Geologia CroaticaGeologia Croatica AB STRA CT In this study two small, but genetically related iron carbonate deposits Mačje Jame and Vranjski Potok, south west of Busovača (MBSM), located in the pre-Devonian metamorphic complex were investigated in detail. Analyses of the main chemical components, trace elements, REE, isotope composition of C, O, S, 87Sr/86Sr ratio of rhyolite, plot of REE normalized to CI chondrites and a microscopic study of thin and polished sections were performed. Three mineralization phases were identifi ed: the oldest is the main phase (90-95 wt %) with Fe (Ca, Mg, Mn) carbonates (siderite, ankerite, Fe-dolomite) as the predominant minerals, whereas magnetite, haematite, albite, allanite, pyrite I, quartz I represent subordinate minerals. The second phase is the pneumatolytic-kata-thermal phase (5-10 wt %) characterized by pyrrhotite relicts, pyrite II, quartz II, arsenopyrite and some supposed accessory minerals such as cassiterite, wolframite, gersdorffi te, and columbite. The youngest is the kata-meso-epithermal-hydatogene phase (<1 wt %) which gave quartz III-chalcedony as gangue mineral and marmatite, chalcopyrite, boulangerite, gel-py- rite-marcasite, sphalerite, enargite, tetrahedrite, galena, cosalite, bismuth and sternbergite as ore minerals. An almost identical paragenesis has been observed in the oldest ore deposit of the Gemericum Palaeozoic metamorphic com- plex (RADVANEC and BARTALSKY, 1987). The fi rst and second mineralization phase of both ore deposits formed in the Carboniferous from metamorphogeno- hydrothermal fl uids generated from S-granitoid magmatic rocks and their protoliths. This claim is strongly sup- ported by very similar REE and their interior disposition between these deposits and metarhyolites as well as by the obtained strontium ratios. The third, youngest phase is the product of a very weak overprint of hydrothermal activ- ity in the Late Variscan (290-260 Ma) and in the Upper Permian-Lower Triassic (260-240 Ma). Keywords: iron deposits, Mačje Jame, Vranjski Potok, Hercynian metallogeny, Mid-Bosnian Schist Mts. Geologia Croatica 67/2 145–161 3 Figs. 9 Tabs. 2 Pls. Zagreb 2014 Geochemical characteristics and genesis of Mačje Jame and Vranjski Potok As-Cu-bearing iron occurrences west and southwest of the town of Busovača, Mid-Bosnian Schist Mountains (MBSM)  Ivan Jurković1 and Hazim Hrvatović2 1 Faculty of Mining, Geology and Petroleum Engineering, University of Zagreb, Pierottijeva 6, Zagreb, Croatia 2 Federal Geological Institute for Geology, 71210 Ilidža, Republic of Bosnia and Herzegovina doi: 10.4154/gc.2014.11 the north-eastern side, by the Kozica river on the south-east- ern and southern sides, by the Krušćica river on the south- western side and by the Lašva river on the north side. The Mačje Jame deposit is located in the spring zone of the Kozica river in the Živčička Mt. Similar paragenetic but smaller ore occurrences were observed at the Rudno 1. INTRODUCTION The Busovača region with the Mačje Jame and Vranjski Po- tok ore deposits is situated in the north-eastern part of the Mid-Bosnian Schist Mountains (MBSMts) (Fig. 1). It is the oldest part of MBSMts. The Palaeozoic complex area (3000 km2) is delimited by the deep fi rst order Busovača Fault on Geologia Croatica 67/2Geologia Croatica 146 with 23-26 mol % of a Mg-chloritoid component; c) chlorite richer in the Mg-component and d) barroisitic type amphib- ole. MAJER et al., (1991) carried out a phase analysis of py- rophyllite, white micas, chlorite, chloritoid and amphibole from the metamorphic rocks in the Busovača-Fojnica- Kiseljak-Kreševo region. These analyses demonstrated very low to low grade metamorphism of rocks in the SW part of the MBSM, and the local presence of barroisitic amphibole in the NE part of this territory (south of Busovača) indicat- ing higher P - T conditions. 2.2. Variscan rocks The Silurian metaclastic formations, scarcely intercalated with pelagic limestone chert interlayers and metavolcanic rocks are represented by slates, phyllites, quartz-muscovite schists, black graphite-bearing quartzitic schists, chlorite- muscovite-quartz schists, chloritoid schists, calcic phyllites (calcareous schists) with subordinate pyrophyllite schists, metasandstones and quartzites (KARAMATA & KRSTIĆ, 1996, HRVATOVIĆ, 1996, 2006). According to MAJER et al., (1991) the predominant Variscan rocks of Silurian age contain phengitic muscovite with less than 10 mol % cela- donite, chloritoid with mainly 8-15 mol % of Mg-chloritoid component and chlorite rich in the Fe-component. These rocks were generated under low-grade P-T conditions rang- ing between 350 - 400°C and approximately 300-400 MPa. A group of pyrophyllite-bearing rocks originated under P-T conditions of 350-430°C and 300-400 MPa. The first dating of the MBSM rocks was performed on a phyllite sample from the Fojnica area by BALOGH at the Institute of Deb- recen, Hungary, PALINKAŠ et al., (1996). The obtained K-Ar age of 343 ± 13 Ma suggests a Middle Viséan (Car- boniferous) thermometamorphic event, a metamorphic over- print of an inferred pre-Variscan complex in the Busovača- Fojnica region (PAMIĆ et al., 2004). Devonian. The Silurian rocks are overlain by massive reef limestones, dolomites, locally marbles characterized by tabular coral Favosites vranicae and stromatoporoid Amp- hipora ramosa. Lower parts of the carbonate sequence be- long to the Early Devonian (Emsian), whereas the upper parts belong to the Middle Devonian, mostly to the Eifelian and to a lesser extent to the Givetian (ŽIVANOVIĆ, 1979). Upper Devonian formations, which belong to the Frasnian, contain conodont Ancyrodella ooids (ŽIVANOVIĆ, 1972), only recorded at the village of Dusina. MUDRENOVIĆ et al., (1969) consider that greywacke- sandstones, without fossils, which overlie Devonian layers with conodonts at Jezero (Jajce) are of the Lower Carbonif- erous age. ŽIVANOVIĆ and MILOJEVIĆ (1975) stated that argillites and clay shales at Medenik (Rostovo), although with- out fossils, but covering fossiliferous Devonian sediments must be attributed to the Lower Carboniferous. VUJ NOVIĆ (1981) included greywacke sandstones and chlorite-sericite schists with locally rare phyllite breccias located at the village of Komar (Travnik), into the Lower Carboniferous. A dry land period existed from the end of the Lower Carboniferous to the Upper Permian. mountain ridge (+843 m) locality, SW of the village of Ti- sovac and at the locality of Gornje Brizove Stijene, 6.5 km SE to the town of Busovača. These small ore occurrences are characterized by siderite and ankerite as the main miner- als, with subordinate magnetite, haematite, albite, pyrite, quartz and Fe, As, Cu, Zn, Pb and Sb sulphides and sulpho- salts. Mining investigations at the locations of Rudno and Brizove stijene only involved the oxidation zone of both ore occurrences, whereas the Mačje Jame deposit had been mined in the primary ore zone as well (KATZER, 1905, 1910, 1924) (Fig. 1). The Vranjski Potok ore deposit is situated on the west bank of the Vranjski Potok (Creek), 150 m above its bed. The ore occurrence is located in the strongly tectonized Pal- aeozoic metasandstone of pre-Devonian age, approximately ten metres thick. Metasandstones are fine to coarse-grained rocks giving the appearance of a conglomerate (Fig. 2). Green-grey metarhyolite is located at the footwall of the metasandstone, in the Duboki Potok creek, the tributary of the Krušćica river. The ore deposits are friable at the outcrops and the interstices are filled with limonite and different sul- phides. The most abundant mineral is quartz, followed by muscovite as deformed