Ladislav Palinkaš

Volcanic facies and hydrothermal processes in Triassic pillow basalts from the Darnó Unit, NE Hungary

The Darno Unit within the Zagorje-Mid-Transdanubian Megaunit is an allochtonous part of Dinarides in NE-Hungary and represents a relict of the Neotethyan accretionary complex. It contains blocks of submarine basalts of Triassic age in turbiditic sediments (olistrostrome) of Jurassic age. The lava clogged in the lime mud at the original site of volcanism and developed closely packed pillow, pillow fragment hyaloclastite breccia, and peperite facies. Interaction between the lava and the sea water produced mostly chloritic alteration of basalt and precipitation of hydrothermal calcite in amygdales, feeding channels of lava lobes and hyaloclastite breccia cements. Calcite is associated with chlorite, epidote, hematite and pyrite. Fluid inclusions in calcite infillings record conditions of fluid/rock interaction. Salinities of fluid inclusions (3.2 – 5.6 wt.% NaCl equiv. wt.%.) are close to the salinity of recent sea water and their homogenization temperatures in the range of 80 – 150oC. Fluid inclusion data support interpretation that volcanic facies represent rapidly cooled distal zones away from the submarine volcanic centre. This is also confirmed by the comparison to the volcanic and hydrothermal alteration facies of the submarine basalt lava-flow complex and associated pillow lava formation of Triassic age in the Hruskovec quarry in the Kalnik Mts., NW-Croatia. The obtained data contribute to understanding of the early history of Neotethyan evolution, i.e. dilemma about rifting or oceanization in Triassic time and offer new aspects of correlation between units of Dinaridic origin which had been displaced from their original setting by large scale Tertiary tectonic processes.

Discrimination criteria for assigning ore deposits located in the Dinaridic Palaeozoic-Triassic formations to Variscan or Alpidic metallogeny

Abstract Among the ore deposits located in the Palaeozoic-Triassic formations of the Dinarides, siderite (± ankerite) and barite mineralization hosted by Carboniferous and Lower Permian sediments as well as polymetallic deposits in the Mid-Bosnian Schist Mts (MB), caused a long standing dispute concerning their metallogenic affiliation.

Hydrothermal processes related to Triassic and Jurassic submarine basaltic complexes in northeastern Hungary and in the Dinarides and Hellenides

Comparative studies on hydrothermal alteration of submarine peperitic basalt occurrences related to the Triassic early rifting of the Neotethys were carried out in various parts of the Dinarides and Hellenides. The study areas included the displaced fragments of the Dinarides in the Darno Unit, NE Hungary, the Kalnik Mts in Croatia and the Vares-Smreka area in Bosnia and Herzegovina. In the Hellenides, similar environments were studied in the Stragopetra Mts., Greece. Jurassic pillow basalts formed in a back-arc-basin of the Neotethys were also studied (in the Szarvaskő Unit, NE Hungary, which also represents a displaced unit of Dinaridic origin). Within the submarine basaltic lava flows, six volcanic facies were distinguished. The hydrothermal alteration was characterized according to those facies. The first process was the albitization of the rock-forming plagioclase at ~300°C temperature in all localities. During the higher temperature stage of the subsequent cooling, chloritization in the ground mass is typical for all types of basalts, however chlorite and rarely quartz formed in the fractures and amygdales of the Triassic basalts, while chlorite, quartz and prehnite precipitated in the fractures of the Jurassic rocks. At lower temperatures of this cooling-related process, calcite is a common mineral filling up the larger amygdales, jig-saw type fractures and other open spaces, but some epidote, pumpellyite, prehnite and laumontite also occur in the Triassic basalts. The late stage alteration (happened at the lowest temperature) is characterized by argillitization at every locality. The observed hydrothermal alteration patterns also show slight differences according to the volcanic facies as a function of the distal/proximal setting in relation to the eruptive centers and the presence/absence of water-saturated and unconsolidated carbonate or siliciclastic sediments at the time of the emplacement of lava flows. The study revealed that the most important factors influencing mineralogy and zoning of hydrothermal alteration in these short living local hydrothermal systems are the rapid cooling of the hydrothermal fluid, the dominance of the not much evolved seawater as the source of hydrothermal fluid and the local, i.e. effective water/rock ratio, determined by the degree of fracturing in the rock. The mineralogical-textural peculiarities of the highly localized hydrothermal fluid/rock interaction in the studied submarine sea-mount type volcanoes are clearly different from the products of the large-scaled hydrothermal processes occurring at mid-oceanic ridges. Recognition of these differences is important in the evaluation of ore potential of Neotethyan realm or other areas with occurrences of submarine basaltic units

