BIRPS deep seismic reflection studies of the British Caledonides

The Western Isles–North Channel (WINCH) traverse (Fig. 1), an extension of the successful MOIST profile1, was recorded in 1982 at sea along the west coast of Britain for BIRPS (British Institutions Reflection Profiling Syndicate) by the Geophysical Company of Norway (GECO). The purpose of the WINCH traverse was to study crustal structure of the Caledonian foreland, to cross the Caledonian orogen, and to establish the three-dimensional geometry of mantle reflectors originally seen on MOIST. We describe here the data, first emphasizing British Caledonian structures, and then discussing features of the deep crust of wider significance. The data are of very good quality and contain clear Moho and upper mantle reflections. The lower crust is surprisingly reflective, deeply penetrative thrusts are observed and there is firm evidence that several of the Mesozoic basins round the shores of the United Kingdom were formed by reactivation of older features