SLOAN, BENJAMIN J., MARTIN B. LAGOE, and WILLIAM E. GALLOWAY, Department of Geological Sciences, University of Texas at Austin, Austin, TX

ABSTRACT: Foraminiferal Analyses as Constraints on Sequence Stratigraphic Interpretations, North Sea Basin

Eocene siliciclastics of the North Sea Basin have been divided into five stratigraphic sequences regionally correlated on reflection seismic and well log data. These include: a sand-rich, onlapping lower Eocene unit; two middle Eocene mud-prone outbuildings from the Moray Firth area; a middle to upper Eocene basin-centered amalgamation of muddy and sandy slump deposits; and a regressive, coarse-grained upper Eocene prism of sediments perched on the easternmost East Shetland Platform.

Ditch samples have been acquired from wells located in an outer shelf position on the eastern margin of the Shetland Platform intersecting all five sequences. Picked samples allow correlation of interpreted sequences to established foraminiferal biostratigraphies, providing confirmation of sequence ages ranging from Ypresian to Priabonian. Trends in faunal abundance suggest the location of several condensed intervals, only some of which coincide with those identified regionally on well logs; others are considered locally developed. Biofacies analysis reveals an interplay of calcareous and agglutinated forms, attributed to changing paleoenvironment and paleoceanography. These are related to changes in sediment supply rateand texture and relative sea level, as predicted by sequence stra igraphic analysis, and such paleoceanographic factors as currents and dissolved oxygen, which are less easily interpreted using seismic or well log data.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.