A synthesis of <scp>C</scp>enozoic sedimentation in the <scp>N</scp>orth <scp>S</scp>ea

Abstract

Abstract The N orth S ea B asin contains an almost complete record of C enozoic sedimentation, separated by clear regional unconformities. The changes in sediment characteristics, rate and source, and expression of the unconformities reflect the tectonic, eustatic and climatic changes that the N orth S ea and its margins have undergone. While the N orth S ea has been mapped locally, we present the first regional mapping of the C enozoic sedimentary strata. Our study provides a new regional sub‐division of the main seismic units in the N orth S ea together with maps of depocentres, influx direction and source areas. Our study provides a regional synthesis of sedimentation based on a comprehensive interpretation of a regionally covering reflection seismic data set. We relate observations of sediment characteristics and unconformities to the geological evolution. The timing, regional expression and stratigraphic characteristics of many unconformities indicate that they were generated by eustatic sea‐level fall, often in conjunction with other processes. Early C enozoic unconformities, however, relate to tectonism associated with the opening of the N orth A tlantic. From observation on a regional scale, we infer that the sediment influx into the N orth S ea during the C enozoic is more complex than previously suggested clockwise rotation from early northwestern to late southern sources. The S hetland P latform supplied sediment continuously, although at varying rates, until the latest C enozoic. Sedimentation around N orway changed from early C enozoic influx from the southwestern margin, to almost exclusively from the southern margin in the O ligocene and from all of southern N orway in the latest C enozoic. Thick E ocene deposits in the C entral G raben are sourced mainly from a western and a likely southern source, indicating that prominent influx from the south did not only occur from the mid‐ M iocene onwards. We infer a new age for the increased progradational sediment influx in the P leistocene of 2.5 Ma, coeval with F ennoscandian glaciation.