The reactivation of the ancient massif and metallogeny; the example of the Bohemian Massif

The ancient Moldanubian structure of the Bohemian Massif probably was poor in ore deposits. The upper Proterozoic and Paleozoic geosynclinal development and regional metamorphism effected a new redistribution and supply of material and are believed to be metallogically of the highest importance. A model of a process that might enrich some zones and areas in ore-forming constituents is given. Units with characteristic structure and development in the Bohemian Massif contain specific types of mineralization. These types of endogenous, mainly hydrothermal min-eralization have been defined as isogenous mineral associations. Two main and different groups of Variscan intrusives, each with a different source and each with related isog-enous mineral associations, form two principal petrometallogenic groups. The main accumulations of the endogenous mineralization of both petrometallogenic groups are distributed along the weakened zones of the margins of the former geosyn-clinal basins. The ore manifestations follow the deep-seated faults and are dispersed into the surrounding wall rocks. The relatively stable blocks are mostly barren of ores.