THE ORIGIN OF THE WEST SPITSBERGEN FOLD BELT FROM GEOLOGICAL CONSTRAINTS AND PLATE KINEMATICS - IMPLICATIONS FOR THE ARCTIC

The West Spitsbergen Fold Belt, which extends for 300 km along the wes tern margin of Svalbard and is up to 80 km wide, has much in common wi th foreland fold and thrust belts. The near-foreland segment of the fo ld belt exhibits ramp-flat thrust trajectories whilst structurally hig her nappes are typified by more listric thrusts. Higher nappes to the west contain imbricated Carboniferous and basement rocks showing that the latter were actively involved in the fold belt deformation and a m inimum of 80 km total shortening perpendicular to the western margin o f Svalbard is estimated. The early stages of the Eurekan deformation i n North Greenland can be linked to that of the West Spitsbergen Fold B elt and the combined shortening across the two fold belts may exceed 8 0 km. In Ellesmere Island Eurekan structures are distributed in an arc -like belt which records between 50 to 100 km of shortening since the Late Cretaceous. Kinematic reconstructions suggest that before the ope ning of the Eurasian Basin and Norwegian-Greenland Sea (Chron 25), Sva lbard was linked to North America. In the Late Cretaceous-Palaeocene i nterval the motion across the Greenland-Svalbard margin, was mainly co nvergent giving rise to the West Spitsbergen Fold Belt and the Eurekan structures of North Greenland. The dextral separation of Greenland an d Svalbard in post-Chron 24 time was accompanied by extension followed by pure extension in post-Chron 13 time.