Geomorphology of buried glacigenic horizons in the Barents Sea from three-dimensional seismic data

Abstract

The glacigenic sequence of the southwestern Barents Sea shelf has for the first time been studied using 3-D seismic data. The close spacing of 3-D lines and powerful computer workstation interpretation techniques have allowed detailed mapping of the observed features. Several generations of subglacial lineations observed on four different palaeo-surfaces are interpreted to reflect the flow patterns of palaeo-ice sheets. To our knowledge, this is the first time that multiple levels of subglacial lineations have been observed. The lineations are 2.5-8 m in relief, 50 to 180 m wide and 0.5 to 20 km long. All four surfaces show a main lineation pattern comprising lineations with a N-S trend, suggesting that the dominant ice flow was directed northwards across the Barents Sea shelf at least four times during the last 0.8 Ma. Two of the surfaces display semi-circular to oblong depressions trending mainly in the same direction as the sub-parallel lineations. These depressions are 9-53 m in relief, 1.25-3.2 km wide and 1.9-9 km long. In contrast to the buried surfaces, the sea floor is dominated by 2.5-25 m deep cross-cutting iceberg plough-marks from the deglaciation phase of the last Barents Sea ice sheet. The 3-D seismic data are conventional industry data. Despite relatively low seismic frequencies and, hence, limited vertical resolution of seismic profiles, time slices and sub-horizontal time maps are of high spatial resolution, providing detailed images of different stages of buried Quaternary glacial geomorphology.

Hydrocarbon plumbing systems above the Snøhvit gas field: Structural control and implications for thermogenic methane leakage in the Hammerfest Basin, SW Barents Sea

“…Seabed furrows are particularly well preserved and abundant in water depths shallower M A N U S C R I P T A C C E P T E D 10 than ~330 m. We interpret these features as iceberg ploughmarks formed due to the scouring of the seabed sediments by wind and current-transported icebergs, resulting from glacier calving in deep waters during the late Weichselian (19 -15 cal ka BP) deglaciation phase (Judd and Hovland, 2007;Winsborrow et al, 2010). Similar ploughmarks have been reported in many other areas of the Barents Sea (Rafaelsen et al, 2002;Andreassen et al, 2008). Acquisition footprint is parallel to the inline direction trending 0°N…”

Seafloor glacial features reveal the extent and decay of the last British Ice Sheet, east of Scotland

“…3). It is inconclusive whether all features observed on the seafloor are ridges or whether the surface comprises a combination of ridges and grooves, as it is often difficult to distinguish between the two on corrugated surfaces, particularly at the resolution of commercial 3D seismic data (Rafaelsen et al, 2002).…”

“…While not of the resolution of multibeam data, 3D seismic reflection data have a number of advantages over higherfrequency 2D seismic reflection techniques (Boomer and Sparker profiles), more typically used for marine Quaternary studies. In particular, the 3D sampling and 3D migration algorithms used for processing these data give far superior lateral spatial coverage and resolution (Rafaelsen et al, 2002;Lonergan et al, 2006), allowing a better appreciation of the plan-form geometry of glacial landforms.…”

Neoproterozoic Glaciated Basins: A Critical Review of the Snowball Earth Hypothesis by Comparison with Phanerozoic Glaciations

“…Glacial and non-glacially influenced strata deposited over the past 800,000 years on the southwestern part of the Barents Sea Shelf are known to approach 150 m in thickness (Rafaelsen et al, 2002), Miocene to Quaternary strata in the Polar North Atlantic exceed 1 km in thickness (Thiede et al, 1998), Miocene and Pliocene deposits of the Pagodroma Group in Antarctica are ~300 m thick (Hambrey & McKelvey, 2000) and Miocene to Pleistocene deposits of the Yakataga Formation along the southern continental margin of Alaska arẽ 7 km thick (Zellers & Lagoe, 1992). In the lower part, the Yakataga Formation consists primarily of debrites and turbidites, passing up into glacimarine diamictites, sandstones and mudstones (Eyles & Lagoe, 1990;Zellers & Lagoe, 1992), and in this respect bears similarity to many Neoproterozoic glacially influenced facies associations.…”