Fintor.indd 75 � AB STRA CT In many parts of the metapelitic (gneiss, mica schist) rock section of the Baksa Complex, signifi cant wall-rock al- teration is observable along the Ca-Al silicate veins, which show a di → ep ± czo →sp → ab ± kfs → chl → adu → prh → py → cal mineral sequence (FINTOR et al., 2009). These alterations appear as narrow (few cm thick) bleached margins beside thin veins, and broad alteration bands along thick veins where detailed epidotization and chloritiza- tion of the adjacent rock are recognizable. Based on petrographic and mineralogical examination of the altered wall- rocks, metasomatic zones with characteristic mineral paragenesis can be distinguished: Zone 1 (ab + ttn ± ep), Zone 2 (ep + chl+ ttn + ab ± ser), Zone 3 (chl + ep + ser + rt ± ttn), Zone 4 (ser ± chl). Bulk rock chemical analyses were made from the different metasomatic zones. The results show that fl uid circulated in the propylitic veins caused meta- somatic alteration of the wall-rock, with transport of considerable amount of Ca2+ toward the adjacent rocks. The hy- drothermal leaching almost totally removed the K, Fe, Mg, and Mn ions from the wall rock. The main alteration processes are the epidotization and chloritization of biotite, and albitization of micas (muscovite + biotite) content of metapelites. Based on mobilization of different cations alteration was due to a near neutral fl uid (~pH 5–7). The per- vasive hydrothermal leaching caused signifi cant secondary porosity (cavities) in the altered domains, which were partially fi lled by epidote. Fluid inclusions of cavity fi lling epidote indicate a similar character (Th: 180–360 °C; Sa- linity: 0.2–1.6 mass% eq. NaCl) to that can be found in Ca-Al silicate veins. The alteration most probably occurred in the 360–480 °C temperature range as products of 'near vein metasomatism' and the altered rock can be related to the propylite metasomatic family. Keywords: Baksa Complex, metasomatic zones, epidotization, chloritization, element mobilization, hydrother- mal leaching, propylitization Near vein metasomatism along propylitic veins in the Baksa Gneiss Complex, Pannonian Basin, Hungary � Krisztián Fintor1, Tivadar M. Tóth1 and Félix Schubert1 1Department of Mineralogy, Geochemistry and Petrology, University of Szeged, H-6701, Szeged, P.O. Box 651, Hungary; (efkrisz@gmail.com; mtoth@geo.u-szeged.hu; schubert@geo.u-szeged.hu) doi: 104154/gc.2010.05 Geologia Croatica 63/1 75–91 11 Figs. 3 Tabs. Zagreb 2010 Geologia CroaticaGeologia Croatica 1. INTRODUCTION The wall rock alteration activity of hydrothermal fl uids that circulate in fractures of crystalline rock bodies of the conti- nental crust, has a signifi cant role in different geological pro- cesses. Considerable secondary porosity may develop if metasomatic alteration is associated with leaching, and the locally increased porosity can play a pivotal role in the hy- drological behaviour of otherwise low permeability crystal- line rocks (MAZUREK et al., 2003; JAKOB et al., 2003). Another important aspect is that hydrothermal metasoma- tism can be frequently associated with formation of mineral deposits. Ore mineral deposition sometimes containing sul- phide minerals (pyrite, chalcopyrite, pyrrhotite, and sphal- erite) iron oxides (hematite, magnetite), or in other cases Geologia Croatica 63/1Geologia Croatica 76 stead covered by thin (50–100 m) Tertiary and Quaternary sediments in the area of the Görcsöny Ridge. The crystalline schists of the Babócsa Complex border the BC to the west (Fig. 1). The Villány deep fracture zone (KASSAI, 1972), which has a NW–SE strike, separates the Baksa metamor- phic block from the Mórágy Granite Complex, and Permo- Triassic sediments to the east. The Mecsekalja Tectonic Zone borders the complex in the north. It separates metamorphic rocks from non-metamorphic Mesozoic sediments of the Mecsek Mountains (Fig. 1). Further to the south, formations of the complex can be traced over the Slavonian regions, in the Papuk and Krndija Mountains. Petrology and metamorphic evolution of the BC has been investigated by many researchers (RAVASZ-BARANYAI, 1969; SZEDERKÉNYI, 1976, 1983; ÁRKAI, 1985; ÁRKAI et al., 1999; KIRÁLY, 1996; HORVÁTH et al., 2003). The complex consists of polymetamorphic rocks, mainly gneiss, marble bearing mica-schist, dolomite, marble, and amphibo- lite. Five metamorphic events can be detected in the rocks of the