| dc.description.abstract | Detailed 3-D seismic analysis of the F6 block was carried out to evaluate the tectonostratigraphic history of the margin of the Dutch Central Graben during the Late Jurassic. Isopach and attribute mapping suggests that the basin physiography, sediment accumulation and sediment transport directions were significantly controlled by active tectonics in the NE part of the Dutch Central Graben.
Ten seismic stratigraphic units are defined and enabled to study thickness distributions of intra-Upper Jurassic intervals in 3-D, which provide insights into the paleotopographic effects on sedimentation, as well as the evolution of differential subsidence in space and time. Seismic attribute analysis was carried out and revealed several tectonically influenced sedimentary elements that provide information about varying sediment transport directions and rate of structural control. With the aid of palynological data, sedimentation rates were estimated for each defined unit in order to constrain the overall subsidence evolution during the deposition of the Upper Jurassic growth units.
Stratigraphic thickness distributions show high variability of differential subsidence during the deposition of the Lower-, Middle-, and Upper Graben Formations. In contrast, the subsidence is occurring at a broader scale during the deposition of the Kimmeridge Clay Formation.
For the first time, several fluvial channels and small deltas have been clearly imaged using attribute mapping in the Lower Graben Formation and at the base of Middle Graben Formation. These features show east to west, transverse sediment transport direction from the basin margin to the basin axis. An extensive channel-delta system in the Upper Graben Formation suggests SE to NW sediment transport direction and fluvio-deltaic sedimentary development. A submarine channel was detected in the lower part of Kimmeridge Clay Formation, while slumps and a potential deepwater slope fans are interpreted in the upper part of the Kimmeridge Clay Formation.
Estimated sedimentation rates of the purely seismically defined intra-Upper Jurassic stratigraphic units suggest four phases of subsidence during the deposition of the Upper Jurassic units. High values during the deposition of the Lower Graben Formation and the middle Kimmeridge Clay Formation are in contrast with low values for the Middle- and Upper Graben Formations, earliest and latest Kimmeridge Clay Formation and the Scruff Greensand Formation.
Integration of seismic horizon, isopach and attribute mapping combined with sedimentation rate quantification allowed to further constrain the relation between paleo-topographic features, controlled by active structures, and depositional systems in the Dutch Central Graben and highlight the potential for detailed stratigraphic/structural analysis. | |
