Origin of Pb-Zn mineralising fluids in the Variscides of Belgium.

Microthermometric and crush-leach analysis of high-salinity H2O-NaCl-CaCl2 fluid inclusions in calcite veins related to the Bleiberg Pb-Zn deposit in eastern Belgium indicate an evaporative origin of the mineralising fluid. The Pb-Zn mineralisation occurs mainly in Lower Carboniferous carbonates. Evaporation of seawater occurred during several periods within the Devonian-Carboniferous and this high salinity fluid probably migrated downward into the basement along extensional faults during the Palaeozoic. The composition of the fluid evolved through interaction with Palaeozoic and basement rocks. At depth, the high salinity fluid mixed with gravity-driven meteoric water, which migrated in the subsurface after the Variscan deformation. During the Mesozoic, the mineralising fluids were released along faults, causing the widespread Pb-Zn mineralisation found at the Variscan front zone in Belgium.
Microthermometric and crush-leach analysis of high-salinity H2O-NaCl-CaCl2 fluid inclusions in calcite veins related to the Bleiberg Pb-Zn deposit in eastern Belgium indicate an evaporative origin of the mineralising fluid. The Pb-Zn mineralisation occurs mainly in Lower Carboniferous carbonates. Evaporation of seawater occurred during several periods within the Devonian-Carboniferous and this high salinity fluid probably migrated downward into the basement along extensional faults during the Palaeozoic. The composition of the fluid evolved through interaction with Palaeozoic and basement rocks. At depth, the high salinity fluid mixed with gravity-driven meteoric water, which migrated in the subsurface after the Variscan deformation. During the Mesozoic, the mineralising fluids were released along faults, causing the widespread Pb-Zn mineralisation found at the Variscan front zone in Belgium.