BC. RAVASZ-BARANYAI (1969) detected a high pres- sure phase that was followed by a signifi cant decompression. The peak conditions of this P–T path were around 1300–1500 MPa and 600–650 °C down to approximately 800 MPa and 500 °C (HORVÁTH et al., 2003). Peak conditions of the Bar- rowian event (SZEDERKÉNYI, 1976) occurring after the pre- vious high pressure phase, were around 750±50 MPa, and 660±20 °C according to ÁRKAI et al. (1999), but KIRÁLY (1996) suggests conditions of 500–700 MPa and 540–650 °C. After the Barrowian event, the area underwent secondary al- bitization and isothermal decompression down to 440±20 MPa and 650±40 °C according to ÁRKAI et al. (1999) or < 200 MPa, 400–560 °C according to KIRÁLY (1996). The isothermal decompression was followed by contact metasomatism related to aplite intrusions. These aplite dykes with unknown origin, caused considerable alteration but only in the carbonate rocks of the complex. Signifi cant alteration products include epidote, diopside, garnet and a wide spec- trum of sulphide minerals. There are indications of two phases of hydrothermal ores in the rock body, an earlier phase with disseminated ores, can be distinguished form a younger for- mation of veins with massive sulphide infi llings. In the earlier phase, minor amounts of pyrite, and spha- lerite grew sporadically in the veins. FINTOR et al. (2009) determined a Ca-Al silicate dominant mineral assemblage with a di → ep ± czo →sp → ab ± kfs → chl → adu → prh → py → cal mineral sequence (mineral abbreviations after SIIVOLA & SCHMID (2007), Table I., except for adularia: adu). A detailed geochemical and fl uid inclusion investigation of the vein fi lling minerals indicates that mineral precipita- tion occurred during cooling of the hydrothermal system. The T-X character of the fl uid changed from high tem perature (467–370 °C) and low salinity (0.2–1.5 mass% eq. NaCl) down to lower temperature (~150 °C) and low- to moderate salinity (3–6 mass% eq. NaCl) appear in fl uid inclusions of diopside, epidote, and calcite phases (FINTOR et al., 2009). Chlorite thermometry data (300 → 140 °C) also supports decreasing temperatures during the vein fi lling process. Many of these studied veins are surrounded by 0.5–2 cm thick al- teration halos. precious metal minerals, can occur during hydrothermal me ta- somatism that mainly relates to magmatic intrusions (ZHA RI- KOV et al., 2007; SCHERBAN, 1996; GRYAZNOV, 1992; RUSINOV, 1989). Study of wall rocks where alteration is caused by hydrothermal fl uid/rock interaction, may provide important information about the thermodynamic parameters (e. g.: pH, Eh, T, P, X) of fl uids circulated in the rock body (PARSONS & LEE, 2000; KULLERUD, 2000; GRESENS, 1967; MEYER & HEMLEY, 1967). The study area is the Baksa Complex which represents part of the metamorphic crystalline basement of the south- western area of the Pannonian Basin. The Baksa-2 explora- tory drillhole penetrated deeply into the Baksa Complex. With almost 100% core recovery, this exposed almost 1200 m of crystalline rocks of the basement. It is the most com- plete drillcore available from the crystalline basement of the Pannonian Basin. A lot of evidence for postmetamorphic hydrothermal fl uid migration and alteration can be observed in the drill- cores of the Baksa-2 well. This alteration can be grouped into two main hydrothermal mineral parageneses. TARNAI (1997; 1998) provided detailed studies of a thick (6–7 cm) sulphide ore vein, cross cutting the metamorphic block. Ore paragenesis (pyr+po+sp+hem+ccp+gn+pn) and fl uid in clu si- on studies of the vein fi lling minerals indicate a postmagmat ic hydrothermal origin (TARNAI, 1998). The other assemblage suggests that the hydrothermal effect is the occurrence of Ca-Al silicate dominant fracture fi lling in several Baksa gneiss samples (SZEDERKÉNYI, 1979). Comprehensive examination of the latter vein-fi lling process was made by FINTOR et al. (2009) and they report the presence of spo- radic pyrite crystals among the Ca-Al silicate minerals. De- tailed mineral chemical analyses of pyrite crystals from both the Ca-Al silicate and the thick sulphide veins (FINTOR et al., 2009) exhibit similar Co/Ni ratios (1–5), which is in the range of pyrites formed in postmagmatic hydrothermal sys- tems (PRICE, 1972). In this study, detailed petrographic, bulk rock chemical, and fl uid inclusion analysis of the altered wall rocks along the Ca-Al-silicate veins was undertaken. The aims are to de- tect the type and physicochemical conditions of metasoma- tism and element mobilization that occurred along the veins, and to determine the hydrological relationship between the alteration halos and the veins. 