Right place, wrong time: anomalous post-rift subsidence in sedimentary basins around the North Atlantic Ocean

Abstract

Abstract The central and northern North Sea Basin was formed as a result of at least two extensional episodes, the latest of which took place during the Late Jurassic. During the Early Tertiary, some 80 Ma later, the basin experienced a dramatic acceleration in subsidence. Subsidence acceleration of Early Tertiary age has also been reported from a number of other extensional basins, on both sides of the North Atlantic, in which stretching had ceased several tens of millions of years previously. This phenomenon is not in agreement with the published models of extensional basin formation, which predict that the rate of thermal subsidence should progressively decline following extension. It is possible that the predicted pattern of thermal subsidence was obscured by the effects of a mantle hot spot beneath the North Atlantic lithosphere during the Cretaceous to Early Tertiary. However, it is difficult to explain the subsidence phenomena observed in basins around the North Atlantic Ocean using simple hot spot models. It is concluded that the relationships between hot spot activity, continental break-up and vertical crustal movements in the North Atlantic region are subtle and complex, but that subsidence history analysis can yield valuable insights into these relationships.