Dk. Smythe, GEOPHYSICAL EVIDENCE FOR ULTRAWIDE DYKES OF THE LATE CARBONIFEROUS QUARTZ-DOLERITE SWARM OF NORTHERN BRITAIN, Geophysical journal international, 119(1), 1994, pp. 20-30
A compilation of the late Carboniferous quartz-dolerite dyke swarm of
northern Britain has been made using existing geological maps, augment
ed by new ground and airborne magnetic surveys. Aeromagnetic data in t
he North Sea show that dyke anomalies can be traced eastwards on an ar
cuate trend for up to 200 km from the UK coast, as far as the western
margin of the Central Graben. Individual dykes, which are generally up
to 30 m wide onshore, attain widths of well over 1 km offshore. These
are at least as wide as any known dykes. The swarm is probably as ext
ensive and voluminous as the well-known and better-exposed Palaeocene
tholeiitic swarm of NW Britain.