Journal of the Geological Society, London, zyxwvutsrq Vol. zyxwvut 148, zyxwvuts 1991, pp. zyxwvuts 595-596, Printed in Northern Ireland Conference report Petroleum geology and basin development on the North West Seaboard J. PARNELL School of Geosciences, Queen zyxwvu 'S University, Belfast BT7 lNN, UK Report of a meeting of the British Sedimentological Research Group of the Geological Society held at the Queen 'S University of Belfast on 25-28 September zyxwvutsrq 1990. The organizers were J. Parnell and B. Monson. There is currently much interest in the extensive series of basins stretching from west of Shetland through the Hebrides to Northern Ireland and the west coast of Ireland. Each of theseregionshas seen drilling activity as part of hydrocarbon exploration programmes. The meeting was convened to review research into the development of basins of Carboniferous to Tertiary age on the northwestern seaboard of the British Isles. Twenty eight papers were presented, followed by a two-day field excursion to examine basins in the north of Ireland. W. I. MitcheU (Geological Survey, N. Ireland) discussed the evolution of Carboniferous basins in north west Ireland, and particularly of the Fintona Block, a series of fault-bounded tracts of Devonian-Carboniferous red beds. The northwards migration of the early Carboniferous marine transgression was associated with a sequential propagation of back-stepping faults and the development of diachronous facies belts of Courceyan-Arundian age. M. E. Philcox (Consultant, Co. Wicklow), G. Clayton, G. D. Sevastapulo and H. Baily reported stratigraphic data for the Dinantian Lough Allen Basin in north west Ireland, incorporating information from a gas exploration pro- gramme by Aran Energy. Basin evolution was partially fault-controlled, and some faults were later reactivated during Hercynian deformation. B. M o w n (Queen's Univ., Belfast) presented a reconstruction for the burial history of Carboniferous rocks in north west Irelandand concluded that hydrocarbons were generated before theend of the Carboniferous. Hydrocarbon shows occur in Holkerian sandstones particularly infilling secondary porosity after the dissolution of carbonate cements. Early hydrocarbon emplacement may have arrested clay diagenesis in these rocks. D. Naylor (Environmental Resources Analysis) summarized the history of Permian and Mesozoic sedimentation onshore in Ireland. Over most of Ireland, Permian to Jurassic sedimentation was very limited, and high maturation values in the Carboniferous can be attributed to high heat flows rather than deep post- Carboniferous burial. R. McCaffrey (Queen's Univ., Belfast) outlined the post-Permianhistories of basinsin northeast Ireland through the use of computer-contoured isopach diagramscompiled fromboreholeandoutcropdata.Two basins, the Larne Basin and the Rathlin Trough, are delimited by major faults which bound long-term structural highs including the Southern Uplands (Longford-Down Massif) and the Highland Border Ridge. J. ParneU (Queen's Univ., Belfast) reviewed the potential source rocks in basins on the north west seaboard, which range from Ordovician to Tertiary age. Pyrolysis data for Carboniferous rocks in Northern Ireland and western Scotland show them to have both gas and oil potential. Occurrences of onshore hydrocarbon shows particularly include those in Jurassic sandstones in the Hebrides and in Carboniferous sandstones in north west Ireland. A. H. Ruffell and M. Coward (Imperial College, London) described the structure and evolution of the Pembrokeshire Ridge which separates the North Celtic Sea Basin from the South Celtic Sea Basin. The Ridge can be traced 300 km southwest from the Welsh mainland, where it forms a major inverted structure with evidence for several periods of uplift from late Jurassic to mid-Tertiary. S. Trueblood (Hamilton Brothers Oil & Gas) evaluated the hydrocarbon potential of the Slyne Trough and adjacent basins. Source, reservoir and seals can all be identified within the Jurassic of the Slyne Trough. The potential of theErnsTrough relies onthe preservation of full Liassic sequences in fault blocks, as there was generally great erosion during the early Cretaceous. Liassic source rocks were completely eroded in the North Porcupine sub-basin, and oil in that basin probably has an upper Jurassic source. P. F. Croker (Dept. of Energy, Dublin) described the structural evolution of the Erns trough using a combination of magnetic, gravity, seismic and well data.The basin has a similar structural origin to the West Shetland Basin, 700 km distant, but differs in the timing of basin development. J. Moore (Univ. College, Dublin) considered the evolution of the Porcupine Basin in terms of pre-rift, syn-rift and post-rift phases, and focussed attention on the transition between extensive tectonism (syn-rift) and thermal sub- sidence (post-rift). Fault-bounded sub-basins up to 30 km X 20 km developed during this transitional phase, which probably dates from latest Jurassic to early Cretaceous. M. Tate (Total Oil Marine), N. White and J.-J. Conroy applied the lithospheric stretching model to the Porcupine Seabight Basin, which has evolved through repeated episodes of rifting since the Carboniferous. The principal rifting episodes of Middle Jurassic-earliest Cretaceous has been modelled and used to calculate heat flux and source rock maturation. The results are consistent with maturity indices measured from well data. J.-J. Conroy (Marathon Petroleum,Ireland) and N. White discussed the origin of post-rift stratigraphic onlap (Steer's Head geometry) in the Porcupine Basin. The observations were explained in terms of differential stretching between the crust and the lithospheric mantle, whereby the mantle experienced stretching over a significantly wider area than the crust. P. M. Shannon (Univ. Coll., Dublin) showed that the 595 by guest on October 13, 2021 http://jgs.lyellcollection.org/ Downloaded from