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Timanide Fold-and-Thrust Belt |
1 Geological Survey of Norway, N-7491 Trondheim, Norway david.roberts{at}ngu.no
2 Institute of Geology, Komi Research Centre, Ural Division RAS, Pervomayskaya 54, Syktyvkar, 167000 Russia david.roberts{at}ngu.no
The northeastern margin of the East European Craton developed passively in an extensional regime from late Mesoproterozoic through to the later stages of Neoproterozoic time. Along the exposed parts of the Timan-Varanger Belt, a major fault zone separates pericratonic (platformal) and basinal domains. Successions of the basinal domain can be traced beneath the Pechora Basin, via drillcore and geophysical data, to where intra-oceanic subduction systems with island arcs are inferred to have existed in the later stages of the Late Riphean. In terminal Riphean to Vendian time, inferred subduction polarity reversal resulted in a progressive telescoping, dissection and accretion of these diverse magmatosedimentary assemblages against the northeastern margin of the craton, culminating in Mid to Late Vendian, Timanian orogenesis. The Timan Range exposes SW-verging upright folds with anchizone to lower greenschist-facies cleavages. Higher-grade rocks in the Kanin-North Timan area occur in anticlinal cores and thrust slices. Isotopic dating constraints suggest that peak Timanian metamorphism occurred during the time interval 600–550 Ma.
