Romanian Journal of

MINERAL DEPOSITS

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Geodynamics and Ore Deposit Evolution

VoI. 79 S uppl. 2

of the Alpine-Balkan-Carpathian-Dinaride Provin ce

ABel) - GEOD[ 2001 wonKSHOP VA TA BAI, nOMANIA

8 - 12 Junc, 2001

ABSTRACTS VOLUME Bucharest, 2001

11l,.; t.iillrlll G (·o lugi,· ,II Il' )III<Î IIÎ . , j

DII "lIl' l'~ li 2001

77

EPITEI ERMAL GOLD DEPOSITS IN CENTRAL BOSNIA

Ladislav A. Palin kas·, Sabina Strmic\ Iva" J urkovic2, Haz Îm Hrva tovicJ

I Faculty of Natural Sciences, University of Zagreb, Horvatovac bb. Zagreb, Croatia 1 Croatian Academy of Science, A. Kovac!ica 5, Zagreb, Croatia J Geological Survey Sarajevo, UstanÎcka 3, Sarajevo, Bosnia and Herzegovina

BASIC GEOLOGICAL DATA The Midd-BosnÎan Schist Mountains (MBSM) built up the centra l part of the Dinarides. The mosi widespread rocks of the MBSM are pre-Devonian metamorphic rocks: sericite-chlorite­quartz schists. Subordinate are graphite-quartz schists. caJcschists, schistose sandstones and intercalations of crystalline carbonate rocks. Crystallization age of these rocks, obtained by K-N dating is 343±13 Ma (palinkas et al. , 1996). They were formed by low-grade metamorphism at 3S0-4S0' C and pressure of 3-S kbars (Majer et al. , 1991). Fossiliferous Devonian reer carhonate rocks overlie this metamorphic complex. Lower Carboniferous marine facies is scaree. The up lift of this area accompanied with large extrusions and minor suhvolcanic intrusions of rhyolites took place between Middle Carboniferous and Middle Permian. These magmatic rocks were metamorphosed ioto metarhyolites during Cretaceous time (120 to 90 Ma) (palnikas et al., 1996). Numerous pyrite Qccurrences, mostly gold-bearing in the NE part of the MBSM are spatially intimately related to rhyolites.

T he Ba kovici ty pe of pyrite depos its The biggest depasit ofthis group is the 8akovici vein system with 250.000 t proven, minable ore reserves containing 3.45 t of gold and 11.7 t of silver. The Bakovici vein follows the contact between schists and metarhyolites entering part ly into both of these rocks. The paragenesis consists: 40-70 wt% pyrite, 40-60 wt% quartz and subordinate siderite; accessories are tetrahedrite, ga lena, stibnite, arsenopyrite, calcite, barite, gypsum and gold.

Fluid inclusions data The objects of fluid inclusion (FI) study were colourless quanz cryslals. Microthermometric examinat ion distinguished following types of FIs: 1. The three phase aqueous-carbonic, NaCI-H,O-CO" Fis. 2. The poly-phase aqueous-carbonic FIs with anysotropic daughter minerals. Microthermometric measurements were performed an the bOlh types of Fis. The last melting of solid COl was observed in the interval between -61 and -68°C what is assigned to the presence of the other voiati les (C~, N2) . Temperature of the final ice melting is recorded between -3 and -IO°C and the final melting temperature of c1athrates between +2.3 and +3.2°C what corresponds ta salinity between 11.7 and 12.4 wt .% equ. NaCI. Total homogenization temperature is in interval between +360 and +41O°C.

References: MajerV. et al. (1991): Metamorphism ofMBSM, ANUBiH, Sarajevo Palinkas L. A. el al. (1996) : On use of hyalophane for K-Ar dating in the Central Bosnian

Schist Mts.-Acta geologica Hungarica, Budapest

18

GENETIC CON OITIONS OF TIJE HIGII TEMPERATURE MELILIT E BEARING SKARNS OFTHE APUSENI MO UNTAINS (CARPATHlANS, ROMANIA).

Marie-Lola Pasca ll, Michel Fonteilles2

, Jean VerkaerenJ, Regis Piree a nd Stefan

Marincea-t 'CNRS-ISTO, IA rue de la Ferollerie, 45071 Orleans, France. 2Laboratoire de Petrologie, Universite Pierre el Marie Curie,4 Place Jussieu,75252 Paris Cedex OS, France l Unite de Geologie, Uel, 3, Place Louis Pasteur, Louvain-Ia-Neuve, Belgium 4GeoiogicaJ Institute of Romania - 1, Caransebes Str ., RO-78344, Bucharest, Romania

The petrological slUdy of the melilite-wollastonite (Upper Cerboaia VaUey) aRd meJilite - spurrite - tilleyite (Cornet Hill) sknrn occurrences of the Apuseni mountnins has shown Ihat coarse melilile mainly oecurs as veins, formed at 750°C aRd very low pressure of C02, al the contact between monzodiorites and marbles which wtre transformed at the same time into wollastonÎle or spurriteltilleyite, afler an early formation of aluminian diopside - bea ring endoskarns.

The melil ite-bearing skarns of Cornet Hill (CH) and Upper Cerboaia Valley (UCV) occur at the contact between monzodiorite bodies of Danian-Ypresian age aod neojurassic calcic marbles. Typical wollastonite-grossular-diopside endoskarns are separated from exoskams (tilleyite and spurrite or wollastonite at eH, wollastonite only at UCV), at most places, by a melilite - rich rock in which veins and vein-like recrystallizations are only composed of idiomorphic melilite crystals with a grain size reaching 5 cm. Titanian gamet and wollastonite are the principal minera ls associated wi th melilite (and also montieellite, perovskite, vesuvianite, euspidite, spurrite, tilleyite, calci te, ellestadite, hydrogrossular and other minor alterat ion minerals). A differem association that includes aluminian diopside and grossular oeeurs (1 ) as veinlets in the marble close to lhe skams and (2) as reliel inclusio ns in endoskams.

From the geometrical relationships of the zone sequences and lhe veins, the textural features ofthe mineral associations and the ca lculated fluid - minera l equilibrium conditions. these mineralogical pecu liarities are interpreted as resulting from the superposition of two main stages :

1 - The circulation ofa comparati\"ely C02 - rich fluid formed early aluminian diopside - grossular ( O wollastonite - perovskite) endoskams, with depletion in Si (and Fe, Na. K) and inert behaviour ofMg. Al . Ti.

2 - A high temperature (750°C) fluid circulation on both sides of the contact between marb le and endoskams developped the melilite - rich, titanian gamet - bearing rocks panly at the expense of previously fo rmed endoskams. and the spurrite (CH) or woJlastonÎte (UCV and CH) exoskarns al the expense ofmarble. The pressure ofC02 was very low. less Ihan 26 bars at UCV and 16 bars at CH, with a H,O pressure less than 750 bars. Not only Si and Ca were mobilized, but a1so Mg, AI and Ti. leached from the endoskams and deposited in the veins and the nearby part of exoskarns. This stage, whieh occurred in the temperature range corresponding 10 the end of the crystallization of plagioclase in the monzodiorile. has pegmatitic chemi cal and textural features

The main fluid flow ended with the development of tilleyite partly al Ihe expense of spumte and wollastonite at CH. and local high temperature (about 710°C) reworking of the zonation mostly in veins, especially in the endoskam-exoskam boundary, but a1so within the endoskams. A monticellite - gehleni te association followed by vesuvianite appeared in the

79

melilite-rÎch rocks, while the endoskam was also reworked by vesuvianite and coarse -grained recrystallizations ofwollastonite

SIMULTANEOUS C RYSTALLlZATION OI' QUARTZ ANO SULPHlDE MINE:RALS [N MADAN PB-ZN DE:POSITS

Petroy, P. , B. Koslova Sofia Universily "SI . Klimenl Ohridski", 1000 Sofia, Bulgaria

The mosI widespread mineral in the Madan ore field Îs quartz. The main paragenetic association incJudes also a few major ore minerals (gale"a, sphalerite. pyrite and chalcopyrite). Despite thal the relatively simultaneous crystalization of quartz and 5ulphide minerals has taken place in equilibrium conditions, their spatia l-timing relations are distinguished for zonaVrhythmical distributian. Thus difTerent mineral aggregates have been formed : polymineral aggregates consisting of qU3nz and several ore minerals; bimineral aggregates consisting of quartz and only one sulphide mineral ; monomineral aggregates composed only of quartz. The specific features of intercrystal boundaries between the quartz and the ore minerals are considered as well as the "induction" fluid inclusions in quartz from the monomineral quartz aggregate type.

NEW HNDING OF PGE-MlNERALISATION IN PORPHYRY-COPPER ENVIRONMENT - TRE BUCEHM DE:POSIT, MACEDONIA: PRELlMlNARY MICROSCOPE ANO MICROPROBE DATA

Pelrunov, R\ Serafimovski, T.2 & Dragov, P.l

1 GeologicalInslilute, Bulgarian Academy ofSciences, 1113 Sofia 2 Facuity ofMining & Geology, 902 Slip, R. of Macedonia

Increased con lent or Pd as welJ as Pd-mineralisation (PGM) was established in the Cu-Au ores or the deposit or Buchim, Macedonia. Thus, this is the forth case on the territory of Ihe Balkan Peninsula after Bor-Majdanpek- Serbia (Yankovich, 1990), Skouries-Greece (Tarkian el al., 1991) and Elatsile-Bulgaria (Pelrunov el aJ., 1992) were porphyry copper 'tyle of hydrothermal PGM ha, been found,

The Buchim porphyry copper deposit is situated in the border area between the Serbo­Macedonian massif and the Vardar zone. In terms of ils metallogeny it belongs to Ihe Lece­Chalkidiki metaliogenic zone (Serafimovski, 1993), where porphyry copper and epilhermal ore manifestations are developed. Buchim is the only depos it in exploitation with an annual mining production of 4 million lones of ores grading 0.30 % Cu and 0.35 git Au. Estimated reserves are approximately 100 milI ion lones of low grade Cu-Au ores wilh some Ag and Mo and include primary (the most important Cu-Au resources), as well as secondary (related to zone of oxidalion-cementation enrichment) and mixed types of ores.

The ore deposition is genetically eonneeted with the intrusion of Tert iary (Oligocene­Mioeene 27.5-24.5 my.) subvolcanie latilie and latite-andesitie bodies within Preeambrian metamorphie rocks-gneisses, micashists and amphibolites. Primary Cu-Au mineralisation occurs round ofthe subvolcanie bodies, being most abundant amid the hosting gneisses.

80

Our preliminary microscope and microprobe investigations have determined merenskyite. micheneri te, Pd-bearing cobaltite and tennantite as a part ofthe rich presence of subordinate and rare minerals in the twa main mineral assemblages: magnetite-pyrite­chalcopyrite (Mt-Py-Cp) and pyrite-chalcopyrite (Py-Cp). Characteristic for the Mt-Py-Cp assemblage (earlier and high-temperature) Îs the geochemical association Fe-Cu-Ni,Co-As­O-S + Au, Ag and Pd, with magnetite, chalcopyrite, pyri te (main) and cobalt ite, Ni-Co-Fe­sulphides and native Au (subordinate and rare). Pd is included in the st ructure of the main and the subordinate and rare minerals. Later enrichrnent of the hydrothermal tl uids with Cu, Bi, Se, Te, Pb, As, Au, Ag led to the formation of Py-Cp assemblage, overpri nting Mt-Py-Cp aggregates. New minerals were formed, as a result partly of including of elements "i n sito": aikinite, bismuthinite. freidrichite. witt ichenite. soucekite, emplecti te. hodrushite. paderaite. merenskyite, michenerite, other Pd-Bi-Te phases. tennantite (inel. Pd, Ca and Ni- bearing),

i-Co pyrite, Ni-Te phases, Bi-Pb-Ag-S phases, Cu-Fe-Bi-S phases, galena, clausthalite, sphalerite, native gold and electrum and (in the uppennost levels) enargite. lusonite and pi rseite.

Next detai led sludies can provide more information an lhe composit ion, distribution and nature of the PGE-mineralisation in the Buchim deposit. The combined analysis of aII to­date PGE-findings at the Balkan Peninsula wi ll ofTer valuable informat ion for close and remote genetic considerations and model ing.

References: Petrunov el al. (1992). Compt.rend.Bulg.Acad.Sci., 45, 4, 37-40. Serafimovski, T. (1 993) Types of Mineral Deposits and Distribution. Special edition of RGF

Stip, No l, p. 328.Structural metal logenetic characterislics ofthe Lece-Chakidiki zone: Tarkian et al. (1991). N. Yahrbuch Miner. Mh., 12, 529-537 Yankovich, S. (1 990). Ore deposit of Serbia. Faculty of Mining and Geology, Belgrade,

p.765.

MAJOR TO TRACE EL.EMENT ANALYSIS OF SlNGLE MELT INCLUSIONS BY LASER-ABLATION ICP-MS: METHODS OF QUANTlFlCATlON

Thomas Peuke, \Verner E. Halter and Christoph A. Ueinrich ETH Zorich, lsolope Geochemistry and Mineral Resources. Depanment of Eanh Sciences, 8092 Zurich, Switzerland (penke@erdw.ethz.ch)

LA-ICP-MS oflers a novel teehnique for the quantitative analysis of heterogeneous melt inclusions hosted by chemieaHy complex minerals, and it avoids the prerequisite eonditions for analylieal approaehes used hitherto. Rigorous mathematieal treatment of the uneertainties of the data enables the calculation of the error-weighted mea" chemieal composition of stages in melt evolution more reliably, based on statistically signifieant numbers (>20) of single melt inclusion analyses.

Linie droplets of melt trapped during crystal growth (" melt inc1 usions) potentia lly hold a wealth of information an igneous processes that occur in magma chambers and during volcanic activity. Current approaches for the quantifi cation of melt inclusion chem istry ali require that inc1usions are compositionally homogeneous and representative of the inc1usion melt , i.e., no devitrification or crystallization onto the incJusion wall has occurred during cooling. Moreover, incJusions must be exposed to the sample surface for analysis.

81

Laser·ablation ICP-MS provides a navei technique by which heterogeneous bulk incJusions can be analyzed, thus avoiding these prerequisite conditions. Because host mineral is ablated with the inclusion, quantification of the melt inc\usion composition necessitates deconvolution of this mixed sigoa\. This can be achieved in various ways, four of which are illustrated and evaJuated: (1) determination of the volume ratie between the inclusion and total ablated volume ofthe mixed sigoal , (2) a fixed , pre-determined, concentration of a given element; (3) a constant distributian coefficient between the host and the incJusion melt and (4) whole rock fractionation trends in a given igneous suite.

