A major late Proterozoic tectonic event in southwestern Spitsbergen

Abstract

Abstract A newly-recognized angular unconformity within upper Proterozoic rocks of northern Wedel Jarlsberg Land (WJL), SW Spitsbergen, records a major deformational episode in late Proterozoic time. Cross-bedding and other younging-direction indicators in the sub-unconformity rocks show that they were mostly overturned at the time the Proterozoic sequence above the unconformity was deposited. Recumbent isoclinal folds, sheath folds, and fold axis-parallel lineations in the older sequence rocks, combined with their regional stratigraphic inversion, suggest that the Proterozoic event involved large-scale translation of nappe-like structures. Recognition of this late Proterozoic event also has implications for models of early Paleozoic (Caledonian) deformation in Spitsbergen. Regional outcrop patterns of the two Proterozoic sequences in WJL suggest that there is stratigraphic continuity across a Caledonian strike-slip terrane boundary fault inferred by other workers and that the Proterozoic angular unconformity occurs near the site of this postulated fault.