2. GEOLOGICAL SETTING The Baksa Complex (BC) is located in the SW part of the Tisza Mega unit (Fig. 1), a microplate that forms the base- ment of South Hungary. The Tisza Mega unit was originally part of the European margin of Neo-Tethys and was sepa- rated from the European plate by opening of the Penninic Ocean (Alpine Tethys) (GÉCZY, 1973; HAAS & PÉRÓ, 2004). SZEDERKÉNYI (1996) divided the pre-Alpine base- ment complexes of the Tisza Mega unit into three major parts: the Paraautochton, Békés-Codru (BC) and Drava ter- rains, and related the BC to the Drava Terrain. The metamor- phic formations of the complex do not outcrop. They are in- Fintor et al.: Near vein metasomatism along propylitic veins in the Baksa Gneiss Complex, Pannonian Basin, Hungary Geologia Croatica 77 Upper marble section (57–224 m) Chloritic two-mica gneiss (224–822 m) Lower marble section (822–867 m) Garnetiferous two-mica gneiss (867–922 m) Garnetiferous two-mica schist (922–1200 m) Upper marble section Marble and dolomite marble are the predominant rock types in this section with gneiss and mica-schist intercalations. Aplite dykes frequently occur in the section and signifi cant alterations in carbonate rocks can be related to them. These alterations are accompanied by the formation of calc-silicate hornfels with epidote and diopside. Ore showings caused by hydrothermal fl uids are also common. The most signifi cant ore vein (6–7 cm thick) is found at 186.4 m depth. The formation conditions and ore mineral paragenesis (pyrite, pyrrhotite, sphalerite, chalco- pyrite, galena, pentlandite, hematite, covellite, marcasite) of the vein were investigated in detail by TARNAI (1997; 1998); who assumed that these veins were formed in relation to the rhyolitic volcanism that occurred near the northern margin of the Villány Mountains (FAZEKAS & VINCZE, 1991). A detailed investigation of mineralogy and ore genesis of the veins with massive sulphide ore infi llings was carried out by TARNAI (1997, 1998). In a study of fl uid inclusions of the quartz which was cogenetic with the later ore minerals, he de- termined a trapping temperature (Tt), of 240 to 300 °C and trap- ping pressure (pt), of 15–30 MPa (TARNAI, 1998). The young- est alteration phase that can be investigated in the rocks is a retrograde greenschist facies event, which caused chloritiza- tion and secondary albitization (SZEDERKÉNYI, 1979). Its temperature range is assumed to be 200–400 °C by ÁRKAI et al. (1985). The beginning of this event is related to the Alpine orogeny (SZEDERKÉNYI, 1984). FINTOR et al. (2008) de- tected traces of high salinity fl uids (~20–25 mass% eq. NaCl) in the post-metamorphic quartz-carbonate veins that penetrate the rock body. Using microthermometry, they obtained condi- tions of approximately 80–180 °C and 20–100 MPa for the formation parameters of the quartz-carbonate veins. The Baksa-2 exploratory well (bottom-hole: 1200 m) enables the most detailed investigation of the BC (Fig. 2). It exposes the crystalline basement formation with a total thick- ness of over 1100 m and near 100% core recovery. The meta- morphic mass was divided (SZEDERKÉNYI, 1979) into the following lithostratigraphic units: Fi gu re 1: The geological map of the Baksa Complex and its environs is presented with- out Tertiary and Quaternary sediments. Leg- end: 1. Baksa Complex (study area), 2. Babócsa Complex, 3. Mórágy Complex (Car bo niferous), 4. Carboniferous sediments, 5. Permian for- mations, 6. Triassic formations, 7. Jurassic for- mations, 8. Cretaceous formations, 9. Mec- sekalja Tectonic Zone,, 10. Villány-Szalatnak deep fracture zone. Inset: Location of the study area (BC) in the Pannonian Basin (AL- CAPA and Tisza mega unit are also represent- ed on the map); Inset legend: 1. Flysch Belt, 2. Pieniny Klippen Belt, 3. Inner Carpathian Moun- tain Belt. Geologia Croatica 63/1Geologia Croatica 78 Chloritic two-mica gneiss This section is composed of two-mica gneiss and schist with some amphibolite. Signifi cant chloritization (after biotite) is observed in some parts of the rocks (SZEDERKÉNYI, 1979). Aplite dykes are rare in this section and a cross-cutting