Architecture of shoreface to deep-water systems in segmented rift systems: Evidence from the southern margin of the Sogn Graben, northern North Sea

Abstract

The spatial distribution of syn-rift deposits and temporal evolution of sandy gravity flows in the context of rift segmentation are poorly constrained. Based on conventional core description, well log analysis, and 3D seismic interpretation, this study focuses on the Upper Jurassic successions in the southern margin of the Sogn Graben, northern North Sea. Thirteen facies associations are classified in order to discuss the architecture of shoreface, gravity-driven submarine fans, and basin-plain deposits on the scale of centimeters to meters. In the eastern part of the study area, gamma-ray log stacking patterns suggest that northeast–southwest oriented shoreface successions underwent progradational-to-retrogradational deposition during the Oxfordian age. Lithological description of conventional cores indicates that large submarine fan system formed by debris-flow-dominated channels and turbidity-flow-dominated lobe complexes covers a broad (22 × 20 km) depositional area. The entry of regional drainages and the location of sandy gravity flow deposits were controlled by first-order rift segmentation, whereas the route of submarine canyon feeder system and the orientation of submarine fan lobes were determined by second-order rift segmentation. Thus, both first-order and second-order rift segmentation should be considered when determining the sedimentary facies and depositional architecture of sandy gravity flow deposits in individual rift segments. • Upper Jurassic shoreface and sandy gravity-flow deposits are described. • First-order rift segmentation controls drainage entry points and gravity-flow locations. • Second-order rift segmentation determines feeder system and fan-lobe orientation. • Sedimentation in segmented rift system is compared with non-segmented rift system.