GEOLOGY AND GEOCHEMISTRY OF THE MINERALIZATION FROM THE GORNJI VAKUF AREA, BOSNIA

Abstract

In the Gornji Vakuf area, which is built up of Palaeozoic sediments and metarhyolites, the authors investigated 47 ore occurrences by geological and different geochemical methods. They distinguish; (a) alluvial, diluvial and fluvio-glacial placers; (b) epigenetic hydrothermal barite-sideritc-tetrahedrite veins located in the Silurian-Devonian schist complex and Upper Permian, and almost monomineralic barite (± tetrahedri-te) veins, breccias and bodies in the Middle Devonian carbonate complex; (c) post-kinematic monomineralic metamorpho-genic quartz deposits interlaying the schists. The hydrothermal deposits have common characteristics as follows: location exclusively in Palaeozoic strata, epigenetic character; simple, monotonous paragencsis (barite ± siderite as main nonmetallic minerals and Hg-tetrahedrite as preponderant ore mineral); siderite characterized by high CaO, MgO and low MnO content; all tetrahedrites are Hg, Ag, Au, Hi-bearing; barite with average content of 2.9 wt% of SrS04. The stable isotope study revealed:  34S= + 15.0‰ in barites, -10.1‰ in tetrahedrites,  18O = -9.6‰ and  l3C = -3.7‰ in siderites. The microthermometric measurements gave: Th=+200 ºC. in barites. The very close similarity of all above mentioned results with those found in the minerals of the Kreševo area deposits, urged the authors to assign also the Gornji Vakuf area deposits to the post-Variscan tectonic event.

Keywords

• gold-bearing placers
• epigenetic hydrothermal barite (± siderite) deposits
• Hg-tetrahedrite
• stable isotope study
• Sr-content in barite
• Post-Variscan tectonics
• Palaeozoic
• Bosnia