ribbons, while sericitized feldspars, pyrite, limonite and clay minerals are sporadic. Layers of quartz and mica-schists, mm-cm thick, are interbedded in the faulted host rock. 2. GEOLOGY 2.1. Pre-Variscan metamorphic rocks The oldest rocks in the Mid-Bosnian Schist Mountains (MB- SMts) are phyllites and mica schists, interlayered with meta- volcanics, amphibolites and flaser gneisses. These rocks are exposed in a zone several km long at Modri Kamen and Za- hor in the Busovača region. KATZER (1906,1924) interpret ed these rocks as being Azoic. ŽIVANOVIĆ and MILOJEVIĆ (1975) interpreted them as being of Ordovician age. KARA- MATA and KRSTIĆ (1996) supposed a Cambrian-Ordovi- cian age for these rocks. According to PAMIĆ and JURKO- VIĆ (2002) and PAMIĆ et al., (2004), the pre-Variscan meta morphic rocks could be compared not only to the Ötztal complex of the Eastern Alps, but also to Palaeozoic meta- morphic complexes of the Drina-Ivanjica area (SW Serbia) and of Eastern Macedonia. According to HRVATOVIĆ (1999, 2006) the oldest rocks in the MBSM are Ordovician metaclastics and metabasalt. Dinaridic Cambrian-Ordovician formations were meta- morphosed during the Late Ordovician deformation, under P-T conditions of greenshist facies, and to a lesser extent of epidote-amphibolite facies (400-500°C; 4-5 kbars), in con- formity with the statement of MATTÉ (1984) for Central Europe (PAMIĆ et al., 2004). A detailed microscopic study performed by MAJER et al. (1991) of the pre-Variscan metamorphic rocks (Cambrian- Ordovician) in the Busovača zone demonstrated a significant difference compared to the Silurian-Devonian Variscan rocks. The pre-Variscan rocks include: a) phengitic musco- vite containing more than 10 mol % celadonite; b) chloritoid Ivan Jurković and Hazim Hrvatović: Geochemical characteristics and genesis of Mačje Jame and Vranjski Potok As-Cu-bearing iron occurrences ... Geologia Croatica 147 Figure 1: Simplified geological map of the northeastern part of the Mid Bosnian Schist Mountains. Figure 2: Vranjski Potok ore deposit. On the right side of this photo are visible outcrops of thick banded coarse-grained quartz sandstones and conglome- rates inserted with different ore and gangue minerals. Geologia Croatica 67/2Geologia Croatica 148 Three Upper Permian formations have been identi- fied: (1) Upper Permian Bojska series in the region of Bu- gojno, Kalin; (2) Upper Permian Opara series; (3) Permo- Triassic series in the area of Travnik. 2.3. Variscan magmatic rocks Detailed microscopic and chemical investigations of quartz- porphyry and metaquartz porphyry of Vranica Mountain (2107 m) and albite porphyry of Sinjakovo (Jajce) were con- ducted by JURKOVIĆ and MAJER (1954). The rocks have been identified as rhyolites, metarhyolites and albite rhyo- lite, generated from magma of a leucogranitic-aplitic char- acter. Southwest of Jezero-Jajce, near the village of Aljino- vac, in the western tributary to the Peručica river, the authors established contact metamorphism between albite rhyolite and crinoid limestone at that time supposed to be of Lower Permian age (KATZER, 1906, 1924. geological map (M 1: 200 000). In addition, on Vranica Mountain they established contact metamorphism between rhyolites and at that time con sidered Carboniferous phyllite. Further data concerning chemical compositions of the MBSM rhyolites are found in the explanations of the basic geological maps (M 1 : 100 000). According to ŽIVANOVIĆ and MILOJEVIĆ (1975), four successive eruptive phases of rhyolites in the MBSM have been established: the first phase as shallow Silurian intrusions in the Gornji Vakuf area; the second phase between the Lower Car- boniferous and the Upper Permian; the third phase, very su- bordinate, during the Permo-Triassic and the last phase, only locally in the Lower Triassic. ŽIVANOVIĆ (1979) and JOVANOVIĆ et al. (1978) presented the case for a two-stage magmatic history: 1) the older stage resulted in porphyrite sills found in the Silurian muscovite-chlorite schists (1Pz) and quartz-sericite schists (3Pz), and 2) the younger one which oc- curred in Carboniferous-Permian time and produced quartz porphyries penetrating Silurian and Devonian rocks, thus caus- ing contact metamorphic changes in carbonate rocks. They considered that quartz keratophyres were partly Carboniferous- Permian and partly Triassic in age. TRUBELJA (1978) and SOFILJ et al. (1980) suggested that metarhyolites intruded as intrusive and extrusive rocks during Carboniferous and early Permian time. They considered that quartz keratophyres are partly of Triassic age. HRVATOVIĆ (1996, 2006) considers that most of rhyolites are synsedimentary with presumed Silu- rian metasediments and are of Silurian age. Some hypabyssal rhyolites intruded into the Late Silurian and Early Devonian limestones which also occur as xenoliths within the volcanic body. Large masses of pyroclastics are either interlayered with metaclastics or represent shallow hypabyssal bodies. MAJER and GARAŠIĆ (2001) defined the composition of the major elements, compatible elements (Ni,Cu,Co) as well as incompatible elements with low (K, Rb, Ba, Th) and high ionic potential (Y, Zr, Nb). A low content of compatible elements and a high content of incompatible elements in rhyolites compared to the average contents in chondrites prompted the authors to express their doubt as to the juve- nile origin of rhyolites from the mantle, and to attribute them to a crustal origin. JURKOVIĆ et al. (2010a) determined in one Vranica Mountain rhyolite sample an extremely high 87Sr/86Sr ratio of 0.776995 ± 2 s, performed by thermal ion- isation mass spectrometry (TIMS) in the Activation Labora- tory, Ancaster, Ontario, Canada. This high strontium ratio of rhyolite might indicate the crustal source of an S-type of granitoid magma. 3. PARAGENESIS OF THE MAČJE JAME AND VRANJSKI POTOK ORE DEPOSITS A significant difference exists between the paragenesis of the ancient, abandoned mine Mačje Jame characterized by opened primary and oxidation ore zones and the paragenesis of the recently discovered ore locality Vranjski Potok, open only in the oxidation zone. The difference is also between host rocks: schists are present in the Mačje Jame and meta sand- stones (conglomerates) in the Vranjski Potok ore deposit. 3.1. Petrography of ore and gangue minerals 3.1.1. The ore deposit Mačje Jame JURKOVIĆ conducted the first unpublished microscope study of the Mačje Jame ore and gangue minerals as early as 1956a and 1958 (references). These minerals were identi- fied exclusively under polarizing microscope using thin transparent (petrographic) and polished ore sections (here- inafter marked with an asterisk, *). Quantitative values of their amounts were performed exclusively by recalculation from chemical analyses performed during this study (2012- 2013), displayed in Tables 2a, 2b, 4a, 4b, 5a, 5b, 6a, 6b and 9b. Minerals marked with a dot (●) were identified by com- bining microscopic analyses and analyses of trace elements and REE analyses. Minerals identified by trace element anal- yses, anticipating genetic type of ore deposits, are marked with a symbol (○). Minerals identified during this study us- ing optical methods are marked with a symbol (**). The earliest phase of mineralization which makes up 90 to 99 % of the ore, is characterized by different Fe-Mg- Ca-Mn carbonate minerals (siderite, ankerite, dolomite) as the main minerals, and by subordinate magnetite, haematite, albite and scarce pyrite I and quartz I. Magnetite I. (*, content: < 5 wt%) is the earliest mineral component, idiomorphically developed, isometric, and mar- ginally martitized. Haematite