Subsidence patterns in western margin basins: evidence from the Faeroe–Shetland Basin

Publisher Website
Google Scholar
Abstract
Anomalously high rates of Paleocene tectonic subsidence have been documented from a number of basins on the NW European continental shelf. This period of accelerated subsidence occurs during what is conventionally regarded as the post-rift phase of basin development. It cannot, therefore, be explained by theoretical models of basin formation in which the post-rift subsidence is driven only by the decay of the thermal anomaly generated during active extension. The Faeroe-Shetland Basin developed as a major Cretaceous depocentre, with Late Cretaceous times in particular characterized by extremely high rates of tectonic subsidence. Subsidence rates on the flanks of the basin slowed dramatically into Paleocene times as a major mid-Paleocene unconformity developed across the eastern side of the basin. Wells from the basin centre, on the other hand, show extremely high and accelerating rates of Late Paleocene subsidence associated with normal faulting. These high rates of observed tectonic subsidence lasted for less than 5 Ma and cannot easily be explained in terms of fluctuations in sediment supply rates or eustatic sea-level. This simultaneous flank uplift and basin centre subsidence acceleration is the same age as both the anomalous Paleocene subsidence reported from other nearby basins, and the oldest magmatism associated with the proto-Icelandic plume. Subsidence behaviour returned to normal, across the entire basin, at the same time as continental break-up was achieved between Greenland and Northwest Europe. This suggests that there is a link between regional tectonics and the anomalous Paleocene subsidence patterns observed in this and other basins on the NW European continental shelf.