Results suggest that quantification through whole rock rractionation trends is the mOSI widely applicable, the most accurate and the least time-consuming technique. Uncertainties on the calculated element concent rations in the melt inc1usions mainly depend on the mass ratio between the inc1usion and the host mineral for a given mixed signal and the compatibility of a given element in the host mineral. Uncertainties below 10% can be achieved in multi-element mode (n=25) if the melt inc1usion contributes more than 20% to the mixed signal and the signal-to-noise ratio is bigger than about 10. Uncertainties in the melt inc1usion concentration are larger for elemems that are enriched in the host mineral. Limits of detection obtained for spherica l lOJ..tm melt inc1usions in plagioc1ase calculated for each individual ablation are ofthe order of a few ppm for incompatible elements and of a few tens or hundreds of ppm for major elements in the host. These LOD can be further improved significantly by reducing the element menu to a few elements and special tuning of the mass spectrometer.

Reference: Halter, W. E., et al. (200 1), Chemi cal Geology, in press.

THE PORPHYRY TO EPITHERMAL LINK: PRE LlMINARY FLUID CHEMICAL RESULTS FROM ROSIA POIEN I, ROMA NIA, AND FAMATINA, ARGENTINIA

Thomas Pettke, \Verner E. Halter, lan Maclntosh and Christoph A. Ueinrich ETH Ziirich, Isotope Geochemistry and Mineral Resources, Depanmem of Earth Sciences, 8092 Ziirich, Swilzerland (penke@erdw.elhz.ch)

Spatially c10se occurrences of porphyry-style and epithermal ore deposits are common and suggest a genetic link between the two. It is demonstrated by LA-ICP-MS ana lys is of coexisting brîne and vapour inclusions that some elements preferentially partition into the vapour phase upon phase separation at the porphyry stage, and Ihat such vapour is indeed a potentially important source of components for epithermal mineralizations.

Laser-ablation (LA-) ICP-MS microanalysis of liquid and vapour inclusions rrom boiling assemblages in porphyry systems have revealed that , compared to mosi metals dissolved in the brine (e.g., Na, K. Ca, Fe, Mn,) elements such as Cu, Au, As and other volatile metals selectively partition into the vapour phase[ 1]. The characteristic element suite of low- to high-sulfidation epithermal ores broadly corresponds to that of the vapor phase of boii ing fluids in porphyry-type deposits. If rising vapour condensates at higher crustal levels, it could, thus, form an epithermal aqueous Iiquid enriched chiefly in Au, and gold could precipitate in response to fluid mixing or low-pressure boii ing.

82

Rosia Poieni in Ihe nonhern sector of the Apuseni Mountains, Romania, is the locality investigated in dctail. Here, a late Miocene volcanic centre contains numerous andesitic subvolcanic intrusions. Same of these such as the Fundoaia andesitic to microdioritic slock show economic porphyry-type Cu±Au mineralizations associated with a serÎ es of hydrothermal aheration types. Cha1copyrite, pyrite, bomite, magnctitc, hematite and molybdenÎtc dominate porphyry-stage ore minerals. This multi-slage mineralization is cut by stccp epithermal structures associated with acid su lfate alteratÎon dominated by quartz, pyrite and alunitc. Fluids of the caTly porphyry slage were trapped in the two-phase field characteri zed by co-existing vapour (5 wt-% NaClcqul\) and brines (67 wt-% aCl~quh ) thal contain halite, sylvite. chalcopyrite and hematite daughter crystals. Epilhermal fluid inc1usion assemblages consisls of tiny low-salin ity aqueous two-phase inc1usions within <2 mm sized quartz crystals.

Results for the early porphyry-slage boiling assemblage show a c1ear relative enrichment of As and Sb, and Cu te a les ser extent . in the vapour phase relative te other elements such as Na, K. Rb, Cs, Pb, Zn and Fe. Concentrations of Cu in the vapour are high and variable, while those of As and Sb are ofthe order of several hundreds of ~ş gol of fluid . Concentrat ions of Au in the brine were belew Ihe limit of detectien of 0.76 ~g g" .

The data for the early porphyry stage boiling fluid assemblages in Rosia Poieni confirm that Cu together with As and Sb teod to become relatively enriched in the vapour upon phase separation. These low-deosi ty magmatic fluids thus are a promising source candidate for overlying epithermal deposits for which results wi ll be presented at the conference.

A similar slUdy was conducted on spatially related porphyry and epi thermal deposits in Famatina. Analyses from porphyry aod epilhermal fluids yielded very similar element ralios in the vapour phase of the porphyry stage and the aqueous phase of the epithermal stage, respectively, funher supponing a direct genetic link between these two types of deposits.

Re(erence: Il Heinrieh, C.A., el al. ( 1999), Geology, 27(8): 755-758.

NEW ISOTOPE DATA FOR UPPER CRETACEOUS MAGMA EMPLACEMENT IN TUE SOUTI·IERN ANO SOUTH-WESTERN PARTS OF CENTRAL SREDNOGORIE

PeychevR, LI, Von Quadt, A.2, Kamenov, B)., lvanov, Zh.J,Georgiev, NJ

•

1: "Eanh and Men" National Museum, Sofia; ireoa@web.bg 2: Institute of lsOlope Geology and Mineral Resources, ETH-Zurich; vonguadt@erdw.ethzch 3: Dep. ofGeology and Geography, SI. Kliment Ohridski Universi lY, Sofia

Plutonic bodies on the border between Central Srednogorie and the Rhodopes were sludied using high precise single zireon U-Pb-Hf method, whole rock Sm-Nd, Rb-Sr, Pb-Pb methods, as well petrological and geochemical data. They confirm the idea for the intrusion of basic magma (81 J ± 1.5 Ma) wi th an enriched mantie origin in a crystallizing granitoid magma chamber, the granitoids showing an age of 82.25 ± 0.4 Ma and mixed crust-mantle origin.

Presented slUdies are conceotrated 0 0 Upper Cretaceous volcanic, sub-volcanic and intrusive bodies in the westem and southwestern parts of the Central Srednogorie in Bulgaria with special attention to the Panagyurishte conidor where the most important Cu-(Mo-Au) ore deposits of Bulgaria are si tuated. First isotope and petrologic-geochemical investigations

8.1

are carried out on plulons from Ihe border area between Ihe Central Srednogorie and the Rhodopes - Vitosha, Plana, Gutsal , Boshulia and Elshitsa , and also Varshilo, Lesichovo and Poibrene, accepted by some former authors as Palaeozoic in age.

The preliminary field . structural and palaeomagnetic studies of Ivanov el al. (2001 , this volume) refer ta some specific characteristics ofthese plutons. (1) Magma emplacementand and later imposed (solid-state) deformations are genetically related ta a shear zone trending NW-SE - Iskar-Yavontsa Shear Zone (IYSZ) and associated sub-parallel or synthetic second arder shear zones; (2) In regional scale magma emplacement was accomplished in laccolith­like chamhers. Syn- and post-magmatic strike-slip deformations overprinted the rocks; (3) Some ofthe plutons possess the characteristics of layered intrusions ' their lower pans consist of crystal phase rich (most oflen) porphyry granodiorites and granites. and the upper ones -rrom fel sic, crystal phase poor granites. Between these two parts thin sheet-like gabbro or gabbro-diorites bodies are intruded. Above the latter swarms of basic enelaves are formed .

AII these data allow us to consider the plutonic complex along the Iskar-Yavoritsa Shear Zone as a result of a bimodal magmatism (granitic and gabbroic) and magma mingling and mixing. Preliminary petrological and geochemical studies support so far this model : the gabbroic rocks, even these with some cumulate characteristics, are mesocratic. KFs-bearing, Py is usually replaced by Amf. The granitoids of the layered complex are meta-a luminous in compasition and withoul good fractionation trends ofthe major chemical elements.

First high precise single UlPb zircon data for the leucogranites of the Varshilo pluton showan intrusÎon age of 82.25 ± 0,4 Ma. The E- dT.90 Ma value of +0,3 displays young crust source with participati an of enriched mantIe material. An age of 81 3 ± 15 Ma was calculated for the gabbros, cropping out near the village of Vetren Three types of accessory zircons are distinguished in the gabbro, which is another evidence for the reaction between the acid and ba sic magmas.

The Cretaceous magmatism in Central Srednogorie lasted at least from the Cenomanian to the Campanian, the oldest rocks (monzo-diorite porphyries with an age of 92 ± 1.4 Ma) and related ore deposits cropping out in the nonhem parts ofthe Panagyurishte corridor (see von Quadt et al ., 2001 , this volume; Lilov and Chipchakova, 1999)

Rererences: Lilov, P., S. Chipchakova. 1999. K-Ar dating of the Upper Cretaceaus magmatic rocks and

hydrothermal metasomatic rocks from the Central Srednogorie. - Geochem., Mineral. And Petrol. , Sofia, 36, 77-91.

C O NTRm UTJONS TO OI STI NG UIS EI BETW EEN PORPElYRY - C OPPER ANO RELATE O EPITFl ERMAL ORE OEPOS ITS: A TRIBUTE O F 1E LT A O F LU ID INCLUSIONS

Ioan Pintea Romanian Geological Institute, Cluj Napoca branch, Fluid '"e1usion Research Group P.O .Box 181 , 3400 Cluj Napoca, 1, Romania, iointea@email ro

.. A greal deaJ of redistribution of material in porphyry deposits is probably caused by circulating meteoric fluids" (James A. Wlumey el al .. 1985),

The importance or fluid inelusion study in porphyry type deposits (PTO' s) consist mainly in the evidence of boiJing i.e. fluid phases immiscibility, as particular precipitat ion

mechanism of ore minerals Several decades of intensive work since Lindgren (1905), mainly between 70's and 9O's of Ihe last century. showed that the mOSI important fluid phase involved in PTD's formation is representative for a salt rich liquid associated with a low density vapor phase (eg. Roedder, 1 97 1; Whitney, 1975, 1984; Nash, 1976; Titley & Beane, 1985; Bodnar, 1995; Ciine, 1995; Shinohara & Hedenquist, 1997). Moreover it was established that such fluid incJusions wirh homogenization temperarures ranged between 500 to more than SOO°C were exsolved directly rrom silicate melt by immiscibifity al magmatic Slage (e.g. Wilson et al., 1980; Roedder, 1992 ;Pintea, 1993 ;Cline & Bodnar, 1994).The first evidence of immiscibility belween si licate melt, a salt rich liquid and a low density aqueous phase in PTO's was documented by EaSloe (1978, 1982) and EaSloe and Eadington, 1987 in quartz phenocrysts from biotite granodiorite al Panguna an the island of Bougainville in Papua New Guinea.The presence of silicate melt , fused salt and vapor as coeval fluid inclusions in quartz veins from protore zones in several porphyry Cu - Au (Mo) depasits fro m Metaliferi Mountains (e g. Deva, Rosia Poieni, Tarnita, Bolcana, Valea Morii , Talagiu etc) was largely documented by Pintea since 1993 . It should be emphasized that this peculiar melt and fluid inclusions association is characteristic for the pOlassic zone in PTD's from Metaliferi Mountains and must be considered, until now, as unique i.e. "'OCIIS lipiclIs " from porphyry copper alpi ne metallogeny's perspective.

Another imponant feature related 10 fluid inclusion study in PTD's from Metaliferi Mountains is the presence of low salinity aqueous fluids describing secondary ore depasit enrichment as high and low sulfidation epithermal type mineralizations. Frequently these kind of ore deposits such as veins, breccia and diseminated zones were generated in a convective meteoric fluid syslem, overprinted on the prolore ones. Our observations on melt and flu id inclusion allowed to discriminate during overall magmatic - hydrothermal processes two main fluid phase evolution lines: one continuous slaning by an exsolved dense metallic chloride phase 10 a diluted electrolyte solution via several boii ing episodes and another where is difficult to recognize a direct relationship between epithermal stages and underlying magmatic intrusives.

References: Bodnar R.1 . (1995) In Magmas, fluid s, and o re deposilS, J.F.H. Thompson (ed), 7 ,139-1 52; Ciine J.S., Bodnar R.1 . (1994) Econ. Geol., 89, 1780- 1802; Ciine J.S. (1995) Ariz. Geol. Soc.

Dig., 20 , 62-82; EaSloe C.1. (1978) Econ. GeeI. , v. 73, 72-748 ; EaSloe C.1 . (1982) Econ. Geol., 77, 12-153 ;

EaSloe C.1 ., Eadington P.1 . (1986) Econ. GeeI., 81 , 478-483 ; Nash J.T. (1976) U. S. GeeI. Survey Prof Paper 907-0 , 16p; Pintea 1. (1993) Arch.Mineral XLIX, 165-167;

Roedder E. (1971) Econ.Geol. , 66, 98- 120; Roedder E. (1992) Geochim.Cosmochim.Acta, 56, 5-20;

Shinohara H., HedenquiSl J.W. (1997) Jour.Petrol., 38, 12, 1741- 1752; Titley S.R., Beane R.E. (1981) Econ. GeeI., 75~ Ann. VoI., 214 -269;

Wilson W. J. , Kesler S. E., Cloke P.L., Kelly C. W. (1980) Econ. Geei , 75,4-61 ; Whitney J.A.(1 975) Econ. GeeI. , 70, 346-358;

Whitney (1984) Rev. in Econ. GeeI., 4, 183-201; Whitney J.A., Hemley J.J ., F.O. Simon (1985) Econ. Geol. , 80, 444 - 460.

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PETROLOGICAL ANO METALLOGENETICAL CHARACTERISTICS INOUCEO BY TBE PARTICULARITY OF SUBOUCTION IN THE BAIA MARE AREA (THE EAST CARPATHIANS, ROMANIA)

G heorghe C. Popescu Faculty of Geology and Geophysics, Bucharest Universi ly

The plate tectonics concept has fundamenta lly influenced the interpretation of the geological structure of Romania and of the related petrogeneticJmetaliogenetic phenomena.

Some cJassic siudies such as those of Radulescu and Sandulescu 1973, Bleahu el al. 1973, reflected especially geotectonic and igneous problems. Later, studies regarding the metallogeny of Romania have been approached by Popescu 1985,1994, Seghedi et al. 1998 based on the plate tectonics concept.

Subduction related metallogeny rrom the East Carpathians has resulted in a specific subprovince containing the consequences of the differential st ress regime both in space and time (popescu 1985). Along the subduction there are three ingneous districts with difTerent morphologies and associated metallogeny. The district situated to the north of Dragos Voda fault has been generated under the conditions of a tensional stress and contains andesites, dominantly base-metals and subordinately Au-Ag metallogeneses (Popescu 1994).

The central district situated between Dragos Voda and Somesului faults has been formed under the conditions of a compressive stress and has some base-metals with cupriferous trend metalogenesis.

The southern district, a very extended one, has been generated under the conditions of a tensional st ress, contains andes ite and a diverse (varied) metalogenesis with native sulphur, cinnabar. base-melals and iron (volcano-sedimentary ores).

In the Gutai Mountains, or the Baia Mare metallogenetic district, the ages of volcanic rocks are arrange contarily with respect of subductions directions. For explaining this contradiction we proposed a new model.

