Geneza dolnocechsztyńskiej mineralizacji polimetalicznej

Andrzej Rydzewski



On the basis of the analysis of a series of research works and results of the author's observations ten features of rocks and ores determining the manner and time of origin, and source of metals present in Lower Zechstein ores in the Central Europe are discussed. Consolidation of marine sediments from their syngenetic formation to early-diagenetic alternation of the resulting deposit may be regarded as a basic phase of mineralization. Formation of mineralization in the successive phases of diagenesis proceeded on a limited scale similarly as all the epigenetic processes enriching mineralization during catagenesis stages. The present study support the concept explaining the origin of metals present in Lower Zechstein deposits in the Central Europe as an intermediate effect of the Late Variscan mineralizing activity. It seems: probable that metals or metalizing solusions were trapped in deep waters occurring in oxidized sediments of the molasse type (red beds) during the Rotliegendes times and that they were carried away along with waters of the transgressing Zechstein sea. The processes of accumulation of metals of weathering origin, derived from ores related to earlier and the same stages of metallogenic activity, and occurring in the neighbourhood of the intraplatform accumulational basin, also had a remarkable contribution in the supply of ground- and deep-seated-waters during the Late Carboniferous and Rotliegendes times. The importance of these processes was emphasized by J. Oberc and J. Serkies (1968) and J. Rentzsch (1974). Deep tectonic fractures acted here as channels facilitating migration. The migration also proceeded in marginal parts of the oxidized deposits, where ,,rote Fäule" are found nowadays. There is an analogy to mineralizing brines outflowing at present along deep fractures in the Red Sea bottom (J. L. Bischoff, 1969). A marked concentration at coloured metals ores and traces of mineralization above red clastic deposits are found throughout the world. Thus, . it appears that the origin of polymetallic Zechstein mineralization depended on both the role played by Rotliegendes strata subjected to long-term oxidization and on the marine Zechstein transgression resulting in a change of conditions to reducing ones.

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