The recently discovered, ~ 4 km long, E–W trending so-called Kavala vein is a sheeted quartz vein system of Bi–Te–Pb–Sb ± Au mineralization that crosscuts the Kavala pluton and the schists and gneisses of the Rhodope Massif. The Kavala vein system is comprised of quartz with lesser amounts of K-feldspar, plagioclase and muscovite. Quartz–sericite–pyrite alteration is pervasive but minor kaolinite is also present. Pyrite (~ 5 % of vein volume) contains inclusions of tetradymite (some gold-bearing), bismuthinite, and cosalite. Sulfur isotope values (n = 27) of pyrite from the Kavala and Chalkero veins, as well as pyrite and galena from Garizo Hill Fe–Mn–Pb vein range from − 1.9 to 1.0‰ (with one outlier of − 4.6‰) and suggest a magmatic sulfur source. Homogenization temperatures (Th) of type I (two-phase aqueous liquid–vapor) and type II (three-phase, H2O–CO2-rich) fluid inclusions that homogenize into the liquid phase in quartz from the Kavala and Chalkero veins range from 216.0° to 420.0 °C (n = 216) and 255.7° to 414.0 °C (n = 112), respectively. The Th of type III (two-phase aqueous liquid–vapor), which homogenize into the vapor phase, ranges from 210.4° to 323.4 °C (n = 28). The salinities of type I and type II inclusions range from 15.9 to 22.6 wt. % NaCl equiv. and 5.5 to 11.2 wt. % NaCl equiv., respectively. Eutectic temperatures of − 58.5° to − 44.3 °C for type I inclusions suggest the presence of appreciable CaCl2 in addition to NaCl. Clathrate melting temperatures for type II inclusions of ~−56.7 °C indicate that CO2 is the major component of the gaseous phase, however up to ~ 6 % CH4 is present in some inclusions. The presence of a zoned metallogenetic district centered on Bi–Te–Pb–Sb ± Au mineralization within the Kavala pluton, the presence of both magnetite and ilmenite in the Kavala pluton, and the two high-temperature, high-salinity, immiscible carbonic and aqueous fluids associated with the Kavala and Chalkero veins are consistent with them being part of an intrusion-related gold system that formed along the ilmenite–magnetite buffer.