Mapping the bathymetric evolution of the Northern North Sea: from Jurassic synrift archipelago through Cretaceous–Tertiary post-rift subsidence

Abstract

The post-rift history of the North Viking Graben has been backstripped in 3D, producing a sequence of palaeobathymetric maps that culminates at the Late Jurassic synrift stage. The backstripping takes into account the three main processes which drive post-rift basin development: thermal subsidence, flexural-isostatic loading and sediment compaction. Before backstripping was performed, the Norwegian Trench, a bathymetric feature within the present-day seabed, was smoothed in order to remove associated decompaction artefacts within the backstripping results. Palaeobathymetric restorations at the top and base of the Paleocene take into account regional transient dynamic uplift, probably related to the Iceland Plume. 350 m of uplift is incorporated at the Base Tertiary (65 Ma) and 300 m at the Top Balder Formation (54 Ma), followed by rapid collapse of this same uplift. At the top of the Lower Cretaceous (98.9 Ma), very localized fault-block topography, inherited from the Jurassic rift, is predicted to have remained emergent within the basin. At the Base Cretaceous (140 Ma), the fault-block topography is much more prominent and numerous isolated footwall islands are shown to have been present. At the Late Jurassic synrift stage (155 Ma), these islands are linked to form emergent island chains along the footwalls of all of the major faults. This is the Jurassic archipelago, the islands of which were the products of synrift footwall uplift. The predicted magnitude and distribution of footwall emergence calibrates well against available well data and published stratigraphic information, providing important constraints on the reliability of the results.

Quantitative analysis of a footwall‐scarp degradation complex and syn‐rift stratigraphic architecture, Exmouth Plateau, NW Shelf, offshore Australia

“…Our interpretation is consistent with large‐scale, palaeogeographic maps from the J30 sequence (Longley et al, 2002) that show deposition in narrow rift valleys and palaeo‐coastlines fringing exposed fault blocks. Similar scenarios of uplifted and exposed footwall highs and islands supplying hangingwall basins are interpreted in the Late Jurassic North Sea (Berger & Roberts, 1999; McArthur, Jolley, Hartley, Archer, & Lawrence, 2016; Nøttvedt et al, 2000; Roberts, Kusznir, Yielding, & Beeley, 2019; Yielding, Badley, & Roberts, 1992) and the Quaternary‐modern Aegean Sea (Papadopoulos & Pavlides, 1992; Stiros et al., 1994).…”

Syn‐rift sediment gravity flow deposition on a Late Jurassic fault‐terraced slope, northern North Sea

“…None of the wells penetrate coarse‐grained deep‐water deposits on the terraces. The uplifted eastern parts of the Horda Platform and the Ryggsteinen Ridge have been interpreted to have been footwall islands fringed by shoreface sands during a pronounced Tithonian sea‐level lowstand (Fraser et al., 2003; Roberts et al., 2019). Coarse‐grained sediment supply from the regional hinterland catchment ceased during SU5 as the Late Jurassic rift entered a phase of thermal cooling and a gradual rise of the relative sea level occurred throughout the late Tithonian (Fraser et al., 2003; Jackson et al., 2008).…”

Tectono‐stratigraphic development of a salt‐influenced rift margin: Halten Terrace, offshore Mid‐Norway

“…The VFC continued to grow via tip propagation, resulting in breaching of the basin‐margin monocline and the formation of a surface‐breaching normal fault that drove uplift its footwall and the formation of a hangingwall half‐graben (Figure 15b). Uplift caused sub‐aerial exposure and erosion of the immediate crest of the footwall of VFC, which at this time likely represented an intra‐rift island (Bell et al., 2014; Roberts et al., 2019; Roberts & Yielding, 1991; Yielding, 1990). Some of the sediment derived from erosion of the VFC footwall will have been transported eastwards onto the hangingwall dipslope, likely deposited in shallow marine‐to‐shelfal environments fringing an intra‐rift island (Figure 15b).…”