In the nonh pan of the East Carpathians, there are five stages of subduction. The first stage had a compressive character (Pre-Badenian?) and favoured an intrusive calk-alkaline magmatism - Toroiaga Massif, assoCÎated with a base-metals with copper. The second slage (Badenian) had a tensional stress regime and favoured the first volcanic manifestation, expressed by rhyolites and dacites. The third stage (Sarmatian) was a typical tensional regime of st ress and favoured pyroxene andesitic volcanism and associated base-metals metallogenesis. The founh stage (Pannonian) is represented by eruptions of quartz-andesites and gold and silver metallogenesis. The IasI stage (pontian) is represented by andesites with pyroxene and amphibole and has an important base-metals and partially gold and si lver metalogenesis

References Bleahu, M., Boccaletti, M., Manetli , P., Peltz, S. (1973), Neogene Carpathian arc; A

continental arc displaying the features of an "Island Arc". J. of Geopgy.Research, v01.78, no 23, p. 5025-5032

Popescu, Gh. C., (1985), Stress regime, Neogene magmatism and metallogenesis in the East Carpathians (Romania). Proc rep. of the XIlI-th Congress of KBGA, Poland, Cracow, sept. 5- 10, 1985

Popescu, Gh c., (1994), A geodynamic model regarding the Neogene volcanism and the associated metallogenesis in Baia Mare District (East Carpath.). An.Univ.Buc .. XLIU, p. 19-27

86

Radulescu, D., Sandulcscu, M., (1973), The plate-tectonics concept and the geological structureofthe Carpathians. Tectonophysics 16, p. 155-1 6 1

Seghedi, 1., Balintoni, 1. , Szakacs, A. , (1998, Interplay of tectonics and post-collisional in the intracarpathians region. Lithos 45, p. 483-497

PORPBYRY COPPER - MASSlVE SU LPHIDE SYSTEM IN T HE RADKA ORE FlE LD (BULGA RIA)

Ka men Popov University ofMining and Geology, Sofia 1700, Bulgaria; kpopov@stafT.mgu .bg

The Radka ore fi eld of the Pa nagyurishte ore regio" is formed in relat ioD with t he Upper C retaceous magmatic activity. It is example for de\'elopment of an asymmetric linea r porphyry copper - mass ive sulphide ore sys tem.

Geology. The Radka ore tield is related to the evolutien of the Elshitsa volcano-intrusive complex. This complex is compound by the rocks of the EIshitsa stratovolcano, the Elshitsa pluton as well as numerous subvolcanic and subvolcano-hypoabyssal minor intrusives and dikes. The stratovolcano is distinguished in two packets: lower - andesitic and upper -dacitic. The Elshitsa pluton consists of granodiorite to granite, rarely diorite or gabbro. The minor intrusions and dikes are mainly dacite-rhyodacite or granodioritic porphyrites in composition. The Ovchihulm, Svoboda and Pesovets volcanoes occur nonhem of the arca. The Upper Senonian marlstone and terrigenous flysch cover the volcanic rocks .

Structure of the ore field is determined by difTerent elements of the vo lcano-intrusive complex. The Radka ore field represents a stripe-like area with E-SE direction, about 20 km long and 4 km wide in the northern slope of the Elshitsa stratovolcano. The Elshitsa pluton is exposed along the southern border as a result of the fault uplifting of the central block of the vo1cano. The development of faults with ESE (120- 130°) direction is very typical. Two groups represent them: a) subvertical to no rthern dipping (80- 65°) faults ; b) southern dipping (45-60") faults These relations probably mark a conjugated faulting. which accompany up lifting of the central part of the Elshitsa vo lcano. The subvolcanic and subvolcano­hypoabyssal minor intrusives and dikes are emplased predominantly along these faults. In addition, faults with 60-80°, 150- 170° and 20_40° are developed. They increase the permeability in the separate localities ofthe area.

Porphyry - mass ive sulphide ore s)'stem of linear type is developed in the ore field . It is formed after the volcano-tectonÎc faulting and block segmentat ion of the Elshitsa stratovolcano. The fault swarm of ESE (120-130°) direction as well as the accompanying stock and dike-like minor intrusions control its space position. The ore-fonning process is characterized by asymmet rical development along the ore controlling fault swarm. The porphyry copper depasit Tsar Asen occurs in the SE flank ofthe ore field . The massive sulphide deposits Radka and Chervena Mogila and a number of ore occurrences are situated consecutive to the NW direction. The quantity of the sulphosahs, lead-zinc and gold mineralization is increased in trus direction. as weB as the temperature of ore emplacement. These circumstances show the trend of porphyry ta epithermal transition Similar pattern is developed in the NW Oank of the ore field. The Turnichevo porphyry copper and Stiptsata massive sulphide ore occurrences are located in this area. K-silicate and

8'

propylitic aherations associate with the porphyry copper deposits as wel! as sericitic and argillic alterations in liuocap. Predominantly propylitie, sericitic to advanced argillic (in some localities) alterations are zonal developed around the massive sulphide deposits. Some other feature of the ore system is the discrete forming of the different ore deposits. They are separated each other by non-mineralized intervals. The individual ore deposits are formed in relatian with panicular subvolcanic to hypabissal minor intrusion or dykes. It Îs mosI Iikely thal the separate streams of ore-bearing fluids are connected with uniform souree through the ore controlling fault swarm.

GEOTECTONIC MODELS OF T HE ALPINE M ETALLOGENY IN TH E EASTE RN PART OF TH E BALKAN PEN INSU LA

Petko Popov University ofMining and Geology, Sofia 1700, Bulgaria; e-mail · kpopov@staff.mgu.bg

T he Alpine melallogeny ofthe easter" part ofth e Bstka" Peninsula is characterized by a broad variety of genetic types of ore deposits. They are formed as a result of consecutive development of different geotectonic sett ings a ud accompanied magmatic, sedimentary and metallogenic events, similary to \Vilson's cyele.

O re deposits related to intracontinental rirting are established in Strandzha allochthon. Volcano-sedimentary Cu-Zn-Pb massive sulphide depasits associate with Triassic green­schist and metadiabase, as well as ilmenite-chlorite schist accurs in this region. Besides, the primary Fe-Mn hydrothermal-sedimentary mineralization is formed in the Kremikovtsi area in relation with intracontinental faulting. The strata-bound Cu-U deposits in Permian and Triassic sandstones in West-Balkan Region are possibly related with this setting, too.

Ore deposiu related to ocean spreading setting are developed in the Vardar ophiolite complex. Numerous podiform chromite deposits as weB as Cu-Ni-Co and Fe-Ti occurrences associates with the gabbro-pendotite massifs. Volcanogenic and volcano-sedimentary deposits are related to the Diabase-Chen fonnation . Massive sulphide or disseminated Cu and strata-bound Mn deposits represent thern. A series of Fe-Ni and magnesite deposits is developed during the lateritisation of peridotites. Some asbestos deposits are formed as a result of hydrothermal-metamorphic processes. Numerous sedimentary Fe deposits are developed in the continental shelfarea during the time ofspreading.

Ore deposits of subduction-relaled gra nitic inlrusions along the eastem border of Vardar Ocean are not developed.

Ore deposits of collision-related setting associates with the Middle Cretaceous granitic plutons in the area of the Rhodopes and the Pirin Mts. Hydrothermal Mo, Pb-Zn, U and nuonte as well as skarn Fe small deposits and occurrences represent them.

Ore deposils of pos t-collision rift-related setting are widespread in the Apuseni-Banat­Timok-Serednogorie Selt. They associate with the Upper Cretaceous volcanic aod plutonic rocks. The porphyry copper (±Au, Mo) and massive sulphide (Cu±Au) deposilS are mo" imponant. The skarn Fe, Cu, Pb-Zn and Mo-W deposilS as weB as the hydrothermal Cu (

88

±Au), Cu-Pb-Zn (±Au, Ag), Au, Ba and U deposilS are also developed. The volcano­sedimentary Mn and Fe deposits are occurred as well . Upper Cretaceous metallogeny look place in the West Balkan region too. This region can be interpreted as collision relaled back-arc tnrust belt uplifted during the rifting. Hydrothermal Pb-Zn-Ag. Cu and U deposils, mainly of strata-bound type, and barile vei"s are formed .

Ore depasit! of late ta post-collision-related seuing are developed in association with the Tertiary magmatism in Trans-Balkan zone. Numerous vein-type rarely metasomatic Pb-Zn ore deposilS are widespread developed. Porphyry copper (Au-bearing) deposits are fonned in some places. A series of hydrothennal U, Sb (±Au) and fluorite as well as small skarn Fe or Mo-W depasits accurs, 100. Tumerous infiltration-type uranium deposits are related ta molassa formation in grabens. Several sedimentary Mn depasits are deveJoped on the continental shelfin the Circum-Black Sea region.

MlXEO ANO MINGLEO LAVAS AT LOWER OLIGOCENE MAOJAROVO ANO ZVEZOEL VOLCANOES, EA STERN RHOOOPES (BULGA RIA).

Raya Raicheva', Peter Marchev', Orlando Vase11i2

I Geologicallnstitute _ BAS, Acad G Bonchev str , bl. 24, 1113 Sofia, Bulgaria ] Dipartamento di Scienze delIa Terra, Via G. La Pira 4, 50121 Firenze, Italy

Magma mixing has probably played an important role in the genesis of the Tertiary extensional volcanism in the Rhodope massif, Bulgaria. Our research describes mixing and mingling processes in the Lower Oligocene Madjarovo and Zvezdel volcanoes.

Madjarovo (MD) and Zvezdel (ZD) paleovolcanoes are located in the Eastern Rhodope volcanic area, which represents a part of the Macedonian-Rhodope- onh Aegean volcanic zone. The lavas from MD have the composition of shoshonitic and high-K calc-alkaline basic to intermediate varieties with latites being the mosI voluminous rock type. The overall Si contents range from 51 up to 68 wt.% SiO] with noticeable increase of K during volcano evolution. The volcanic activity produced two unites of mixed basaltic andesite and shoshonites, enclosed by latites (SiO,~59-60 wt.%) and high-AI high-K basalts (SiO,~51-52 wt.%). The vo lcanic rocks in ZD are predominantly high-K calc-alkaline with subordinate shoshonitic varieties ranging in Si02 from 49 to 70wt.%. Mixing phenomena have been recorded in a number of basaltic-andesite and andesite lava flows.

1agma mingling Mingling in MD is distinguished in a high-K andesite flow. An alternation of dark, white and pink-brown, compositionaJly difTerent flow bands and lenses varying in size rrom a few mm to 1-2 cm, is well seen in the thin-sections. The white and black bands consist of olivine (Fo" ... ), clinopyroxene (Mg#79-71), plagioclase (An ..... ), titanomagnetite and groundmass composition with SiO]=59-60 wt.%. The pink-brown bands and lenses consiSl of plagioclase (An77-60), resorbed biotite, cl inopyroxene and titanomagnetite and groundmass with SiO,~. 7 wt.%. An amphibole-biotÎte high-K andesite rrom ZD contains ellipsoidal, quenched textured magmatic inclusions, which show evidence ofhaving been mollen when incorporated into the host magma The host rock consists of plagioclase (An, .... ), clinopyroxene (Mg#75), onhopyroxene (Mg#68-70), amphibo le and biotite phenocrysts. The inclusions range in size

89

from I mm to 15xlO cm and contain phenocrysts of plagiocJase (AnS0-82), cJinopyroxene (Mg# 80-82) and titanomagnetite. Mixing involves transfer of phenocrysts from cne component to anotheT in both direction and volatile transfer to the indusions with chemical exchange, which modify the chemical composi tion ofthe Înclusions.

Magma mixing Various disequilibrium features of the phenocrysts in both volcanoes can be referred ta magma mixing processes. Two main plagioclase populations can be distinguished in a same sample on the basis of composition, zonning panems and textures - (1) reverse zoned, sieved textured and (2) normal zoned, cleaT plagioclases. Normal zoned and reverse zoned (with resorbed cores) c1inopyroxenes are common in the mixed lavas. Some onhopyroxenes are euhedral whereas others have resorbed cores with Mg-rich c1inopyroxene rims. Groundmass plagioc1ase and c1inopyroxene with unusually high An and Mg# content respectively are also present in some andesites and shoshonites. The mineralogical and textural evidences for magma mixing events are supponed by linear increase of B1Srf'6Sr and 0180 isotope ratios in MD, the laner exeeding the values thal can be expected from simple fractionation .

Z IRCONS IN T El E VOLCANIC ROCKS OF THE NEOGENE M AGMA TITES FROM SOUTH APUSENI MOUNTAlNS. PETROGNETIC lMPLICATIONS

1. N. Robu, L. Robu Geological Institute of Romania, Bucuresti

Zircon crystals from the volcanic roc k! of the South Apuseni Mountains ha\'e emphasized the similar morphologica l ch a racteristics for aII investigates andesite types, excepting Caraciu and Uroi ones. They are mainly S or G and P types, belonging to a mix material (c rust + mantie) and respectively mantie one. Some interest ing aspects, as zones, overgrowth and inclusions have been ident ified.

Previous studies regarding the volcanic roeks of the South Apuseni Mountains, investigated till now using geological (mineralogieal , pet rographieal, petrochemieal and fluid inc1usions) and geophysies (gravimetric, magnetometric and petrophisies) methods did not involved aceessory minerals in the deciphering of the problems of the volcanism from this area.

This study trays to present morphologieal and optical aspects of the zircon populatÎons, met in different kinds of andesites and to involve them in petrogenetie processes what have developed in this area. Zireon populations, identified in the granulometric fraetions down to 0.250 mm and studied under mieroscope and stereomicroseope, has emphasized well­developed idiomorph crystals. with pyramidat and bipyramidat-prismatic habit .

Color is variable between Jight and dark pink for majority of erystals, but a few of them are colored in light brown. These color variations have not intluenced the typology of zircon crystals.

Zi rcons are characterized by some interesting aspects, observed in their inside: ~, are presented in a few erystals, have unequal development and are variable as

thickness, from thin to thick; a parallel or oblique position, comparable with the edges ofthe erystals have been emphasized. They are disposed in prismatic part of the crystals and sometimes they are met in the pyramidal part of the crystals. Exeeptionally they can develop

90

around of the pre-existed rounded ar geometric shaped nuc1eus. These kind of nuc1eus are disposed in the cemral part of the crystal, are transparent or opaque and have difTerent dimensions. They ha ve bee" considered pre-existed zireon crystals.

Q\'Crrţrown crvslals a few, are composed from nucleus and overgrown zone, presenting t wO aspects: first , nucJeus disposed in the central part of the crystals and the corresponded overgrowth, symmetric disposed around the nucleus, and second, eccentric nucJeus, when the overgrown zone have an asymmetric development . The overgrowth lones have idiomorphic aspects, like thase of their host crystals and the same optical orient alian with crystals, which enclosed them.

luclusioJ1s are minute and mei in majority of crystals, with three aspects: needles, baci llus and prisms; they are disposed chaotic or parallel with the edges ofthe crystals, in the prismatic part of the zircon crystals. They have been defined according to their optical properties, as zircon and apatite, but sometimes their minute dimensions have done impossible their recognizing.

The morphological typology of the zircon crystals has emphasized an obvious predominance of the 5 type (5,; 5.; 5,; 5,; 5,,; 5,6-18) and a few of them are G and P (P,., ) types. They represent crusta] fonns (S above mentioned types), met in majority of considered andesites and mantie anes (G and P types), representatively for Uroi and Caraciu andesites.

