No abstract

This paper presents the results of a cross-border study of the Middle Jurassic-Early Cretaceous rift phase in the Danish-German-Dutch Central Graben area. Based on long-distance correlations of palynologically interpreted wells, a stepwise basin evolution pattern was determined. Four phases are defined and described as tectonostratigraphic mega-sequences (TMS). The TMS are governed by changes in the tectonic regime. TMS-1 reflects the onset of rifting, triggered by regional east-west extension. Rift climax was reached during TMS-1, reflected by thick mudstone accumulations. TMS-2 reflects a change in the tectonic regime from east-west to NE-SW extension. NW-SE-trending normal faults became active during this phase, switching the depocentres from the graben axis into adjacent basins. TMS-3 displays divergent basin development. In the Dutch Central Graben area, it is characterized by a basal unconformity and widespread sandstone deposition, indicating continued salt and fault activity. Organic-rich mudstone deposition prevails in the Danish and German Central Graben area, indicating sediment starvation and water-mass stratification. With TMS-4 the rift phase ended, reflected by regionally uniform mudstone deposition. The basin evolution model presented here coherently places the lithostratigraphic units occurring in a stratigraphic framework and provides a valuable basis for hydrocarbon exploration activities in the region.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.

The Middle Jurassic-Lower Cretaceous in the eastern Dutch offshore provides excellent examples of sand-rich sediments that locally accumulated in the vicinity of rift basin margins affected by salt tectonics. These types of deposits are often geographically restricted and difficult to identify, but can be valuable targets for hydrocarbon exploration. The distribution, thickness and preservation potential of fluvio-lacustrine, shallow-and deep-marine sediments is discussed to provide new insights into the regional and local tectonostratigraphy of the Dutch Central Graben, the Terschelling Basin and their neighbouring platforms. New sedimentological, geochemical, biostratigraphic, stratigraphic and structural information have been analysed and integrated into a new tectonostratigraphic model for the Callovian Lower Graben Formation, Oxfordian Middle and Upper Graben formations, Early-Middle Volgian Terschelling Sandstone and Noordvaarder members, and the Late VolgianEarly Ryazanian Scruff Greensand Formation. It is demonstrated that salt withdrawal at the basin axis was the primary control on the generation of high accommodation during the Callovian-Early Kimmeridgian. Incised valleys developed on the platforms providing lateral sediment input. During the Late Kimmeridgian-Ryazanian salt migration shifted laterally towards the basin margins, providing accommodation adjacent to active salt bodies and deposition of overthickened sandy strata.

Cover images: from top left clockwise: (a) Outcrop photograph of the thinning-upward sheet sandstones, Lower Pennsylvanian Jackfork Group, Baumgartner Quarry, Arkansas. (b and c) Core photograph and image log are from the Upper Cretaceous Dad Sandstone, Lewis Shale, Wyoming. Images are from the CSM Strat Text #61 core (Chapters 6, 7, 12). (d) Seismic profile across the Marlim Field, Campos Basin (Chapter 15). Figure courtesy of Carlos Bruhn and AAPG. (e) 3-D image of the reservoir interval at the Thunder Horse and Thunder Horse North Fields, northern deep Gulf of Mexico. Surface dipping to lower right shows the top reservoir interval. Allochthonous salt body and the three well paths are shown. Figure is courtesy of Cindy Yeilding and BP. (f) Schematic 3-D block diagram of a migrating channel levee-system (Chapter 7). Figure is courtesy of Mike Roberts (g) Wireline log from offshore Angola (Chapters 6-9). Figure is courtesy of Gulf Coast Section SEPM Foundation.

No abstract