I (*, content: < 5 wt%) is rod- shaped, rodlike formed, 1-4 mm long, 30-60 μm thick. It forms parallel, radial, or bent bundles densely or thinly scattered within carbonates. Basal cross–sections or irregular small ag- gregates are very rare. A significant amount of haematite I was transformed into magnetite II (*) most probably at the begin- ning of the sulphide phase. Particular bundles and even par- ticular sticks of haematite I were replaced to different degrees during the process of reduction in which enlargement of mag- netite II crystals occurred, and therefore the margins are less acute (Plate I, photo 1, 2, 5). Calculation of amounts of ir- regularly martitized magnetite and oxidized haematite were not calculated individually but alongside goethite. Siderite (*, content: 64.7 wt %), is in rombohedral habit with a diameter of up to 0.5 mm. These crystals build up subparallel or radial bundles as siderite II. In Table 9 iso- morphic components of the Mačje Jame siderite-ankerite Ivan Jurković and Hazim Hrvatović: Geochemical characteristics and genesis of Mačje Jame and Vranjski Potok As-Cu-bearing iron occurrences ... Geologia Croatica 149 Table 1: Paragenesis of the Mačje Jame deposit (Table 1a) and Vranjski Potok deposit (Table 1b) located in the MBSMts (Captions: see text). Parageneses Method of identification MAČJE JAME Method of identification VRANJSKI POTOK ANALYTE wt. % wt. % quartz (SiO2) * 5.665  61,000 albite (K(Na)AlSi3O8) * 5.680  0,570 siderite (Fe,Ca,Mg,Mn)CO3 * 45.695 – pyrite (FeS2) * 3.090  – arsenopyrite (FeAsS) * 1.745  0,018 magnetite (Fe3O4) * SEE content of goethite – haematite (Fe2O3) * marmatite (Zn,Fe)S * 0.107 – tennantite (tetrahedrite) * 0.086 – chalcopyrite (CuFeS2) * 0.058  1,993 boulangerite (Pb5Sb4S11) * 0.029 – chalcedony (SiO2xH2O) * <0.100 – cassiterite (SnO2) * 0.024  0,006 galena (PbS) * 0.018 – wolframite (Fe,Mn)WO4) ● 0.012 – cosalite (Pb2Bi2S5) ● 0.010  0,058 sphalerite (ZnS) ● <0.010  0,023 enargite (luzonite) (Cu3As(Sb)S4) * <0.005 – sternbergite (AgFe2S3) * <0.005 – silver (Ag) * ppm <1.6  0,001 gold (Au) ● ppm 0.029  0,339 bismuth (Bi) ● <0.010  0,329 molybdenite (MoS2) ○ <0.001  0,0004 barite (BaSO4) ● 0.004  0,040 cobalite (CoAsS) ○ 0.022  – gersdorffite (NiAsS) ○ 0.030 – columbite (FeMn) (Nb,Ta)2O6 ○ 0.012  – allanite (Ce,Y)•(Al,Fe)3(SiO4)3•OH ** <0.100  – Trace elements (Tr-El) ● 0.071  0,109 REE ● 0.017  0,018 goethite (FeO•OH) + magnetite + haematite * 39.315  26,955 kaolin (Al2Si2O5(OH)4) ppm ○ 56.800  10,164 calcite (CaCO3) * trace – Pb-As-Sb oxydes ● trace  >0,016 (FeO, CaO, MgO and MnO) ore samples were calculated: 62.5 wt % FeCO3; 8.8 wt % CaCO3; 19.3 wt % MgCO3 and 9.4 wt% MnCO3. These values are significantly elevated, particularly the values of MgCO3 and MnCO3 in relation to the younger Maškara siderite-barite-tetrahedrite ore deposit in the MBSM. Obviously siderite-ankerite generation in the Mačje Jame deposit represents the earlier generation of iron carbonates in the MBSMts generated under higher P-T con- ditions (350-400°C and 1.5 kPa) (Plate I, photos 1, 4, 5). Albite (* content: 5.7 wt %), develops as single crystals, twins or polysynthetic crystals: 0.5 to 1 mm long, even 3 to 4 mm in druses. Greater albite crystals occlude fragments or crystals of older carbonates, magnetite and Ti-oxides. Albite is very irregularly distributed in the ore. Quartz I (*, 5.7 wt %) is very coarse-grained, cataclased and optically anomalous. Quartz is mostly concentrated along salbands. It is younger than carbonate minerals replac- ing their particular zones (Plate I, photo 3). Pneumatolytic-katathermal phase of mineralization This phase accounts for between 2 and 4 wt.% of the ore of the Mačje Jame deposit (Table 1.). Geologia Croatica 67/2Geologia Croatica 150 Plate I Six photomicrographs of the Mačje Jame ore samples. Legend: hm – haematite, sd – siderite, pb – galena, mg – magnetite, py – pyrite, q – quartz, as – arsenopyrite, tennantite, chc – chalcedony, sf – sphaterite, ch – chalcopyrite Quartz II (*) is coarse-grained, most often associated with arsenopyrite crystals. Arsenopyrite (*, 1.8 wt %) has been found in the three ore samples which gave 2.70, 0.79 and 0.36 wt.% FeAsS. It is most abundant within carbonate minerals and as single Pyrite II (*, 3.1 wt %) is partly or strongly oxidized. Unoxidized relicts of pyrite of two ore samples gave 0.65 and 5.62 wt.%. Many bigger crystals are cataclased and lo- cally mylonitized. It is the most abundant sulphide mineral (Plate I, photo 2). 1 2 3 4 5 6 Ivan Jurković and Hazim Hrvatović: Geochemical characteristics and genesis of Mačje Jame and Vranjski Potok As-Cu-bearing iron occurrences ... Geologia Croatica 151 crystals, and as aggregates 50-200 μm in diameter. Arsenopy- rite crystals are sometimes occluded and associated in the coeval quartz crystals and distinguished predominantly with idiomorphic (rhombic) forms (Plate I, photos 3, 4). Mesothermal-epithermal phase of mineralization During this phase some Co, Fe, As, Sb, Bi and Pb sul- phides and sulphosalts were formed. Marmatite (*) (average content is 0.11 wt%) is the old- est mineral of this phase replaced by other younger minerals, particularly by boulangerite in the form of small irregular masses or as bands of needles or crystals characterized by rhombic sections. Marmatite is distinguished by yellow-brow- nish, red-brownish and red internal reflections, which indicate sphalerite, rich in iron. It is visible to the naked eye and its content in the ore is 0.107 wt. % (Plate I, photos 5, 6). Chalcopyrite (*) (average content is 0.06 wt.%) and associated tennantite (*) (av. content is 0.086 wt.%) are the main copper minerals (Plate I, photos 5, 6). Enargite-luzonite (*) (average content is 0.005 wt.%) is a very rare mineral in the form of minute crystals some tens μm in diameter, most often occluded in chalcopyrite. It is partly lamellar in habit (luzonite). Galena (*) (average content is < 0.018 wt.%) is associ- ated with other sulphides, or it selectively replaces haema- tite. Drusy epithermal-hydatogene mineralization phase Small irregular cavities in the ore have their interior walls encrusted with small quartz III crystals or with chalcedony showing relicts of primary colloid structure. Using optical methods, the following drusy minerals were identified (Plate I, photos 4, 6). Chalcedony (*) (average content is < 0.1 wt%) is the main gangue mineral of this mineralization phase. Small grains of chalcedony are often characterized by their radial- concentric structure. Quartz III (*) grown on the drusy walls has a bipyramidal-prismatic habit. Boulangerite (*) (average contents in three different samples calculated from the trace element analyses are 0.029, 0.019, 0.012 wt.%). It predominantly occurs within chalcedony in the form of numerous small aggregates or as very dense needle bundles or particular needles marked by rhombic cross-sections. Droplets of pinkish bismuth (*) (av- erage content < 0.01 wt.%) are noticeable within boulang- erite. Locally, there is a single grain or densely arranged minute yellow-pinkish grains with higher relief than that of the boulangerite replacing it, probably of argyropyrite (X) or sternbergite (X) (average content < 0.005 wt.%), goldish- yellow coloured and of higher reflection than boulangerite (Plate I, photo 6). Yellow sphalerite (*) (average content < 0.01 wt.