The aspects emphasized by zi rcon study are in concordance with chemistry (major, minor and REE elements) of their host rocks.

TIlE GEODYNAMIC EVOLUTION OF HYDROTH ERMAL VEIN DEPOSITS IN TIfE MADAN METAMORPBlC COMPLEX, BULGA RIA

Majka Rohrmeier, Albrecht v. Quadt, Maria OVlcharova, Thomas Driessner, Ch. Eleinrich ETH Zentrum NO, 892, Zurich, Switzerland

Large lead-zinc mineralized vein swa rms are associated with the Madan Dome in the Central Rhodopes, South Bulgaria which is interpreted as a large metamorphic core complex. Studies in the Central Rhodopian area are carried oul using high-precision geochronology to determine the relationship between alld the tim ing of extensional detachment motion, core com plex uplifl , local acid magmatism aod hydrothermal ore formation. In conjunction with iso topic tracer aod fluid inclusion data, we hope to identify the sources of ore-forming components aod the mechanism of hydrothermal metal transport and precipitation.

Geological context The Madan Dome has been interpreted as a large (tens of km diameter) metamorphic core complex (Ivanov, 1989) that resulted from orogenic collapse after the Alpine collision between the Eurasian and African plaIes nonh of the Aegean sea. Burg and Ivanov (1990) distinguish two phases in the evolution of the Central Rhodopes: The first is a compressional phase which caused large-scale, south vergent thrusts and amphiboli te-facies metamorphism in the Late Cretaceous. The second phase led to an extensienal regime and, to associated a group of gently dipping detachment-faults were developed. One of them, the Madan detachment, is a continuously mapped, outward-dipping fault zone and is considered to be the last active majer extensienal detachment . It separates the complex into an upper plate and a lewer plate ef the dome. Half-graben basins above the detachment are filled by continental

9 1

sediments of middle-Iate Oligocene age based on fossil record, and contain some acid sub­aereal volcanic rocks The rocks of the upper plate consist of meta-pelites and metacarbonates in the upper pans and onho- and paragneisses in the lower pans. The age of amphibolite facies metamorphism in the upper plate crystalline rocks is currently not well known. The lower plate of the inferred core complex consisls of gneisses, micaschists. amphibolites and marbles. Migmatitization and local anatexis are camman. The youngest available leucosome age is ca. 36 Ma (UlPb zircon; Arkadaksky et al., 2000). The detachment is loca ll y cut by non deformed rhyolite dykes and shallow rhyolitic intrusives what indicates Ihat volcanism postdates not ooly extensiaoal movement on the detachment bUl also uplift and denudation of the lower plate of the core complex. In the Madan Dome, ore veins of a very rich Pb-Zn mineralisation can be found which crosscut the detachment faults and overprints the rhyolite dykes by an associated carbonate - seri cite alteration. These observations show that mineralization postdated extensional movement of the dome and occurred during or after uplift and magmatism.

Melhods and results Current work focuses on radiogenic dating of the uplifting and cooling history of the metamorphic rocks of the dome: Preliminary results from Rb-Sr-measurements (this study) and Ar-Ar- dat ing (Ovtcharova et al., 2001) on biotite yielded cooling-ages ofboth the upper plate and the lower plate of 35 Ma Therefore, a difTerent cooling history of both plates, typical for metamorphic core complexes, could not be confirmed. Dating of rhyolitic magmatism (U-Pb dating of zircons) indicates thal rhyolites intruded in the core about 32-30 Ma ago (Ovtcharova et al., 2001). Accurate dating ofthe vein-forming and alteration events in the four main ore fields as well as the detennination ofthe time interval ofthe detachment are canied out by Ar-Ar- analyses on white mica. To identify the feeder(s) of the mineralisation. isotope tracing on feldspar is applied

Conclusions The Rb-Sr and Ar-Ar data imply that the cool ing ofthe core and the upper plate ofthe Madan core complex occurred at the same time. A metamorphic core complex, however, is expected to show a different cooling history of the core and the upper plate: The cooling ages of rocks from the core should be younger because their exhumation, caused by the extensional detachment occurred when rocks of the upper plate had already been exposed. Funher measurements on both core and upper plate will be needed to decide whether the Madan Dome can be confirmed as a metamorphic core complex or not. The U-Pb measurements on zircons of rhyolitic dykes yield an intrusion age of 32-30 Ma, postdating uplift and cooling of the dome.

References Arkadakskiy S., Boehm C., Heman L. , Cherneva Z. & Stancheva E. 2000. ABCD GEODE

Workshop - Borovets, Abstracts, 1, 5. Burg J-P., lvanov Z., Ricou L-E., Dimov D. & Klain L. 1990. Implication of shear sense

criteria for the tectonic evolution of the CentraJ Rhodope Massif. Southem Bulgaria. Geology, 18: 451-454.

Ivanov Z. 1989 Strucure and tectonic evolution ofthe central parts ofthe Rhodope Massif. Guide to excursion E-3, CBGA-XlV- congre", S., Bulg. 126 p

Ivanov Z. 2000. ABCD GEODE Workshop - Borovets, Guide to excursion B. 50p. Ovtcharova M., v. Quadt A., Peytcheva 1., Neubauer F. 2001. Exhumation ofthe Central Core

Complex and related Magmatism - lsotope and Geochronologic Studies of the Madan Dome (Bulgaria). EUG Xl, J Con( Abs., 6, 1.

GOLD OCCURRENCES IN THE EASTERN PART OF THE BAIA MARE DISTRICT, ROMANIA

Randy Ruff and 8arbara Stefanini SAMAX Romania SRL, Str. Moldovei 15/ 1,4800 Baia Mare, Romania

Recent exploration activity in the Baia Mare District by SAMAX Romania has delineated gold mineralization of potential economic significance. Gold mineralization may be related ta a late mineralizing event Ihat cross-cut earlier base-metal mineralization.

SAM.AX Romania SRL (a wholly owned subsidiary of Carpathian Gold Ltd) is actively exploring for gold deposits along the Neogene Inner Volcanic Arc and the Banat- Balkan zone in the Carpathians of Romania. The main areas ofinterest are the Baia Mare District and the Apuseni Mts.

The Baia Mare District is comprised of approximately 25 epithermal base-metal and gold deposits which exhibit the features of low-to-intermediate sulfidation epithermal mineralization. The District is best known for its world·c1ass base·metal vein deposits such as the Baia Sprie and Cavnic mines which have yielded word·c1ass mineral specimens as well . Less well known however, is the signiflcant gold production from mineralization proximal to base metal veins or alone. An estimated minimum of 4 million ozs of gold have been produced from the Baia Mare District from Au-rich veins and stoc"'-works and Au·rich base· metal ore.

At the Suoir Mine, open pit mining extracted 740,000 ozs gold at an overall average grade of 5 git Au. Below the open pit , active mining ofthe Pb-Zn +Au ore (2-3 git Au) has yielded an additional 400,000 ozs of gold. Gold grades from the open pit shows a remarkable grade gradient occuning in the top 100 m ofthe deposit. The average mined grades decreased from the top (6. 15 git Au), through a middle part (4 .77 git Au) to the bonom ofthe open pit (2 .64 git Au). The average grade from the presently active underground mining levellocated 300 m below the bottom ofthe open pit is 2.8 git Au. This grade gradient over 100 vertical meters suggests a boiling precipitation process typical ofBonanza·style precious metals deposits.

On Dealul Minei, Baia Sprie Mine, recent surface sampling results by SAMAX have defined a Au-rich and base·metal poor zone with an intercept of 30 m at 5.2 git Au. This zone occurs just nonh of the base·metal rich Principal Vein and at the same elevat ion. The Au mineralization is related to sheeted quartz vein arrays with inter·vein stockworks in contrast te the planar vein geometry ofthe Principal Vein.

Al the Breiner Vein system al the Baiul Mine, underground cross·cuts reveal Au-mineralized breccia zones. These zones are locally > 8 m thick and grade from 3·6 git Au and locally > 1 ° git Au. Gold is associated with breccia·c1ast coatings of banded chalcedonic and crystalline quanz. This Au mineralization is anomalous for the District in thal it is locally associated with Cu grades of I - 2.3 %.

Gold mineralization al Baia Mare has been widely interpreted as a vertically zoned base· metal to gold continuum. In the context of epithermal ore deposition models and integration of lithogeochemistry data along with the contrasting ore·textures of base-metal and gold mineralization, we propose a model for Au mineralization resultant from difTerent fluid processes than those responsible for base·metal mineralization. Gold mineralization may be a

93

late event related to repeated boiJing episodes in which fluids rapidly ascended; whereas base-metal mjneralization resulted from an earlier fluid mixing process.

STR UCTURE AND EVOLUTION OF THE INNER CA RPATHIANS AREAS

Mircea Sandulescu Faculty ofGeology and Geophysics. Bucharest University

The main group of units, in respect with which is basically necessary to analyse the Carpathian structure, evolutian and paleogeography, is the Main Tethyan Suture Zone. It groups together the units proceeded from the Tethyan oceanic crust domain and are squeezed actually between the former continental margins, which are a150 deformed du ring Cretaceous and/or Miocene tectogeneses.

The Mai" Tethyan Suture Zone is, within the Carpathians, the continuat ion of the Vardaf Zone (which units crops out since Beograd in its nonhem segment). Nonh of Danube (at Beograd) the Suture is covered by the more younger formations ofthe south-eastem sector of the Pannonian Depression. North of Beograd, the Suture is div-ided in two branches: the South Pannonian Suture, running toward west-nonh-west and reaching, west of Zagreb, the Insburg "Line", and the Transylvanidian-Pienidian Suture which crops out in the Southem Apusenides, follows below the Transylvanian Depression and, nonh of the Nonh Transylvanian Fault, reach the Pienidian units (Magura, Pieniny Zone and connects) prolonging into the Liguro-Piemontais domain ofthe Alps.

The European Continental Margin, deformed in Cretaceous and Miocene times, is well expressed by the cropping out the East and South Carpathians and also in the Northem Carpathians (extemal in respect with the Magura Group). The Central East Carpathians nape system, the Getic-Supragetic napes and the Danubian Domain, shows classically continental­crust-shearing-napes. Within this European Continental Margin a Jurassic-Lower Cretaceous rift develops, from which proceeded the Ceahlau-Severin napes system.

The Fore-Apulian Domain represent a Mesozoic deformed continental block situated within the oceanic Thethys, bounded by the South Pannonian Suture, toward the south and the Transylvanidian- Pienidian suture, toward the south-east , east and nonh. The units belonging ta this domain crops out in the Nonhem Apusenides, the Central \Vest Carpathians, as well as in the Bakony, Mecsek and Villany Mts. An exotic terranne - the Buk.k Terranne - was inserted into the Fore-Apulian Domain, perphas in the Jurassic time. The Fore-Apulian Domain include also the Austro-Alpine nape system of Eastem Alps.

The Apulian Continentla Margin is situated south and west of the South Pannonian Suture and Vardar Zone (Suture). From this continental margin proceed the "Buk.k Terranne" which migrated, atler the Middle? or Upper? Triassic, toward The Fore-Apulian Domain.

The opening ofthe Tethyan Ocean is certainly Midd-Triassic in the South Pannonian and Transylvanidian branches, consequently in the Vardar Zone too. The spreading develops during the Upper Triassic, and the Jurassic (since the lowennost Upper Jurassic). The Pienidian segment of the oceanic thethys was opened in the Lower (?) or Middle (l) Jurasic. The opening of the Pienidian ocean may be regarded in two ways: as a continuat ion of the Triassic opening of the Transylvanidian one, therefore propagating from east toward \Vest or as an etrect of the opening of the Central Atlantic, therefore propagat ing from west toward east.

The development of the intracontinental extensive rifling processes within the European Continental Margin, are in close conneclion with the compressive deformat ion of the Nonh Dobrogea Orogene and the anti-clockwise rotation ofthe Moesian Platform

TECTONIC SETTING ANO HYOROTHERMAL MI NERALlZATlONS IN THE CALIMANI-G URG HI U-HARGHITA VOLCANIC CHAIN - EAST CARPATHIANS ­ROMA NIA

Ioan Seghedi l, Alexandru Szak.1cs 1

I Geological lnstitute of Romania, st r. Caransebes 1, 788344, Bucharest 32, Romania, e-mail: seghedi@igr.ro 2 Sociedad Contractual Minera Carola, Copiapo, Casi lla 196,.Chile

Large-scale tectonic features are imponant factors in the fonnation and location of magmatic hydrothermal ore deposits in subduction-related magmatic arcs. The C3limani­Gurghiu-Harghita voJcanic chain is the largest occurrence area of Neogene voJcanism in the Carpatho-Pannonian area. Examination of spatial and temporal distribution ofm ineralizations relative to the regional tectonic model of Mason at al. (1998) showed that most of the mineralizations formed at the ceasing of volcanic activity following the period of along-arc migration of break-ofT processes, and are localized in the central pans of voJcanic edifices. The oldest mineralizations are localized in C31imani area and are related to intrusive events al around 10 Ma and are represented by gold-base metal vein occurrences (Colibi ta, Zebrac). The mineralizatiens and associated hydrothermal alterations related to volcanism between 9.5-0.1 Ma are located withi n calderas (Călima ni , Fancel-Lapusna) or in craterial areas or near volcanic vents (Seaca-Tatarca, Sumuleu, Ciumani-Fierastraie, Ostoros, Ivo-Cocoizas, Varghis, Luci-Lazul, Cucu). Alteration-mineralization displays many complexities, related to multiple intrus ion events, brecciation and consequent multiphase overprinting. Main mineralizations are porphyry-like, someti mes associated with high-sulfidation epithermal gold-base metal veins or impregnations. Metallogenetic features seem to have been influenced by changes in the tectonic regime, reflected by change of the magmatic activity from intrusive to effusive and by the along-arc migrat ien of volcanÎsm from nonhwest to southeast due to slab break-off Of slab tearing.

Reference Mason P.R D., Seghedi 1., Szakacs A., Downes H (1998) Magmatic constraints on

geodynamic model of subduction in the Eastern Carpatians, Romania. Tectonophysics, 297, 157-176.

THE Pb-Zn and Cu PROGNOSIS MAP OI' THE LECE VOLCANOGENIC COMPLEX

Todor Serafim o\'skil, Rade J elenkovic2

, Goran Tasev l

IFaculty ofMining and Geology. University of Skopje, R. Macedonia 'Faculty ofMining and Geology, University of Belgrade, FR Yugoslavia

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In the nonhern part ofthe Lece-Chalkidiki metallogenic zone (Serba-Macedonia" metalloge­nic province), has been situated the Lece volcanogenic complex, thal has bec" connected, spatialy and geneticaly, with polymetallic and gold mineralizations. By the structural· volcanological features of the massive, morphogenetic features and position of the ore deposits and ore bodies. The deposits were grouped in three ore fields: Gajtansko, Tulare and Djavolj Varos ore field.

