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- Title
Žune Ba-F epithermal deposit Part 1: Mineralogical and geochemical characteristics.
- Authors
Šoštarić, Sibila Borojević; Roglić, Martin; Milošević, Aleksej; Brenko, Tomislav
- Abstract
The Žune Ba-F epithermal deposit is situated in the Ljubija ore field (NW Bosnia and Herzegovina), within Upper Palaeozoic dolostone. A typical ESE-WNW Variscan vergency fault zone separates the dolostone from Lower Triassic schists and sandstones. External and internal pseudo-bedding, with massive, homogenous structure and partial limonitization characterizes the dolostone. Its geochemical composition exhibits low SiO2 (1.33 - 2.06 mass. %), Al2O3 (0.27 -0.38 mass. %), BaO (0.02 - 0.83 mass. %), ΣREE (5.7 - 9.4 ppm), Sr (61.7 - 120.4 ppm), Sm (0.3 - 2.2 ppm) and Eu (0.1 - 0.6 ppm), while having high CaO (30.24 - 32.38 mass. %), MgO (16.47 - 17.35 mass. %) and LOI (44.6 - 45.58 mass. %). The dolostone-mineralization contact zone consists of metasomatically recrystallised host dolostone with quartz and pyrite, where the presence of accessory tremolite, magnesiochloritoid and pyknite indicates peak formation conditions in the pre-mineralization phase with temperatures above 300°C. Two ore types are described: (i) Ba-F vein-type mineralization composed of barite - fluorite ± quartz, and (ii) hydrothermal breccia composed of coarse-grained fluorite and barite, surrounding fragments of dolostone, and occupying ≈20 % of the deposit. Mineralized samples show slightly elevated SiO2 (2.20 - 5.53 mass. %) and Al2O3 (0.24 - 0.74 mass. %), low MgO (below 0.02 mass. %) and LOI (0.3 - 3.1 %), with high BaO (up to 50.74 mass. %), CaO (up to 66.03 mass. %), ΣREE (20 - 166 ppm), Sr (exceeding 1 mass. %), Sm (up to 118 ppm) and Eu (up to 44 ppm). Elevated Sr can be correlated to other barite epigenetic hydrothermal deposits in the Dinarides, interpreted as BaSr substitution in the barite crystal lattice. Fluorite-rich samples are characterized by Y (0.6 -49.2 ppm) and HREE enrichment, accompanied by depletion of LREE. The Ba-F deposit Žune, having variable REE concentration and a negative cerium and ytterbium anomaly corresponds geochemically to world-class fluorite deposits associated with carbonate sedimentary rocks.
- Subjects
DINARIC Alps; BOSNIA &; Herzegovina; CARBONATE rocks; SEDIMENTARY rocks; STRUCTURAL geology; HYDROTHERMAL deposits; DOLOMITE; RARE earth metals; CERIUM oxides
- Publication
Geologia Croatica, 2022, Vol 75, Issue 3, p393
- ISSN
1330-030X
- Publication type
Article
- DOI
10.4154/gc.2022.24