bio- tite-andesite dyke is observed in a fault zone at approxi- mately 460 m depth. Lower marble section This section is comprised of amphibolites, although marble intercalations are the most important rock type of the sec- tion. The marble bands are almost pure dolomite. This sec- tion is very rich in aplite dykes, which caused alterations similar to those found in the upper marble section. Garnetiferous two-mica gneiss This rock section is dominated by gneiss with some mica schist intercalations. Large garnet grains (> 2 cm in diame- ter) are a common occurrence throughout the section. Aplite dykes do not occur in this section. Garnetiferous two-mica schist This section consists predominantly of mica schist, with les- ser amounts of gneiss and some amphibolite. Garnets with similar characteristics to those of the garnetiferous two-mica gneiss also occur in considerable amounts. One aplite dyke was discovered in the section, which suffered comprehen- sive epidotization and tourmalinization. 3. SAMPLES AND METHODS Samples used for analysis were collected throughout the pro- fi le of the Baksa-2 drillhole, as detailed locations on Fig. 2 show. Mineral abbreviations used in the whole study (Table I) are after SIIVOLA & SCHMID (2007). X-ray element maps and bulk rock chemical analyses were made using a Horiba Jobin Yvon XGT 5000 X-ray fl u- orescence spectrometer. Beam diameter was 100 μm and ac- celeration voltage was 30 kV in each case. Bulk analyses were made from 5 mm x 5 mm areas of rock surfaces. Ana- lyzed areas were divided into 512 x 512 pixels with 0.01 mm2 size of each pixel. Natural standards were used for standardization of each measured element. The Surfer 8 sur- face mapping system was used for the representation of ele- ment maps obtained by XRF analyses. Isocon analysis was made from bulk rock chemical data using the computer program GEOISO (COELHO, 2006). This program can calculate and plot (Isocon diagram), the mass and volume changes that can occur in a wide variety of open system geological processes. The Isocon diagram is based on the study of GRANT (1986, 2005) and is a simple solution to GRESENS (1967) equation for metasomatic alteration. Gresens’ basic argument is that some components are likely to have been immobile during the alteration process, and if these can be identifi ed, they can be used to establish any change in volume which has taken place. Gains or losses of other components can then be calculated, assuming that the volume change is a factor common to the behaviour of all components. GRESENS (1967) shows that the transfor- mation of a generic rock A into another generic rock B can be expressed as follows: Xn = [fv (gB / gA) C Bn – C An] a Fi gu re 2: Lithological profi le of the Baksa-2 borehole. (after SZEDERKÉNYI, 1979) Legend: 1. Biotite-andesite dyke 2. Aplite dykes 3. Amphibolite 4. Marble and Dolomite marble 5. Two-mica gneiss 6. Chloritic gneiss 7. Chlo- ritic schist 8. Two-mica schist 9. Sampling points. Fintor et al.: Near vein metasomatism along propylitic veins in the Baksa Gneiss Complex, Pannonian Basin, Hungary Geologia Croatica 79 where “X” is the mass change of component “n” relative to “a”, “n” the considered component, “g” the densities of each rock, “v” the volume of each rock, “fv” a volume factor, “a” the mass of the original sample (A) and “C” the concentration. Even if effi cient, the Gresens’ method is neither easy nor practical to use. GRANT (1986) proposed a more direct and easier process of using Gresens’ equation in the following expression: C fi = (M0 / Mf) (C 0i + DCi) where “C fi” is the resulting concentration of component “i”, “Mo” is the mass of the original, while “Mf” is the mass of the transformed rock, “C 0i ” is the original concentration of component “i” while “ΔCi” is the change of concentration of component “i”. For each component there is an equation of this form, in which (Mo/Mf) is constant. The “perfectly inert” elements must defi ne a line C fi = f(C 0i ), of slope Mo/Mf passing through the graph origin. The line connecting “points with the same concentration”, GARY et al. (1974), is defi ned as an “iso- con”. Using the computer software GEOISO, the whole rock mass change (Mf-Mo/Mo) and volume change (Vf-Vo/Vo) are also calculable. The program estimates the element mass changes during alteration using two different approaches. In one case the program compares each elements mass