Palaeocene uplift and Eocene subsidence in the northern North Sea Basin from 2D forward and reverse stratigraphic modelling

Abstract

Structural and stratigraphic basin modelling has been used to examine quantitatively the Cretaceous and Tertiary post-rift subsidence history of the northern North Sea Basin following Late Jurassic extension. 2D forward and reverse, syn-rift and post-rift modelling has been used to determine the magnitude and timing of departures from the McKenzie post-rift thermal subsidence trend for regional stratigraphic profiles in the Outer Moray Firth, the South Viking Graben and the North Viking Graben. Observed stratigraphy has been reverse post-rift modelled using flexural backstripping combined with decompaction and reverse thermal subsidence calculations, and forward modelled through the syn-rift and post-rift period using the flexural cantilever model of continental rift basin formation. Long-term global eustasy has been included in the analysis. Only reliable palaeobathymetric markers, such as erosion surfaces and coals, have been used to constrain subsidence history. Both forward and reverse 2D modelling show that a Palaeocene regional uplift followed by a rapid Eocene subsidence must be superimposed on McKenzie post-rift Cretaceous and Tertiary basement subsidence in order to generate the stratigraphy observed. The magnitude of Palaeocene uplift deduced from modelling was of the order of 375 m in the Outer Moray Firth (central North Sea) increasing to 525 m in the North Viking Graben (northern North Sea). Rapid Early Eocene subsidence was of the order of 160–310 m. The most likely mechanism for regional Palaeocene uplift and rapid Eocene subsidence in the northern North Sea was the Palaeocene development of the Iceland plume situated at a distance of 700–900 km from the study area in the Early Tertiary. Forward and reverse modelling predict axial bathymetries in the graben of up to 1300 m for the Early Cretaceous and 900 m for the Upper Cretaceous. The large palaeobathymetries at the end of the Cretaceous provided much of the accommodation space for Tertiary sedimentation.

Quaternary uplift of northern England

“…This 'traditional' viewpoint was fundamentally challenged from the late 1980s onwards by fission-track dating studies (e.g., Green, 1986Green, , 1989Green, , 2002Brown, 1991;Lewis et al, 1992;Green et al, 1995;Holliday, 1993;McCulloch, 1994;Japsen 1997;Hillis et al, 2008), which indicate that up to~2 km of cover has been eroded from northern England since the start of the Cenozoic. Numerical modelling studies (e.g., Brodie and White, 1994;Nadin and Kusznir, 1995;White and Lovell, 1997) later tried to develop this story by suggesting that this phase of Cenozoic erosion was initiated by uplift caused by the heating effect of the Iceland mantle plume. This view seems entirely reasonable.…”

Kinematics of Polygonal Fault Systems: Observations from the Northern North Sea

“…The post-rift sag phase began in the Early Cretaceous, marking the transition from faultto thermally-controlled subsidence (Joy, 1993;Jordt et al, 2000;Kyrkjebø et al, 2001;Faleide et al, 2002). Subsequently, the North Viking Graben has undergone two major uplift events: (1) an early Palaeocene phase related to rifting, magmatism, and the break-up of the NE Atlantic (e.g., Nadin and Kusznir, 1995); and (2) a middle Miocene phase, possibly related to long-wavelength doming during regional compression (e.g., Løseth et al, 2013).…”

Anomalous Cenozoic subsidence along the ‘passive’ continental margin from Ireland to mid-Norway

“…Departures from the predicted amounts of post-rift subsidence were also recognised using backstripping techniques (e.g. Nadin and Kusznir, 1995;Nadin et al, 1997;Clift and Turner, 1998). The subsidence anomalies of the NW European margin have been attributed to various syn-to post-rift tectonic mechanisms, mainly in the context of a mantle plume postulated to occur beneath the Iceland hotspot (White, 1988;White and McKenzie, 1989).…”