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

Abstract

The evolution of the Olga Basin region in the northern Norwegian Barents Sea and its relation to the Caledonian and Timanian orogenies is poorly understood due to sparse geophysical data and the lack of well control. In 2015, the German Federal Institute for Geosciences and Natural Resources (BGR) acquired deep multichannel seismic lines as well as gravity and magnetic data. The new seismic data reveal that the Olga and Sørkapp Basins evolved as a W-E striking half-graben system along a major normal fault in the north and a smaller normal fault in the south, respectively. Deep crustal undulating high-amplitude reflections below the Olga and Sørkapp Basins coincide with W-E striking local magnetic maxima and may imply that the basins evolved on top of old collisional fabrics. The absence of major compressional deformation implies a post-Caledonian onset of subsidence. The W-E structural configuration of the sedimentary basins is difficult to reconcile with an earlier proposed NE striking Caledonian branch in the northern Barents Sea. Instead, the orientation of the Olga and Sørkapp Basins lines up with Timanian structural trends from the Pechora Basin. We propose that the Olga and Sørkapp Basins experienced transtensional deformation during the late Devonian/early Carboniferous NE-SW regional extension phase whereby inherited Timanian lineaments controlled the final W-E basin configuration. A salient pre-Caledonian Olga-Sørkapp crustal block in the central Barents Sea would also explain the recently proposed NNW rotation of Caledonian nappes and thrust sheets in the southwestern Barents Sea.

Deformation Analysis in the Barents Sea in Relation to Paleogene Transpression Along the Greenland‐Eurasia Plate Boundary

“…North of the Olga Basin (77°N), the trend of faults and lineaments associated with the structure of crystalline basement is roughly SW–NE to SSW–NNE, following the general trend of the mid‐Carboniferous rifts within the Caledonian domain (Faleide et al, 2008; Grogan et al, 1999). Southward structures are NW–SE oriented following the Timanian structural trend (Faleide et al, 2018; Hassaan et al, 2020; Klitzke et al, 2019; Riztmann & Faleide, 2009).…”

“…In the north, large parts of the Kong Karl Platform are marked by NNE trending anticlines ( at x = 50 km in Figures 1b and 1d ) developed above normal faults (Grogan et al, 1999). These structures correlate with the NNE–SSW strike of Caledonian thrusts and nappes in the north (Barrère et al, 2009, 2011; Gernigon et al, 2014; Gernigon & Brönner, 2012; Klitzke et al, 2019). The faults are mainly extensional and their ages are Paleozoic (Kairanov et al, 2018).…”

“…The graben system follows the NW‐SE orientation of the Timanian terrane grain that extends from the Pechora system to the Norwegian SE Barents Sea (Gernigon et al, 2018; Roberts & Siedlecka, 2002; Shulgin et al, 2018). Based on the analysis of magnetic and gravity anomaly trends, Klitzke et al (2019) proposed the Timanian terrane extends further north, incorporating the Olga‐Sørkapp Basin system. The transect ends at the border of the Finnmark Platform and is marked by shallowing of sediment layers approaching the Fennoscandian craton.…”

Structural inheritance in the North Atlantic

“…The Timanian fold-and-thrust belt records ocean-continent collisions along the northern margin of Baltica and the accretion of island arc complexes, terranes and microcontinents at ~0.62-0.55 Ga stretching from the Scandinavian Arctic to the Arctic Urals (Roberts and Siedlecka 2002;Gee and Pease 2004;Gee et al 2006Gee et al , 2008. The Trollfjorden-Komagelva Fault Zone is a major Timanian structure extending from the Urals across the Timan Range to northernmost Norway, where it was later reworked by the Caledonides (Gernigon and Brönner 2012;Gernigon et al 2014Gernigon et al , 2018Klitzke et al 2019). 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 Torellian orogeny on Svalbard may be a Timanian equivalent or prolongation (Majka et al 2008).…”