Mid‐Palaeocene palaeogeography of the eastern North Sea basin: integrating geological evidence and 3D geodynamic modelling

Abstract

The Mid‐Palaeocene palaeogeography of Denmark and the surrounding areas have been reconstructed on the basis of published geological data integrated with 3D geodynamic modelling. The use of numerical modelling enables quantitative testing of scenarios based on geological input alone and thus helps constrain likely palaeo‐water depths in areas where the geological data are inconclusive or incomplete. The interpretation of large‐scale erosional valleys and small‐scale circular depressions at the Mid‐Palaeocene Top Chalk surface in the Norwegian–Danish basin as either submarine or subaerial features is enigmatic and has strong implications for palaeogeographical reconstructions of the eastern North Sea basin. A 3D thermo‐mechanical model is employed in order to constrain the likely palaeo‐water depths of the eastern North Sea basin during the Palaeocene. The model treats the lithosphere as an elasto‐visco‐plastic continuum and models the lithospheric response to the regional stress field and thermal structure. The model includes the effects of sea‐level change, sedimentation and erosion, from the Mid Cretaceous to the present. Modelling results reproduce to first order geological data such as present sediment isopachs and palaeo‐water depths. It is concluded that the Mid Palaeocene water depths in the Norwegian–Danish basin were about 250 m. The erosional valleys and circular depressions at the top of the Upper Cretaceous‐Danian Chalk Group are thus interpreted to have formed in relatively deep water rather than due to subaerial exposure. Likely interpretations of the structures are therefore submarine valleys and pockmarks.

Fluid flow features in hydrocarbon plumbing systems: What do they tell us about the basin evolution?

“…In the eastern North Sea the Paleocene sand-filled Siri Canyon is associated with sand injections observed on core and seismic scale (Hamberg et al, 2007;Svendsen et al, 2010). Other fluid flow features in the central North Sea includes pockmarks and gas chimneys (Heggland, 1998;Gemmer et al, 2002). The features observed in the case studies from the North Sea include Late Cretaceous, Oligocene and Miocene sediment intrusions and extrusions, and Oligocene and Miocene pockmarks (Fig.…”

Cenozoic uplift and denudation of southern Norway: insights from the North Sea Basin

“…This topography probably coincided with the Shetland Platform and the present-day Norwegian mainland. Some topography was probably also generated along the late Cretaceous and early Paleogene inversion zones (Ziegler 1990;Gemmer et al 2002). The elevation and relief of the topography of southern Norway and Shetland is difficult to constrain because of the absence of late Mesozoic and Cenozoic sediments, but a maximum elevation of the order of a few hundred metres above (palaeo-) sea level, gently sloping towards the shoreline with only minor local relief seems plausible.…”

Canyon-confined pockmarks on the western Niger Delta slope

“…They occur predominantly in fine-grained siliciclastic depositional settings, although a few case studies have been reported in carbonate settings (Gemmer et al, 2002;Judd and Hovland, 2007;Betzler et al, 2011). Seafloor depressions of variable sizes are also known to form from the expulsion of fluidized sediments from depth and the subsequent collapse of the overburden (e.g., Davies, 2003).…”