Rauhwacken und ihre Entstehung

This publication comprises the results of a detailed investigation of rauhwackes regarding both their stratigraphic/tectonic positions and their macroscopic/microscopic aspects. The conclusion drawn is that rauhwackes are carbonate breccias of tectonic origin, which usually suffered extensive recrystallization and calcitization. Moreover, these breccias became strongly weathered as a result of which they acquired a typical porous to cavernous appearance. Rauhwackes were formed by way of brecciation of carbonate rocks with a comparatively slight cohesion of their constituting grains; these rocks have been deposited in a saline environment. Rauhwackes may be divided into two main varieties:

1. monomict rauhwaekes, formed by fragmentation of only one type of rock (usually a sucrose dolostone), and
2. polymict rauhwackes, formed by fragmentation and mixing of two or more types of rock.

The typical boxwork rauhwackes represent a subtype of monomict rauhwackes. They originated from fractured dolostones and are extensively developed in only slightly tectonized regions, e. g. in the German Zechstein and Muschelkalk. Polymict rauhwackes represent intraformational crush-breccias which were formed by sliding (décollement) parallel to the bedding. Examination of polymict rauhwackes occurring in the metamorphic nappes of Tertiary orogenes may increase our knowledge about the relation existing between the tectonic evolution and Alpine metamorphism in these orogenes.