Basin evolution and destruction in an early proterozoic continental margin: The rinkian fold-thrust belt of central west greenland

Abstract

In central West Greenland, early Palaeoproterozoic siliciclastic and carbonate sequences of the Karrat Group (shelf sequences of the Rae cratonmargin) were deposited in sedimentary basins controlled by NW-and SW-trending linked extensional fault systems. The shelf basins were later filled and overtopped by turbidite systems filling a foredeep advancing ahead of a thrust system-the Karrat Fjord thrust system-that propagated west to east. Deformation culminated in emplacement of basement-cored nappes, progressive deformation and high-grade metamorphism at c. 1.87 Ga. Reactivation of lower plate growth faults formed dome-and basin-like folds and related thrusts that refolded the structure of the Karrat Fjord thrust system and inverted the shelf basins. The southern Karrat Fjord thrust systemwas reworked in a belt of intense ductile NW-directed thrusting-the Nunaarsussuaq thrust system-formed at c. 1.84 Ga at the northern limit of the Nagssugtoqidian orogen. Kinematics of these events are at odds with the consensus view that the Rinkian fold-thrust belt is a northward extension of the Nagssugtoqidian orogen resulting from north- south convergence between the Rae and North Atlantic cratons. Application of structural restoration techniques to basin analysis of Palaeoproterozoic rocks has potential to provide new insights into Proterozoic orogenic processes worldwide.