Bryan D. Ritchie1,
Rob L. Gawthorpe1,
John R. Underhill2,
Hugh G. Kerr3
(1) Manchester University, Manchester, United Kingdom
(2) Edinburgh University, Edinburgh, United Kingdom
(3) Mobil North Sea Ltd, Aberdeen, United Kingdom
Abstract: Three-dimensional deltaic sequence variability in the Paleogene of the Beryl Embayment (Quad 9, North Sea); observations and numerical modelling
A seismic sequence stratigraphic analysis of Paleogene strata in the Beryl Embayment reveals complex and highly variable deltaic geometries in three-dimensions. Extensive 3D seismic and well data allow the temporal and spatial variability of deltaic sedimentation in the prospective Paleogene strata to be determined. The deltaic interval is 200-350 m thick and extends over much of the East Shetland Platform and Beryl Embayment. Detailed analysis has identified distinct deltaic packages which vary in thickness and geometry along-strike reflecting the interplay of sediment supply and accommodation space. The earliest package is sheet-like, deposited mainly in the north of the Beryl Embayment and progrades over 15 km. Smaller, wedge-shaped packages are deposited at the front of the earlier delta and are identified by their onlap terminations against it. The main locus of deposition for the later wedges is further south.
A three-dimensional numerical model of deltaic deposition is used to investigate the controls on the Paleogene delta development. By varying the controlling processes such as sea-level change, basin subsidence and sediment supply, their influence on the geometries observed on the seismic data has been investigated. This has indicated that much of the complexity imaged in the Paleogene delta is due to the inherent three-dimensional nature of deltaic deposition.
The integration of the two methods leads to an improved understanding of the controls on deltaic deposition and sequence variability which has important implications for the application of the sequence stratigraphic methodology to many sedimentary basins.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana