Constraining onset of deformation in Pai-Khoi fold-and-thrust belt (Russia), via multi-proxy provenance study

The NW-SE trending Pai-Khoi fold-and-thrust-belt (PKFB) is a key feature of the Arctic Uralides, linking the most northerly sector of the main Uralian orogen, the Polar Urals, with Novaya Zemlya, ~ 600 km to the NW. The PKFB plays a critical role in the tectonic evolution of the Arctic Uralides, yet the onset of deformation within the fold belt is poorly constrained, with estimates ranging from Permian to Early Jurassic. To address this issue the thick Permo-Triassic flysch and molasse deposits, that accumulated during the Uralian Orogeny across the Pai-Khoi region (Korotaikha and Kara basins), were studied to establish environments of deposition, as well as sediment provenance. These included petrographic, conventional heavy mineral, single-grain geochemistry and U-Pb on detrital zircons determinations.

An overall progradation from deep marine Cisuralian deposits to fluvial Guadalupian to Anisian-Ladinian sediments was observed in both the eastern and central part of the Korotaikha Basin, with the eastern part showing more proximal depositional environments. This is consistent with the principal source area of these deposits having been located in the Urals. A profound reconfiguration in palaeocurrent directions within the Triassic succession of the north-central Korotaikha Basin, together with variations in provenance characteristics, is interpreted to constrain the onset of uplift and exhumation in PKFB to be mid-Triassic in age.