Abstract:

Southwest Spitsbergen, Wedel Jarlsberg Land, consists of two Proterozoic terranes with differing structural and metamorphic histories. The northern terrane experienced two Early Palaeozoic deformation events both accompanied by greenschist-facies metamorphism of similar grade. The southern terrane records a Neoproterozoic pervasive amphibolite-facies metamorphism and strong deformational fabric only locally retrogressed during a Caledonian greenschist-grade event. These terranes are separated by an important sinistral ductile shear zone defined as the Vimsodden–Kosibapasset zone, which comprises wrench- and contraction-dominated domains characteristic of strain partitioning in transpression zones; in this case apparently controlled by contrasting rheologies of the juxtaposed crustal domains. The northern terrane of Wedel Jarlsberg Land shares affinities with Pearya in northern Ellesmere Island of Arctic Canada whereas the southern one resembles the Timanide belt of NE Europe. A quantitative approach facilitated by a numerical plate model demonstrates that correlation with Pearya is feasible if sinistral displacement of c. 600 km occurred during the Caledonian orogeny. The correlation with the Timanides is valid if the southern terrane represents an outlier of the Timanide belt separated from Baltica by the opening of the Iapetus Ocean.

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