A large (> 300 km2) dome-shaped structure (Ben Nevis dome) lies beneath a thin basalt layer in the far north of the UK continental shelf. A large gravity and magnetic anomaly (known confusingly as Brendan's Dome) lies only 20 km to its north-west. Shell/BPA modelled these features using high-resolution gravity and magnetic datasets and concluded that, whereas the anomaly is generated by an igneous intrusion, the Ben Nevis dome is composed of sedimentary material. A 3D seismic survey was subsequently acquired over Ben Nevis, greatly improving imaging of the sub-basalt dome, and also showing fine details of the intra-basalt structure. After considering several models for the formation of the Ben Nevis dome, Shell/BPA's preferred model is that it was probably formed by localised inversion of a Cretacous graben-fill when the adjacent Brendan's Dome gabbroic pluton was intruded.

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