The Govezhda gold deposit, Western Balkan Mountains, Bulgaria

摘要

The Govezhda gold deposit is situated in the Western Balkan mountains, NW Bulgaria. Il has been operating during the 1961-1992 period, but the mineralization remains not completely well known. Four mineralization stages, reflecting the following geochemical trend are defined: Fe-As-Au; Pb-Zn-Cu-Ag-Au; Ag-Pb-Cu-Sb; Ca. (1) The products of the first stage are Fe sulphides. Prevailing species are arsenopyrite and pyrite, while pyrrhotite and marcasite are less frequent. (2) The second stage bears the main sulphides and gold. The gold, together with the sulphides most commonly fills cracks in arsenopyrite and pyrite. (3) During the third stage a complex assemblage, comprising different Sb sulphosalts (tetrahedrite, boulangerite, bournonite, pyrargyrite, owyheeite) is deposited. (4) The fourth stage is characterized with the deposition of calcite and less frequent gypsum. The gold is the economically important component in the deposit. It is found in three mineral associations. We suggest that it is initially deposited as invisible gold in arsenopyrite and pyrite during the first stage and later part (or all) of it is remobilized and redeposited together with the sulphides of the second stage. The Govezhda deposit, just like Svishti Plaz in central Balkan Mountains has the typical features of some great mesothermal gold deposits in shear zones, deposited in Archaean or Hercynian greenschist terrains, known from South Africa, Western Australia, Canada, Portugal and France.