Are Precambrian gold deposits in eastern Serbia metamorphic or metamorphosed?

Precambrian rocks in the eastern Serbia make the deformed basement of the Alpine collisional zone and appear in the Danubian and Getic units of the Serbian Carpathians. These metamorphosed magmatic and sedimentary rocks localize some major gold deposits, which were historically mined.

The most prominent deposit is Blagojev kamen, located around 10km east from the town of Kučevo in eastern Serbia. This deposit was mined for gold and tungsten until 1964 (Janković, 1990). The mineralization is in foliated quartz veins in Precambrian greenschists of the Getic unit. Beside native gold and scheelite, these veins also incorporate pyrite and occasionally sphalerite, galena and chalcopyrite.

The genesis of Blagojev kamen was historically associated with the proximal paleozoic Neresnica granitoid complex, however Janković (1990) argues that this deposit is most likely a metamorphosed VMS deposit. Bugarin & Ljubojev (2007) state that this deposit was formed during syngenetic stage (formed during magmatic-metamorphic events) and epigenetic stage (formed during younger magmatic events).

Bugarin and Krgović (1997) report that the fluid inclusions from Blagojev kamen area homogenize in the interval of 200-300° and contain increased amount of chlorine and CO₂. The recent studies like Başer (2022) also measured that the homogenization temperatures of inclusions are between 250-350°C and argue that the deposit was probably formed in metamorphic conditions.

Another similar deposit is Mijin Kladenac, located between the town of Zaječar and the border with Bulgaria. This deposit was mined in the Middle Ages and in the period before WW2 and explored again during the 1980s. Some of the mining corridors are still preserved on the surface. The mineralization in Mijin kladenac locality is found in altered Precambrian greenschists of the Danubian unit, in form of parallel quartz veins. This mineralization mainly contains pyrite, marcasite, galena, sphalerite and arsenopyrite, with significant gold and silver content (Kovačević et al, 2003). Mijin Kladenac is also classified as a metamorphosed VMS deposit by different authors like Kovačević et al. (2003).

Our preliminary results of inclusion studies from Mijin Kladenac imply that the fluids in quartz veins were formed in temperatures between 100 and 300°C and contain increased amounts of CO₂. Ore paragenesis, mineralogy and fluid contents imply that these two deposits are more likely metamorphic deposits, similar to Precambrian orogenic gold deposits in Canadian Abitibi belt.