change to the original rock mass: (M fi– M 0i) M0 = (Mf / M0) M fi – C 0i where M fi is the mass of component “i” in the transformed rock, and M 0i is the mass of component “i” in the original rock. Alternativley, the program compares each elements mass change to its mass in the original sample: (M fi– M 0i) M 0i = (Mf / M0) C fi / C 0i – 1 Given the better approach, the latter equation was used in this study to estimate element mass changes. In our study we use the nomenclature and abbreviations by GRANT (1986). Densities of the different metasomatic zones were calcu- lated using the THERIAK (HOLLAND & POWELL, 1998; DE CAPITANI, 1994; DE CAPITANI & BROWN, 1987) thermodynamic program package. Fluid inclusions were studied in 75–150 μm double-pol- ished thick sections prepared from the vein fi lling minerals. Microthermometric measurements were carried out by means of a Linkam THMSG 600 heating-freezing stage, operating over a temperature range from –190 to 600 °C. Synthetic fl uid inclusions were used to calibrate at –56.6, 0.0 and 374.0 °C. The accuracy of the data is ±0.2 °C under freezing and ±0.5 °C under heating conditions. An Olympus LMPlanFI 100X objective was used to analyze the inclusions. The cy- cling method (GOLDSTEIN & REYNOLDS, 1994) was used to determine the last ice melting temperatures, and each melting of ice occurred in the presence of a vapour phase. Estimations of volume fractions of vapour bubbles (φvap=Vvap/ Vliq+vap) were obtained from area analysis of a two-dimen- sional projection of the fl uid inclusions. Terms and symbols of DIAMOND (2003) were used. The computer package FLUIDS (BAKKER 2003) was used to calculate fl uid properties. The program AqSo2e was used to calculate salinities in the NaCl-H2O systems (NADEN, 1996) based on the equivalent mass % principle. The pro- gram BULK (BAKKER, 2003) allowed us to calculate the bulk fl uid properties molar volume (Vm), and bulk composi- tion of individual fl uid inclusions. This calculation was ac- complished using a purely empirical thermodynamic model, the equation of state for electrolyte-bearing aqueous solu- tions of KRUMGALZ et al. (1996) and the volume fractions of the liquid phase of the inclusions at room temperature. A Jobin Yvon LABRAM confocal Raman spectrometer, equipped with a frequency doubled Nd-YAG laser (100 mW, 532.2 nm), with a 100X/0.80 objective lens was used to iden- tify fl uid phases in inclusions. The spectrometer was cali- brated using a silicon chip. The spectral resolution of the instruments was 4 cm–1 and the spatial resolution was a few μm3. The acquisition time was 100 s with 20 s accumulation periods in each spectrum. 4. RESULTS 4.1. Petrography and Mineralogy In many parts of the metapelitic (gneiss, mica schist) section of the BC, signifi cant wall-rock alteration is observable along Ca-Al silicate veins (Figs. 3A, B). These alterations appear as symmetrical narrow (up to few cm thick) bleached Table I: Summarized list of abbreviations of minerals used (after SIIVOLA & SCHMID, 2007). Mineral Abbreviation albite ab adularia adu biotite bio calcite cal chalcopyrite ccp chlorite chl clinozoisite czo diopside di epidote ep galena gn hematite hem K-feldspar kfs muscovite mu pentlandite pn pyrite py pyrrhotite po prehnite prh rutile rt sericite ser sphalerite sp titanite ttn Geologia Croatica 63/1Geologia Croatica 80 margins beside thin veins and broad alteration bands along thick veins where epidotization and chloritization of the ad- jacent rock are recognizable. The following mineralogical characteristics were observed from the veins toward the un- altered wall rocks. Very close to the vein wall (in a 2–5 mm thick band) the feldspar porphyroblasts (albite) exhibit a turbid appearance because of micro-sized pores (<2 μm fl uid inclusions), that fi ll the entire grain (Fig. 4A, C). The micas (muscovite+biotite) of the unaltered wall rock found among feldspar porphyrob- lasts are totally replaced by albite. These albite pseudo- morphs form elongated grains with irregular grain bounda- ries (Fig. 4A) and frequently contain tiny euhedral titanite inclusions (Fig. 4B). In both the albite pseudomorphs and in the albite porphyroblasts, small (<0.5 mm) cavities occur in signifi cant amounts. Euhedral albite crystals have frequently Fi gu re 3: Typical symmetrical wall-rock alteration patterns along propylitic veins. A) Symmetrical bleached margin along Vcpx-ep vein (wall-rock: biotite gneiss); B) symmetrical bleached margin along Vep-chl vein (wall-rock: chloritic two-mica gneiss) Fi gu re 4: Alteration mineral assemblages in the margin closest to the veins. A) Irregularly bordered elongated albite pseudomorph after mica (+N); B) group of euhedral titanite inclusions in an albite pseudomorph (1N); C) euhedral albite crystal growth in a cavity fi lled by epidote, (note the many micro pores in albite) (1N); D) well developed growing zonation in a cavity fi lling epidote crystal (1N) A B A B C D Fintor et al.: Near vein metasomatism along propylitic veins in the Baksa Gneiss Complex, Pannonian Basin, Hungary Geologia Croatica 81 grown on the walls of the cavities (Fig. 4C). The cavities are fi lled with epidote that often shows a characteristic zoned growth pattern (Fig. 4D). The alteration mineral paragenesis of this domain is: ab + ttn±ep Towards the wall rock the amount of albite pseudomor- phs after micas markedly decreases. The amounts of micro- pores observable in the albite porphyroblasts also gradually decreases. Small patches of sericite inclusions appear in the feldspar crystals and their amount progressively increases towards the wall-rock. Epidote and chlorite replacement af- ter biotite become dominant in the altered domains of the wall-rock (Fig. 5A–F). Well developed epidote and chlorite pseudomorphs occur in the formerly mica rich bands (Fig. 5A). Among the epidote and chlorite pseudomorphs, euhe- dral titanite crystals frequently occur (Fig. 5B). Elongated cavities in the strongly epdotized metapelites, are some times fi lled by very fi ne grained epidote (Fig. 5C). Nevertheless epidote occurs as hypidiomorphic inclusions in chlorite along the cleavage (Fig. 5D). In some places, anhedral epidote ag- gregates “fl oat” in a chlorite rich matrix (Fig. 5E) together Fi gu re 5: Alteration mineral assemblages from the most epidotized and chloritized parts of the margin. A) epidote and chlorite pseudomorphs after bi- otite (+N); B) euhedral titanite crystal among a mass of replacement epidote and chlorite (1N); C) elongated cavities fi lled by fi ne grained epidote crystals in a chlorite matrix (1N); D) epidote pseudomorphs as inclusions in chlorite replacing biotite (1N); E) fi ne grained anhedral epidote aggregates among chlorite and quartz rich bands along schistosity (1N); F) subhedral elongated epidote crystals among fi ne grained anhedral epidote (1N) A B C D E F Geologia Croatica 63/1Geologia Croatica 82 with anhedral fusiform quartz grains. Here, epidote shows strongly dissolved surfaces and is composed of very fi ne epi- dote grains (Fig. 5F). Among the little grains, elongated hy- pidiomorphic, almost clear epidote crystals are observable (Fig. 5F). The alteration mineral paragenesis is: ep + chl + ttn + ab ± ser. Towards the unaltered wall-rock, the amount of epidote replacing biotite decreases and chloritization of biotite be- comes characteristic. Furthermore, increasing numbers of biotite relics can be observed in the chloritized domains (Figs. 6A, B). Titanite is almost totally absent from this area, but acicular sagenite rutile inclusions can occasionally be ob- served in the chlorite pseudomorphs (Fig. 6C). Muscovite does not show any alteration except for minor sericitic re- crystallization at some places. The alteration mineral para- genesis is: chl + ep + ser + rt ± ttn. In the unaltered wall rock part of the alteration zones, sericite is the major alteration mineral. It occurs as tiny la- mellar inclusions in feldspars, and frequently forms sericitic rims around the clear cores of feldspar grains (Fig. 6D). Mi- cas show a fresh appearance except for partially chloritized biotite fl akes. Epidote occurs only as a cavity fi lling mineral phase, which frequently occurs, even in the unaltered wall- rock far from alteration zones. Alteration mineral paragen- esis in this domain is: ser ± chl. 4.2. Element maps and bulk rock chemistry Element distribution maps were made from the veins and their adjacent environments including alteration halos and unaltered wall-rocks of gneiss and mica schist (Fig. 7). The results show that characteristic element distribution patterns can be observed along the studied veins. Based on X-ray maps, the most characteristic distribution patterns can be ob- served in the case of Si, Fe, Ca, K, and Ti in the veins and their immediate environments (Fig. 7). Bulk rock analyses made from domains show individual alteration parageneses. Results are summarized in Table II where the numbers in brackets (1 to 4) on the head of the columns refer to the dif- ferent domains (show individual mineral parageneses), from vein to wall rock. The results of bulk rock chemical analyses (Table II) support the estimations from element maps. Be- sides the obvious differences between margins and unaltered wall-rock, with regard to their composition (wt %), the rock density data show that the bulk rock density markedly in- creases from the veins toward the adjacent rocks (Table II). 4.3. Fluid inclusion petrography and microthermometry Analyses were made of fl uid inclusions from cavity fi lling epidote (Fig. 4D) and elongated epidote crystals that occur Fi gu re 6: Alteration mineral assemblages in the margin closest to the unaltered wall-rock. A) Chlorite rich band with muscovite in the strongly chloritized domains (+N); B) chloritization and epidotization of biotite (1N); C) acicular rutile inclusions in chlorite pseudomorph after biotite (1N); D) sericitization of feldspar, albite crystal core with a well developed sericite crown (+N) C D A B Fintor et al.: Near vein metasomatism along propylitic veins in the Baksa Gneiss Complex, Pannonian Basin, Hungary Geologia Croatica 83 among fi ne grained epidote aggregates (Fig. 5F). The four selected samples originated from 80.6 m, 436.2 m, 730 m, and 858.8 m depths in the drillhole. In cavity fi lling epidote grains (Fig. 8A), four types of fl uid inclusion assemblages (FIA) can be distinguished based on fl uid inclusion petrography. A group of fl uid inclusions composed of solitary two phase (L+V) liquid dominant fl uid inclusions occur ran- domly, or in small clusters in the host crystals (Figs. 8B, C). Their longest dimension is 5–10 µm. They are not related to growth zones of the host mineral and can not be found along cleavage planes or microcracks. Defi nitive evidence for their primary origin is the occurrence of fl uid inclusions along growth zones (GOLDSTEIN & REYNOLDS, 1994; BOD- NAR, 2003). Less conclusive is the occurrence of one, or a few inclusions, in the interiors of the minerals (BODNAR, 2003) as is the case for the aforementioned group of inclu- sions. These inclusions are considered to be primary based on their distribution within the crystal (BODNAR, 2003). Based on phase volume ratios, two primary FIAs, a P1 with Fi gu re 7: X-ray element maps about a vein with characteristic symmetrical margins (3D surfaces were constructed by Surfer 8), where relief and colour intensity represent the relative concentration of the diff erent elements. Bar scale is 1 cm. Table II: Whole rock chemical data from the margins and the unaltered wall-rock. Numbers 1 to 4 in brackets at the head of the columns refer to domains characterized by individual alteration mineral paragenesis. Leg- end: (1) ab+ttn±ep; (2): ep + chl + ttn + ab ± ser; (3): chl + ep + ser + rt ± ttn; (4): ser ± chl, abbreviation UA refer to unaltered. Oxides (wt%) 637 (1) 637 (2) 637 (3) 637 (4) 637 UA (average of 4 measurements) SiO2 68.81 63.53 64.80 60.59 60.59 TiO2 0.95 0.88 0.85 0.91 0.88 Al2O3 17.65 18.09 19.19 19.05 19.07 Fe2O3 1.15 1.48 2.10 5.47 7.21 MnO2 0.13 0.15 0.17 0.23 0.37 MgO 0.00 0.26 0.78 1.33 1.09 CaO 4.25 4.09 3.84 4.07 2.10 Na2O 6.07 8.99 4.63 5.43 5.23 K2O 0.31 1.72 2.98 2.27 2.70 P2O5 0.43 0.57 0.41 0.38 0.56 Total 99.75 99.75 99.76 99.74 99.78 Density (g/cm3) 2.67 2.65 2.72 2.76 2.77 Geologia Croatica 63/1Geologia Croatica 84 Fi gu re 8: Results of fl uid inclusion studies: A) cavity fi lled by epidote and euhedral albite crystallised cloase to the cavity wall (+N); B) schematic sketch of the distribution of diff erent fl uid inclusion assemblages in the cavity fi lling epidote; C) primary fl uid inclusion assemblage in a cavity fi lling epidote (1N); D) pseudo secondary fl uid inclusion assemblage in cavity fi lling epidote (1N); E) schematic sketch of the appearance and distribution of diff erent FIA in the subhedral epidote grains that can be found among fi ne grained epidote; F) primary fl uid inclusion in subhedral elongated epidote grain (1N); G) histograms of Th values of each FIA; H) Th vs Tm(Ice) plot of each investigated FIA. C D A B E F G H Fintor et al.: Near vein metasomatism along propylitic veins in the Baksa Gneiss Complex, Pannonian Basin, Hungary Geologia Croatica 85 higher (φvap= 