KONTIKI Final Report, CONTInental Crust and Heat Generation In 3D
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The KONTIKI final report summarises the results from the three-year KONTIKI project (CONTInental Crust and Heat Generation In 3D) established by NGU and StatoilHydro to improve the understanding of heat flow along the Norwegian continental margin. A compilation of c. 4000 new and old geochemical data is used to produce the first map of radiogenic heat production in bedrock, covering large tracts of Norway. In general granitic rocks have higher heat production than intermediate and mafic rocks. Sedimentary rocks display variation in heat production that can be ascribed to sedimentary processes. Age and metamorphic grade do not appear to affect heat production significantly, whereas tectonic setting appears to impart some effect in that extensional or within-plate rocks have higher heat production than similar rocks formed along plate margins. A total of 11 deep wells (c. 350-1000 m) have been established for temperature logging and heat flow calculations in mainland Norway. Calculated palaeoclimatic corrections range fro +2 to +9 mW\/m2 (i.e. 5-20% of original heat flow values). The new heat flow map shows that heat flow values in Norway are much higher than previously proposed. The two most robust features on the map are the relatively high and low heat flows in the Oslo Region and Nordland respectively. New geochronological data from basement samples from the North Sea and Norwegian Sea show that the upper basement to a large degree consists of magmatic and metasedimentary rocks that can be correlated with rocks in tectonostratigraphically high (i.e. Upper and Uppermost Allochthons) nappes within the Scandinavian Caledonides. Both 3D crustal and thermal models have been produced from the Mid-Norwegian continental margin. Our 3D modelling suggests that substantial heat flow variations between 35 and 65 mW\/m2 occur at the base of the sedimentary basins in the inner parts of the mid-Norwegian Margin. We show that the structure and nature of the basement underlying these basins are the most likely factors influencing heat flow variations at typical wavelengths of 10s to 100s of km. One of the major outcomes of the modelling and the heat flow and heat production data collected on land, is that the Moho heat flow should range in between 30 to 40 mW\/m2, a value in the lower part of this range being the preferred one. The temperature of the outer Nid-Norwegian margin is lower than previously assumed and the petroleum potential of the area should be considered.