The role of magmatic and hydrothermal processes in the evolution of Be-bearing pegmatites: Evidence from beryl and its breakdown products

Abstract Beryl and euclase crystals from the Mina do Santino and the Jacú pegmatites in the Borborema Pegmatite Province in northeastern Brazil contain several generations of melt and fluid inclusions, which allow interpretation of P-T-X conditions responsible for beryl crystallization and for alteration of a primary pegmatitic mineral assemblage to a mixture of hydrothermal minerals (euclase, bertrandite, kaolinite, and quartz). Primary melt and fluid inclusions hosted by beryl were trapped simultaneously. However, their homogenization temperatures are significantly higher (870-900 °C) than the values previously reported for pegmatitic systems (<712 °C) and should be treated with caution. An isobaric drop of temperature resulted in the exsolution of a fluid. A low-salinity CO2-enriched phase and a saline water-rich phase were trapped in pseudosecondary inclusions in beryl at a pressure of 2.1-2.7 kbar and temperature of 390-480 °C. Cooling of the country rocks below 400 °C caused a ductile-to-brittle transition and allowed infiltration of cold groundwater, which further decreased the temperature in the system to 190-240 °C. At the same time, the pressure dropped from a lithostatic (2.1-2.7 kbar) to a hydrostatic value (0.57-0.73 kbar). Consequently, minerals deposited under magmatic conditions (feldspars and beryl) became unstable and a newly formed hydrothermal mineral paragenesis (euclase, bertrandite, kaolinite, and quartz) overprinted the earlier one. The hydrothermal fluids responsible for the alteration differ from the earlier-exsolved fluids in having a lower salinity, lower homogenization temperature, the absence of CO2, and the presence of CH4.

Environmental geochemistry of the polymetallic ore deposits: Case studies from the Rude and the Sv. Jakob historical mining sites, NW Croatia

This paper presents the results of the sampling surveys carried out in order to evaluate the environmental impact of the Rude and the Sv. Jakob historical mining sites, NW Croatia. The studied polymetallic ore deposits are differing in the mineralogical and geochemical features as well as in the host rock lithology. The Rude Fe-Cu-Pb-Zn-Ba deposit is hosted by Permian siliciclastic sediments. Siderite, hematite, galena, sphalerite, chalcopyrite, pyrite, barite and gypsum are the major ore minerals, whereas quartz is the principal gangue mineral. The Sv. Jakob Pb-Zn-Ag deposit occurs in the Middle Triassic dolostone. The most abundant ore minerals are galena, sphalerite and pyrite. Calcite and quartz represent the principal gangue minerals. Although the deposits represent the potential sources of numerous toxic metals, the pollution of the drainage streams and associated stream sediments was not recorded. The studied mining sites are characterized by the high carbonate/sulfide ratios responsible for the alkaline character of the drainage streams. Consequently, the mining sites have very low potential for generation of acid mine drainage as well as very low potential for leaching of heavy metals into the drainage systems. Furthermore, the presented study revealed that the populated areas (stream waters with decreased redox potential, increased organic matter content, high NO 3 - , NH 4 + and PO 4 3- concentrations; stream sediments enriched in exchangeable Pb and Zn) and the Sava river alluvium (overflowing streams enriched in Hg) represent bigger environmental threat than the investigated polymetallic ore deposits.