%) mostly within chalcedony is distinguished by clearer inter- nal reflection, preponderantly yellowish. It forms minute drops reminiscent of a colloid structure. Marcasite (*) is associated with gel-pyrite indicating generation from older weathered pyrrhotite. Hypergene mineralization During the oxidation phase of the Mačje Jame ore deposit, the main mineral that formed is goethite, whereas lepi- docrocite is rare. Covellite, chalcocite, malachite, azurite and Sb (As) oxides are subordinate or occur as accessories. Small masses of elemental silver (φ 100-150 μm) were ob- served in two polished sections of the ore. 3.1.2. Minerals identified during this study Minerals identified using the data of trace element analyses, REE analyses and detailed microscopic investigations are indicated with a small black dot (●) and probable minerals with the symbol (○) (see Table 1a). Cassiterite (●) (average content 0.024 wt%) was ob- served in some ore samples (polished sections) as micro- scopically fine masses, distinguished by high relief, and great hardness. It is dark-grey or pinkish, characterized by low re- flectivity, clear anisotropy and white-light-dark brown inter- nal reflection. Trace element analysis indicate 189 and 151 ppm Sn which equates to 0,024 and 0,019 wt.% SnO2. The Mačje Jame ore deposit is the second cassiterite bearing lo- cality in the MBSM, the first locality being Vrtlasce several km east of the town of Fojnica (JURKOVIĆ, 1956). Wolframite (○) (average content 0.012 wt%) is a pre- sumed mineral, because trace element analysis of one ore sample produced a high content of 71.6 ppm W. The second reason for this presumption is the discovery of wolframite in the Main Vein of the big Čemernica quartz-antimonite- sphalerite-veiny system (RAMOVIĆ, 1956). Wolframite crystals in the Čemernica ore deposit are visible to the naked eye and contain 74 wt.% WO3, 18 wt.% FeO and 6.2 wt.% MnO which corresponds to the mineral hibernite. Gersdorffite (○) (average content 0.03 wt %) is also a presumed mineral in the Mačje Jame ore deposit. Trace ele- ment analyses produced 182 ppm of Co and 244.2 ppm of Ni. The recalculation of these values gives 0.022 wt.% of CoAsS (cobaltite), and 0.030 wt.% of NiAsS (gersdorffite). Their isomorphic arsenide (gersdorffite) is a typical pegma- titc-pneumatolytic high-temperature mineral (RAMDOHR, 1983). Columbite-tantalite (○). (average content 0.012 wt%) Heightened contents of Nb (26.8 ppm) and Ta (10.9 ppm) in the same ore sample indicate presumed minerals from the isomorphic pair columbite-tantalite. Recalculation gives (Fe, Mn,Nb0.711Ta0.289)2O6 with the participation of 0.012 wt.%. The high presence of Y (58.8, 70 and 90.4 ppm) and 129 ppm of Ce (Table 5a) proves formation of the mineral allanite (**), whereas the presence of 28.1 ppm of Th indi- cates monazite. 3.1.3. Microscopic investigation of ore samples from the Vranjski Potok deposit Twelve mineralized rock samples marked by symbols BOS- 1, 2, 3, 4, 5, 6, 9, 10, 11, 13, 15 and 25 were investigated under the ore microscope. The mining investigations were conducted recently (in 2013, Table 1b) in the initial phase, and therefore the ore samples have been picked up only in Geologia Croatica 67/2Geologia Croatica 152 Plate II Photos 2-6 are photomicrographs of the Vranjski Potok ore deposit. Photo 1 is from Mačje Jame ore deposit. Legend: hm – haematite, sd – siderite, pb – galena, mg – magnetite, py – pyrite, q – quartz, as – arsenopyrite, tennantite, chc – chalcedony, sf – sphaterite, ch – chalcopyrite, Ag – silver, Au – gold ement analyses anticipating a genetic type of ore deposits, were indicated by two small darkened triangles (). The polished sections of BOS-1, 3, 4, 15 and 25 samples were taken from quartzose conglomeratic metasandstone composed of rounded or semirounded particles. In the BOS- the oxidation zone of the Vranjski Potok deposit. All miner- als are displayed in Table 1b. Minerals identified under the microscope during this study in 2013 are indicated by a small darkened triangle (), and their contents were calculated from the chemical analyses. Minerals identified by trace el- 1 2 3 4 5 6 Ivan Jurković and Hazim Hrvatović: Geochemical characteristics and genesis of Mačje Jame and Vranjski Potok As-Cu-bearing iron occurrences ... Geologia Croatica 153 Table 2: Chemical analyses of two ore samples from the Mačje Jame ore deposit (Table 2a) and five samples from the Vranjski Potok ore deposit (Table 2b). MAČJE JAME Table 2a Sample MA-JA MA-JS Chemical method MDL FUS-ICP FUS-ICP Average Analyte wt. % wt. % wt. % wt. % SiO2 0.010 14.380 5.060 9.720 Al2O3 0.010 2.320 0.180 1.250 Fe2O3 0.010 27.240 39.990 33.610 FeO 0.010 17.990 17.310 17.650 MnO 0.001 2.050 2.670 2.360 MgO 0.010 4.350 3.630 3.990 CaO 0.010 3.130 1.460 2.290 Na2O 0.010 1.300 0.040 0.670 K2O 0.010 0.030 0.010 0.020 TiO2 0.001 0.020 0.100 0.060 P2O5 0.010 <0.01 0.010 <0.01 As 5 ppm 1.290 0.360 0.830 LOI 26.520 30.410 28.470 Total 0.01 100.620 101.230 100.980 Table 2 (a+b) VRANJSKI POTOK Table 2b Sample MDL BOS-9 BOS-10 BOS-12 BOS-13 BOS-15 Average Analyte wt. % wt. % wt. % wt. % wt. % wt. % wt. % SiO2 0.010 69.000 41.000 61.000 50.000 78.000 59.800 Al2O3 0.010 5.330 4.910 2.140 7.160 3.040 4.520 TiO2 0.010 0.020 0.010 0.010 0.020 0.010 0.010 Fe2O3 0.040 17.470 42.810 29.640 30.730 12.210 26.570 CaO 0.010 0.030 0.030 0.520 0.040 <0.01 0.120 MgO 0.010 2.630 1.760 0.430 2.310 0.810 1.590 Na2O 0.010 <0.01 0.004 0.020 0.005 0.005 0.010 K2O 0.010 0.024 0.060 0.080 0.120 0.070 0.070 MnO 0.010 0.100 0.080 0.270 0.080 0.030 0.110 P2O5 0.010 0.030 0.120 0.160 0.130 0.030 0.090 S 0.170 0.080 0.170 0.180 1.510 0.420 H2O+ (gt) 1.970 4.840 3.350 3.470 1.380 3.000 H2O+ (kl) 3.550 3.280 1.420 4.780 2.030 3.010 Total 0.010 99.728 99.809 99.220 99.034 99.137 99.320 25 sample microbrecciated and mylonitized particles of host rock are visible. Polished sections of these ore samples stud- ied here contain different colloform limonite structures (Fe oxides and hydroxides). Irregular relict patches of pyrite I and coarse-grained porous and strongly cataclased pyrite II are also present. Locally, small masses of chalcopyrite, rarely sphalerite and one very weathered copper mineral, associated with malachite and azurite, probably tetrahe- drite, are observed. Hollows in the rock are encrusted with fine layers of younger pyrite and Fe-hydroxide. Sample BOS-25 contains partly metasandstone and partly micro- grained quartz as the main gangue, coloured by iron oxides (Plate II, photos 1-6). The BOS-2, 5, 6, 9, 10, 12 and 13 samples are composed only of ore with predominantly micrograined quartz (di- ameter in μm). Many quartz grains contain occluded pyrite and micrograins or micromasses of elemental gold or elec- trum which is bright yellow or silver-yellowish in colour. Pyrite, gold and silver occluded in quartz grains are not ox- Geologia Croatica 67/2Geologia Croatica 154 idised because they are totally isolated in quartz grains. Younger pyrite II and mica flakes often occur in the fine fractures and rarely on the short faults in the quartz gangue. Fine encrustations of arsenic and antimony oxides formed by weathering of arsenopyrite, tetrahedrite and lead an- timonides are also visible in the small masses of chalcopy- rite and malachite. 3.2. Chemical composition of the ore of both deposits 3.2.1. The chemical composition of the main components of the Mačje Jame deposit By recalculating the data of two samples (Table 2a) on the minerals identified earlier by optical methods (JURKO VIĆ, 1956), a mineral composition model was obtained as dis- played in Table 3c. It is for the most part an iron carbonate deposit with different Fe-Mg-Ca-Mn carbonates and with subordinate iron oxides magnetite and haematite. Almost 50% of the siderite has been oxidized to goethite and lepi- docrocite. Only pyrite I, II (av. content 3.1 wt%) and arse- nopyrite (max. value 2.7 wt%) are visible to the naked eye, all other numerous sulphides and sulphosalts are accessories (Table 1). Although pyrrhotite was not identified microscop- ically, the presence of typical “birds eye” structure of gel- pyrite-marcasite indicates its formation. When we attempted to recalculate all TOT/S (total sulphur) only on pyrite, we obtained a lack of sulphur. 