High-frequency sequence stratigraphy of upper cenozoic deposits in the central and southeastern North Sea areas

During late Cenozoic times, southwestward prograding deposits filled in the central and southern part of the epicontinental North Sea Basin. The Ringkøbing-Fyn High acted as a topographical high partly separating the central and southeastern North Sea into two embayments, which were connected towards the west by a deeper seaway located in the Central Graben area. The stratal geometry deduced from seismic sections indicates different basin physiography, subsidence rates, and sediment influx between the two embayments. Eustatic sea-level cycles of several frequencies interacted with low subsidence rates in the southern embayment to generate composite relative sea-level cycles each composed of relative sea-level cycles of higher frequencies. Forty-five Upper Cenozoic sequences are identified in the southern embayment, whereas only 21 sequences are recognized in the northern embayment. Major hiati and intervals of starved sedimentation may therefore be present in the northern embayment. The sequences stack into nine composite sequences, each reflecting a depositional cycle representing lowstand succeeded by transgressive/highstand conditions. In general, a composite sequence is characterized by a period of increasing sediment accumulation rates.