by Alan M. Roberts, Nick J. Kusznir, Graham Yielding, and Hugh Beeley Mapping the bathymetric evolution of the Northern North Sea: from Jurassic synrift archipelago through Cretaceous–Tertiary post-rift subsidence by Alan M. Roberts, Nick J. Kusznir, Graham Yielding, and Hugh Beeley Petroleum Geoscience Volume ():petgeo2018-066 February 1, 2019 © 2019 The Author(s). Published by The Geological Society of London for GSL and EAGE

(a) Shaded-relief bathymetry/topography (Smith & Sandwell 1997; scale in metres) for the Northern North Sea, Faeroe Shetland Basin and southernmost Møre Basin. (a) Shaded-relief bathymetry/topography (Smith & Sandwell 1997; scale in metres) for the Northern North Sea, Faeroe Shetland Basin and southernmost Møre Basin. The main study area of interest (AOI) of the North Viking Graben (NVG) is highlighted by an inset map of bathymetry (see also c). All maps in this paper are georeferenced by coordinates (m) within UTM Zone 31N. (b) The main Late Jurassic structural elements of the Northern North Sea, locating the NVG (after Zanella & Coward 2003, fig.4.4b). The main study area is in the magenta box. The UK–Norway offshore boundary is shown by a red line. (c) Present-day bathymetry of the NVG (see also a), highlighting the Quaternary erosional feature of the Norwegian Trench cutting into a regional background bathymetry of c. 100–200 m. (d) Smoothed bathymetry for the NVG, in which the Norwegian Trench has been ‘filled’ by extrapolating the contour trend from the west. (e) Thickness of sediment restored by smoothing the seabed. All depths/thicknesses are in metres. Alan M. Roberts et al. Petroleum Geoscience 2019;petgeo2018-066 © 2019 The Author(s). Published by The Geological Society of London for GSL and EAGE

Four cross-sections used as the basis for quantitative modelling in the Northern Viking Graben. Four cross-sections used as the basis for quantitative modelling in the Northern Viking Graben. (a) Marsden et al. 1990, Profile 1, along the Britoil NW–SE deep-seismic profile (Beach et al. 1987). (b) From Roberts et al. (1993b) and Kusznir et al. (1995), along west–east seismic line NNST-84-10. Reproduced here in colour. (c) Christiansson et al. 2000, Transect 1, along BIRPS NW–SE deep-seismic profile NSDP84-1 (Klemperer & Hobbs 1991). (d) NW–SE cross-section extracted from the grids used in the current study, located in Figure 4b. The seabed is the present-day unsmoothed seabed. V:H, vertical:horizontal. Alan M. Roberts et al. Petroleum Geoscience 2019;petgeo2018-066 © 2019 The Author(s). Published by The Geological Society of London for GSL and EAGE

A selection of the present-day stratigraphic input maps used for backstripping. A selection of the present-day stratigraphic input maps used for backstripping. See Table 1 for the full backstripped stratigraphy. (a) Top Balder Formation, 54 Ma. (b) Base Tertiary, 65 Ma. (c) Top Lower Cretaceous, 98.9 Ma. (d) Base Cretaceous, 140 Ma. (e) Interpolated Intra-Upper Jurassic synrift, approximating to the Top Heather Formation, 155 Ma. All depths are in metres. In the east the Top Balder and Base Tertiary surfaces are both eroded at the younger Base Quaternary surface. The maps here do not represent the true stratigraphic tops and therefore have a mask placed over them. Alan M. Roberts et al. Petroleum Geoscience 2019;petgeo2018-066 © 2019 The Author(s). Published by The Geological Society of London for GSL and EAGE

(a) Map of the stretching (β) factor for the Late Jurassic rift at 155 Ma, based on Roberts et al. (a) Map of the stretching (β) factor for the Late Jurassic rift at 155 Ma, based on Roberts et al. (1993b, fig. 8b), with subsequent updates. (b) Major structural features of the North Viking Graben and significant structural highs coincident with hydrocarbon fields, overlaid on the present-day Base Cretaceous map (Fig. 3d). Hydrocarbon fields: B, Brent; C, Cormorant; G, Gullfaks; H, Huldra; K, Knarr; M, Magnus; N, Ninian; O, Oseberg; Sn, Snorre; St, Statfjord; T, Troll; T/E, Tern/Eider; V, Visund; Z, Zeta Ridge. The blue line is the line of the extracted cross-sections in Figures 2d and 8. Alan M. Roberts et al. Petroleum Geoscience 2019;petgeo2018-066 © 2019 The Author(s). Published by The Geological Society of London for GSL and EAGE

