MINERAL ASSEMBLAGES AND GENESIS OF THE Cu-Au EPITHERMAL DEPOSITS IN THE SOUTHERN PART OF THE PANAGUYRISHTE ORE DISTRICT, BULGARIA

Epithermal Cu-Au deposits hosted within volcanic rocks (Radka, Elshitsa, Krassen) are related to Late Cretaceous andesite-dacite volcanic terrain in the Panagyurishte ore district. The Cu-Au ores are linked by a similar mineralogy and differ by the ratio of tennantite, bornite, enargite and discrete trace minerals of Ga, Ge, In and Bi (e.g., roquesite, germanite, betekhtinite, renierite, vinciennite, aikinite). Bi-Se-Te and Ga-Ge-ln-Sn signature with pronounced Au-enrichment of the bornite rich ores is a characteristic feature underlying the increasing role of the fS2/f02 control during the transition from IS te HS environment. Formation of the epithermal Cu-Au deposits appears to have occurred during a single broad event of contemporaneous formation of epithermal and porphyry systems.The close connection between the volcano-plutonic structures facilitates the multistage and polycyclic character of their hydrothermal systems, the similar character of the epithermal ores and the mineral succession in Elshitsa, Radka and Krassen deposits. The ô^S ratios in the sulphide minerals range from -6.7 to 4.0, suggesting comparable magmatic sources for the epithermal mineralizing fluids and close link with porphyry environment.