Automated Thermo-Tectono-Stratigraphic Basin Reconstruction - Examples from the Norwegian Sea and North Sea

Lars Rupke¹, Daniel W. Schmid², Stefan M. Schmalholz³, and Yuri Y. Podladchikov^2
1The Future Ocean, IFM-GEOMAR, Kiel, Germany
²Physics of Geological Processes, Oslo University, Oslo, Norway
³Geological Institute, ETH, Zurich, Switzerland

Computational analysis is a powerful tool for understanding the evolution of rifted margins and sedimentary basins. Models are, however, only as good as the input and reference data on which they are based. A key fitting parameter is the seismically observed stratigraphy. We present an algorithm for the automated inversion of stratigraphy for crustal stretching, mantle stretching, and paleobathimetry. The method is based on the coupling a 2-D thermo-tectono-stratigraphic forward model to an inverse scheme that updates the model parameters. The forward model solves for lithospheric thinning, flexural isostasy, sediment deposition, transient heat flow and mineral phase transformations. Metamorphic phase changes are implemented by precomputing density maps in P-T-X space. The inverse model updates the crustal and mantle thinning factors and paleo-water depth until the input stratigraphy is fitted to a desired accuracy. Both models combined allow for automated forward modeling of the structural and thermal evolution of sedimentary basins.

The potential and robustness of this method is demonstrated through two case studies. In the first case study, we apply the algorithm to the well studied Viking Graben. This study demonstrates how multiple datasets (e.g. stratigraphy, well temperature, vitrinite reflectance) can be integrated into the autmomated inversion. The second case study addresses the structural and thermal evolution of the Voring basin in the Norwegian Sea. A striking feature of the Voring basin is an uplift event accompanied by erosion during the last rifting phase prior to break-up. We show how the presented algorithm can be used to test different scenarios for this late syn-rift uplift event. Two end-members will be discussed: a 'hot' model where uplift is induced by extreme mantle thinning and a 'cold' model where uplift results from mantle phase transitions.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas