Jurassic volcanic centres in the Central North Sea

Abstract

Well data and seismic reflection profiles have been used to pinpoint three Jurassic volcanic centres in the Central North Sea: the Fisher Bank and Glenn centres are closely juxtaposed and form part of the Forties volcanic province, and the Puffin centre occurs separately on the northern flanks of the Mid North Sea High. A fourth centre, Ivanhoe, has been tentatively located in the Outer Moray Firth. The thickness, distribution, age and stratigraphic relationships of the associated volcanic rocks are described with the aid of maps and seismic sections. In a speculative regional synthesis, it is suggested that various intra-Jurassic unconformities can be related to the growth and development of the volcanic centres. The onset of volcanism at the Fisher Bank centre may have occurred during the late Early Jurassic; the Puffin centre was active during the Mid-Jurassic, and the Glenn centre may be predominantly Callovian in age. As a result, the relationship between the volcanic rocks and the fluvio-deltaic sediments of the Pentland Formation varies across the area. The occurrence of widespread volcanic-related uplift favours models involving a thermal perturbation in the mantle, rather than a period of lithospheric stretching, to account for Jurassic volcanism in the Central North Sea.