In the frame ofthose ore fie lds are localized numerous Pb-Zn-Au hydrothermal deposits, mostly ofvein lype (Lece, Jezerina, Brajsor etc.) and porphyry Cu mineralization with precious metals. MineraJ potencial ofthis ore zone has been estimated as high because in this zone are enclosed few milions tons of Pb-Zn and Cu ore with high contents of gold and silver.

ln trus paper has been given review of estimation methods used in the mineral potential estimation of the Lece volcanogenic complex, from the polymetalic and precious metals aspect followed with apropriate disscusion of the results. The prognosis map was based on detailed analysis of numerous geological fearures that point out to a possible presence of ore mineralizations in some areas and apropriate geological settings, where ore presence has been espected from recognition and performed analysis of earlier defined orebearing criteria and indicators. Detailed analysis of colected data was perfonned with computers and specialy developed method named MAPO - Multiatributive prognosis estimation of mineral resources. The map was done in 1 :200.000 fonnat , with dimension ofelementary cell of 500 x 500 m.

According to the usual methodological actions performed during the prognosis of mineral potential at 1:100.000-1:500.000 level , by programme were defined the following levels and criteria: I « IS0) Perspective, from Ihe metallogenic point of view desirable settings with known economically important mineral deposits; U (120- 149) Metallogeneticaly desirable settings with smaller deposits, ore occurrences or indicators that point out existence of ore mineralization; IU (90- 11 9) Settings interesting from the metallogenic point of view, bul without significant mineralization occurrences; IV (SO-89) Settings with blurred potential for some kind of mineral deposit ; V«SO) Areas, not attractive for the prognosis of minera­lizalion ofspecific interest.

Areas distingiushed on the map are reflection of author's subjective estimat ion of noticed specific prognosis indicators, based on current knowledge about the geology of the area of considerat ion. This estimation can undergo some reshaping with increase of the data about the area analyzed. Levels are distinguished from Wm1n' = 0, 10 up to Wmax- = 1,50 based an experience and data about the genetic type of the deposit , mineralization and geological setting lhal was treated in this paper.

SVANBERGITE-WOODBO USE ITE lN ALTERATION ASSEMBLAGES OF T B E CHELOPECH ENARGITE-GOLD DEPOSIT, BULGA RlA : SPATIAL AN D TEMPORAL DEVELOPMENT AN D PREUMLNA RY GENETIC CO NSIDERA T IONS

SimOV8, Sot, Velinova, NoI, Petrunov, Ro" Velinov, t I, Moritz, Rol & C hambefo r1 , 1.1

lGeological Institute, Bulgarian Academy ofSciences, Sofia, Bulgaria 2Section des Sciences de la Terre, University of Geneva, Switzerland

%

The pre-ore hydrothermal activity led to the formation (from the axes to the periphery of the fluid-conducting structures) of zenes of "vuggy silica"(rarely developed), advanced argillic (quanz-kaoliniteldickite), quanz-sericitic and propylitic alterations of the wall-rocks (volcanic and volcanic-sedimentary of mainly andesitic composition). The economic Cu-Au Ofe bodies are hosted in the advanced argilJic alteration.

Svanbergite-woodhouseite (Sv-Wh) occur laterally within the lones of quanz-sericitic, advanced argillic and vuggy silica alterations, and vertically up to 1500 m below the recent surface. Within the quartz-sericitic zone they accur as rare 10·40 (m hazy skeleta l crystals floating in sericite and/or quanz and there is no evidence whether they are beginning to form or are in process of dissolution. Some grains are composed from apatite in the core and Sv­Wh in the periphery. Wit hin the zone of advanced argillic alt eration Sv-Wh are more abundant, associating with kaolinite, dickite, quartz, pyrite and minor Na-alunite, pyrophill ite, diaspore, zunyite, mtile and barite. They form clusters. bands or separate 5-60 (m pseudocubic zonal (by variation in Sr and Ca contents) grains. Similar zonal grains are growing on the rim of cavities and veinlets, filled in with quartz, clay minerals, pyrite and Cu-As sulfides. In some cases the pseudocubic grains are enclosed in alunite. Within the vuggy silica zone Sv-Wh can rarely be found as 5-10 (m pseudocubic grains in close association with finely disseminated pyrite.

The microprobe analyses show mixed chemi cal composition, marked by variat ion in Sr and Ca with prevalence of Sr in most samples. Small amounts of Ba, K and Ce are presented as well . End members have not been identified . The molar ratio of pol- and so.t is almost constant, nearly 1: 1.

The relationships with apatite in the zone of quartz-sericite alterations give reason to accept that at least a pan of the Sv-Wh could be fonned by dissolution andlor replacement of lhis mineral, as proposed by Sloffregen & AI pers (1987).

According to Ripp et al . (1998), Sv-Wh phases fonn in environment of high activity of pol- ions, high oxygen potential and wide interval of pH, from strong acid to neutra! (pH 3-8). The association of Sv-Wh wit h abundant kaoliniteldickite and minor Na-alunite might be considered as a sign of rather neutral-acidic than strong acidic pH values of the mineral­forming environment for the advanced argillic alteration assemblages in the Chelopech deposit.

The c10se spatial and temporal relationship between Sv-Wh and the Cu-Au ore mineralisation suggests almost the same Eh-pH conditions for the ore-formation. Thus, Sv­Wh represent indicati ve minerals of the potentially ore-containing zones in the Chelopech deposit.

References SlofITegen, R & A1pers, Ch. (1987). The Canadian Mineralogisl, 25, 201-211. Ripp el al. (1998). ZVMO, 6, 98-108 (in Russian).

GEODYNAMICS AND EVOLUTION OF TOE LATE MIOCENE MINERALIZATION IN TOE CYCLADIC - PELAGONIAN BELT, GREECE

Nikos Skarpeli s Depanment of Geology, University of Athens, Greece. E-mail : skarpelis@geol.uoa.gr

The Aegean region has witnessed a prolonged history of convergence and colii sion between the African and Eurasian plates. Early Miocene extensional tectonics were

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superimposed on crustal material previously thickened during the Mesozoic-Tertiary arogeny. Low-angle fault systems were developed al crustallevels and gradually exhumed ta upper crustal levels and the surface HP/L T metamorphic rocks and associated metabauxites and metamorphosed manganese-rich sediments were exhumed during this extensian event. Detachment faulting has been accompanied by emplacement al shallow crustal levels of syn­tectonic granitoids, as evidenced from their clase relationship to dacitic intrusives and the PT conditions in the contact metamorphic aureoles. Intrusion of granitoids post-date the ansel of detachment faulting. Dating of the granitoids indicates difTerent magma pulses with distinct emplacement ages within the late Miocene (- 14-9 Ma). Contact metamorphism affected parts of various tectonic units as a result of granitoid intrusion.

Our recent studies an the metallogenetic evolution of the Cyc1adic - Pelagonian Belt resulted in revision of existing metallogenetic models. Three major ore depasit types are recogmised:

8 . Skam-type, associated with the contact metamorphic aureoles (e.g. Seriphos, Tinos, Thera, Laurium). b. Mamo-type, associated with NW-SE extension (e.g. Laurium, Siphnos). The

ores oecur as massive replacements and Iinings within the marbles. Fluid inc1usions studies in sphalerite and gangue minerals indicate temperatures of deposition between 200-280°C from hydrothennal fluids of moderate salinities. Replacements of marbles by ascending hydrothennal fluids and deposition of Pb-Zn-Ag massive sulphides (CHMS) followed skarn formation. The Laurium mineralization is the major representative of the CHMS class in the Cyclades. On the basis ofthe amount of Pb produced and the ore grade, it is conc1uded that the Laurium ore depasit could be considered as a giant wilhin the c1ass of the CHMS type ore deposits.

c. Epilhermal preciolls aud base melal quarlz- aud barile-l'ei"s. They are associated with steeply dipping, britt le normal faults which affected the metamorphic rocks and the Miocene granitoids. when they were exhumed ta very shallow crustal levels in the Late Miocene - Early Pliocene. They are associated with fE-SW extension. Deposition of the precious- and base metals subeconomic mineralization in Myconos, Tinos, Antiparos, Kythnos, Andros and Euboea islands. and the Pelion peninsula is attributed to that mineralizing event. In one case (Myconos island) partly eroded si lica caps indicate that a precious metal epithermal system (sensu Buchanan, 1981) was active in Late Miocene.

References Avigad, D. & Garfunkel, Z. (1991) Tectonophysics, 188, 357-372. Lips, A. (1998) PhD Thesis, University of Utrecht , 220p. Skarpelis, N. & Avigad, D. (2000) GEODE 2000 Workshop, Abstracts VoI. , Borovets, p. 71.

TirE GEOLOGICAL E VIRONM ENT OF T UE CHELOPEC U Au-Cu DEPOSIT, CENTRAL SREDNOGORIE VOLCANO - INTRUSlVE ZONE, BULGA RIA.

Stanislav Stoykov Geological Institute, Bulgarian Academy of ScÎences. Acad. G. Bonchev Str 24, Sofia 1113, Bulgaria. E-mail : stenly@geology.bas.bg

Chelopech Au-Cu depasit is situated about 65 km eastem of Sofia in the feet of Stara planina mountain It is Europe's largest gold depasit containing well in excess of 5.5 miII ion ounces of gold (> 1 O miII ion ounees gold equivalent) (Andrew, 1997). It is hosted in Upper

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Cretaceaus andesite lavas and subvolcanic bodies. The Chelopech Au-Cu depasit is loc8ted in the Elatsite - Chelopech Ofe field, aCCQunts for the nonhernmosl pan of Panagyurishte volcano-intrusive region. This region is characterized by the development of Upper Cretaceous volcano-plulonic complex consisting mainly andesites. dacites, granodiorites and quartzmonzodiorites grouped in 4 phases (Li Iov & Chipchakova, 1999). This magmatic rocks are pan of Srednogorie volcano-intrusive zone, produCI of Late Cretaceous island arc (Dahovski el aL , 1991). The fo rmation of different types afe deposits predominated by copper ones is connected ta Late Cretaceous magmatism developed in this region.

The pre-Mesozoic basement in the Chelopech region is composed by Precambrian -Lower Paleozoic gneisses, two-mica schists, quartzites and amphibolites. This basement is overlain by sedimentary rocks (sandstones, breccio-conglomerates, caJcareous argillites) of Late Cretaceous (Cenomanian - Maastrichtian) age. The region of the deposit is built up predominately by Upper Cretaceous volcanics. volcano-sedimentary, flisch-type ca1careous turbidites and sandstones. Magmatites are presented by andesite lavas and subvolcanic bodies. Their phenocryst mineralogy is dominated by plagioclase, contains minor amounts of amphibole, biotite, quartz, titanite and apatite.

The exact age of magmatism in Chelopech region is stiH poorly known. Only few radiometric age determinations of volcanites and hydrothermal alterations exists (Li Iov & Chipchakova, 1999). Lavas, subvolcanic bodies and altered rocks (K-silicate-sericitic and argillic type) have been dated by K-Ar method. This data suggests Cenomanian - Campanian age (92 + 74 Ma) ofthe 1$1. and 3rd voJcanic phases and hydrothermal alteration products and Late Maastrichtian (67 + 65) ofthe 4'" one.

Referen ces

Andrew, C. 1997. The geology and genesis ofthe Chelopech Au-Cu deposit, Bulgaria; Europe ' s largest gold recourse. In: Europe 's Major Cold Deposits. Abstracts volume. 68-72.

Dabovski, Ch., A. Harkovska, B. Kamenov. B. Mavrudchiev, G. Stanisheva-Vasileva, Y. Yanev. 1991. A geodynamic model of the Alpine magmatism in Bulgaria. Ceologica Balcanica, 21 , 4, 3-15.

Lilov, P., S. Chipchakova. 1999. K-Ar dating ofthe Late Cretaceous magmatic rocks and hydrothennal metasomatic rocks from Central Srednogorie. Ceochem., Mineral. and Petrol., Sofia, 36, 77-91. (in Bulgarian with English abstract).

GO LD IN PORPHYRY COPPE R DEPOS ITS FROM T AE CENTRA L S REDNOGORrE ZO NE (B ULGARIA)

Strashimir Strashimirov University ofMining and Geology " St. Ivan Rilski", Sofia 1700, Bulgaria

The main porphyry copper depesits (Asarel , Elatsite and Medet) in the Central Srednogorie zone are characterised by difTerent grade and irregular distribution of gold in their mineral associations. Average gold content in ores varies within traces (Asarel) 10 0.2 git (Elatsite) but in some cases there are local enrichments (> 2 git) .

Gold is usually found as very fine semi-rounded or irregular shaped inclusions of micronic size in chalcopyrite or pyrite from the main economic assoCÎation (quartz - pyrite -chalcopyrite ( molybdenite) or in pyrite from the later formed qual1z - pyrite ( calcite

I()O

The ,cope of PANCARDI The Pannonian Basin, Carpathian arc, Dinaride (PANCARD I) syslem ofTers an oUIstanding opportunity ta study the interaelio" of lithospheric and aSlhenospheric processes and their mutual dependencies during volcanic arc and related fore- and back-arc basi" development. The evolutian oflhe highly arcuate Carpathians (250°) is drivcn by interrelated processes of oceanic and cOnlinental subduction of slab roll-back type and plate boundary rClreal into a continental embayment . The main goals ofPANCARDI are following : 1) Reconstructing the eogene to Quatemary evolutia" of the arc-basi" syslem, with

kinematic and paleomagnetic constraints contributing to the palinspastic resloration oflhe orogen.

2) Relating the long-term pracesses of subduction, arc fonnation aod basin development to the neotectonics and the on-going seismicity, pravidiog a basis for seismic hazard assesment and earthquake engineering in this densely populated area .

3) Understanding the oTigin ofthe nearly vertical Vrancea slab, as it is defined by seismicity in the mantie below the foothills of the eastem Carpalhians.

4) Establishing the Miocene to Recent magmatic history ofthe Carpathian arc, defining the source oflhe c1ac-alkaline and alkaline magmas that were coupled in time and space to the west-to-east progression of deformat ion in the foreland fald and thrust belt .

5) Understanding the chemical evolution ofthe mantie lithosphere beneath the Pannonian Basin and the relative importance of subduction and plume-related processes

Results and answers ofthe PANCARDI scientist5 to the above wriuen problems will be shortly discussed.

PRELIMINARY FLUID INCLUS IONS DATA ON Q UARTZ SAMPLES FROM COSTESTI COLD MINERALIZATION, SOUTHE IU .. CARPATHIANS, ROMANIA

Sorin Silviu Udubasa1, Marc Lespinasse2

, Gheorghe UdubasaJ, Gheorghe C. Popescu l

I University of Bucharest, Mineralogy Dept. , Bucharest, Romania 2 University "H Poincare" Nancy, UMR G2R., Nancy, France J Institutul Geologic al Romaniei, Bucharest , Romania

Costesti gold mineralization is one ofthe shear zone related mineralization examples in Romania . It comprises quartz-carbonate-sulfide discordant veins and concordant lenses within a small size shear zone (Udubasa & Udubasa, 1998) developed in biotite blastomylonites (Hanopanu et al., 1992, unpubl.). The ore mineral, are represented by arsenopyrite, pyrite, pyrrhotite, galena, chalcopyrite, native gold , native bismuth. bismuthinite, greenockite, sphalerite, jamesonite etc. (Udubasa & Topa, 1995).

