We use three‐dimensional (3D) seismic reflection and magnetic data to interpret and describe the 3D geometry of igneous dykes in the southern North Sea. The dykes were emplaced into Paleozoic and Mesozoic sediments and have a common upper termination in Early Tertiary sediments. We interpret the dykes to be part of the British Tertiary volcanic province and estimate the age of the dykes to be 58 Ma. The dykes are characterized by a narrow 0.5–2 km wide vertical disturbance of seismic reflections that have linear plan view geometry. Negative magnetic anomalies directly align with the vertical seismic disturbance zones and indicate the presence of igneous material. Linear coalesced collapse craters are found above the dykes. The collapse craters have been defined and visualized in 3D. Collapse craters have formed above the dyke due to the release of volatiles at the dyke tip and resulting volume loss. Larger craters have potentially formed due to explosive phreatomagmatic interaction between magma and pore water. The collapse craters are a new Earth analogue to Martian pit chain craters.

Three-dimensional seismic analysis is used to describe the detailed morphology of the Silverpit crater, a proposed marine impact crater located in the southern North Sea, UK. We examine and constrain for the first time the geometry, extent and age of the post-crater sediment units that define the crater fill. A circular bowl-shaped depression has been mapped and interpreted to represent the upper limit of impact deformation and the geometry of the crater at the end of cratering processes. Reflections exhibit a parallel onlap fill onto the bowl-shaped crater floor, indicating that accommodation space was created instantaneously without any contemporaneous sedimentation. Using regional lithostratigraphic markers constrained by microfossil and calcareous nannofossil analysis, we have dated the first onlapping sediments onto the crater. The age of the onlapping sediments allows us to constrain the crater formation to be Middle Eocene in age. This date is c. 10-15 Ma younger than the previous ascribed age for the crater formation and rules out the Silverpit crater as a K-T boundary impact. The age of crater formation considerably predates regional folding and accompanying salt flowage, effectively ruling out a salt withdrawal origin for the Silverpit crater.

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