Analysis of the pre-Tertiary rifting history of the Rockall Trough

Abstract

The Rockall Trough is a large, lightly explored, deep water basin offshore West of Britain. Only the 132/15-1 well has penetrated Mesozoic section within the Rockall Trough encountering a syn-rift section, interpreted on seismic reflection data, of early Cretaceous age (Hauterivian-Cenomanian) lying directly on crystalline basement. Older rift events have been proposed in the Rockall Trough to explain the extensive crustal thinning (Beta = 3 to 5) and because of the presence of older rifts on adjacent basins. Although the evidence is not conclusive, analysis of seismic reflection data within the Rockall Trough and of rift system trends on an early Cretaceous plate reconstruction do not require or suggest older than Cretaceous rifts in the Rockall Trough but also do not preclude them. Structurally, the Cretaceous rifting is highly assymetric being dominated by faults downthrowing to the southeast. A model of a reactivated Caledonian foreland thrust belt is proposed similar to that reported on the adjacent Hebridean shelf.