In order ta identify the fluid types implicated in the mineralizing processes, a series of microthermometric analyses were performed an several quartz samples. Both mineralized and non-mineralized quartz veins have been sampled. Ice melting temperatures. eutectic temperatures (when possible) and homogenization temperatures have been observed for the primary fluid Înclusions. Several Raman spectrascopy analyzes were performed also on the vapor phases of the inclusions.

The observed fluid inclusions match the two-phase aqueous inclusion type. The results of the measurements indicate high sa linity fluids for the non-mineralized

veins (10-1 8 WI . % NaCI eq.) and low salinity fluid, (6-11 WI. % NaCI eq.) for the mi neralized veins

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Raman spectroscopy analyzes pointed out the presence in the vapor phase Ofe02, Cf-4 and N2. CH... and N2 predominate in the vapor phase of the inclusions from the 1100-

mÎneraJized quartz veins. whereas C02 and C~ predominate in the vapor phase of the inclusions from the mineralized quartz veins.

The structural data suggest that the studied mineralized veins are younger as the 000-

mineralized ooes. Thus it can be conc1uded that the fluids involved in the mineralizing process underwent a dilution during their space and time evolutian.

Aclmawledgemel11S: The fluid incJusion analyses and the Raman spectroscopy analyses were performed al UMR G2R, University of ancy, France.

References: Udubasa Gh., Topa D. (1995) Arsenopyrite composition, microinc1usions, and parageneses,

Costesti occurrence, Capatana Mts. Rom. J. ofMin., voI. 77, sup. 1, Bucuresti. Udubasa S.S., Udubasa Gh. (1998) Shear zone relaled gold ores, an example - Valea lui Slan,

South Carpathians. 16th Congress of the Carpathian-Balkan Geological Association, Vienna, Austria, Abstr. voI. , p. 610.

MlNERAL RELATIONS ANO PAR>\GENETIC SEQ UENCES IN TU E SKARN A NO POSTSKARN M INERALlZATIONS IN T A E PB-ZN ORE OEPOSITS, CENTRAL RHOOOPES

Rossitza D. Vassileva, Ivan K. Bonev Geological Institute, BAS, 1113 Sofia, Bulgaria

The replacement skam-ore mineralizations are a major part of the economically important Teniary (30-40 Ma) ore deposits in the Central Rhodopes, South Bulgaria. The skam-ore bodies are embedded in the marble horizons of the Rhodopian metamorphic complex, consisting of various gneisses and amphibolites. They are developed along steep ore veins, running along large (10-15 km long) fault zones with NNW or WNW direction. The infiltration type skams presented in the Madan, Luki , Ardino and Nedelino districts host rich Pb-Zn replacement ores of economic importance.

The primary skam minerals are those of the c1inopyroxene group, varying from pure johannsenite to manganoan hedenbergite. While in similar deposits usually prevail Fe-rich Mn-bearing pyroxenes, here they have mangaRoan specialization. The systematic EPMA study of the radiate and spherulitic aggregates of these minerals reveals crystal inhomogeneity and zonation generally depending on the various MnlFe ratio . Different silicate mineral associations replace clinopyroxenes: 1. amphibole-bustamite-andradite (Iower levels of Zapadno Gradishte); 2. amphibole-rhodonile-ilvaite (Ossikovo-Mogilala) .

Rhodonite is also a characteristic and extensively distributed , although subordinate silicate mineral in the skarns. It forms a narrow 1-2 cm pink zone at the skam replacement front or nests and veinlets in pyroxene mass. Common chemical characteristic for this mineral is increased CaD content, reaching 1 1 wt. %. Microscope and SEM observations proved that everywhere rhodonite has been formed later than pyroxene, replacing and overgrowing its crystals. Thus, the observed zoning, pyroxene-rhodonite-marble, is not a real infiltration metasomatic column, formed by replacement ofthe outer zones by the advancing inner ones.

Fine fibrous manganoan amphiboles were formed during the early retrograde skam alteration. Manganoferroactinolite is a common mineral (up te 10 wt . % MoD) though in very

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small quanolleS. Ofie" ilS fibre-like crystals replace topotaxically the manganoan hedenbergile crySials Ca-free amphiboles (13 .90 \\1 % MnO), presenled by manganocummingtonite-maganogrunerite series, al50 aceur replacing the johannsenite aggregates and inheriling the radiale texture of pyroxene. Amphiboles are observed as relics of fine whiskers in the alher later-formed phases - rhodonite, ilvaite, gamels. carbonate minerals, sphalerite and gale"a.

Carbonatization is important and widespread type of postskam alteration showing a clese link to the main sulphide deposition Rhodohrosite and manganoan calcite prevail.

Manganoan ilvaite is deposited as an alterat ion producI afier manganoan hedenbergite in Ossikovo, Mogilata, Baram and Govedamika. It fonns single crystals and nests in the pyroxene zone or/and at the skam-marble boundary. Common chemical feature is the extremely high Mn content ofthat mineral , varying in the range 11-14.90 wt. %. Sometimes the central parts of ilvaite crystals include small sphalerite grains, thus, showing a c10se link to the sulphide mineralization.

Bustamite is presented as fibrous pink-brownish radiating aggregates atler pyroxene in Govedamika and Zapadno Gradiste. It comains to several wt % FeO.

A honey-yellow andraditic gamet (up to 2.5 wt . % MnO) is formed as a rare retrograde mineral, although it is typical for Zapadno Gradiste .

The manganese pyroxene skarns are the most favorable environment for localizat ion of the rich Pb-Zn ores.

T HE INTE RACTIVE RAW MATE RIAL IN FORMATION SYSTEM ("IRJS") O F AUSTRIA - TH E COMPUTE R BASE D META LLOGENETIC MA P OF AUSTRIA

Leopold Weber t, Frit z Ebne,-l & G iinther El ausbergerJ

1 Federal Ministry of Economy and Labor, Mining Authority, Vienna, Austria 2 University of Leoben, Institute of Geological Sciences, Leoben, Austria J Geo- und Umweltinformatik, Leoben, Austria

During the past years intensive programs were carried out to document the mineral occurrences and deposits, and the geochemical and geophysical distributions in Austria. These data were the base for the "Metallogenetic Map of Austria" which was printed along wilh an explanation texi book by the Austrian Geological Survey (Weber, 1997). As a fimher step an Interactive Raw material Information System (OOS) was established.

Contenl of IRJS The IRIS data base provides the possibility of dynamically completing or correcting data as a main advantage of a computer based system. It is in strict contrast to a printed map which exists only in a static and unchangeable form . IRIS is a simultaneous approach based on 5 layers containing the following maps: geological map, metalJogenetic map, geochemical map, aeromagnetic map, topography (situat ion), and drainage system. Comprehensive informat ion such as location of metallic raw materials, industrial minerals and mineral fuels in Austria can be generated by visualizing data for more than 3000 mineralizations (occurrences and deposits) in an interactive way. This data base contains: name of the occurrenceldeposit, mineral content, geographic position and coordinates, geological data. shape and orientation of the deposits, metallogenetic district, isotopic data (if known), vitrinite reflectance of coals, remarks, figures and sections if available, and references. The geochemical background informat ion is provided for the Bohemian Massif and the

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Austroalpine crystalline and Paleozoic lones and derived from 29717 stream sediment samples, analyzed on 35 elements (Ag, AI , As, Ba, Be, Ca, Ce, Cr, Co, Cu, Fe, Ga, K, La, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, Sb, Sc, Sn, Sr, Th, Ti , U, V, W, Y, Zn, Zr) . Aeromagnetic data (total magnetic intensity in nT and altitude of the flight levels in melers) is based on aeromagnetic survey work in J 977 - 1982.

GIS-software IRIS was developed in Visual Basic 6.0 from Microsoft and MapObjects 2.0 from ESRl . MapObjecI is an ACliveX control (OCX) with more than 4S programmable ActiveX Automation objects thal can be plugged inte many standard Windows development environments such as Visual Basic. The required GlS-functionality is supplied by MapObjects. The development \\las dane under Windows NT 4.0.

Technical requirements to fun IRIS Operating System: Windows 95, 98 or NT (version 4.0 and SP3 or higher), Hardware: 64MB RAM. a minimum of 250MB free disk space. Pentium with 166 MHz or higher.

Reference: Weber, L. (ed. 1997): Handbuch der Lagerstanen der ETze, Industrieminerale und

Energierohstoffe Osterreichs. Erlauterungen zur metallogenetischen Karte Osterreichs 1:500.000. Areh. f. Lagers!. forsehung Geol. B.-A. , 19, 607 p., Vienna.

GENERAL FEATURES OF THE ULTRABASIC-BASIC SERlES OF THE EASTERN MEDITERRANEAN HERCYNIDES

G.S. Zakariadze\ B.A. Bazylev'" S.F. Karpenko', Kr. Kolcheva b, M. Zhelyaskova­

Panayotovab, N.V. Solov'eva

• Vernadsky Inst. ofGeochemistry and Analytical Chemistry, Kosigina 19, Moscow, 117975; gurzak@rinet.ru bDepartment of Minaralogy, Patrology and Economic Geology, Sofia University

Similar ta Central European Hercynides, the Eastem Mediterranean Hercynides (Erv1H) display extensive development of granitoid series and restricted distributian of fragments of strongly dismembered metaophiolites, the latteT usually much older than it could be expected for wide Middle Paleozoic ocean. Granitoids ofthe Hercynian stage proper ofthe EMH (340-270 Ma) show a lot of common features- mainly VAG type, lower crusta] sources of initial melts, significant involvement of depleted mantie source component «Nd=2.80 ta -7.1) etc. Pre-Hercynian ultrabasic-basic and associated continental margin series of Etv1H reveal however notable heterogeneity. Three groups of the pre-Hercynian ultrabasic-basic and associated continental margin series ofthe EMH can be distinguished : a) the Transcaucasian massif (TCM)- Balkan terrane(BT) group; b) Thracian terrane (TT) group and e) Great Caucasu, (GC) group

Metaophiolites ofthe TeM-BT terrane group are represented by MOR-type sequences­residual spinel harzburgites of ocean type and N- and T -MOR tholeiitic series (Dzirula salient of TeM and Stara Planina ophiolites of BT). The paleooceanic sequence is extensively intruded by fractionated tholeitic and calc-alkaline intrusions of immature arc type (Diabase and Diorite formations of the TeM and Struma Diorite Fonnatiom of the sT -

I().I

HA YDOUTOV et al , 1994). Geological setting of formation of the whole complex is identified as initial arc accretion stages of Pan·African cycle. followed by Lower-Middle Paleozoic sedimentary-volcanic sequence of inter-arc or fore-arc natuTe. Peri-Gondwanian provenance Îs accepted for the whole TCM-BT immature island arc succession. However metaophiolites and arc type series ofTCM (800±IOO Ma, 750-600 Ma) are respectively older than those ofBT (563±5 Ma, QUADT et al., 1998 and 560-660 Ma, LILOV 1981).

Metaophiolites of Thracian terrane (TI) exhibit notable heterogeneity. Ultramafic series are represented by residual harzburgites and dunite-orthpyroxenÎte and dunÎte-wehrlite­cJinopyroxenite cumulates. Only restricted part ofthe harzburgites could be analogs of MOR­type residuals, mOSI of the harzburgite restites as weB as cumulate series evidently originale in suprasubduction conditions. This conclusion is in good accordance with the composition of mafic dikes closely associated with some of the ultramafic bodies (Zhalty chal-boninitic; Dobromirtsy- lAT). The overwhelming volume of ophiolitic metabasites represented by HP metamorphic rocks (crusta! eclogites, eclogite-amphibolites, gamet amphibolites etc.), however, corresponds MOR-type series (N-and T -MORB). This strong compositional discrepancy between ultrabasic and basÎC ophiolitic series of TT caUs for revision of geodynamic models for initial stages of formation of the Thracian massif. Gondwanian provenance and Middle Proterozoic (or older) age ofTT metaophiolites are not excluded.

Thrust-imbricated accretionary sequences of the fo re Range and Laba-Boolgen Se r iu of the Grea t Caucasus comprise a vast series of allochtonous paleooceanic tectonic sheets of Lower-Middle Paleozoic age (mainly of suprasubduction- and MORB- types, 500-360 Ma) and pervasive intrusions of gabbros, diorites and plagiogranites of immature island arc type (460-320 Ma), penetrating accreted metabasic and metasedimentary series of the sequences an various levels. The whole succession is attributed to immature arc-back-arc complex that marked suturing (350-320 Ma) of the Lower-Middle Paleozoic oceanic strand situated to the north ofTranscaucasian massif.

The presented data a1lows to suggest that significant portions of pre-Hercynian basement of EMH is farmeci by peri -Gondwanian terrane assemblages. which include considerable amount of immature active continental margin type successions. Detailed correlations of these successions as well as the study of their relations ta pre-Hercynian gneiss-migmatite series of cominental type is the subject of further investigations.

IOl

ADDENDA

MORPBOGENETIC TYPES OF COPPER DEPOSITS lN TBE TlMOK MAGMA TIC COM PLEX Dejan Kozeljl, Sasa Cocie l

I Copper Institute, Bor, Yugaslavia

Abstract

This paper shows the morphogenetic types of copper deposits in the Timok magma tic complex where gold appears as the most important supporting component. The mOSI important depasits and occurrences of copper mineralization occurrences have been formed in vulcanoclastites and vulcanite mainly of andesite composition. These are dominant magmatic rocks in the whole Timok eruptive area and can be divided inta five petrochemical voleaoic slages: timacite, basaltic-andesite, tatite, trachyandesite aod albite trachytt phase. The formation of depasits and copper mineralization Qccurrences is associated with the embossing of intrusive stage (monconite and diorite stage) and the embossing of their veins or extrusive equivalents. The above mentioned rocks are connected with hydrothermal orebearing solutions that transported and deposited copper mineralization. The deposits have been formed al different depths and under various conditions depending on physical-chemical features of hydrothermal solutions and surrounding environment. As the most important associated component in copper deposits in the Timok magmatic complex gold occurs. The pa per wiH present ooly the deposits and the occurrences in the Timok magmatic complex where gold appears as the important supporting componeot. Various types of copper mineralization have been selected: porphyry deposics, hydrothermal -vulcanogenetic deposiCS in the forms of stock or lentil (with massive sulphides), hydrothermal - vulcanogeoetic deposits in the form of vein (with deposited and impregnated sulphide minerals), mechaoically overdeposited sediments (formed by disintegration of previously formed massive sulphide deposits) and ska rn deposits. The main features of the mentioned deposits will be presented, alleration mineralogy zoning in their adjacent vicinity aod compared with the similar deposits aod occurrences in the Timok magmatic complex.