Lanthanide Geochemistry and Fluid Inclusion Peculiarities of the Fluorite from the Barite Deposits South of Kresevo (Bosnia and Herzegovina)

Strata-bound barite deposits occur in Devonian dolomites, situated in the Mid-Bosnian Palaeozoic Schist Mountains. These contain barite as the main ore mineral (5.9 wt% SrSO4 on average and d34S= +8.3‰) which comprises 90-99 wt% of the bulk ores. The subordinate components are calcite, fluorite, Hg-Sb-tetrahedrite, pyrite and quartz. Analysis of REE by INAA revealed an extremely low content of lanthanides (1.584 ppm), negative Eu anomalies (Eu3+/Eu+ = 0.7398), and (Tb)N/(La)N = 6.2 indicating late-stage mineralization. Primary fluid inclusions show a uniform number of infilling phases (L+V+S), and persistent volume ratio. This indicates homogeneity of the hydrothermal ore-forming fluids and an absence of boiling phenomena at the time of fluorite formation. Th is between 200° and 310°C, with a distinctive maximum at 250°C. Tfm -20.3°C predominates but careful examinations of the early melting behaviour of the inclusions warrants the existence of Tfm -51°C, and the presence of CaCl2. High salinity between 25 and 26 wt% eq. NaCl was determined from the hydrohalite melting temperature (Tmh). Some additional daughter minerals are also present. Fluorite, barite and calcite formed from the high saline waters probably originated by mixing of heated hydrothermal fluids with the highly evolved post-Variscan Upper Permian formation waters. This is supported by the study of the isotopic composition of the carbon, oxygen and sulphur of the paragenetic carbonates and sulphides.

The Lokve Barite Deposit, Croatia: an Example of Early Diagenetic Sedimentary Ore Deposits

Syngenesis versus epigenesis in the Kupferschiefer genetic model is still a matter of controversy. The title of the article seems to be a paraphrase of a well-known paper by WEDEPOHL (1971), “Kupferschiefer as a prototype of syngenetic sedimentary ore deposits”. It is intended, however, more as a paradigm for the genesis of the hydrogen-sulphide geochemical barrier, an important ore formation episode prior to heavy metal accumulation, which shows the utility of RENFRO’s (1974) epigenetic model. Barite mineralization in Lokve is a stratabound ore deposit conformably situated at the Permian-Triassic boundary. It bears only two ore minerals, barite and pyrite exclusively, separated into two distinct, juxtaposed horizons stretching for tens of kilometers. The discovery of cryptalgal fabrics and other conspicious sedimentary features in underlying siliciclastics with massive pyrite and surmounting barite-bearing dolomites supports their affiliation to a tidal flat facies and sabkha environment. Barite and pyrite accumulation were formed by an early diagenetic, bacteriogenic sulphate reduction in a peritidal muddy environment, concommitant to a widespread process of evaporative dolomitization. The early diagenetic model is supported by an analysis of the sedimentary facies, trace element geochemistry and sulfur isotope distribution along two vertical profiles across the stratabound barite and pyrite mineralization.

Heavy metals in liming materials from NW Croatia: possible effect of liming on permissible contents of heavy metals in arable soil

The evaluation of the heavy metal discharge from liming materials into the arable soil in NW Croatia is based upon the contents of Fe, Mn, Pb, Cu, Zn, Cd, Co and Hg in the studied carbonate raw materials, obtained under simulated conditions of the lowest presumed acidity (pH>3) which can occur in the agroecological environment. From the agroecological viewpoint, the heavy metal contents of the analyzed liming materials are much lower than the permissible levels. Only cadmium contents indicate that a certain amount of care should be taken into account. Because cadmium is bound in labile forms (pH>3 soluble fraction), it has to be considered quite mobile and biologically available in limed arable soils that are affected by drastic pH changes in the agroecological environment.

