ABSTRACT
Origin of the ore-bearing dolomite, hosting the sulphide Zn-Pb ores in the Silesian-Cracow area, has been explained on the basis of the fluid inclusion studies. Five types of inclusions, differing in homogenisation temperatures, filling salinity and composition of the trapped fluid, have been distinguished. The process of dolomitisation started from low to moderately saline (3-10 wt.% of total salts), sodium dominated (80-85% NaCl in total salts, the balance is MgCl2) fluids at temperature <50 to 65°C. Subsequently temperature and salinity increased to highly saline (16-20 wt.% of total salts), sodium-calcium-magnesium fluids (ca. 60% NaCl, ca. 30% CaCl2 and ca. 20% MgCl2 in total salts) at temperature 70-95°C. The last stage has been characterised by dilute low-temperature solutions. Dolomite formed from solutions resembling meteoric and formation waters, different from the parent solutions of the sulphide Zn-Pb ores, which had the distinct third component, determined as ascending solutions of relatively high temperature.
