Mesozoic and Cenozoic basin configurations in the North Sea - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 417

Mesozoic and Cenozoic basin configurations in the North Sea
ERLEND MORISBAK JARSVE, JAN INGE FALEIDE, ROY HELGE GABRIELSEN
and JOHAN PETTER NYSTUEN
Department of Geology, University of Oslo, P.O. Box 1047, Blindern, N-0316 Oslo, Norway
(E-mail: [e-mail])
ABSTRACT
The North Sea Basin system is the result of repeated episodes of extension and
differential subsidence. In order to inspect changes in style, geometry and basin infill
dynamics of basin development in relation to source-to-sink relationships, a series of
2D seismic sections have been studied. This study shows the spatial distribution of
source and sink areas in the North Sea area throughout the Late Mesozoic and Cenozoic
and, hence, periods of uplift and denudation of the hinterland. The results suggest
that the structural framework in the North Sea Basin can be divided into four main
basin configurations in Late Mesozoic and Cenozoic times. The tectonic episodes
were associated with asymmetrical uplift and erosion of the basin flanks, resulting in
temporal, asymmetric, basin configuration. The later basin configurations of the
Jurassic graben formation were characterised by a complex system of rotated fault
blocks and sub-basins, with infill sourced by sediments derived from the Norwegian
mainland. Parts of the sediments were trapped in structural lows at the Horda Platform,
Stord Basin and the Egersund Basin, whereas a considerable volume bypassed the
platform area. The Jurassic extension was followed by a typical post-rift development
where the earliest Cretaceous sedimentation was partly sourced from local, rotated,
fault blocks and uplifted areas at the margins of the basin system. This suggests that
the basin configuration, which had developed during the syn-rift stage in Late Jurassic,
prevailed throughout the early post-rift phase in Early Cretaceous. During the Late
Cretaceous the hitherto subaerially exposed margins eventually became drowned.
Thus, the subsidence pattern associated with the post-rift stage of the Jurassic to
Cretaceous North Sea Basin system, although interrupted by periods of uplift affecting
semi-regional and local parts of the basin system, can be traced throughout the
Cretaceous. Also, truncation of lower Cretaceous siliciclastics is observed within gra-
ben structures developed during the Late Jurassic syn-rift stage, which indicates denu-
dation of a substantial part of the North Sea area. However, from early Palaeogene
times, the basin system was characterised by a much wider subsidence area and also
by the development of migrating depocentres and uplift of source areas. A western
source area dominated in the Palaeogene, switching to a main eastern source area in
the Late Palaeogene and Neogene, concurrently with diachronous development of
accommodation space across the North Sea area, which continued to develop through-
out Neogene times. This indicates lithospheric processes acting on both the hinter-
land and the basin part of the north-western European continental plate; a structurally
coupled source-to-sink system.
Keywords: North Sea, basin configurations, differential subsidence, sequence
stratigraphy, structural geology.