Core samples are examined using a 10 MHz NMR spectrometer and results are compared with those from the Magnetic Resonance Imaging Log*(MRIL) (operating frequency 1 MHz) in the same rock formations. The frequency dependence of this technology and its link to petrophysics is investigated, thus offering the first link between core and log NMR data for this new tool.

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The Lithospheric Seismic Profile in Britain (LISPB), shot in 1974, included a 310 km profile LISPB DELTA, crossing the Palaeozoic Welsh Basin, the western extent of the Midland microcraton and the Cornubian zone of southern England. This first comprehensive analysis of these data has produced a sub-horizontally layered seismic and associated gravity model that correlates well with surface geology. A north-south decrease in crustal velocity and density corresponds to the change from Avalonian crust into the Rheno-Hercynian zone at the south end of the profile. High velocities and densities in the lowest crustal layer beneath north Wales are proposed to result from Cenozoic and possibly Ordovician igneous intrusive rocks, the former derived from an upwelling plume associated with the opening of the North Atlantic. Examination of the load distribution throughout the model shows that it is strongly correlated with the earthquake distribution along LISPB DELTA. Earthquake focal depth also correlates with heat flow. A simple heat-flow profile has been derived, and the seismic velocity model used to constrain crustal heat production values. A long-wavelength excursion from published data can be explained in terms of an increase in mantle heat flow resulting from a previously identified deep thermal anomaly beneath the Irish Sea. Supplementary material: normalised, synthetic and true amplitude seismic record sections including picks and modelled phases for shots SP04, SP05, SPS1, SPS2 are available at http://www.geolsoc.org.uk/SUP18450. The 1974 Lithospheric Seismic Profile in Britain (LISPB) (Bamford et al. 1976; Fig. 1a) was one of the first projects undertaken at the start of the era of long-range controlled source seismic profiling in Europe before the advent of deep seismic reflection and present teleseismic studies. The aim of the crustal profiles (ALPHA to DELTA) was 'to provide velocity crosssections that would be useful to discussions of tectonic problems in the British Isles, in particular the evolution of the Caledonian orogenic belts ' (Bamford et al. 1978). LISPB's northern section has been extensively reported elsewhere, most recently by Barton (1992). Preliminary results from LISPB DELTA from north Wales to the English Channel have been reported (Nunn 1978) and discussed elsewhere (Edwards & Blundell 1984;Griffiths & Westbrook 1992). This paper is the outcome of applying well-established 2D seismic ray-tracing and amplitude modelling techniques to LISPB DELTA data, combined with analysis of associated gravity data along the profile to develop the model of crustal structure and processes beneath this region of the British Isles. It provides the first comprehensive analysis of these data.Long-range refraction-wide-angle reflection profiles such as LISPB form the basis for our understanding of the physical properties of the crust, its evolution and behaviour. It could be argued that the UK crust is typical of large parts of the continental crust. It records major past orogenic events and now lies some distanc...