Abstract: Permian rugose corals underwent evolutionary episodes of assemblage changeover, biogeographical separation and extinction, which are closely related to geological events during this time. Two coral realms were recognized, the Tethyan Realm and the Cordilleran–Arctic–Uralian Realm. These are characterized by the families Kepingophyllidae and Waagenophyllidae during the Cisuralian, Waagenophyllidae in the Guadalupian and the subfamily Waagenophyllinae in the Lopingian, and the families Durhaminidae and Kleopatrinidae during the Cisuralian and major disappearance of colonial and dissepimented solitary rugose corals from the Guadalupian to the Lopingian, respectively. The development of these coral realms is controlled by the geographical barrier resulting from the Pangaea formation. According to the changes in the composition and diversity of the Permian rugose corals, a changeover event might have occurred at the end-Sakmarian and is characterized by the mixed Pennsylvanian and Permian faunas to typical Permian faunas, probably related to a global regression. In addition, three extinction events are present at the end-Kungurian, the end-Guadalupian and the end-Permian, which are respectively triggered by the northward movement of Pangaea, the Emeishan volcanic eruptions and subsequent global regression, and the global climate warming induced by the Siberian Traps eruption.

Abstract The NW–SE-trending Pai-Khoi fold–thrust belt links the Permian Uralian Orogen in the Polar Urals with the early Mesozoic fold belt on Novaya Zemlya. An interpretation of structural lineaments present in southern Novaya Zemlya suggests that the NW–SE-trending fold belt in southernmost Novaya Zemlya may have formed contemporaneously with parallel sinistral strike-slip faults. Analysis of regional-scale geological maps of the adjacent Pai-Khoi fold–thrust belt reveals large-scale structural relationships indicative of sinistral shear along the fold–thrust belt, including the presence of left-stepping en echelon folds within the Kara Shale Allochthon. This interpretation is corroborated by a field study of the allochthon-bounding Main Pai-Khoi Thrust, which reveals a consistently oblique tectonic stretching lineation, pitching 56° towards the east, suggesting tectonic displacement towards the west. It is therefore proposed that the Pai-Khoi fold–thrust belt is best described as a zone of sinistral inclined transpression. The interpretation of the Pai-Khoi fold–thrust belt as a zone of sinistral transpression has important implications for the interpretation of this tectonic boundary. This is reflected in a new structural cross-section through southernmost Novaya Zemlya, which is characterized by thick-skinned tectonics and steep strike-slip faults. These faults may link at depth with the Baidaratsky Fault.

Abstract 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.