Permian–polysulphide-siderite–barite–haematite deposit Rude in Samoborska Gora Mts., Zagorje–Transdanubian zone of the Inner Dinarides

Samoborska Gora Mts. is situated within the westernmost part of the Zagorje–Mid–Transdanubian zone of the Internal Dinarides. The Samoborska Gora Mts. predominantly consists of Permian unmetamorphosed siliciclastic sediments and evaporites, overlain by Lower Triassic sediments. Rude mineralisation is hosted by Permian siliciclastic sediments, below gypsum and anhydrite strata. The central part of the deposit consists of a 1.5 km long stratabound mineralisation, grading laterally into ferruginous sandstone and protruding vertically into a gypsum–anhydrite layer. Siderite–polysulphide–barite–quartz veins are located below the stratabound mineralisation. The stratiform part ofthe deposit is situated above the stratabound and consists of haematite layer with barite concretions and veinlets. Late stage galena–barite veins overprint earlier types of mineralisation. The Rude ore deposit was generated by predominantly NaCl±CaCl 2 –H 2 O solutions. Detrital quartz from stratiform mineralisation contains fluid inclusions with salinities between 7 and 11 wt. % NaCl equ., homogenizing between 150°C to 230°C. Stratabound/siderite–polysulphide–barite–quartz vein type mineralisation was derived from solutions with salinities between 5 and 19 wt. % NaCl equ., homogenizing between 60°C and 160°C, while late stage galena–barite veins were precipitated from solutions with salinities between 11 and 16 wt. % NaCl equ., homogenizing between 100°C to 140 °C. Fluid inclusion bulk leachate chemistry recorded Na + >Mg 2+ >K + >Ca 2+ >Li + and Cl - >SO 4 2- ions. Sulphur isotope composition of barites and overlying gypsum stems from Permian seawater sulphate, supported by increased Br - content, which follows successively the seawater evaporation line. The sulphur isotopic composition of sulphides varies between –0.2 and +12.5 ‰, as a result of thermal reduction of Permian marine sulphate. Ore–forming fl uids were produced by hydrothermal convective cells (reflux brine model), and were derived primarily from Permian seawater, modified by evaporation and interaction with Permian sedimentary rocks. Rude deposits in Samoborska Gora Mts. may be declared as a prototype of the Permian siderite–polysulphide–barite deposits (products of rifting along the passive Gondwana margin), in the Inner Dinarides, and their equivalents extending northeastward into the Zagorje–Mid–Transdanubian Zone and the Gemerides, and southeastward to the Hellenide–Albanides.

The role of uranium(V) ion in the chemical composition of meta-autunite from pegmatites of Quintos de Baixo, Brazil

Meta-autunite from the pegmatite mineralization of Quintos de Baixo, Brazil was investigated. The total uranium content and elemental analysis yield the formula Ca(UVIO2)2-x(UVO2)x(H3O+)x(PO4)2.(6-x)H2O for the meta-autunite. The natural sample crystallizes tetragonally in the space group P4/nmm having unit cell parameters a=6.990(1) A ; ; ; , c=8.445 (1) A ; ; ; and V=412.6(1) A ; ; ; 3 calculated from X-ray diffraction data. Thermal analysis showed a weight loss of 16.03 wt% in four distinct processes up to 1500o ; ; ; C. Electron paramagnetic resonance (EPR) spectroscopy provides evidence that part of the uranium present in meta-autunite is in the pentavalent state. High temperature diffraction data show lowering of the symmetry, decreasing the unit cell parameters and finally, the breaking of the structure of the phosphate phase and formation of monoclinic uranium oxide and an amorphous phase. At 80°C meta-autunite I transforms into the meta-autunite II with orthorhombic symmetry, while further heating produces changes in the diffraction pattern due to dehydration, although all the heating products could be by analogy identified as meta-autunite II. The calculated unit cell parameters for this phase decrease from a=7.253(4) A ; ; ; , b=6.537(3) A ; ; ; , c=7.008(4) A ; ; ; at 82°C to a=6.38(2) A ; ; ; , b=5.82(1) A ; ; ; , c=6.68(1) A ; ; ; at 204°C. Uranium oxide phases originating from the breakdown of the phosphate structure show temperature dependant stability. At 1050°C hexagonal U2O3 analogous with  -Al2O3 is present with symmetry (R c) and unit cell parameters (a=4.806(1) A ; ; ; , c=13.138(4) A ; ; ; , V=262.9(1) A ; ; ; 3).