The Cenozoic pre-glacial tectono-sedimentary development of the western Barents Sea margin: implications for uplift and erosion of the sediment source areas

Abstract

<p>The Cenozoic development of the western Barents Sea continental margin is strongly related to the rifting and seafloor spreading between Norway and Greenland. The margin is characterized by a series of highs and basins that formed as part of the development of a mega-transform zone. To the north, the Spitsbergen Fold and Thrust Belt and the Eocene clinoform development in the Central Basin that were initiated in the Paleocene Early Eocene are the evident of compression / transpression, and sediment erosion, transport and deposition respectively. At that time, the Vestbakken Volcanic Province and the Sørvestsnaget Basin to the south experienced a period of subsidence. A marginal high and an intra- basinal high in the Sørvestsnaget Basin, as well as the Senja Ridge and the Veslemøy High are identified as positive bathymetric features that acted as local source areas. Seismic data also shows a set of Eocene clinoform in the eastern part of the Sørvestsnaget Basin that probably was sourced from the Stappen High area. Available well data show an overall deep-water paleoenvironment during the Paleocene-Eocene in the south western Barents Sea, probably shallowing north of Bjørnøya. <p>During the Oligocene, a period of plate reorganization occurred that resulted in the onset of extension also in the north western Barents Sea including sea floor spreading west of Svalbard. Here, the Forlandsundet and Bellsund grabens as well as most of the extensional faults show a significant growth. In the southwestern Barents Sea, traces of compression structures are seen on seismic data suggesting a period of tectonic inversion. An overall shallow marine paleoenvironment characterized the south western Barents Sea shelf during the Oligocene being deeper towards the west. Seismic data shows contourite development in the continentalslope areacontemporaneouswiththeopeningoftheFramStrait that connected the oceanic circulation of the Atlantic and the Arctic Ocean. <p>Seismic mapping of the Paleogene-Neogene strata shows an eastward and northward increasing uplift trend in the western Barents Sea that was amplified in the late Cenozoic due to glacio-isostatic subsidence and uplift due to sediment loading/unloading process. This study suggests also a period of pre glacial’s subsidence and uplift during the Eocene due to the rifting and sea floor spreading between Norway and Greenland. A local secondary uplift in the Oligocene with lesser magnitude is also identified. Erosion estimates for the western margin is calculated to be 900-1400 m in the southwestern and probably more than 2000 m in the north western BarentsSea. The sedimentation rates and erosion rates for the Cenozoic preglacial period shows values one order of magnitude lower than during the Late Cenozoic.