Structure and evolution of the northern Barents-Kara Sea continental margin from integrated analysis of potential fields, bathymetry and sparse seismic data

Abstract

SUMMARY The northern Barents–Kara Sea continental margin is a poorly investigated area because of a permanent ice cover hampering seismic exploration. The available geological and geophysical data show that the magma‐poor margin developed in response to early Cenozoic break‐up and subsequent opening of the Arctic Eurasia Basin. In this study, a series of crustal‐scale geotransects illustrating the architecture of the continental margin are constructed using sparse seismic reflection profiles and a gravity inversion method incorporating a thermal model of rifting. The continental side of the northern Barents Sea margin is underlain by Palaeozoic–Early Mesozoic deep sedimentary basins separated from the oceanic side by the marginal uplift. A bathymetry analysis complements low‐resolution seismic data to predict the sedimentary depocenters beyond the shelf break. These depocenters are associated with troughs, perpendicular to the shelf edge. The depocenter in front of the St. Anna Trough may contain a sedimentary section more than 4 km thick. The gravity correction for the effect of sedimentary cover was added to the inversion. This correction used an exponential density–depth function. The inversion supports a narrow and steep continent–ocean transition (COT; ca. 100 km). The conjugate Lomonosov Ridge margin is modelled using the same technique. Palaeoreconstructions were made to predict the break‐up setting. The northern Barents Sea–Lomonosov Ridge rift system can be described as an initially narrow symmetric rift. A transitional zone of extreme thinning is assumed between the oldest spreading magnetic anomaly and the stretched continental crust. The free‐air gravity anomaly in the western part of the margin can be predicted by the upwelling divergent flow model implying the exhumation of the lower crust and the continental upper mantle within the COT. It is suggested that an episode of shear or oblique extension before breakup is required to explain the observed narrow symmetric conjugate margins in the Eurasia Basin.

A lithosphere-scale structural model of the Barents Sea and Kara Sea region

“…1; Breivik et al, 1999;Minakov et al, 2012a). This is supported by a number of seismic reflection and refraction profiles crossing the continent-ocean transition (Breivik et al, 2003;Czuba et al, 2011;Ljones et al, 2004;Ritzmann et al, 2002Ritzmann et al, , 2004Jokat, 2007, 2009).…”

“…Mid-Permian Brekhuntsov et al (2011) Southern Kara Sea Henriksen et al (2011b) Barents Sea Ivanova et al (2011) Barents Sea/Kara Sea Johansen (1992) Barents Sea Khutorskoi et al (2008) Barents Sea Nikishin et al (2011) Southern Kara Sea Piskarev and Shkatov (2012) Eastern Barents and Kara seas Top crystalline crust Aplonov et al (1996) Eastern Barents and Kara seas Drachev (2011) Eastern Barents and Kara seas Gramberg et al (2001) Western Barents Sea Hauser et al (2011) European Arctic Ivanova et al (2011) Barents and Kara seas Johansen (1992) Barents Sea Myklebust 1994) Barents Sea Barents Sea Skilbrei (1991) Barents Sea Moho Aplonov et al (1996) Eastern Barents and Kara seas Dahl-Jensen et al (2003) NE Greenland Hauser et al (2011) European Arctic Ivanova et al (2011) Barents Sea Kostyuchenko et al (2006) Eastern Barents and Kara seas Minakov et al (2012a) Northern Barents Sea Barents Sea…”

Initial Opening of the Eurasian Basin, Arctic Ocean

“…The dislocation in the 15-20 km wide fault zone, with normal faults dipping at about 20 • , reaches values up to 2000 m (Geissler and Jokat, 2004). Minakov et al (2012) published a series of crustal-scale transects illustrating the architecture of the margin based on sparse seismic reflection lines and gravity modeling. Their gravity inversion supports a narrow and steep continent-ocean transition.…”

“…The split off of the elongated and about 1500 km long crustal splinter of the Lomonosov Ridge from the North Barents Sea continental margin and its eastern prolongation, the Kara Sea continental margin, is difficult to be explained with current rifting models. An episode of shear or oblique extension has been suggested before breakup to explain the observed narrow symmetric conjugate margins in the Eurasia Basin (Minakov et al, 2012(Minakov et al, , 2013. (Jakobsson et al, 2012).…”

Arctic Ocean Bathymetry: A Necessary Geospatial Framework

“…IBCAO has since served as the base bathymetry for numerous ocean circulation modeling experiments (e.g., Maslowski and Walczowski, 2002;Padman and Erofeeva, 2004;Maltrud and McClean, 2005;Manizza et al, 2011) and in projects involving direct analyses of the Arctic Ocean seafloor or where detailed analyses of higher resolution local bathymetric surveys must be placed in a regional context (e.g., Minakov et al, 2012;Rajan et al, 2012). At the time of release of the latest IBCAO Version 3.0 in 2012, approximately 11% of the Arctic Ocean seafloor had been mapped with modern multibeam echo sounders (Jakobsson et al, 2012), which shows that the work of describing the Arctic Ocean seafloor is still in its infancy.…”