Key ..... ords: Bor. copper, gold, minera/Jsarion. hydrorhermal alrerarton. porphyry. andesire

Introduction

The Timok magmatic complex is part of the Bor metallogenic zone which is sector of the Carpatho-Balkan metallogenic province (CBMP) in the Tethyan Eurasian metallogenic belt (Jankovie, 1965, 1977, I 990b). The CBMP eontains a number of major porphyry and epilhermal gold deposits in Hungary (Reesk, Lahoea) Romania (Moldova Nova, Deva, Rolia Poeni, Oraviea, Ciklora), Yugoslavia (Majdanpek, Cerovo, Lipa, Bor, Veliki Krivelj), Bulgaria (Assarel , Medel, Vlajkov Vrh, Elalsile, Chelopeeh) (Figure 1).

106

The Bar metallogenetic zone (BMZ) is a sector of the Carpatho - BaJkan metaJlogenetic province in metallogenetic sense of view with strike line which could be followed from the Carpaths, over East Serbia ta Bulgaria and Blaek Sea (Jankovi). 1990) (Figure 1). The mentioned province presents the west pan, over 10 000 krn long in the Tethyan Eurasian metallogenetic belt, formed at the edge of European platform as the result of closing the protooeean Tethys in a period rrom Mesozoie ta Tertiary (J.nkovi). 1977). It is possible ta connect ilS formation with the processes of global tectonic of plates, i.e., colii sion of European and African platforms in a period of Upper Cretaceous ta Miocene (Jankovi), 1977~ Sillitoe. 1980), where the mineral deposits were formed in the rift structures, formed aver and in the rear of subdiction zone of Afro - Arabian ocean crust under Euro - Asian continental crust (Jankovi), 1990). The mOsi important copper deposits of this area are: Moldova Nava, Deva, Ro(ia Poeni, Oravie. and Ciklora (Romania); Bar, Lipa, Majdanpek, Veliki Krivelj (Yugoslavia); Pan.djuri(te, Medet, EI(ie., Vlajkov Vrh and Asarel (Bulgari.) Jankovi , 1980 .

. .... ---I.R~I'_

2 ~"I

1. ~hl6o ... ~o ..

4 . ~bj.u..pck

, Velil" Kn .... lJ ..... 1. C.ktpd

'.M""" lO . ... ....d

11 . R.adh

Il. Vlajkow VrIo

t N

200 lan

Eocene • Pliocene belt

Carpatho - Balkan metallogenetic province

Figure 1: Tbe Carpatho· Balkan mctaUogenetic pro"ioce

The Bar Metallogenetic zone spreads the area from Dobra in the nonh to Donje Nevlje in the south It has appraximate meridian strike line, at length of about 100 k.m and width up ta 20 km, with bending to the Southeast. It is presented by volcanic rocks (andesites, andesite basaltes, lates, trachytes) and intrusive rocks (diorites, gabros,

107

monzonites. syenites, granodiorites) (Jankovi}. 1980). In the nonh of Dobra, the Bor metallogenetic zone is continued iota Romania by regional dislocat ion to the Bc'ovi} region and further by scartered present volcanic (andesites) and intrusive (quanz dionte porphyrites, quanz monzonites) rocks of imennediary composition). in the southeast of Donje Nevlje, the Bor metallogenetic zone is continued iota Bulgaria by Medium - rock metallogenetic zone which strikes to the Black Sea in the east.

Conditionally, the Bor metallogenetic zone could be divided iota north part, which lies in the nonh of Ba- evica, and south part , which lies in the southeast from Pirot (Borovo -Donje Nevlje) (Jankovi }, 1990 a) . Spatially and genetically observed, the north part of the Bor metallogenetic zone coincides with the Timok magmatic complex which is connected with the ali important copper and epithermal gold mineralization deposits. Total area of the Timok magmatic complex is about I 130 km2 and the largest part is formed of voJcanic and volcanoclastites mostly of andesite content.

The Timok magmatic complex comains substantial porphyry related copper gold mineralisation including the world-c1ass Majdanpek porphyry copper and Bar porphyry copper-high sulphidation deposits. The Timok magmatic complex has a metal resource estimated at over 20 miII ion tonnes of contained copper and 1000 tannes of gold. In the Timok magmatic complex there are al present three main porphyry copper mines in operation and smaller production from secondary sulphide enrichmem zone above Corovo porphyry sistem. In addition to the working mines, substantial low-grade porphyry deposits have been drilled in the westem part of In the Timok magmatic complex.

Morphogenetic types of copper deposits in the Timok magmat ic complex

The most important deposits and copper occurrences formed in the volcanites and volcanoclaslites, have andesite content. They were formed al various depths and various conditions depending on physico - chemica! characteristics of hydrothermal solutions and environment. The aII important deposils are connected la the zones of occurrence the deep fractures which reach, probably, to lhe deep pans of continental crust, Le., ta the upper parts of magmatic opening go!d appears as important associated component in deposits and occurrences of copper minera!ization. According to the way of occurrence and conditions of formation, many genetic types of copper deposits are known, where the ooly one with gold occurrence as important associated component will be described in the following text . The following types given, in Table 1, beloog ta them:

Table 1: Morphogenettc {)'pe! or the BMZ copper deposits

Genet.ic type Morphologicilil

Porphyrittc

for~

Stoc;': Irre~~1ar

exten:::le:: lena H1g!\

extended lena

:'e~.s

Str ... ctur.l text .. r.1 varJety

Stoc:;.;work -i:-,~reijlnillted

M.ss~·.·e lIIu.phldes .·e~ ~e:::! -

!."..p:e~,.-•• te-d ",~ne

ve::;:et.

~lr.er.1

para~e!\ellli'

Pyrlte Ch.lccpyr1t

• Maqnet1te

~ol ybdenl te

Pyr:te ::n.r;lte

Cta:eoc1 te Cc",e:ll-:e

Cr,a~ecpyr~t

• S~h.:erite

:;a!e-,:te

Cu "' ::xal"ples

• :, J

Ecrska Re;':.

0.1-0 . 1 0.07-0.25 Borskl Fatoot

"!ilIjdillr:~ek

\"el J kl Krivell Cerovo

SCr LJ.p.

1.1"-" . u 0.8-3 . 0 0<0

~ilIr:~

'" I<"ru~a

volcanoQe:.eo_l

Meehllnleal overdepositej

sedlme:n:s

Scarnlc .;:c~~

:'e:.:5

108

Py: ~ •. ~ 1-':".l;E:";e s":p~,:'d,,ş E:l1a:;:'_~ ~':''',.\J

::-re'l;Jlar Tetrl~.I!:::';:' O.1-O.6~ 0.1-.' B\,;garesku 3::.:- .. 1atln.'!: Cot

Bor~,;·e

Chalc::: .. yra

Pyr~ :e Cove::1~e

Enat<;:te r~asl:ve su:phldea Chalc".:lt.e

Chalct::py:l t

• Bor:'l: :e

GalerJ!te I~ass: ... e sulJ::hldes Sph.J:e:1te o~ :r-.pregnatlon Ma;ne':ite

Chalec;:~·:-lt

3.5 5. ,

0.21

NovO Okno KI rId' i j s ,.

potol!.

Val ja 5aiola

Potaj c.ka

Porphyritic eopper deposîts

were formed al the lowest intrusions. The presence of hypoabyssal intrusions of granodioritic magma (mainly quanz - diorite porphyrites) was observed in deposit area. Simultaneously, they are a150 the areas with the highest concentrations of sulphide mineral. ~1ineral content is relatively simple, and pyrite, cha1copyrite, magnetite and molibdenite are predominant. Bomite and enargite appear locally at deeper parts. Neodigenite, chalcocÎte and covellite appear totally local. Toward the edge part of mineral areas, the concentration of sulphide minerals and useful copper components is decreased, and a transition toward surrounding rocks is gradual.

The sizes of porphyritic deposits are high and overexceed the volume of other copper depasit types in the Bor metallogenetic zone. The largesl deposils have cross section area of over 0.5 km2 until vertical interval of mineralization is over 2000 m. Namely, the previous geological prospecting have not established with cenainly the vertical interval of mineralization. Toward depth, the mineralization is gets narrower and it is limited ta narrow areas in quatzdiorite porphyrite intrusions in the deepest prospected areas.

Spacious pasit ion and concentrat ion degree of main and associated e1ements are clase connected with a type and degree of hydrothermal alterations. As a result of magma intrusion and formation of intrusive rocks, the breaking of volcanogenetic - sedimentary rocks appeared. Also, the propylization of rocks in a large surroundings appeared by magma degasification and influence of initial solutions enriched with gases. Besides that, the Încreased permeability of surrounded roeks and formation of quartz stockwork over and around porphyritic imrusions (Veliki Krivelj) appeared by the influence of solutions. Repetead alterat ion of surrounding rocks appeared by later influence of mineralized hydrothermal solutions with intensity of hydrothermal alterations reversely proportional ta a distance of porphyritic intrusions.

K-silicate metasomatism, cam posed of biotited, silificated and scattered sericited andes ites, was developed in the narrowest surrounding of porphyritic intrusions. Hydrobiotites replace part ly the primary coloured minerals - hornblende and biotite. The highest concentrations of pyrite and chalcopyrite are connected ta the K - metasomatism regarding to the other facies of hydrothermal alterations. In contrast to the rifts, appeared in the rear of subduction zones, with characteristic felsitic intrusions and dominant of K­feldspar in the K - metasomatism zone (Hedenquist, 1995), biotite is a dominant one in calco - alkaline magmatic complexes in the vicinity of porphyritic intrusions. A ditTerence could be due to the increased Fe and Mg concentration in magmatic belts or impossibility of porphyritic systems ofsubduction zone rear ta mobile Fe and Mg.

109

Gold concentrations vary in the wide ranges and do not depend on porphyritic mineralization depth In such way, gold concentration vary rrom 0.07 git (Veliki Krivelj) ta about 0.25 git (Majdanpek) in the porphyritic deposits, appeared in the vicinÎty of surface conditions. Average gold concentrations are ahout 0.20 FJt in the porphyritic deposits of deep level,. Mostly, gold is connected to pyrite (30%), chalcopyrite (30%) and waste mineral, (40'10). Appearance of rock 5ulphatization and gypsum and anhydrite formation Îs very much developed, but it does nOI poi"t out some regularity regarding to the OIheT types of hydrothermal alterations. Sulphatization aod gypsum and anhydrite formation are specially developed al deeper parts of depasit. Their spacious appearance is not strictly connected to the appearances of mineralized deposit pans, but it also appears in the surrounded sterile volcanites. Typical representatives of porphyritic copper mineralization are Majdanpek, Cerovo, Mali Krivelj , Dumitri pOlok, Valja Str', Veliki Krivelj , Borska reka, Borski potok. There are numerous appearances ofporphyritic type ofmineralization stated on the surface but without any economical imponance. Their appearance is also imponant from that aspect , what points out a deep erosion level of this terrain type and/or high level of inlrusion the porphyritic intrusi ve rocks.

Hidrothermal - volcanogenetic ore bodies of stock or lens for m (with massi\'e sulphides) Appear mainly over porphyritic copper deposits (Bor). Rarely, they could appear

laterally (Lipa, "'oka Kuruga), but oflen at the same hypsometric level with surrounded porphyritic mineralization (Valja Str', Dumitrov potok). Regarding to the porphyritic deposits, massive sulphide deposits ha ve Sol aII sizes but with some times higher concentrations of sulphide minerals, up to 2% of Cooper and over 1 git Au, average. Locally, concentrations are much more higher with massive pyrite, up to 70% of panicipation in total mass. Enargite, chalcocite, covellite, bomite and chalcopyrite appears as copper minerals. The most imponant representatives of massive sulphide deposits are Bor, Lipa, "oka Marin, "oka Kuruga.

Hydrothermal - volcanogenetic ore bodies of vein form (with accumuJat ions and impregnations)

Have limited appearance. They were formed along fracture zones (Kraku Bugaresl-."U) ar presented by a system of subvenical parallel veins. The majority of appearances is presented by quanz veins of nearly venical drop with enargite, chalcopyrite and, locally with bomite and chalcocite. They could be followed some hundreds of meters by their strike, until their thickness is up to a few meters (average abaut 2 m). Vein strike line is NNW - SSE according to the extension of the Bor metallogenetic zone, longitudinal structures and dikes of porphyritic intrusion. The veins are mainly located in fresh volcanoclastites with sharp edges forward surrounded rocks.

Mechanical overdeposited sediments Were formed by disintegration of previously formed deposit with massive sulphides

by Înf1uence of younger volcanic activity. Fragments were stocked in local sedimentary area (Novo Dkno) (Jankovi}) or they were arranged along tectonic zone (Kirid ' ij,ki potok). The ore bodies have small sizes and relatively low economic effecl. Their spatious position is caused by local conditions, existed that time, and there are no geological features what point out their presence

110

Scarnic mineral iza tion ty pe

Is limited ta the contacts ofsedimentary stones and volcanites. Their origin is connected to the contact - metasomatic appearances ofintrused or surrounded sedimentary rocks. typical representative ofValja Saka depasit in the vicinity ofmonzomatic pluton Valja Str'. Usually, they have no economic interes! , except they are in the vicinity oflarge porphyritic mineralizations (Veliki Krivelj, Majdanpek).

References Hernngton R J, Jankovic, S. i Kozelj, D. 1998: The Bor and Majdanpek Copper-Gold

DeposilS in the Context ofthe Bor Metallogenic Zone (Serbia Yugoslavia) MDSG 98 PROGRAMME AT ST ANDREWS SCOTLAND J3th-15th DECEMBER 1998, p.21-30

Kozelj ,D., 1999: Morphogenetic types ofepithermal gold mineralization in Ihe Bor metallogenic zone (doc.diss.) Fac. ofMin. and Geology, Belgrade, 196 (in Serbian)

Kozelj ,D., 1999: Morfogenetski tipovi epitermalne mineralizacije zlata u Borskoj metalogenetskoj zoni, Doktorska disenacija, Rudarsko-geolo~ki fakultet Beograd, s.196

Kozelj ,D., 1984 . Sinteza o rudnim formacijama TMK.- Institut za bakar, Zavod za geologiju, Odei Za geol. Istr. u Boru,

Kozelj,D., Krstic,S. i Cocie,S., 1998: Geohemijske karakterislike epitermalne mineralizacije zlata u timoekom magmatskom kompleksu.- 13 . Kongres geologa Jugoslavije, Herceg Novi, 6-9 oktobra 1998, s. 85-92;

Jankovie,S, 1977: The Copper Deposils and Geoleclonic Setting oflhe Thelhyan Euroasian Metallogenetic Selt.- Mineral. Deposita, v.12, s.37-47;

Jankovic,S , 1980: Porphyry - Copper and Massive - Sulfide Ore DeposilS in the Northeastem Mediterranein.- Fifth QuadrennaiallAGOD Symposium, Stuttgart 1980, German y;

Jankovic,S., Jovanovic,M., Karamata,S. i Lovric,A., 1981 : Izolopska starost nekih slena timotke eruptivne oblasti .- Glas SANU, Od pror.-matem. Nauka, 48, c.87-94, Beograd;

Jankovic,S., 1990a: RUDNA LEZISTA SRBlJE, regionalni metalogenetski poloiaj, sredine stvaranja i tipovi leigla.- Rudarsko-geolo~ki fakultet, Beograd, 5.760;

Jankovic,S., 1990b: Types of copper deposils relaled 10 volcanic environment in the Bor district, Yugoslavia.- Geol.Round.79, 467-478;

III

~IAGMATIC IIYDROTIIERMAL T RANS ITION 11\ PORP IIYRY EI\V IRO.\I EI\T. SOUTII AP US E:-il ~IO LINTAI:; S. RO~IANIA . OrTLlN E FRO~I S INGLE INCLUS ION LA-I C P-MS ANALYSES. Paul M. Ivasca nu ', T . Thol11:ls Pettke1

, C hrisloph A. Heinrich l Emi li a n Rosul, L. Nedelcu l

, Ioa n Pintra l

I Geological lnslilute of Romania. Bucharest 2 ETH Zenlrum :-"0. 892. Zunch, Swilzerland

Recent research in the South Apuseni I\lountains dealing with LA- IC P-M S :tllalysis in single meh (l\ II ) and fluid inclus ion ( FI) has show the partition of Cu and Au in " olatile phase exolved fro m magmas in li rsts s tages of porphyries. COfva l multiphase salt rich FI and MI in hydrothermaJ po rphyry quartz uystals sho\\' flevated COIICCIHration of CI, S, As, TI , K. N:I :lud same metals (Cu, Au) aud sustaÎn th e orthomaglll:lt ic model of porphyries rrom SA~1.