(a) Backstripped palaeobathymetry at Top Balder (54 Ma), with no transient dynamic uplift. (a) Backstripped palaeobathymetry at Top Balder (54 Ma), with no transient dynamic uplift. (b) Backstripped palaeobathymetry at Top Balder (54 Ma), with 300 m of transient dynamic uplift. G, Gullfaks; ND, Ninian Delta. (c) Backstripped palaeobathymetry at Base Tertiary (65 Ma), with 350 m of transient dynamic uplift. (d) Backstripped palaeobathymetry at Base Tertiary (65 Ma), with no transient dynamic uplift. All depths are in metres. Alan M. Roberts et al. Petroleum Geoscience 2019;petgeo2018-066 © 2019 The Author(s). Published by The Geological Society of London for GSL and EAGE

(a) Backstripped palaeobathymetry at Top Lower Cretaceous (98 (a) Backstripped palaeobathymetry at Top Lower Cretaceous (98.9 Ma); note the local emergence at the crest of Gullfaks (G). (a) Backstripped palaeobathymetry at Top Lower Cretaceous (98.9 Ma); note the local emergence at the crest of Gullfaks (G). (b) Backstripped palaeobathymetry/topography at Base Cretaceous (140 Ma). Elements of the island archipelago remain. (c) Backstripped palaeobathymetry/topography at the Late Jurassic synrift (155 Ma). The emergent island archipelago is at its maximum size. All depths/heights are in metres. Grey denotes predicted emergence. (d) Wells referred to in the text, overlaid on Base Cretaceous palaeobathymetry (b above). Alan M. Roberts et al. Petroleum Geoscience 2019;petgeo2018-066 © 2019 The Author(s). Published by The Geological Society of London for GSL and EAGE

Illuminated 3D perspective displays (with 7 Illuminated 3D perspective displays (with 7.5:1 vertical exaggeration) of: (a) backstripped palaeobathymetry at Top Lower Cretaceous (98.9 Ma: Fig. 6a); (b) backstripped palaeobathymetry/topography at Base Cretaceous (140 Ma: Fig. 6b); and (c) backstripped palaeobathymetry/topography at the Late Jurassic synrift (155 Ma, Fig. 6c). Illuminated 3D perspective displays (with 7.5:1 vertical exaggeration) of: (a) backstripped palaeobathymetry at Top Lower Cretaceous (98.9 Ma: Fig. 6a); (b) backstripped palaeobathymetry/topography at Base Cretaceous (140 Ma: Fig. 6b); and (c) backstripped palaeobathymetry/topography at the Late Jurassic synrift (155 Ma, Fig. 6c). All depths/heights are in metres. Grey denotes predicted emergence. (d) Colour-coded Jurassic β factor (Fig. 4b) displayed on the backstripped topography of the Base Cretaceous (b above). The relationship between the β factor and rift structure can be seen in this display. Alan M. Roberts et al. Petroleum Geoscience 2019;petgeo2018-066 © 2019 The Author(s). Published by The Geological Society of London for GSL and EAGE

Three backstripped cross-sections extracted from the 3D results of the current study. Three backstripped cross-sections extracted from the 3D results of the current study. The original, present-day section is Figure 2d, located in Figure 4b. (a) Backstripped to Top Lower Cretaceous (Figs 6a and 7a). All structural highs on the section are below sea level. (b) Backstripped to Base Cretaceous (Figs 6b and 7b). Several structural highs are restored to, or just above, sea level. (c) Backstripped to Intra-Upper Jurassic synrift (Figs 6c and 7c). Several structural highs are emergent footwall islands with crests above sea level. Alan M. Roberts et al. Petroleum Geoscience 2019;petgeo2018-066 © 2019 The Author(s). Published by The Geological Society of London for GSL and EAGE