A regionally consistent 3D seismic-stratigraphic framework and age model for the Quaternary sediments of the northern North Sea

Abstract

The thick succession of Quaternary sediments that is preserved in the northern North Sea provides a valuable record of the climate and environmental changes of the last ∼2.6 million years. However, the general lack of chronological control on these sediments, combined with gaps in high-resolution seismic data coverage, has hindered our understanding of the detailed sediment infill history of this margin. Here we use a large (35,000 km2) high-resolution 3D seismic cube, supplemented by other 2D and 3D seismic datasets, to map more than 20 horizons within the Quaternary Naust Formation. We extend these horizons across large parts of the northern North Sea to establish a robust seismic framework that is used to assess the correspondence between existing chronostratigraphic ages. Whereas there is good agreement between most existing ages, the correlation of horizons between the Troll Field and the North Sea trough-mouth fan suggests that the sediments preserved at the base of the Norwegian Channel may have been deposited significantly later than assumed previously. Geomorphological forms preserved close to the base of the Norwegian Channel provide evidence for sediment disturbance by ice-stream activity, and document a two-stage glacial build-up during a mid-Pleistocene glaciation. We suggest a new age model for the Quaternary sediments of the northern North Sea, in which the deposition of sediments within the Norwegian Channel occurred as recently as 0.35 Ma in response to prior sediment loading and subsidence within the North Sea trough-mouth fan. In addition to providing new insights into the extent and timing of glacial events, the development of a regionally consistent 3D seismic-stratigraphic framework has implications for the age of the Peon gas discovery and for reconstructing spatial and temporal patterns of Quaternary sediment subsidence and fluid overpressure in the North Sea Basin.