3.2.2. Chemical composition of the ore in the Vranjski Potok ore deposit Quartz occurs partly as detrital particles of quartzose metas- andstone, and partly as a chemically precipitated gan gue mineral (Table 2b, Table 2c). The quartz content is approx- imately calculated at 60.6 wt %. The main ore mineral is goethite, whereas lepidocrocite is markedly subordinate. In the oxidation zone of the Vranjski Potok ore deposit, the pri- mary hypogene siderite is almost completely oxidized into goethite, whereas pyrite, magnetite and haematite are partly altered to goethite. The average calculated content of these minerals amounts to 26.8 wt% and varies between 13.6 and 47.7 wt%. Minerals of the clay group. Due to the minute available amounts of the elements Ca, K and Na, conversion into kao- linite was performed out of the three possible minerals (ka- olinite, illite and montmorillonite).. The obtained values range between 5.04 and 17.41 wt. % (the average value is 10.09 wt. %). The average content of albite is low (0.6 wt. %), and it is unevenly distributed in the ore. The content of albite is probably greater in the primary zone. Contents higher than 1 wt% were only observed for oxidized copper minerals: malachite, azurite, cuprite, Cu–sulphate etc. Ta- ble 2c shows that the values of CuFeS2 in the primary zone would range between 0.6 and > 2.9 wt. %. The calculated content of Fe2O3 (12.2 up to 42.8 wt.%) belongs to the min- eral goethite. The Al2O3 (with 2.1, and 7.2 wt. %) is locked into the clay minerals. A high content of H2O+ (crystal wa- ter) between 1.4 and 4.8 wt% is linked to goethite, whereas 1.4 to 4.8 wt% of crystal water is attributed to clay minerals. 3.3. Trace elements in the Mačje Jame and Vranjski Potok ore deposits 3.3.1. Trace elemets in the Mačje Jame deposit Trace element contents in the Mačje Jame deposit are dis- played in Table 3. The most characteristic trace element is As predominantly as the mineral arsenopyrite. The height- ened contents of Co (182 ppm) and Ni (244 ppm) also indi- cate the presence of cobaltite and gersdorffite. High con- tents of Sn (151 and 189 ppm) is evidence of cassiterite and 71.6 ppm of W suggests the probable presence of the min- eral wolframite. The ore sample MA-JS contains 26.8 ppm of Nb and 10.9 ppm of Ta, which probably reflects the pres- ence of the mineral columbite. Among non-ferrous metals, Zn is the most abundant (989 and 220 ppm) occurring in the minerals marmatite, tet- rahedrite and in yellow sphalerite, Cu (20, 25 and 370 ppm) is a constituent of chalcopyrite, tetrahedrite, and enargite- luzonite. Pb (419 ppm) with Sb (74, 35 and 30 ppm) formed the mineral boulangerite and with Bi (44 ppm) the mineral cosalite. It is very interesting to note the low contents of Ag (< 1.6 ppm), Au (0.029 ppm), Hg (0.95 ppm) and Se (2.5 ppm). JURKOVIĆ et al., 2010a, 2011 proved mutual (recip- rocal) genetic interdependence among Bi, Ag, Au, Hg and Se. These trace elements are trace elements in the oldest MBSM deposit (Mačje Jame). In the youngest MBSM ore deposits with Hg-tetrahedrite as the main, almost the only ore mineral (Maškara, Trošnik, Glumac), the very high values of these el- ements incontestably suggest two different mineralising fluids in terms of time and space (JURKOVIĆ et al., 2010a). 3.3.2. Trace element contents in the Vranjski Potok deposit High values of Sn (50 and 181 ppm) indicate relicts of the resistant hypogene cassiterite. Likewise, the values of Zr (average 57 ppm) prove the presence of the mineral zircon. The heightened contents of Y (16 to 47 ppm) and of Ce (av- Table 3: Main mineral components in the Mačje Jame and Vranjski Potok ore deposits. Main mineral components in the Mačje Jame and Vranjski Potok ore deposits Table 3 Ore deposit MAČJE JAME VRANJSKI POTOK Number of samples three five Analyte wt. % wt. % Quartz 5.665 − 60.573 − Siderite 44.730 47.241 − − Albite 5.680 5.999 0.566 1.435 Pyrite I, II 3.090 3.264 − − Arsenopyrite 1.814 1.916 0.018 0.046 Chalcopyrite 0.058 0.062 >1.979 >5.019 Clay mineral trace trace 10.093 25.596 Goethite+Fe3O4 + Fe2O3 39.315 41.520 26.766 67.879 TOTAL 100.352 100.002 99.995 99.975 Ivan Jurković and Hazim Hrvatović: Geochemical characteristics and genesis of Mačje Jame and Vranjski Potok As-Cu-bearing iron occurrences ... Geologia Croatica 155 erage 77 ppm, Table 6b) suggest relicts of the mineral al- lanite. In the BOS-13 sample, 22.8 ppm of Nb is presumed to represent relicts of niobite or columbite. The obtained values of Co (83 ppm) and of As (558 ppm) in the BOS-12 sample presume the relicts of hypogene cobaltite and arse- nopyrite (Tables 5a and 5b). In Vranjski Potok, the third hydrothermal phase is two to three times (see Table 3) better developed than in the Mačje Jame deposit (Table 4 and Tables 5a and 5b), which indicates a stronger Late Variscan overprint. Cu is the predominant trace element with contents of 0.19, 0.44, 0.48, > 1.0 wt%. The dominant copper miner- als in the oxidation zone are malachite, azurite, cuprite, tenorite, Cu-sulphates, chrysocolla. The element Pb with the average values of 422 ppm occurs as cerussite and an- glesite. 3.4. Rare earth elements 3.4.1. REE contents in the Mačje Jame ore deposit Three analyzed ore samples gave completely different Σ REE values (Tables 7a and 7b). The sample MA-JS is characteri- zed by an exceptionally high Σ REE content of 353 ppm. La participates with 57 ppm, Ce with 129 ppm and Nd with 44 ppm (Table 6a). Heightened contents of Y (70 ppm) and Th (28 ppm) in the same sample prove the presence of allanite and monazite as accessory minerals. Unusually elevated val- ues of Pr, Gd, Dy, Er and Yb reflect probably other, not yet identified lanthanide accessory minerals. The sample MA-SP is distinguished by a negative slope of the Σ LREE/ Σ HREE by the lowered negative Eu-anoma ly, redoubled positive Ce anomaly and negative La/SmN and La/YbN fractionation factors (Fig 3). 3.4.2. REE contents in the Vranjski Potok ore deposit Five analyzed ore samples (Table 6b) gave very different REE contents. The BOS-10 and BOS-13 samples have 275 ppm, BOS-12 175 ppm, BOS-09 122 ppm and BOS-15 68 ppm. The main cause for this difference is the share of sand- stone as the mother rock in the analyzed sample and the in- tensity of overprint. Despite this, the majority of REE pa- rameters, with the exception of BOS-12, are roughly equal (Table 7b). The Eu-anomaly is negative, whereas the Ce anomaly is positive. All three fractionation factors are posi- tive, particularly the slope of the (La/YbN) curve. These five samples were affected by Late Variscan over- prints, particularly the BOS-12 (Table 6b), and then BOS- 15 and BOS-10. The BOS-12 sample contains > 1.0 wt.