HR: 15:25h
AN: T33D-08    [Abstracts]
TI: Constraints on post Mid-Jurassic basin evolution in the North Sea from 3D numerical modelling of basin initiation and subsidence.
AU: * Petersen, K D
EM: kenni@geo.au.dk
AF: Department of Earth Science, The University of Aarhus, Hoegh-Guldbergsgade 2, Aarhus C, 8000, Denmark
AU: Nielsen, S B
EM: sbn@geo.au.dk
AF: Department of Earth Science, The University of Aarhus, Hoegh-Guldbergsgade 2, Aarhus C, 8000, Denmark
AB: The North Sea sedimentary basin contains more than 3km of post Mid-Jurassic sediments. These are located in a trilete graben system consisting of the Moray Firth and the Viking and Central grabens, but also in a broad region surrounding the grabens, corresponding to the post-mid Cretaceous sediment deposits During the Mid- Jurassic the area was exposed to volcanism, domal regional uplift and erosion, followed by crustal thinning and normal faulting in the grabens. We use a numerical model considering 3D thermal evolution, flexural isostasy, erosion, sedimentation and compaction together with isopach data to simulate the geodynamic evolution of the area since the Mid-Jurassic. Our modelling studies show that the broad distribution of post Jurassic sediments cannot be explained by uniform stretching in the graben areas alone. Regional Mid-Jurassic thinning of the subcrustal lithosphere producing first uplift and erosion and later accommodation space for Cretaceous and Cenozoic sediments is also required. The uniform crustal thinning factor in the grabens amounts to a maximum of 1.14. The required subcrustal lithospheric thinning amounts to about 15 km. Our results are in accordance with observations from recent rift systems such as the Rhine Graben, Eastern Africa and the Baikal Rift, which show that crustal thinning is restricted to the graben areas while thinning of the subcrustal lithosphere (up to 100 km) and the associated domal surface uplift are more regionally distributed.
DE: 1744 Tectonophysics
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 8020 Mechanics, theory, and modeling
DE: 9611 Jurassic
SC: Tectonophysics [T]
MN: 2007 Fall Meeting