Allchar (North Macedonia) mining area is known for anomalous background Tl concentrations. In this study, we combine accurate detection of Tl stable isotope ratios with data on mineralogy/speciation and chemical extraction of Tl in Tl-contaminated Technosol profiles. We demonstrate that Tl in the studied soils varies significantly in both concentration (500 mg/kg-18 g/kg) and isotopic composition (-1.6 and +3.2 of ε²⁰⁵Tl, a ∼0.5‰ spread), which is due to changes in the phase chemistry and/or mineralogy of Tl. Moreover, the observed ²⁰⁵Tl/²⁰³Tl ratios do not reflect the extent to which individual soils undergo Tl isotopic fractionation during mineral weathering and soil formation. Clearly, they reflect the initial isotopic signal(s) of the primary ore or ore minerals, and thus, the general history or type of their genesis. As the Tl carriers, various types of Tl-Me-arsenates, mixtures of jarosite and dorallcharite and minor Mn-oxides predominated. We revealed intense adsorption of Tl by the identified Mn-oxides (≤6.7 at.%). It is hypothesized that these phases are of key importance in the fractionation of Tl isotopes, meaning at this type of secondary oxide-soil solution interface. However, model studies involving primary/secondary components (sulfides, sulfates, oxides and arsenates) are required to understand the mechanisms that may lead to post-depositional Tl isotopic redistribution in soils, as well as Tl isotope systematics in mining wastes in general.

The Sasa Pb-Zn-Ag deposit belongs to the group of distal base metal skarn deposits. The deposit is located within the Serbo-Macedonian massif, a metamorphosed crystalline terrain of Precambrian to Paleozoic age. The mineralization, hosted by Paleozoic marbles, shows a strong lithological control. It is spatially and temporally associated with the calc-alkaline to shoshonitic post-collisional magmatism that affected the Balkan Peninsula during the Oligocene–Miocene time period and resulted in the formation of numerous magmatic–hydrothermal ore deposits. The mineralization at the Sasa Pb-Zn-Ag deposit shows many distinctive features typical for base metal skarn deposits including: (1) a carbonate lithology as the main immediate host of the mineralization; (2) a close spatial relation between the mineralization and magmatic bodies of an intermediate composition; (3) a presence of the prograde anhydrous Ca-Fe-Mg-Mn-silicate and the retrograde hydrous Ca-Fe-Mg-Mn ± Al-silicate mineral assemblages; (4) a deposition of base metal sulfides, predominately galena and sphalerite, during the hydrothermal stage; and (5) a post-ore stage characterized by the deposition of a large quantity of carbonates. The relatively simple, pyroxene-dominated, prograde mineralization at the Sasa Pb-Zn-Ag skarn deposit represents a product of the infiltration-driven metasomatism which resulted from an interaction of magmatic fluids with the host marble. The prograde stage occurred under conditions of a low water activity, low oxygen, sulfur and CO₂ fugacities and a high K⁺/H⁺ molar ratio. The minimum pressure–temperature (P–T) conditions were estimated at 30 MPa and 405 °C. Mineralizing fluids were moderately saline and low density Ca-Na-chloride bearing aqueous solutions. The transition from the prograde to the retrograde stage was triggered by cooling of the system below 400 °C and the resulting ductile-to-brittle transition. The brittle conditions promoted reactivation of old (pre-Tertiary) faults and allowed progressive infiltration of ground waters and therefore increased the water activity and oxygen fugacity. At the same time, the lithostatic to hydrostatic transition decreased the pressure and enabled a more efficient degassing of magmatic volatiles. The progressive contribution of magmatic CO₂ has been recognized from the retrograde mineral paragenesis as well as from the isotopic composition of associated carbonates. The retrograde mineral assemblages, represented by amphiboles, epidote, chlorites, magnetite, pyrrhotite, quartz and carbonates, reflect conditions of high water activity, high oxygen and CO₂ fugacities, a gradual increase in the sulfur fugacity and a low K⁺/H⁺ molar ratio. Infiltration fluids carried MgCl₂ and had a slightly higher salinity compared to the prograde fluids. The maximum formation conditions for the retrograde stage are set at 375 °C and 200 MPa. The deposition of ore minerals, predominantly galena and sphalerite, occurred during the hydrothermal phase under a diminishing influence of magmatic CO₂. The mixing of ore-bearing, Mg-Na-chloride or Fe²⁺-chloride, aqueous solutions with cold and diluted ground waters is the most plausible reason for the destabilization of metal–chloride complexes. However, neutralization of relatively acidic ore-bearing fluids during the interaction with the host lithology could have significantly contributed to the deposition. The post-ore, carbonate-dominated mineralization was deposited from diluted Ca-Na-Cl-bearing fluids of a near-neutral pH composition. The corresponding depositional temperature is estimated at below 300 °C.

The Plavica Au-Ag-Cu porphyry and high sulfidation (HS) epithermal deposit is located at the Kratovo–Zlatovo volcanic field in Eastern Former Yugoslavian Republic of Macedonia. In this study, new fluid inclusions data provide additional evidence of the presence of a porphyry style mineralization which is associated with an overlain HS epithermal deposit. The Oligocene–Miocene magmatic rocks have a calc–alkaline to high-K calc–alkaline affinity and consist of sub-volcanic intrusions and volcanic rocks. Previous studies distinguished four alteration types: (a) Sericitic, (b) advanced argillic, (c) silicification, and (d) propylitic alteration. Fluid inclusions showed an early magmatic brine in porphyry style veins with high salinity (33–57 wt% NaCl equiv.), which coexists with a vapor rich fluid with lower salinity (14–20 wt% NaCl equiv.), at temperatures 380–500 °C, under boiling conditions. At shallower depths, the fluid inclusions demonstrate various HS–epithermal deposits which were formed by moderate to low salinity (3–14 wt% NaCl equiv.) hydrothermal fluids at lower temperatures from 200 to 300 °C.

Evolution of ore-forming fluids in the Bukovik-Kadiica porphyry Cu deposit, Republic of Macedonia

The paper presents information about our latest study of radon and radium in drinking water from the public water fountains situated in central parts of the Kratovo-Zletovo volcanic area. Results for the radon in water measurements were as follows: Fountain 1 to Fountain 4 samples, ranged from 6.63 up to 157.73 Bq L-1. Obtained results for the radium in water, Fountain 1 to Fountain 4 samples, ranged from 0.20 up to 1.08 Bq L-1. Both, radon and radium measurements, in water samples from certain fountains have shown significantly higher values than the strictest standards given by the United States Environmental Protection Agency (USEPA) and World Health Organization (WHO), respectively. The committed effective doses for the population consuming the water directly from the fountains or as self-bottled waters from the Kratovo-Zletovo volcanic area were estimated using the concentration of 222Rn and 226Ra in water samples, ranged from 45.47 mSv y-1 to 709.36 mSv y-1, which once again for some fountains were higher than the WHO recommended values of max. 100 mSv y-1.