Comparative investigations of continental reflectivity

Based on observations of reflectivity and lengths of reflecting boundaries in various geological units a consistent picture for explaining the different reflectivity patterns is derived. Whereas in the upper, brittle part of old crusts reflectivity concentrates on fault zones of former or present compressional zones it is absent in warm extensional areas, where in addition, granitic plutons may disturb any upper crustal “layering”. The lower crust of these young and warm areas with its reflecting lamellae is dominated by strain and shear processes i.e. by an ordering process in a low-viscosity environment.