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The causal relationship between the Cenozoic sequence development in the southeastern North Sea Basin and sea-level changes, climatic fluctuations and tectonic events is unravelled by relating variations in the relative sea level and base level, based on interpretations of seismic surveys, to published δ 18 O variations and eustatic changes. The latter curve is based on the Earth's orbital forcing, and here informally termed as the GSI curve. The analysis shows that the Cenozoic sequence development in the southeastern North Sea was influenced by climatically and tectonically induced sea-level changes. The major Cenozoic sequence stratigraphic boundaries (lower order) are highly influenced by tectonic events, e.g. uplift of Fennoscandia and increased subsidence rates in the basin centre. Reactivation of Mesozoic fault zones controlled the deposition of minor sand bodies transported to the centre of the basin during the Late Palaeocene by mass flows. The location of an Oligocene mound structure, which constitutes part of a sequence, is controlled by the overall palaeotopography of the basin and local fault-related depressions. Correlation between (i) the ages of our sequences and the δ 18 O variations in the Oligocene succession, and (ii) the GSI curve and the base-level fluctuations of the late Miocene and younger sequences, show that the generation of the higher order sequence boundaries were driven by glacio-eustatic sea-level changes. A climatic control of the sequence formation due to glacio-eustatic sea level changes is therefore suggested for the Oligocene and Pliocene sequences, and probably also for the Upper Miocene sequences.

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The Upper Cenozoic deposits, which cover the "mid-Miocene unconformity" in the southeastern North Sea Basin are subdivided into thirty-one sequences. Progradation from the east to the west is observed. The lowstand systems tracts appear seismically as prograding wedges. The top lowstand surface is recognized as a toplap surface in areas where high-angle progradation dominates the stratal pattern, indicating the presence of a bypass zone formed during lowstand progradation. The maximum flooding surface is identified on logs as a maximum gamma ray peak, which separates an upward fining from an upward coarsening trend. The two trends represent the transgressive and the highstand systems tracts, respectively. Sequence boundaries are commonly associated with widespread erosion. The presence of both fluvial and submarine erosion is interpreted on the basis of the orientation of incision and the position of erosion relative to the depositional shoreline break of the preceding sequence. In Late Miocene times the Ringkøbing-Fyn High partly separated the southeastern North Sea into two embayments, which were connected by a deep seaway towards the west. Sediment accumulation rates seem to have culminated during periods with decreasing palaeo-temperatures. During relatively cold periods, the sequences were deposited as prograding wedges with a limited lateral extent. Two periods with maximum palaeotemperatures are time-equivalent with the two most distinct maximum flooding surfaces and intervals characterized by low sediment accumulation rates.