Vesnica Garašić

Geochemical characteristics of mercurian tetrahedrite, barite and fluorite from the Duboki Vagan, Glumac and Dubrave-Dugi Dol barite deposits, south of Kreševo, Mid-Bosnian Schist Mts.

The geochemical characteristics of tetrahedrite and barite of the Duboki Vagan barite deposit near the town of Kresevo in the MBSM (Mid-Bosnian Schist Mountains) have been determinated and correlated with the results of previously studied barite, from the adjacent Glumac deposit, and fl uorite, from the Dubrave-Dugi Dol barite deposits. The studied tetrahedrite is characterized by a high content of Au (39 ppm) and Ag (>300 ppm), the presence of Co (63.5 ppm), Ni (266.2 ppm) and Cd (313,6 ppm) in the crystal lattice and negative δ34SCDT values (–11.80‰). On the plot of its C1 chondrite-normalized REE abundances, a slightly expressed positive Eu anomaly and high HREE concentrations are observed. The high content of SrSO4 (2.33 to 3.42 wt.%) in the barite crystal lattice indicates hydrothermal parent solutions. The δ34SCDT values of the studied barite are +10.40‰, which is typical for Permian seawater and its δ18OSMOW values range between 15.6 and 17.7‰. A distinct positive Eu anomaly is shown on the plot of the C1 chondrite-normalized REE abundances in barite. Geochemical characteristics of the studied tetrahedrite and barite of Duboki Vagan are very similar to those of previously investigated Glumac and Dubrave-Dugi Dol barite deposits. The fluorite from the Dubrave-Dugi Dol deposits displays a negative Eu anomaly and its Tb/La and Tb/Ca ratios indicate a quite different origin in relation to barite formation. This is all in the accordance with the possible existence of two different paragenetic types of barite deposits in the MBSM and SEB (Southeastern Bosnia), which significantly differ in the δ18OSMOW ranges of their barites and δ34SCDT values of their sulphides. The first type of barite deposits originated in the Late Variscan phase (Lower Permian). It is characterized by numerous Cu, Fe, Zn, Sb, As, Pb sulphides and Cu-Sb-tetrahedrite without mercury, all having positive δ34SCDT values (0 to +5 ‰). Early intercontinental rifting took place between the uppermost Permian and Lower Triassic and enabled, in a great number of barite deposits, (especially in the MBSM), remobilization and partial fluidization of their Fe, Cu, Zn, Sb and Pb sulphides which reacted with ascended mercury, sulphur and fluorine rich mantle fluids and resulted in the formation of Hgtetrahedrite and octahedral fluorite. These processes caused the occurrence of the second paragenetic type of barite deposit with Hg-tetrahedrite as the main ore mineral, but characterized by strongly negative δ34SCDT values.

Urban geochemistry: Sisak in Croatia, a long - lasting historical, urban and industrial city

A soil geochemical survey of the city of Sisak, Croatia, and its surroundings was done to determine the concentration, spatial distribution and sources of the elements in the soil. Factor analysis indicates 8 factors describe the geochemical variations in the topsoil: 4 anthropogenic, 2 geogenic and 2 mixed ones. The main influence in the urban and rural soils was parent material and anthropogenic inputs in the old part of the city, along roads and railways, and in the industrial areas. The results indicate that soils are a very good media for accumulating trace elements in urban and industrial areas.

Cobalt, nickel, wolfram, cadmium, selenium, silver and gold-bearing mercurian tetrahedrite from the Saski Rad barite-siderite deposit in the Mid-Bosnian Schist Mts.

In the Saski Rad barite-siderite ore deposit, Hg-tetrahedrite is the main ore mineral, pyrite and some others are only accessories. Two tetrahedrite samples (fresh and weathered) have been analysed in detail: major and minor components, constituent trace elements, REE, and δ34SCDT values. The following microconstituents have been detected: Ni 71 ppm (in fresh sample) and 70 ppm (in weathered sample); Co 113 and 90 ppm; Cd 27 and 20 ppm; W 20 and 5 ppm, Bi 2500 and 1613 ppm; Se >100 and 72 ppm and Au 11 and 9 ppm. These values have been compared with the only currently available analysis of Hg-tetrahedrite from the Duboki Vagan near Kresevo in the Mid-Bosnian Schist Mts. (MBSM) carried out by JURKOVIC et al. (2010): Ni 266.2 ppm; Co 63.5 ppm, Cd 319.6 ppm; Bi 1466.0 ppm; Au 38.96 ppm which also agrees with our analysis of Hg-tetrahedrite from the Brixlegg barite deposit in Tyrol, Austria: Co 234.4 ppm; Cd 160.5 ppm; W 6.7 ppm; Sn 1.0 ppm; Bi 909.1 ppm; Se > 100 ppm and Au 2.3 ppm. The δ34SCDT isotope values of six tetrahedrites from the Saski Rad are on average –10.11‰, those of three tetrahedrites from the Duboki Vagan –10,05‰ and of the tetrahedrite from the Brixlegg deposit –1.60‰. The ΣREE content is lower in two analysed tetrahedrites from the Saski Rad deposit (10 ppm) compared to the tetrahedrite from Duboki Vagan (15 ppm) and the tetrahedrite from Brixlegg (17.4 ppm). The analysed barite sample from the Saski Rad deposit does not contain microconstituents typical of Hg-tetrahedrite. The distribution and genetic signifi cance of some trace elements, tetrahedrite microconstituents, REE and siderite isomorphic components in the seven most important genetic and paragenetic types of ore deposits in the MBSM and South-Eastern Bosnia have been commented upon.