The crustal structure in the transition zone between the western and eastern Barents Sea

Abstract

We present a crustal-scale seismic profile in the Barents Sea based on new data. Wide-angle seismic data were recorded along a 600 km long profile at 38 ocean bottom seismometer and 52 onshore station locations. The modelling uses the joint refraction/reflection tomography approach where co-located multichannel seismic reflection data constrain the sedimentary structure. Further, forward gravity modelling is based on the seismic model. We also calculate net regional erosion based on the calculated shallow velocity structure. Our model reveals a complex crustal structure of the Baltic Shield to Barents shelf transition zone, as well as strong structural variability on the shelf itself. We document large volumes of pre-Carboniferous sedimentary strata in the transition zone which reach a total thickness of 10 km. A high-velocity crustal domain found below the Varanger Peninsula likely represents an independent crustal block. Large lower crustal bodies with very high velocity and density below the Varanger Peninsula and the Fedynsky High are interpreted as underplated material that may have fed mafic dykes in the Devonian. We speculate that these lower crustal bodies are linked to the Devonian rifting processes in the East European Craton, or belonging to the integral part of the Timanides, as observed onshore in the Pechora Basin.

Gondwana breakup: Messages from the North Natal Valley

“…Such variations are interpreted as a presence of mafic and ultramafic mantle materials in the lower or middle continental crust and as magmatic intrusions (DeRito, Cozzarelli, & Hodge, ; Nunn & Aires, ; Tozer et al, ) or eclogitization of the lower crust (Baird, Knapp, Steer, Brown, & Nelson, ; Haxby, Turcotte, & Bird, ). As described for the Arctic Ocean (Shulgin et al, ), this part of the Indian Ocean has also experienced several magmatic events at different periods (the Karoo volcanic event, the Turonian trapps event, Eocene, Miocene, etc. ), which are observed on the reflection seismic profiles at different levels of the sedimentary layers and may imply the supposed intrusion/transformation of the lower crust.…”

“…In the Parnaïba basin, Tozer et al () proposed that the lower part of the continental crust is overloaded by mafic intrusions, inducing subsidence and the formation of the sedimentary basin. Shulgin et al, , equally proposed a deep originating process with emplacement of intrusive mafic bodies at the transition crust/upper mantle. In line with these authors, we propose that several magmatic events (from Karoo to Miocene events) have played a role in the transformation of the lower crust (intrusion, underplating, metamorphism, etc.…”

Structural inheritance in the North Atlantic

“…Neoproterozoic Timanian basement terranes, metasediments and volcanic sequences were drilled in the Pechora Basin (Roberts and Siedlecka 2002;Dovzhikova et al 2004). The Timanian suture may be deeply buried in the central Barents Sea (Gernigon et al 2018) possibly associated with high velocity-high density lower crustal rocks (Shulgin et al 2018). Basement structures in the eastern and central Barents Sea show a persistent NW-SE oriented Timanian fabric throughout the region (Gee et al 2006(Gee et al , 2008Pease 2011;Klitzke et al 2019).…”

The Paleozoic Evolution of the Olga Basin Region, Northern Barents Sea: A Link to the Timanian Orogeny

“…The Olga‐Sørkapp region is located in prolongation of assumed NW‐SE striking Timanian trends from the Pechora Basin and the SE Barents Sea (Dovzhikova et al, ; Gernigon et al, ; Roberts & Siedlecka, ; Shulgin et al, ). We suggest from similar magnetic and gravity patterns in both regions that Timanian accretion of Neoproterozoic fragments has occurred further west than previously assumed (Figure ).…”