Multiple origin of the ‘Kniest feeder zone’ of the stratiform Zn–Pb–Cu ore deposit of Rammelsberg, Germany

The Zn–Pb–Cu ore deposit of Rammelsberg is characterized by a complex fluid flow history. The main phase of ore deposition occurred during the Middle Devonian in the Rhenohercynian basin. The Kniest zone underlying the stratiform ore is interpreted as the feeder zone, along which hydrothermal fluids migrated upward and were expelled on the sea floor. Mineralizing brines possibly had a minimum temperature of 130°C, and salinity ranged between 4.9 and 10.3 eq. wt.% NaCl. The ore and its host rock became folded during the Variscan orogeny, and low salinity fluids (1.0 to 2.3 eq. wt.% NaCl) were mobilized during this tectonic period. Remobilization of the ore took place during the Mesozoic by a high salinity (17.3 to 20.2 eq. wt.% NaCl) H2O–NaCl–CaCl2 fluid.