THE CALEDONIAN DEFORMATION OF THE BRABANT MASSIF AND THE EARLY PALEOZOIC IN NORTHEAST GERMANY - COMPARED

The Caledonian deformation of the Brabant Massif and the Rugen Early P alaeozoic has been compared by structural analysis including strain de terminations, X-ray texture analysis, illite crystallinity and vitrini te reflectivity. Both areas have experienced weak internal deformation under anchimetamorphic to very low-grade metamorphic conditions. The deformation of the Brabant Massif is characterized by (a) a pronounced diagenetic foliation which resulted from compaction and weak extensio nal tectonics; (b) tilting or weak folding of the Cambrian strata arou nd the Cambrian/Ordovician boundary without internal deformation; (c) a main phase of Caledonian deformation in the Lower Devonian which was associated with open folding and an axial-plane pressure solution cle avage; (d) bending of Caledonian structures from northwest-southeast t o northeast-southwest. The internal deformation appears homogeneous wi th decreasing strain Values towards upper structural levels. The strai n ellipsoid is predominantly prolate with the main axis of extension p arallel to the bedding-cleavage intersection lineation. It is interpre ted as the result of superposition of compaction, tectonic shortening and volume loss through pressure solution. The Rugen Early Palaeozoic is less deformed and less metamorphosed under anchizonal conditions. W hile the upper structural level is almost undeformed, towards the deep er structural levels a spaced and then a continuous slaty cleavage is developed which is successively crenulated by a fracture cleavage. The internal deformation appears inhomogeneous due to several thrust zone s with somewhat higher strain values. Outside the thrust zones strain values increase towards lower structural levels, but not significantly . The strain ellipsoid is prolate with a strongly varying orientation of the X-axis. The structural inventory of both areas is comparable wi th other fold-and-thrust belts. While the Rugen Palaeozoic represents an imbricated thrust-fan of an upper structural level with discrete th rusts and inhomogeneous strain, the Brabant Massif represents a deeper structural level dominated by folding and more homogeneous internal d eformation.