Offset and curvature of the Novaya Zemlya fold-and-thrust belt, Arctic Russia

The Novaya Zemlya archipelago contains a predominantly west-vergent fold-and-thrust belt that separates two contrasting hydrocarbon basins with enigmatic subsidence histories. On the foreland side is the deep depression of the eastern Barents Shelf that hosts the Shtokman gas condensate discovery; on the hinterland side is the South Kara Basin, an offshore continuation of the gas-dominated northern West Siberian Basin. Much of the compressional deformation recorded in Novaya Zemlya appears to have been later than the onset of subsidence in adjacent basins, and may therefore be expected to have had a potentially significant influence on hydrocarbon systems within them. Two characteristics of Novaya Zemlya immediately stand out on any topographic map: the c. 600 km westward offset compared with the remainder of the Uralian Orogen and the plan-view curvature (convex towards the Barents Shelf). Any regional tectonic model developed for the Novaya Zemlya fold-and-thrust belt must be able to explain these first-order features, and a wide range of mechanisms, geometries and timings has been proposed in the literature. However, as far as we are aware, there has been no previous attempt to link the geometry of structures on the archipelago with a potential mechanism that explains their curvature in plan view. Using field observations, information on geological maps and interpretation of satellite imagery, we demonstrate the link between structural geometries in Novaya Zemlya and the basins of the adjacent eastern Barents Shelf. We find no evidence to support previous interpretations of the fold-and-thrust belt as an orocline (bending of an originally straight deformation belt) or a far-travelled thin-skinned allochthon, and conclude that the offset from the remainder of the Uralian Orogen is a primary feature that results from an original embayment on the margin of Baltica.