% of Cu (> 2.9 wt% of CuFeS2), then > 0.2 wt% of Bi (as cosalite and as Bi), 74 ppm of Se, 7.2 ppm Hg, 178 ppm Sb, 471 ppm of Pb, 172 ppm of Zn. The occurrence of Bi, Se, and Hg is regularly associated with the presence of Ag (32 ppm) and Au (381 ppb). The average content of lanthanides in 5 ore samples from the Vranjski Potok deposit amounts to 183 ppm, rang- ing between 68 and 275 ppm (Table 6b). Three lanthanides (La, Ce and Nd) stand out among other lanthanides in terms of their content. Lanthanum is present with an average value Table 4: Trace element contents in the Mačje Jame ore deposit Ba-Y group and Mo-Se group. Trace element contents in the Mačje Jame ore deposit Table 4 Sample MA-JA MA-JS MA-JP Trace Elements MA-JA MA-JS MA-JP Anal. Method FUS-MUS FUS-MUS 4B Method FUS-MUS FUS-MUS IDX MDL MDL MDL MDL Analyte ppm ppm ppm ppm ppm Analyte ppm ppm ppm ppm ppm Ba 3.00 7.00 6.00 1.00 31.00 Mo 2.00 <2.00 <2.00 0.10 3.700 Be 1.00 <1.00 <1.00 1.00 <1.00 Cu 10.00 20.00 370.90 0.10 25.100 Co 1.00 31.00 20.00 0.20 182.00 Pb 5.00 6.00 <5.00 0.10 418.500 Cs 0.10 0.10 0.20 0.10 0.10 Zn 30.00 220.00 <30.00 1.00 989.000 Ga 1.00 3.00 4.00 0.50 2.40 Ni 20.00 40.00 30.00 0.10 244.200 Hf 0.10 <1.00 8.10 0.10 <0.10 As 5.00 1.29 wt% 0.36 wt% 0.50 see Table 2a Nb 0.20 1.00 26.80 0.10 4.90 Cd n.a. n.a. 0.10 1.800 Rb 1.00 2.00 2.00 0.10 1.30 Sb 0.20 74.40 34.60 0.10 30.200 Sn 1.00 4.00 189.00 1.00 151.00 Bi 0.10 1.80 0.60 0.10 43.700 Sr 2.00 58.00 9.00 0.50 11.90 Ag 0.50 <0.50 <0.50 0.10 3.900 Ta 0.01 <0.01 10.90 0.10 <0.10 Au* n.a. n.a. 0.50 29.20* Th 0.05 0.27 28.10 0.20 0.30 Hgx n.a. n.a. 0.01 0.95x U 0.01 1.66 4.57 0.10 1.90 Tlx 0.05 <0.05 0.07 0.10 0.10x V 5.00 51.00 101.00 8.00 127.00 Sex n.a. n.a. 0.50 2.50x W 0.50 2.20 71.60 0.50 3.70 Ge 0.50 1.70 1.30 n.a. Zr 1.00 <1.00 269.00 0.10 2.70 Scx 1.00 11.00 16.00 n.a. Y 0.50 58.80 70.00 0.10 90.40 Cr 20.00 <20.00 <20.00 n.a. Total 220.03 820.27 610.60 Total 374.90 453.47 1763.65 Geologia Croatica 67/2Geologia Croatica 156 of 40 ppm, Ce with 77 ppm, and Nd with 32 ppm. The avera ge value of all three lanthanides (La + Ce + Nd) is 146 ppm, which accounts for 82 wt. % of the content of all 14 lantha- nides in the Vranjski Potok deposit. In view of the fact that metarhyolite and its protolith contain the same or very similar REE and La, Ce and Nd values as the predominant REE elements, it was con- cluded that the metamorphogenic fluids generated in the Table 5: Content of trace elements in the Vranjski Potok deposit Ba-Y group (Table 5a) and Mo-Se group (Table 5b). Trace elements (Ba-Y) in the Vranjski Potok deposit Table 5a Sample MDL BOS-09 BOS-10 BOS-12 BOS-13 BOS-15 Anal.Method 4B 4B 4B 4B 4B 4B Analyte ppm ppm ppm ppm ppm ppm Ba 1.0 48.00 172.00 165.00 360.00 605.00 Be 1.0 <1.00 <1.00 <1.00 1.00 <1.00 Co 0.2 14.90 17.50 83.20 11.80 5.80 Cs 0.1 0.40 1.80 0.50 3.80 1.40 Ga 0.5 13.00 15.60 5.10 25.40 10.30 Hf 0.1 1.70 1.70 0.10 2.30 2.00 Nb 0.1 7.50 9.70 3.10 22.80 7.70 Rb 0.1 5.80 44.90 13.80 93.60 44.80 Sn 1.0 49.00 54.00 181.00 28.00 16.00 Sr 0.5 8.00 12.30 11.20 13.10 8.40 Ta 0.1 0.60 0.80 0.10 1.30 0.60 Th 0.2 6.60 10.40 0.80 17.00 5.50 U 0.1 1.10 2.80 1.20 3.00 0.80 V 8.0 39.00 55.00 13.00 83.00 38.00 W 0.5 <0.50 3.40 <0.50 3.90 0.90 Zr 0.1 60.50 54.70 5.30 85.60 56.80 Y 0.1 15.20 25.80 46.70 26.30 7.40 Total 271.30 482.40 530.10 781.90 811.40 Trace elements (Mo-Se) in the Vranjski Potok deposit Table 5b Sample MDL BOS-09 BOS-10 BOS-12 BOS-13 BOS-15 Anal.Method 4B 4B 4B 4B 4B 4B Analyte ppm ppm ppm ppm ppm Ppm Mo 0.10 4.90 2.50 2.20 1.00 0.60 Cu 0.10 1.954.00 4.807.00 >10.000.00 4.417.00 >10.000.00 Pb 0.10 190.40 562.30 471.40 821.40 63.30 Zn 1.00 155.00 407.00 172.00 84.00 57.00 Ni 0.10 3.00 7.10 21.90 4.30 2.00 As 0.50 25.90 19.80 551.17 24.70 <0.50 Cd 0.10 <0.10 0.20 0.90 0.20 0.20 Sb 0.10 2.10 4.70 178.40 22.10 0.80 Bi 0.10 125.80 81.00 >2.000.00 63.40 14.80 Ag 0.10 1.90 15.30 32.40 1.20 8.70 Au* (ppb) 0.50 240.50 181.00 380.80 89.90 772.10 Hgx 0.01 0.98 0.71 7.15 0.31 2.69 Tlx 0.10 <0.10 <0.10 <0.10 <0.10 <0.10 Sex 0.50 9.60 10.50 74.00 19.50 11.80 Total 2.714.08 6.099.11 >13.892.30 5.549.01 >10.934.00 Ivan Jurković and Hazim Hrvatović: Geochemical characteristics and genesis of Mačje Jame and Vranjski Potok As-Cu-bearing iron occurrences ... Geologia Croatica 157 S-granite magma and their pre-Palaeozoic and Lower Palaeozoic protoliths, might be a source of mineralizing fluids for the generation of the Mačje Jame and Vranjski Potok deposits. 3.4.3. Comparison of the REE contents between the Mačje Jame and Vranjski Potok ore deposits, and the metarhyolites and keratophyres from Bu sovača- Fojnica-Kreševo region The range of REE contents between the ore samples and magmatic rock samples is displayed in Table 8. The range of REE content values range from 158 to 197 ppm (average 180 ppm) for 5 samples of rhyolite and meta- rhyolite from the Fojnica-Kiseljak-Kreševo region. These 5 samples have the following average content of dominant el- ements: La 35 ppm, Ce 76 ppm and Nd 33 ppm. Furthermore, the 3 rhyolite samples from the Šebešić- Kozica-Kruščica (Busovača) region show values of between 205 to 214 ppm (average 209 ppm) with the following dom- inant values: La 43 ppm, Ce 88 ppm and Nd 35 ppm. Five samples from the Vranjski Potok ore deposit produced va- lues between 68 and 275 ppm, with an average value of 183 Table 6: REE content of the samples from the Mačje Jame deposit (Table 6a) and from the Vranjski Potok deposit (Table 6b). REE content in the Mačje Jame deposit Table 6a Sample MA-JA MA-JS MA-JP Chemical method MDL FUS-MUS FUS-MUS MDL 4B Average Analyte ppm ppm ppm ppm ppm ppm La 0.050 9.62 56.60 0.1 2.90 23.04 Ce 0.050 20.10 129.00 0.1 6.50 51.87 Pr 0.010 2.48 14.20 0.02 0.95 5.88 Nd 0.050 9.21 43.70 0.3 4.80 19.24 Sm 0.010 3.27 11.70 0.05 2.64 5.87 Eu 0.005 1.28 4.89 0.02 1.98 2.72 Gd 0.010 4.50 13.70 0.05 5.23 7.81 Tb 0.010 1.16 3.41 0.01 1.49 2.02 Dy 0.010 8.90 25.60 0.05 11.43 15.31 Ho 0.010 2.06 5.73 0.02 3.03 3.61 Er 0.010 6.93 18.60 0.03 9.87 11.80 Tm 0.005 1.18 2.98 0.01 1.58 1.91 Yb 0.010 8.23 19.90 0.05 9.85 12.66 Lu 0.002 1.21 2.80 0.01 1.46 1.82 Total 80.13 352.81 63.71 165.55 REE contents in the Vranjski Potok ore deposit Table 6b Sample MDL BOS-09 BOS-10 BOS-12 BOS-13 BOS-15 Average Analyte ppm ppm ppm ppm ppm ppm ppm La 0.10 30.00 57.60 39.80 60.00 13.60 40.02 Ce 0.10 56.30 114.40 68.30 117.10 29.70 77.16 Pr 0.02 5.47 13.67 8.20 13.42 3.41 8.83 Nd 0.30 17.10 51.10 29.60 50.90 12.90 32.32 Sm 0.05 2.82 10.22 4.47 9.80 2.29 5.92 Eu 0.02 0.87 4.56 1.77 3.07 0.92 2.24 Gd 0.05 2.36 8.61 5.59 8.37 1.80 5.35 Tb 0.01 0.43 1.33 1.08 1.12 0.27 0.85 Dy 0.05 2.43 6.31 6.63 5.09 1.43 4.38 Ho 0.02 0.55 1.03 1.41 0.91 0.23 0.83 Er 0.03 1.63 2.63 3.75 2.39 0.66 2.21 Tm 0.01 0.25 0.40 0.53 0.39 0.10 0.33 Yb 0.05 1.51 2.41 3.19 2.35 0.66 2.02 Lu 0.01 0.23 0.36 0.43 0.35 0.09 0.29 Total 121.95 274.63 174.75 275.26 68.06 182.75 Geologia Croatica 67/2Geologia Croatica 158 ppm. The average values for La, Ce and Nd were 40 ppm, 77 ppm and 32 ppm, respectively. 4. Genesis of the iron deposits Mačje Jame and Vranjski Potok The first mineralization phase of the Mačje Jame deposit (> 90-95 wt. %) is composed of 44.7 wt. % of Fe (Ca, Mg, Mn)CO3 carbonates, 39.3 wt. % of magnetite, haematite and goethite, 5.7 wt. % of albite, 3.1 wt. % of pyrite, 1.8 wt. % arsenopyrite, 0.06 wt. % chalcopyrite, 0.05 wt. % of REE and 0.42 wt. % are trace elements. Siderite as the predominant ore mineral is composed of 62.5 wt. % FeCO3, 8.8 wt. % CaCO3, 19.3 wt. % MgCO3 and of 9.4 wt. % MnCO3 (Table 9b) indicating formation under el- evated PT conditions (350–400°C and 3.5 kbars), MAJER et al., (1991). During the very subordinately developed pegmatitic- pneumatolytic phase, numerous scarce or accessory miner- als were formed: quartz II as gangue and as ore minerals, arsenopyrite (average content 1.81 wt. %), pyrrhotite, cas- siterite (0.024. wt %), wolframite (0.012 wt. %), cobaltite (0.02 wt. %), gersdorffite (0.03 wt. %). One of the three an- alysed Mačje Jame samples contained elevated contents of Nb (26.8 ppm) and Ta (10.9 ppm), indicating the presence of the mineral columbite (0.012 wt. %). Table 7: REE parameters in the ore samples from the Mačje Jame deposit (Table 7a) and from the Vranjski Potok deposit. REE