Northern North Atlantic

The Norwegian - Greenland Sea extends from Iceland to the Fram Straits (Fig. 1) and can be divided into a number of tectono-sedimentary provinces controlled by the transform-ridge system. Sediments immediately north of Iceland are up to 1 km thick but thin rapidly to less than 200 m thick in ponded areas along the remainder of the Kolbensey Ridge to the Jan Mayen Fracture Zone. Quaternary sediments on the southeast Greenland margin are up to 2.5 km thick and overlie at least 4 km thick Tertiary and Mesozoic sediments. Sediments on the Jan Mayen Ridge are up to 3 km thick. Sediment thickness variation in the Lofoten and Greenland Basins is characteristic of passive continental margins with thickest sediments along the continental slope and gradually thinning toward the ridge.

The Norwegian margin developed during continental rifting between Laurentia and Eurasia, which culminated in Late-Paleocene/Early Eocene breakup (Skogseid et al., in press). Due to the Iceland hotspot mantle temperatures were increased during rifting and break-up, leading to extensive volcanism (Eldholm et al., 1989). The mid-Norwegian margin consists of three rifted margin segments (from south to north): the More Margin, the Voring Margin, and the Lofoten-Vesteralen Margin, and an approximately 200 km long sheared margin segment which constitutes the southern boundary of the Voring Margin (Figure 1). Extension of the entire area stopped after continental break-up, and apart from minor Tertiary doming the area became tectonically quiet. Doming focussed along the shelf break and is manifest as the Helland Hansen Arch and the Naglfar, Vema and Ormen Lange domes. The proposed mechanisms for these domes include ridge-push and differential compaction and asymmetric sedimentation (Dore et al., 1997; Vagnes, 1997). Whereas Eocene to Miocene sedimentation along the margin was moderate, Pliocene and Quaternary glaciations increased sediment input, and led to an up to 2 km thick wedge of clastic sediments east of the dome structures. After the last glacial maximum sedimentation on the mid-Norwegian margin was dominated by submarine mass-wasting (Vorren et al., 1998) potentially triggered by earthquakes and gas hydrate dissociation due to climate change (Bugge et al., 1988; Mienert et al., in press).

The Barents Sea is an epicontinental sea extending between Norway and the Svalbard archipelago. It is bounded by Cenozoic passive margins in the north and west. The margin north of Svalbard is a volcanic rifted margin with related igneous intrusions reaching far south into the Barents Sea. The western margin of the Barents Sea is a sheared margin (Eldholm, 1987; Faleide et al., 1991, 1993). Wrench tectonics and an opening component to the predominantly shear setting resulted in complex deformation of the southwestern Barents Sea (Ronnevik & Jacobsen, 1984; Riis et al, 1986, Gabrielsen & Fajrseth, 1988).

The sedimentary strata above the Paleozoic basement comprise an almost complete sequence of sedimentary strata from the Late Paleozoic to the Quaternary (Faleide et al., 1993; Gudlaugsson et al., 1997). However, Neogene uplift and Pliocene-Pleistocene glaciations caused severe erosion of the inner parts of the Barents Sea. Two depocenters developed in the adjacent Norwegian-Greenland: the Bjorneya Fan south of Bj0rn0ya and the Storfjorden Fan north of it. More than half of the sediments in these fans was deposited during the last 3 Ma (Eidvin et al., 1993; Saettem et al., 1994; Faleide et al., 1996, Elverhoi et al., 1998).

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