The Muschelkalk and its lead-zinc mineralization in the eastern Netherlands

The Muschelkalk is made up of sequences of dolomitic lime-mudstones. These are interpreted as stromatolites. Pyrite, marcasite, sphalerite and galena occur widely dispersed in the limestone but have been concentrated more conspicuously in storm layers and mudcrack fillings. A widespread occurrence of algal mats could account for initial concentration of considerable amounts of base metals. These probably did not derive from the deeper portions of the main Triassic basin to the N but are more likely of southern provenance, transported in meteoric water draining the emerged Variscan massifs. Secondary concentration of metals during dolomitization and compaction has demonstrably occurred. Supergene enrichment is inferred from high strontium, lead and zinc values below a red bed interpreted to be a paleosol. A further analysis of the metal distribution is required. -from Authors