Reappraisal of the Rinkian fold belt in central West Greenland: Tectonic evolution during crustal shortening and linkage with the Nagssugtoqidian Orogen

The Rinkian fold belt in West Greenland is a key element in the 1.8 Ga amalgamation of Archaean cratons in the North Atlantic region to form one of the earliest large continents on Earth. The distinction around 1970 of the Rinkian belt from the Nagssugtoqidian orogen (NO) to the south was based on: (1) predominantly flat-lying structure, (2) lack of a persistent trend, and (3) large, dome-shaped structures assumed then to be related to vertical tectonics. New observations in the central Rinkian belt in 2002 reveal abundant evidence for crustal shortening during thrusting and folding, with top-NE and then top-NW tectonic transport, succeeded by late upright non-cylindical buckle folds (the domes). Structures along this transect are spectacularly exposed at all scales and form a world-class site to study mid-crustal collisional processes (reported elsewhere). Results of the new structural analysis are consistent with earlier documentation of large thrust and fold structures in the southernmost Rinkian belt and, together with new geochronology (reported elsewhere), suggest a direct linkage with the NO, where NW-directed transport prior to the final phases of deformation has also been observed. The NO linkage would create a c. 1000 km wide section through a major collisional orogen, similar in across-strike scale to the modern Himalayas. A combined Rinkian-Nagssugtoqidian orogen would link with a similarly highly asymmetric, coupled Baffin-Ungava orogen in Canada, and also support an intercratonic setting for the Rinkian belt rather than an orphaned intracratonic one.