Abstract We demonstrate a non-contact approach to whole-core and split-core resistivity measurements, imaging a 15 mm-thick, dipping, conductive layer, producing a continuous log of the whole core and enabling the development of a framework to allow representative plugs to be taken, for example. Applications include mapping subtle changes in grain fabric (e.g. grain shape) caused by variable sedimentation rates, for example, as well as the well-known dependencies on porosity and water saturation. The method operates at relatively low frequencies (i.e. low induction numbers), needing highly sensitive coil pairs to provide resistivity measurements at the desired resolution. A four-coil arrangement of two pairs of transmitter and receiver coils is used to stabilize the measurement. One ‘coil pair’ acts as a control, enabling the effects of local environmental variations, which can be considerable, to be removed from the measurement at source. Comparing our non-contact approach and independent traditional ‘galvanic’ resistivity measurements indicates that the non-contact measurements are directly proportional to the reciprocal of the sample resistivity (i.e. conductivity). The depth of investigation is discussed in terms of both theory and practical measurements, and the response of the technique to a variety of synthetic ‘structures’ is presented. We demonstrate the potential of the technique for rapid electrical imaging of core and present a whole-core image of a dipping layer with azimuthal discrimination at a resolution of the order of 10 mm. Consequently, the technique could be used to investigate different depths within the core, in agreement with theoretical predictions.

Abstract Reconnaissance mapping of the UK’s continental shelf and slope by the British Geological Survey has led complete cover at a scale of 1:250 000 illustrating the Quaternary geology. The maps and accompanying reports give a summary of the characteristics of its component stratigraphic units. The mapping has revealed that middle Pleistocene, late Pleistocene or Holocene sediments rest unconformably on pre-Quaternary deposits across much of the continental shelf. In the North Sea Basin, pre-Anglian deposits are thin or absent for up to 100 km east of the present coastline, although they are many hundreds of metres thick locally along the international median line. North and west of Scotland and southwest of England, pre-Anglian deposits are restricted to the outer shelf and continental slope. They probably also occur in a shallow basin extending from beneath the centre of St. George’s Channel into the south Irish Sea.