project was continued and finalized at the University of Bergen with Professor Rolf Mjelde as the supervisor. Throughout the whole project period colleagues from Tectonor have been involved, Dr. Willy Fjeldskaar as the main industrial supervisor and Drs. Ingrid Fjeldskaar Løtveit and Ivar Grunnaleite as co-supervisors. The motivation to carry out the present investigation is essentially due to my employment in Tectonor, an enterprise "providing specialized geological expertise to the petroleum exploration industry" (www.tectonor.com). Through the work for the company I was exposed to a number of geological problems, and it was interesting and educational to experience how challenges, faced by the oil and gas industry, raised questions where no clear answer could be found in the research literature. Among the questions surfacing in this way was if it was possible to predict fairly accurately how magmatic intrusions influences the petroleum potential in a sedimentary basin due to acceleration of the maturation of organic material in areas that otherwise would remain immature.

Magmatic intrusions affect the basin temperature in their vicinity. Faulting and physical properties of the basin may influence the magnitudes of their thermal effects and the potential source rock maturation. We present results from a sensitivity study of the most important factors affecting the thermal history in structurally complex sedimentary basins with magmatic sill intrusions. These factors are related to faulting, physical properties, and restoration methods: (1) fault displacement, (2) time span of faulting and deposition, (3) fault angle, (4) thermal conductivity and specific heat capacity, (5) basal heat flow and (6) restoration method. All modeling is performed on the same constructed clastic sedimentary profile containing one normal listric fault with one faulting event. Sills are modeled to intrude into either side of the fault zone with a temperature of 1000 • C. The results show that transient thermal effects may last up to several million years after fault slip. Thermal differences up to 40 • C could occur for sills intruding at time of fault slip, to sills intruding 10 million years later. We have shown that omitting the transient thermal effects of structural development in basins with magmatic intrusions may lead to over-or underestimation of the thermal effects of magmatic intrusions and ultimately the estimated maturation.

Many of the Earth’s sedimentary basins are affected by glaciations. Repeated glaciations over millions of years may have had a significant effect on the physical conditions in sedimentary basins and on basin structuring. This paper presents some of the major effects that ice sheets might have on sedimentary basins, and includes examples of quantifications of their significance. Among the most important effects are movements of the solid Earth caused by glacial loading and unloading, and the related flexural stresses. The driving factor of these movements is isostasy. Most of the production licenses on the Norwegian Continental Shelf are located inside the margin of the former Last Glacial Maximum (LGM) ice sheet. Isostatic modeling shows that sedimentary basins near the former ice margin can be tilted as much as 3 m/km which might significantly alter pathways of hydrocarbon migration. In an example from the SW Barents Sea we show that flexural stresses related to the isostatic uplift after LGM deglaciation can produce stress changes large enough to result in increased fracture-related permeability in the sedimentary basin, and lead to potential spillage of hydrocarbons out of potential reservoirs. The results demonstrate that future basin modeling should consider including the loading effect of glaciations when dealing with petroleum potential in former glaciated areas.