore Ireland



Bailey, W., Shannon, P.M.1, Walsh, J.J. & Unnithan, V.1
1 - Marine and Petroleum Geology Group, Department of Geology, University College Dublin

Abstract - Localised populations of deep water carbonate mounds occur throughout the NE Atlantic margin of Ireland, the UK and Norway, but the mechanisms responsible for their nucleation and growth are not well known. Based on the interpretation of seismic data it has been previously proposed that deeply rooted faults are present immediately beneath mounds and act as conduits for the vertical migration of mound-feeding hydrocarbons. A series of discrete carbonate mound populations or provinces are present in the Porcupine Basin, offshore Ireland, above a number of distinct fault systems at different levels in the stratigraphy. Detailed mapping of the distributions of both faults and mounds, using 3D and 2D seismic data, demonstrates that there is a poor spatial relationship between the faults and carbonate mounds. This finding strongly suggests that seismically mappable faults do not play a pivotal role, as conductive fractures, in the evolution of the mounds. However, mounds on the NW margin of the Porcupine Basin are underlain by a shallow, intensely faulted slide package, which provides one potential association between faults and mounds.


Marine and Petroleum Geology, 20, 509-522, 2003.