The Norwegian Sea

In the Norwegian Sea we have studied the geohistory, the tectonic development, effects of intra plate stress, the temperature history and the effects of sill emplacement and magmatic underplating on the temperature history and maturation in the Vøring area (cf. Fjeldskaar et al., 2003, 2008, 2009; Grunnaleite et al., 2009; Wangen et al. 2008).

The  mid-Norwegian  shelf  has  undergone  a  complex  geological history since Late Mesozoic time with dramatic changes in processes associated with large variety (both in time and space) of stresses affecting the area. A Jurassic–Early Cretaceous extensional phase was followed by a long period of strong post-rift subsidence. The break-up of the North Atlantic started at the Paleocene–Eocene transition with strong volcanism and development of the volcanic Vøring- and Møre-Marginal Highs between the outer basin areas and the developing oceanic  crust.  The  opening  history  of  the  North  Atlantic  involved volcanism on both sides of the Atlantic and creation of large volcanic provinces and marginal highs along the continent–ocean transition both on the Greenland side and along the margins of Møre Basin and Vøring Basin and evolution of the Vestbakken Volcanic Province in the Barents Sea in Early Tertiary time. A hotspot model for volcanism had been suggested since the sixties and a model was presented by White (1988) indicating a lower mantle plume rising near Iceland, heating and uplifting areas in a radius of 2000 km. This model has been used and discussed by many later authors.

Swarms of sill intrusions and possibly larger volcanic bodies were emplaced in the lower crust within the western part of the basins which led to heating (Fjeldskaar et al., 2009) and strong thermal uplift of  the  western  and  central  part  of  the  basins.  Thermal  cooling followed, and the marginal highs and the western basin areas were again subsiding. Modelling of Ocean Bottom Seismograph (OBS) data acquired off Lofoten and in the central part of the Vøring Basin demonstrated that the seismic wide-angle technique by use of OBSs provide important constraints on the crustal structure and distributions of magmatic material emplaced in the sedimentary layers, as well as high-velocity bodies in the lower crust. If the high-velocity body is a magmatic underplating, it will have temperature effects in the basins (see below); this was investigated by Fjeldskaar et al., 2003; 2009. See also www.voetec.com for more info on previous research in the Vøring area.

Calculated temperature effect in the sediments caused by magmatic underplating (red body) over Vøring Basin - at 0.5 Ma, 2.5 Ma and 9 Ma after the intrusion (yellow colour is 100 deg C).