The Apuseni Cu-Au provinee have a particular geological evolution due ta superposition of different magmatic processes and the geodynamic evolution from Crelaceous lrough Teniary An trans-extensional , pull-apan forming, geodynamÎc regime is the trigger for emplacement of Neogene calc-alka line stecks and for formation. at rel ative sha llow levels, of small sized, dense, copper-gold porphyries. VoJcano-p lutenic structures and the spatia l and genetic association of porphyries end high- te low-sulfidation epithermal ba se metal and/or Au, Ag , Te deposits is characteristic . A "gold spoI" related te Neogene magmatism is debated (lJdubasa et al ,thi s vo lume) and two main mechanism are d iscussed to form the high Cu-Au concentration one of direct e'1raction of metals form source via magmatic volati le exolution and successive boii ing of exolved magmatic fluids and another one of extens ive reworking of countly rocks by heated up, deep circulat ing meteoric fluids. Coeval primary (gro\\lh zones) MI and FI from hydrothermal porphyry quarz found as vein clasts in porphyry breccia pipe from Bolcana porphyry copper (Au) depasit show gradual immiscib ility ofsilicate meh - sa lt melt - hypersa line fluid syslem in early stages of porphyry evolution and are interpreled as immiscible materials originated from magma and subsequentl y evoh"ed toward mineralized fluids. and may be used to constrain the magmatic - hydrothermal connection. Simi lar assell1blages of mineral inclusions are also determined in hosted pyrite in potash zone of Valea Morii porphyry copper( Nedelcu et al , this volume) Single inc1u sion LA-ICP-MS analys is (data in prep)has show fairly positives slope of CI. S. As, TI , K. Na and some metals (Cu especially) content. Core multiphase meI! inc1usion has show lower o r under detection limit for Cu, Au whereas rim meit inclusions to salt melt inc1usions (mixture of melt and high sali nity fluid) and hypersaline fluide inc1usions (40010-75% NaEqv.) and final dissolution of sa lt s up to 700° C show a strong signa! for Cu and sometimes gold . Salt vo latile ri c h FI as pseudo secondar)' trails are show hi ghest Cu signals An interesting assemblage of hypersaline FI and sulfide ~11 (or mixture of su!fide melt and hypersaline magmatie fluids) \\ hit homogenization temperature up to 700u C and in the same stage quanz gra ins from Bo lcana as show high go ld contem . mainly hosted the su lfide melt . Moreover it was estab li shed that fluids exsolved directly rrom silieate me lt by immi sc ibilil )' at magmatic slage (Pintea, 1993,Cline & Bodnar, 1994) show clear partition of copper and constrain a onhomagmatic souree of copper and some gold in porphyries from SAr-.1 ( Pintea. 1993, 1996, this vo lume). This suggest that the primary boi ling represent an imponant process for extraction of uti le metals from magmatic source in area ofSouth Apuseni Mt s

111

Disscution The porphyries from South Apuseni ~Iountains are unique by the clear e\ w.

magmatic 10 epithermal. and should be consider as distinct model for Carpal' metallogenesis The especia l geodynamic position ofSAM connected \\hit the pea:.. Neogene magmatism (normal ta adakitic tendency and high fluid content)( Rosu el

volume) favor;tes genesis of porphyries and related epithermal ore deposits as a CO'~_. process of eXlraclion from a rich source of copper and gold. Subsequem secondaJ)· and leaching of porphyries and coumy rocks generale sl11a ll , but rich, epitherma. _ deposits ( by panilion preferentially in !he \"olati le phase, Petlke el al . Ihis volume)

Omli"etl idens are tlte ("0111111011 base /ollmlefl fOcltetlter by ETH-IGR grr ("oorlli"atetl by Cltristopl, A. Hei"ricl, amI E",ilifll, Rosu flIlllll'oultl be tll e cores for IPwrc: foccused re.'ieflrcl, i" tlt l! lIe:d year. Targels 0/ ETH-/(iR SCOPE.~ ~roup for II t!X1 is o",Ii"e lIIf1gIlUlfh'-epitlrermal trflllsitioll ill Apuse" i "'ou "'(lins fiS fi -"pecial !IImlel Il{ el'o/"t;oll ill porplryries em';rollmellt ami to clarify tire relatioll betweell tir e special seni" 0/ ore re/atell .\'eogell magmatites fiS a tiJ:ger to /orm pllrplryrJ-epitltemw/ syl"lel1lJ. sometimes as Il'orltl das." deposits (eg. Rosia AlolI((IIU1, Barza).

Refferences Sodnar R) (1995) In Magmas, fluids, and ore deposilS, ) F H Thompson (ed), 7 , 139-152 Ciine) , S odnar R) (1994) Econ. Oeol , 89, 1780-1802 Heinrich, CA, el al (1999), Oeology, 27(8) 755-758 EaSloeC) (1982) Econ Oeol , 77, 12-1 53, Nedelcu L . Rosu Emilian, Costea c., Mineral microinclusions hosted by sulfides of main

neogene porphyry copper and epithermal ore deposits of the Soulh Apuseni Mountains. Romania (this \oJume)

Pettke T,Halter W E . Maclmosh I Heinrich Ch A , The prophyry to epithermal link prelimilla~' fluide chemical results from Rosia Roeni . Romania, and Fatima. Argentina

Pinlea 1 ,Arch \Iineral XLIX, 165-167.( 1993) Pintea 1, Comribulions 10 distinguish bet\\een porphyry- copper and related epithermal ore deposis· a lribule of melt and fluide inclusion. (this volume) Roşu E. Nedelcu L . Udubasa G , Pintea I . Ivascanu P~1 (2000) The Neogene ore-deposits

of the soulh Apuseni Mountains. Romania Constraints of a typical evolution An Inst Geol Rom . 72. pecial Issue, The ~Ih Symposium Baia ~Iare Branch of the Geological Society of ROll1ania. 16-18 th No\"ember 2000 Baia Mare. 70. Bucuresti

Roşu E , Szakacs A , Downes H . Seghedi 1 , Pecskay Z , PanaiOlu C (2001) The origin of Neogene calc-alkaline and alkaline magmatism the Apuseni Mountains. Romania the adakite connection (this volume)

Udubasa O . Rosu E, Seghedi 1 , Ivascanu P M., The "OOLDEN QUATRANOLE" in Ihe Metaliferi ~1t s ,Romania · What does really means? (this volume)

Preliminary '"Ar/19Ar mineral ages from the Central Srednogorie Zone, Bulgaria: Implications for C retaceous geodynamics

Svetlana Velichko\'au , Robert l-fandlE'r , franz NeubauE'r1, Zivko I V:1110V

I

I Institute ofGeology and Palaeontology. UniversilY of Sofia. Bulgaria 2 Inst. of Geology and Palaeomology, L'ni \'ersity of Salzburg, Hellbrunner Str 34, A-S020 Salzburg. Austria

113

and Kfs + SI + Gr for the migmatites (Dimitrova & 8elmustakova 1982).The age of the basement rocks was believed to be Proterozoic (Dimitrov, 1959) or Archaen (Vergiloy el al. , 1963; Kozhukharov et al., 1978). Ivanov (1988, 1989) refered to thern as "Balkanide type metamorphic complex" on the hasis of their field relations with the Upper Carhoniferous -Permian conglomerates, and the U - Pb ages obtained on zircons from this basement gneisses (406 ± 30 Ma; 480 ± 30 Ma and 485 ± 50 Ma - Amaudov et al. , 1989). However, two samples show well-defined Late Paleozoic plateau ages of c. 316-317 Ma, which indicates a Variscan age for the IasI amphibolite facies metamorphic overprint. During the Cretaceous, the basement was affected by retrograde greenschist facies metamorphic overprint. The laner event is restricted to the southem sectors clase to the marginal de~ra1 , NW-trending ductile Maritsa shear zone. Four samples yielded consistent Cretaceous 40 ArP9 Ar plateau ages of c. 100-102 Ma. Detritial white mica from Upper Cretaceous sediments of rhe Panagyurishte basin in the Central Srednogorie have been analysed by 4tJ ArP9 Ar total fusion experiments of single grains in order to reveal the cooling history of respective source areas. Three samples separated from Late Cretaceous (Campanian.Maastrichtian) flysch sediments have been dated. They rnainly record Variscan ages of c. 3 \3 - 287 Ma. Ages of c. 283- 216 Ma are explained 10 be due 10 pal1ial low-grade Cretaceous metamorphic overprint. No detrital white micas which record Cretaceous ages have been found up to now. Preliminary 40 Arjl9 Ar biotite ages from subvo1canic rocks of the Panagyriste region yielded ages between c. 88 Ma (ElalSite) and c. 90 Ma (east ofChelopech). The new 40 ArP9 Ar ages c1early show that the last amphibolite facÎes metamorphic overprint on the basement rocks is ofVariscan age. FUl1hermore, the data suggest thal the Maritsa shear zone and its splays 10 the N (e.g. Iskar· lavoritsa fault zone, Kamenilsa-Rakovitsa, etc.) can be regarded as a Cretaceous wrench conidor which was active under greenschist facies metamorphic conditions.

Rererences:

Arnaudov, V., Amov, 8., Bratnitzkii, B & Pavlova, M. 1989. Isotopic geochronilogy of magmatic and metamorphic rocks from Balkanides and Rhodope massif XlV­COl/gress ojCBGA, Sofia, sepl., 1989, 1154 - 1157. (in Russian) .

Dimitrova, E., Belmustakova. H. 1982. Metamorphic facies of the Crystalline schists complex of Ihtiman Sredna Gora Mountain. Ceochem., Mineral. And Petro!., 16, 61 - 67. In Bulgarian (abstarcts in English and German).

Dimitrov, Str. 1955. Sostoianie i ocherednie zadachi izuchenia magmaticheskih i rnetarnorficheskih kornpleksov Bolgarii . 1=1'. ANSSSR ser. Geol., 1, 5 - 15. In Russian.

Dimitrov. Str. 1959. Kurze Obersicht der metamorphen Komplexe in Bulgarien. Freib. Forschlll/gshj, c., 57, 62 - 72.

Ivanov, Z. 1988. Apercu general sur l' evolution geologique el structurale du massif des Rhodopes dans le card des Balkanides. BIIII. Soc. Geol. Fral/ce, 8, 4, 2, 227-240.

Ivanov, Z. Tectonics of Bulgaria. (in press) Karagjuleva, J., Kostadinov, V., Tzankov, Tz., Gocev, P. 1974. Structure ofthe Panagjuriste

strip east of the TopolnÎtsa river. 811/1. Ceol. IIIS1., ser. Geoleclol1ics, 13, 231 -301.

Kozhukharov, D., Kozhukharova, e., Zagorchev, 1. 1978. The Precambrian in Bulgaria. In: Precambrial/ il/ YOlIl/gjold bells. IGCP Projecl22, pp.65 .

ROMAN UN OERG ROUND MIN ING WORKINGS FROM CA RNI C HILL (ROSIA MONTANA) - TOPOGRAPRY, ORE BOOY MORPHOLOG l ES, ANO ORE MfflERALOGY Calin G. Tamas l

, Beatrice Cauuetl, Bruno Aneel), Gerhard Lehrberger", Christian Ricol

, Matthieu Bouss icauh2, Vladimir Ruttner-t

I University Babes-Bolyai, Cluj-Napoca, Romania 2 University Toulouse Le Mirail , France ) C.C.S.T.I. L'Argentiere la Bessee, France 4 Technical University Munchen, Germany

Underground explorat ion carried out in Rosia Montana miniog field revealed an intri eate oetwork of underground miniog workings. Several archaeological techniques incJuding field observations aud laboratory analyses (C 14 for example) certify a 100g tenn min iog activity lasting from pre-Roman times until laday. The exploitation activity was focused an high grade Au - Ag ore bodies. The precious metals mineralizations are mainly composed of free gold and silver-rich minerals.

Topography More than 22 km underground mining workings were explored in Camic massif. A

200 meters depth interval, from the uppermost level + 1046 Corhuri 10 the +853 Verches level was pierced by 13 mining levels and 27 intermediate mining levels. From the point ofview of their age three main types of underground workings were separated: recent , modem, and ancient. Ancient workings are recognized to be antique (Roman and pre-Roman) or medieval due to the exploitation techniques. They cover more than 1.5 km and represent access ways and exploitation chambers. too. A Roman mining sector named Carnic 1 - CamÎc II (between +958 and +932 levels) was studied in detail and revealed several archaeological remnants includ ing a whole Roman lamp and also several wood fragments.

Ore body morphology Various types of ore body morphologies are known in Rosia Montana ore deposits:

veins, stockworks, breccias, impregnations, and placers. In Carnic 1 - Camic II mining area the mining activity was focused on breccia bodies and related stockwork zones, as weB as on the veins. Phreatomagmatic breccias, superimposed phreatic breccia chimneys, and breccia pockets were preferentially exploited. Flat ly dipping and steeply dipping veins were also intensely exploited by the ancient miners, being also rewarked more recently.

Ore mineralogy Aui Ag assays, ore microscopy, electron microscopy and microprobe results for the

ore samples picked up from Carnic 1 - Camic II Roman mining field certify the high grade ore zones. Gold-rich and silver-rich electrum, silver minerals (i .e. acanthite. proustite­pyrargirite etc.), tetrahedrite (argentian), and common sulfides (galena, sphalerite, chalcopyrite) occur both in breccias cementing the breccia fragments, and in veins. Widespread potassium silicate alteration, phyllic alteration and intense si licification are common alteration assemblages in breccias, stockworks, and veins. There is also an ubiquitous relationship between the veins and the related silicification that affected the host rocks.