Tectonic setting and timing of orogenesis along the Pai-Khoi fold-and-thrust belt

The NW-SE trending Pai-Khoi fold-and-thrust belt (PKFB) links the northernmost sector of the Uralian Orogeny, the Polar Urals, with the Novaya Zemlya archipelago, approximately 600 km to the northwest. Together with Novaya Zemlya and Taimyr, Pai-Khoi forms an arcuate extension of the Uralian Orogeny, referred to as the Arctic Uralides. The most recent tectonic models propose that the arcuate nature of the Arctic Uralides reflects the presence of a pre-existing continental embayment along the Palaeozoic margin of Baltica in which a fragment of oceanic lithosphere became trapped during Late Palaeozoic collision of Baltica and Siberia. Subsequent roll-back and eventual consumption of this remnant oceanic crust lead to ‘soft’ collision of accretionary crust escaping from West Siberia with Novaya Zemlya in the Late Triassic.

However, significant uncertainties and potential inconsistencies exist between the known geology of Pai-Khoi and tectonic implications of the embayment model, in particular, the tectonic setting and timing of deformation along the southern margin of the inferred embayment. While current CASP research has highlighted the importance of a strike-slip component to deformation of the PKFB, existing tectonic interpretations propose the Pai-Khoi sector was a subducting margin during the Early Permian to Triassic. In the absence of any known oceanic or volcanic arc accretionary terranes within Pai-Khoi, a hypothetical offshore island arc has been proposed. Current estimates for the onset of foreland basin formation along Pai-Khoi, and by association tectonic loading of the margin, suggests it was diachronous from SE to NW, ranging from Early Permian to Late Permian, respectively. However, it is unclear whether or not this Early Permian transition from carbonate platform to fine-grained terrigenous deposition is actually related to denudation of the adjacent Urals.

Ongoing CASP research in Pai-Khoi, both field and laboratory, will focus on detailed structural, sedimentological and provenance studies of the Early Permian to Triassic terrigenous fill of the foreland basin to the southwest of the PKFB, the Korotaikha Basin, to establish the nature and timing of expected changes in sediment transport direction, as well as, associated changes in source areas. The results of this study will have regional significance, as the tectonic evolution of the South Kara Sea is intimately linked to that of the Arctic Uralides, while late Palaeozoic to Mesozoic sediment provenance and transport pathways to the South Kara Basin and eastern Barents Shelf will have been influenced by the evolution of the PKFB.