parameters in the ore samples from the Mačje Jame deposit Table 7a Sample MA-JA MA-JS MA-JP Average Mineral sd sd sd ΣREE 80.13 352.81 63.71 165.55 ΣLREE 44.68 255.20 17.79 105.89 ΣHREE 32.96 89.92 42.48 55.12 ΣLREE ΣHREE 1.36 2.86 0.42 1.55 Eu/Eu* 0.34 0.39 0.53 0.42 Ce/Ce* 4.12 4.55 10.79 6.49 (La/Sm)N 1.90 3.12 0.71 1.91 (Gd/Yb)N 0.45 0.57 0.44 0.49 (La/Yb)N 0.84 2.04 0.21 1.03 REE parameters in the Vranjski Potok ore deposit Table 7b Sample BOS-09 BOS-10 BOS-12 BOS-13 BOS-15 Average ΣREE 121.95 274.63 174.75 275.26 68.06 36.83 ΣLREE 111.69 246.99 150.37 251.22 61.90 148.56 ΣHREE 9.16 22.72 22.18 20.62 5.15 13.85 ΣLREE ΣHREE 12.19 10.87 6.78 12.18 12.02 10.75 Eu/Eu* 0.34 0.49 0.35 0.34 0.45 0.40 Ce/Ce* 4.40 4.08 3.78 4.13 4.36 3.95 (La/Sm)N 6.87 3.64 5.75 3.95 3.83 4.23 (Gd/Yb)N 1.29 2.96 1.45 2.95 2.26 2.17 (La/Yb)N 14.26 17.14 8.95 18.32 14.79 14.55 Table 8: Comparison of the REE contents between rhyolite-keratophyres and ore samples from the Mačje Jame and Vranjski Potok ore deposit. LOCALITIES rocks and ore samples KREŠEVO Rhyolite KREŠEVO Keratophyre BUSOVAČA Metarhyolite BUSOVAČA Metarhyolite MAČJE JAME VRANJSKI POTOK Analyte ppm ppm ppm ppm ppm ppm 1 La 34.60 16.60 43.00 22.30 33.10 40.00 2 Ce 75.70 37.70 87.00 43.90 74.60 77.20 3 Nd 32.70 17.80 43.50 16.30 30.00 32.30 4 La+Ce+Nd 143.00 72.10 174.20 82.50 137.70 149.50 5 ΣREE 179.60 95.40 209.30 105.30 216.80 187.90 6 La+Ce+Nd/ ΣREE 0.80 0.76 0.83 0.78 0.60 0.84 Ivan Jurković and Hazim Hrvatović: Geochemical characteristics and genesis of Mačje Jame and Vranjski Potok As-Cu-bearing iron occurrences ... Geologia Croatica 159 The first and second mineralization phases were most-probably formed during the Middle Carboniferous (Visean-Moscovian) derived from metamorphogenic fluid generated from S-granitoid magma and its protoliths. The third, hydrothermal phase, (very poorly devel- oped, 1-4 wt. %) is characterized by the following minerals: marmatite, tetrahedrite, chalcopyrite, boulangerite, galena, cosalite, yellow sphalerite, enargite–luzonite, sternbergite, elemental bismuth, “birds-eye” structures of gel-pyrite-mar- casite, traces of silver (4 ppm) and traces of gold (29.2 ppb). Gangue minerals are quartz III, chalcedony, and rarely cal- cite. The third mineralization phase of both deposits is characterized by trace elements which are genetically the most important for the youngest deposits in the MBSM: si- derite-barite-Hg tetrahedrite deposits. These elements are Bi, Se, Hg, Ag and Au, built up in the tetrahedrite lattice as the main constituents. These five elements reached Mačje Jame and Vranjski Potok ore deposits as an overprint of post-Var- iscan Permian or Permo-Triassic magmatic activity (JURKO- VIĆ et al., 2011). In the Jezero-Jajce part of the MBSM, there is an old, abandoned Austro-Hungarian copper mine at Sinjakovo, with the ores in the Carboniferous sediments associated with numerous contemporaneous rhyolite sills and veins. Gangue minerals consist of siderite, ankerite, ferrodolomite, with chalcopyrite as the main ore mineral (VASILJEVIĆ, 1972). A very similar paragenesis occurs in Gemericum (Slovakia), in the root zone of siderite veins at the boundary between greenschist and amphibolite facies, as reported by RAD- VANEC & BARTALSKY (1987), BARTALSKY (1991) and BARTALSKY and RADVANEC (1993). Because MAJER and GARAŠIĆ (2001) expressed their doubt about the juvenile origin of the rhyolite magma from Vranica Mountain, JURKOVIĆ et al., (2010a) investigated the 87Sr/86Sr isotopic ratios in the rhyolite sample from this magma. They obtained the first, extremely high result of strontium isotope ratio of 0.776995 which indicates the pre- viously suggested crustal origin. During further scientific investigation, they presented an additional four 87Sr/86Sr iso- topic ratios obtained from the rhyolite samples collected from outcrops in the Kruščica and Kozica river valleys and in the mountains of Ščit (Busovača) and Međuvršje (Kreše vo). The results were lower than in the first sample from Vranica Mountain, but still high. Finally, the last sample taken at the end of 2013 was collected from four separate rhyolite out- crops in the Jezernica river valley. These four samples have been combined and prepared for determination of their 87Sr/86Sr isotopic ratio. The amazingly high result of 0.808079, (grea- ter than the first value), proves that the whole Vranica Moun- tain rhyolite block is one unique laccolite of the same gra- nitic magma. These results convinced us that the metamorphogenic fluids derived from an S-granitoid magma and their proto- liths were the most probable source for the origin of the Mačje Jame and Vranjski Potok ore deposits. Recently, GARAŠIĆ et al., (manuscript) performed de- tailed chemical and geochemical analyses of numerous rhyo- lite, metarhyolite, keratophyre and quartz keratophyre samples from the Busovača-Fojnica-Kiseljak-Kreševo areas. GARAŠIĆ et al. (manuscript, 2014) also accepted our sug- gestion to use the discrimination diagrams for the MBSM granite classification in accordance with their tectonic setting. Therefore, they continued to work on this problem and the re- sults should be published very soon in a new scientific article. Similar opinions with respect to Variscan granitic rocks in the Moldanubian, and in the Eastern and Southern Alps were published by NEUBAUER (1988) and FINGER and STEYRER (1990). Figure 3: Plot of rare-earth elements normalized to C1 chondrites (SUN & McDONOUGH, 1989). MA–Mačje Jame deposit; BOS–Vranjski Potok deposit. Geologia Croatica 67/2Geologia Croatica 160 5. CONCLUSION The Mačje Jame and Vranjski Potok iron ore occurrences situ- ated in the north-eastern part of the MBSM, are the earliest postorogenic ore deposits in the MBSM. They formed from the metamorphogenic fluids generated from S-granitoid magma and its protoliths for the most part during the period between the Visean-Moscovian stages partly even earlier. Both ore deposits are located in the biotite-chlorite zone, the transi- tion zone between amphibolite and greenschist metamorphic zones. In the Late-Variscan time (290-260 Ma and in the Up- per Permian-Lower Triassic (260-240 Ma) time), Mačje Jame and Vranj ski Potok were caught by a younger overprint which brought along Bi, Se, Hg, Ag, Au elements as well as non-fer- rous metals Cu, Pb, Zn. A very similar paragenesis of siderite veins is present in the Gemericum (Slovakia), reported by RADVANEC et al. (2004) who consider that this deposit rep- resents the oldest ore occurrence in the Gemericum Palaeozoic complex. REFERENCES BARTALSKY, B. (1991): Results of the study of vein mineralization in the Rožnava ore field – evidence for the metamorphic – hydrother- mal genetic model.– Unpublished CSc Thesis. Geological Survey of Slovak Republic, Spišska Nova Ves (in Slovak). BARTALSKY, B. & RADVANEC, M. (1993): Relation between minerals of the Fe-Zn-As-S and Fe-Ti-Mn-O element association in conditions of regional metamorphism, Rožnava – Turecka ore field, Spiš-Gemer Ore Mts., Eastern Slovakia.– Mineralia Slovaca 25, 437–450. FINGER, F. & STEYRER, M. P. (1990): I-type granitoids as indicators of a late Palaezoic convergent ocean-continent margin along the southern flank of the central European Variscan orogen.– Geology, 18, 1207–1210. GARAŠIĆ, V., JURKOVIĆ, I., LUGOVIĆ, B.(†) & HRVATOVIĆ, H. (2014): Petrogenesis of Palaeozoic metarhyolites from Mid-Bos- nian Schist Mountain.– Unpublished manuscript. HRVATOVIĆ, H. (1996): Structural and facies analyses of parts of the Mid-Bosnian Schist Mountains (in Bosnian).– Unpublished Ph. D. Thesis, Tuzla University, 112 p. HRVATOVIĆ, H. (1999): Geological guide through Bosnia and Herze- govina. Monography (in Bosnian).