The Barents Sea is on the continental shelf surrounding the Arctic Ocean. It connects with the Norwegian Sea to the west and the Arctic Ocean to the north. Its contours are delineated by the continental slope between Norway and Spitsbergen to the west, the top of the continental slope towards the Arctic Ocean to the north, Novaya Zemlya archipelago to the east, and the coasts of both Norway and Russia to the south (see Figure 2.1.1). It covers an area of approximately 1.4 million km2, has an average depth of 230 m, and a maximum depth of about 500m at the western end of Bear Island Trough (Figure 2.1.1). Its topography is characterized by troughs and basins (300 m – 500m deep), separated by shallow bank areas, with depths ranging from 100-200 m. The three largest banks are Central Bank, Great Bank and Spitsbergen Bank. Several troughs over 300 m deep run from central Barents Sea to the northern (e.g. Franz Victoria Trough) and western (e.g. Bear Island Trough) continental shelf break. These troughs allow the influx of Atlantic waters to the central Barents Sea.
The Barents Sea area has undergone two major orogenic (mountain building) geologic episodes. The first was during the Caledonian orogeny (around 400 million years ago), the second around 240 million years ago during the Uralian orogeny. During the Caroniferous (350 mill years ago), rifting caused the formation of salt basins. Subsequent erosion and collapse of these orogenic belts produced an extensive shallow marine basin systems and delta deposits, and the Barents Sea area has been either an intra- or epi-continental sea since the late Palaeozoic. The structural geology of the Barents Sea is, therefore, a complex patchwork of basins and platforms, covered with thick layers of shallow marine sedimentary rocks from the late Palaeozoic onwards. Carbonates (limestone) and chert dominate the late Palaeozoic, with sands and shales dominating the Mesozoic and later rocks. Sedimentary rocks reach up 12km thick in the basins, with Triassic deposits alone reaching up to 8km thick (Dore, 1994).
Sedimentation and erosion patterns in the Pliocene (last million years) have alternated between strong localized erosion during glacial periods and slow marine sedimentation during inter-glacial periods. Seismic evidence indicates that the Barents Sea was completely glaciated several times during the Pliocene, with grounded ice reaching to the edge of the continental shelf at least 7 times (Andreassen et al., 2004). During the last ice age, which ended about 15,000 years ago, the Barents Sea was covered by grounded ice up to 2,000m thick. Ice cover in the Barents Sea was part of a larger ice sheet which covered north Russia, Scandinavia, parts of northern Europe, and possibly extending into the North Sea and northern and central Britain. The Barents Sea ice sheet was anchored to islands and shallow banks, with fast flowing ice-streams existing in major trough systems — a situation comparable to West Antarctic Ice Sheet today (Howell et al., 1999). Ice streams reached speeds of up to 1km/year, transporting considerable amounts of sediments off the continental shelf, resulting in the rapid growth of several large submarine fans, most notably at the mouth of Bear Island Trough (Howell and Siegert, 2000).
Marine life in the Barents Sea, as we know it today, stretches back to the end of the last ice age. There is a layer of post-glacial marine sediment deposited over older, pre-glacial sediments and bedrock. Thickness of this sediment layer varies over the entire sea, due to underwater topography, currents, and re-suspension. A major bottom mapping project, MAREANO http://www.mareano.no, is now in progress to produce detailed information on the structure and topography of the Barents Sea bottom and the benthic life.
