3-D Geophysical Model of the Barents Sea and Characterization of Crustal Properties

Laura Marello and Jörg Ebbing
Geological Survey of Norway, NGU, Trondheim, Norway.

The tectonic setting of the Barents Sea continental shelf is the result of different tectonic phases which left their imprint in the distribution of physical properties and the geometries of the lithosphere. Here, we present a new 3D model for the density and magnetic properties of the Barents Sea area. The model has been defined using a large number of constraining data, e.g. seismic models (2D, 3D), petrophysical data and well information. The initial geometry was set up applying forward modelling technique and information of a seismic velocity model of the Barents Sea (http://www.norsar.no/seismology/barents3d/). The density distribution was defined using depth dependent velocity-density relations. The resulting 3D model provides the distribution of physical parameters for the entire region and allows defining different crustal units by the dependency of petrophysical parameters.

The magnetic field was used to refine the 3D model. Magnetic properties, densities and seismic velocities have not unambiguous relations. But magnetic inversion based on the geometry of the initial density model, allows investigating the magnetic susceptibility in the upper crust and to outline different magnetic provinces.

The combination of the inverse and forward models provides a refined basement map, and to define different domain as characterized by different properties in the upper crust. The 3D forward model provides now the geometry of the basement with a higher degree of confidence in areas where seismic data are not available.

The final 3D model has a resolution of 25 km. Maps of the top basement and Moho geometries illustrate the large differences over the study area and illustrate the regional Barents Sea crustal setting. The knowledge of the geometry and properties of the Barents Sea provides a basis for detailed evaluation of the geological hypothesis for the evolution of the Barents Sea.

AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia