A foraminiferal biostratigraphy of the Upper Cretaceous of the southern North Sea Basin (UK sector)
The Cenomanian to Maastrictian foraminifera have been studied from borehole material (ditchcuttings) of three wells - 44/2-1,49/19-1 and 49/20-2 - drilled by Shell (UK) Exploration & Production Ltd in the Southern North Sea Basin. The microfaunas have been utilized in the formulation of a zonal scheme comprising twelve foraminiferal biozones based on 'tops' (highest occurrences) of selected taxa; the taxonomy of the stratigraphically diagnostic forms is briefly discussed. The major lithostratigraphic units of the Dutch and British sectors of the Upper Cretaceous of the Southern North Sea Basin are recognised from Gamma Ray and Formation Density wireline log signitures (where available); these are the Chalk Group and the Texel and Ommelanden Formations. . The biozones are related to the lithostratigraphic units in the three well sections and these are correlated across the Southern North Sea Basin. The dating and correlation of the sequences shows significant differences in thicknesses to exist between the sections; these are tentatively related to position relative to 'palaeo-highs', differential subsidence and/or uplift along inversion axes in the area.