New aspects of deformed cross-strata in fluvial sandstones: Examples from Neoproterozoic formations in northern Norway

In less well-exposed fluvial successions, the auto- or allokinetic origin of recumbently folded cross strata may be difficult to determine. However, the common occurrence of recumbent folds in cross-stratified fluvial sandstones and their virtual absence in marine cross-stratified deposits suggests strongly that, in the majority of cases, the deformation was autokinetic, resulting from flow phenomena typical of river channels. This kind of deformation structure should thus not be attributed to an allokinetic seismic triggering mechanism unless independent evidence of fault activity can be documented.