– Geološki glasnik, 24, Sarajevo, 203 p. HRVATOVIĆ, H. (2006): Geological guidebook through Bosnia and Her zegovina.– Geological survey of Federation Bosnia and Herze- govina, Sarajevo, 172 p. JOVANOVIĆ, R., MOJIČEVIĆ, M., TOKIĆ, S. & ROKIĆ, LJ. (1978): Osnovna geološka karta SFRJ 1:100000, Tumač za list Sarajevo [Basic Geological Map of SFRY 1:100000, Geology of Sarajevo sheet – in Serbian].– Savezni geološki zavod, Beograd, 52 p. JURKOVIĆ, I. & MAJER, V. (1954): Rioliti (kremeni porfiri) Vranice planine i albitski riolit Sinjakova u Srednjobosanskom rudogorju [Rhyolithe (Quartzporphyre) of Vranica Mountain and albite rhy- olithe (Quartzkeratophyre) of Sinjakovo in Mid-Bosnian Ore Moun- tains – in Croatian].– Vesnik zavoda za geološka i geofizička is- traživanja RN Srbije, Beograd, Knjiga 11, 207–233. JURKOVIĆ, I. (1956): Mineralne parageneze Srednjobosanskog Rudog- orja s osobitim osvrtom na tetraedrite [Mineral parageneses of the Mid-Bosnian Ore Mountains with special respect to tetrahedrites – in Croatian].– PhD thesis, University of Zagreb, 306 p. JURKOVIĆ, I. (1958): Kasiterit, stamin i molibdenit u rudnoj pojavi Vrtlasce kod Klisa [Cassiterite, stannite and molybdenite from the occurrence Vrtlasce at Klisac].– Geološki glasnik, Sarajevo, 4, 304– 320. JURKOVIĆ, I., GARAŠIĆ, V. & HRVATOVIĆ, H. (2010a): Geochem- ical characteristics of the barite occurrences in the Palaeozoic com- plex of the Southeastern Bosnia and their relationship to the barite deposits of the Mid-Bosnian Schists Mountains.– Geol. Croat., 63/2, 241–258. JURKOVIĆ, B. I., GARAŠIĆ, V. & JURKOVIĆ, M. I. (2011): Cobalt, nickel, tungsten, cadmium, silver and gold-bearing mercurian tet- rahedrite from the Saski Rad barite – siderite deposit in the Mid- Bosnian Schist Mts.– Geol. Croat., 64/3, 223–237. KARAMATA, S. & KRSTIĆ, B. (1996): Terranes of Serbia and neigh- bouring areas.– In: KNEŽEVIĆ, DJORDJEVIĆ, V. & KRSTIĆ, B. (eds): Terranes of Serbia, Barex. Belgrade, 25–40. Table 9: Carbon, oxygen and sulphur isotopic values of siderite and pyrite minerals (Table 9a). Isomorphic composition of the different siderite samples in the MBSMts (Table 9b). Carbon, oxygen and sulphur isotopic values of siderite and pyrite in the Mačje Jame deposit Table 9a Mineral Sample δ13CPDB δ18OVSMOW δ34SVCDT sd MA-JA –9.5 18.0 sd MA-JS –10.1 17.2 py MA-JP +5.3‰ Isomorphic composition of the different siderite samples in the MBSMts Table 9b Ore deposit Mačje Jame Vranjski Potok Vrtlasce Fojnica Trošnik Fojnica Maškara – Saski Rad Bakovići – Čemer- nica Analyte wt. %. wt. %. wt. %. wt. %. wt. %. wt. %. FeCO3 62.53 70.13 71.75 74.39 81.23 86.66 CaCO3 8.78 3.55 15.75 12.89 9.52 1.43 MgCO3 19.30 24.13 10.30 10.03 6.59 2.50 MnCO3 9.40 2.20 2.02 2.69 2.66 10.10 Total 100.01 100.00 99.82 100.00 100.00 100.69 Ivan Jurković and Hazim Hrvatović: Geochemical characteristics and genesis of Mačje Jame and Vranjski Potok As-Cu-bearing iron occurrences ... Geologia Croatica 161 KATZER, F. (1905): Über die Quartzporphyre der Vranica planina in Bosnien und über einen Fund von Rillensteinen.– Zentralblatt f. Min. etc., No 18, 366 p. KATZER, F. (1906): Geologische Übersichtskarte von Bosnien-Herze- govina. I. 1:200000 Seckstelblatt Sarajevo. KATZER, F. (1910): Die Eisenerzlagerstätten Bosniens und der Herze- govina.–Wien. KATZER, F. (1924): Geologie von Bosnien und Herzegovina.– Sarajevo, 527 p. MAJER, V., LUGOVIĆ, B. AND TRUBELJA, F. (1991): Metamorphism of the Mid- Bosnian Schist Mountains: an preliminary investigation (in Croatian).– Radovi ANUBiH, Sarajevo, 87/13, 141–158. MAJER, V. & GARAŠIĆ, V. (2001): Metarioliti Vranice planine u pale- ozoiku središnje Bosne [Metarhyolites of Vranica Mountains in Pal- aeozoic of middle Bosnia – in Croatian].– Rudarsko-geološko-naft- ni zbornik, 13, 9–14. MATTÉ, P. (1984): Tectonics and plate tectonic model for the Variscan belt of Europe.– Tectonophysics, 120, 329–374. MITCHELL, A.H.G., FINGER, F., STEYRER, H.P. & NEUBAUER, F. (1991): Comments and Replies on „I-type granitoids as indicators of a late Paleozoic convergent ocean-continent margin along the southern flank of the central European Variscan orogen.– Geology, 19/12. MUDRENOVIĆ, V., STOJANOVIĆ-KUZENKO, S. & PAJIĆ, V. (1969): Razvoj silura i devona u području Jezera kod Jajca (Zapad- na Bosna) [Development of Silurian and Devonian in the Jezero area near Jajce – in Bosnian].– III. Simpozij Dinarske Asocijacije, Zagreb, 133–146. NEUBAUER, F. (1988): The Variscan orogeny in the Austroalpine and Southalpine domains of the Eastern Alps.– Schweizerische Miner- alogische und Petrographische Mitteilungen, 68, 339–349. PALINKAŠ, L., MAJER, V., BALOGH, K., BERMANEC, V. & JUR- KO VIĆ, I. (1996): Geochronometry and termochronometry of the metamorphism in the Inner Dinarides, MBSM.– Annual Meeting of UNESCO IGCP Project No 356, Sofia 1996. PAMIĆ, J. & JURKOVIĆ, I. (2002): Palaeozoic tectonostratigraphic units of the northwest and central Dinarides and the adjoining South Tisia.– International Journal of Earth Sciences, 91, 538–554. PAMIĆ, J., BALOGH, K., HRVATOVIĆ, H., BALEN, D., JURKOVIĆ, I. & PALINKAŠ, L. (2004): K-Ar and Ar-Ar dating of the Palaeo- zoic metamorphic complex from the Mid-Bosnian Schist Mts., Cen- tral Dinarides, Bosnia and Herzegovina.– Mineralogy and Petro- logy, 82, 65–79. RADVANEC, M. & BARTALSKY, B. (1987): Geochemical zonality of stratiform sulfidic mineralization in the area Smolnik-Štos-Med- zev.– Mineralia Slovaca, 19, 443–445. RADVANEC, M., GRECULA, P. & ŽAK, K. (2004): Siderite minera- li zation of the Gemericum superunit (Western Carpathians, Slova- kia) review and revised genetic model.– Ore Geology Reviews, 24, 267–298. RAMDOHR, P. (1983): The Ore Minerals and Their Intergrowths, 2nd edition, vol. 1 and 2.– Pergamen Press, Berlin,1207 p. RAMOVIĆ, M. (1956): Volframit iz Čemernice kod Fojnice [Volframite from Čemernica near Fojnica – in Bosnian].– Tehnika, 11. SOFILJ, J., ŽIVANOVIĆ, M. & PAMIĆ, J. (1980): Osnovna geološka karta SFRJ 1:100000, Tumač za list Prozor [Basic Geological Map of SFRY 1 : 100000, Geology of the Prozor sheet – in Serbian].– Savezni geološki zavod, Beograd. TRUBELJA, F. (1978): Paleozojski magmatiti srednjobosanskih škrilja- vih planina [Palaeozoic magmatic rocks of the Mid-Bosnian Schist Mountains – in Bosnian].– In: Geology of Bosnia and Herzegovina, Part IV.: Magmatism and Metallogeny, Sarajevo, 11–18. VASILJEVIĆ, R. (1972): Geologija i metalogenija paleozoika u područ- ju Jezera i Sinjakova kod Jajca [Geology and metallogeny of Pal- aeozoic in the Jezero and Sinjakovo near Jajce – in Serbian].– Un- publ. PhD thesis, University of Zagreb, 128 p. VUJNOVIĆ, L. (1981): Osnovna geološka karta SFRJ 1:100000, Tumač za list Bugojno [Basic Geological Map of SFRY 1:100000, Geol- ogy of the Bugojno sheet – in Serbian ].– Savezni geološki zavod, Beograd, 56 p. ŽIVANOVIĆ, M. (1972): Geološki sastav i tektonski sklop šire oblasti Vranice u centralnoj Bosni [Geology and tectonics of the Vranica Mountain in the Central Bosnia – in Serbian].– PhD, University of Beograd, Geoinženjering Sarajevo. ŽIVANOVIĆ, M. & MILIVOJEVIĆ, R. (1975): Osnovna geološka kar- ta SFRJ 1:100000, Tumač za list Zenica [Basic Geological Map of SFRY 1:100000, Geology of the Zenica sheet – in Serbian ].– Savez- ni geološki zavod, Beograd. ŽIVANOVIĆ, M. (1979): Naslage Centralno-bosanskog paleozoika (Vra nica) [Sediments of the Central Bosnian Palaeozoic (Vranica) – in Serbian].– In: “Geologija Bosne i Hercegovine”, knj. I. Paleo- zojske naslage, Sarajevo, 55–68. Manuscript received December 01, 2013 Revised manuscript accepted May 14, 2014 Available online June 17, 2014