The connection between hydrothermal fluids, mineralization, tectonics and magmatism in a continental rift setting: Fluorite Sm-Nd and hematite and carbonates U-Pb geochronology from the Rhinegraben in SW Germany

Fluid properties changed after the deposition of Middle Triassic Muschelkalk evaporites from low salinity, high temperature (1-6 wt.% NaCleq, 200-270 °C, cooling late-metamorphic basement fluids) to high salinity, moderate temperature (20-26 wt.% (NaCl + CaCl2), 50-170 °C, mixture of a modified bittern brine (“basement brine”) with halite dissolution brine). This change led to large scale ore deposition (fluorite-barite-quartz with Pb-Zn-Cu, Bi-Co-Ni-Ag-U, Fe-Mn ores). During the Paleogene and Neogene, previously separated aquifers from various sedimentary units were connected by juxtaposition of the fluid source rocks during Rhinegraben rifting, which resulted in variable salinity and temperature fluids (1-26 wt. % (NaCl + CaCl2), 50-350 °C) by a multi-component fluid mixing process. Typical mineralization related to this shows barren or Pb-Zn-Cu veins with large amounts of barite.