0.3–0.45) and a P2 with lower (φvap~ 0.15) de- gree of fi lling values were distinguished (Table III), although their relative ages cannot be determined. Fluid inclusions of both assemblages contain an aqueous electrolyte solution without any detectable volatile content based on Raman data. Because eutectic melting (Te) could not be determined in the inclusions, the chemical composition was not ascertainable. Salinity is expressed using the mass% eq. principle (NADEN, 1996). In the P1 assemblage the Tm(Ice) values are very simi- lar; all measured values are between –1 and –0.4 °C (n=10) (Fig. 8H; Table III) indicates low salinity (0.4–1.6 mass% eq. NaCl) (Table III). Homogenization temperatures are with in the 303–364 °C (n=10) range (Fig. 8G, H; Table III). In the P2 FIA the Tm(Ice) values vary between –0.8 and –0.3 °C (n=6) (Fig. 8H; Table III) indicating low salinity between 0.2 and 1.2 mass% eq. NaCl, while Th values occur in a narrow range between 201 and 214 °C (n=6) (Fig. 8G, H; Table III). Fluid inclusions also occur along planes that do not reach the grain boundary of the host crystals (Fig. 8B). Their longest dimension is 5–10 µm containing liquid and vapour phases (L+V), and show a liquid dominant (φvap= 0.4–0.45) character (Table III). We regard these inclusions as pseudo- secondary (PS) based on criteria after BODNAR (2003). In the PS assemblage the Tm(Ice) values have a very narrow range around –0.8 °C (n=6; salinity: ~ 1 m% eq. NaCl; Fig. 8H; Table III), while Th values are between 344 and 361 °C (n=6) (Figs. 8G, H; Table III). Healed microcracks can be found in some parts of the host epidote, and these cracks run through the whole grains (Fig. 8B). Fluid inclusions occurring along these healed cracks are very small (less than 3µm), they contain one phase liquid (φvap ~ 0) (Table III) and are defi nitely secondary in origin. They are not appropriate for microthermometry. In the elongated epidote crystals that occur in the fi ne grained epidote matrix (Fig. 5F.), two fl uid inclusion assem- blages can be observed (Fig. 8E). Two phase (L+V) liquid dominant (φvap ~0.1) aqueous inclusions, with elongated shapes (Fig. 8F; Table III) can be found in the crystals. Their longest dimensions are in the 5–15 μm range, and although they are not concentrated in a particular growth zone, their elongation in the direction of crystallographic b-axis of epi- dote (Fig. 8E) indicates formation during crystal growth (KLEMD, 2004). Based on these considerations, the inclu- sions are most probably primary in origin and denominated as P3. The measured Tm(Ice) values of fl uid inclusions of P3 are between –0.1 and –0.9 °C (n=9) (Fig. 8H; Table III) in- dicating a low salinity fl uid (0.2–1.4 mass% eq. NaCl; Table III). The homogenization temperatures are in the 163–186 °C (n=9) interval (Figs. 8G, H; Table III). Small (<3 μm), aqueous one phase (L), irregularly shap ed inclusions can be found along trails which crosscut the en- tire crystals. These inclusions are secondary ones (S) in ori- gin (Table III). They occur in subordinate amounts and they are inappropriate for microthermometry. 5. DISCUSSION 5.1 Metasomatism of the wall-rock The occurrence of the same modifi cation of wall-rock from narrow symmetrical margins along thin veins to wider al- tered domains is observable. Different types of wall rock al- terations along veins have been studied in detail by many researchers (SCHERBAN, 1996; OMEL’YANENKO, 1978; SCHERBAN, 1975; KORZHINSKII, 1946). Occurrence of symmetrical alteration rims around veins is typical feature of so called “near vein metasomatism” (ZHARIKOV et al., 2007). Metasomatic zones (ZHARIKOV et al., 2007) are de- nominated as zone 1 to zone 4 (zone 1 represents the closest and zone 4 the farthest domain from the vein), and can be assigned on the basis of the individual mineral paragenesis of the altered domains. The metasomatic column (metaso- matic facies) (ZHARIKOV et al., 2007) is built up by the following zones: Zone 1: In this zone albite and titanite are the most char- acteristic minerals, mineral paragenesis: ab + ttn ± ep. Zone 2: Here, the appearance of epidote pseudomorphs after biotite fl akes is the most characteristic alteration fea- ture. Mineral paragenesis is ep + chl+ ttn + ab ± ser. Zone 3: The amount of epidote markedly decreases and the chlorite content increases. Sericite is more common and rutile inclusions in chlorite frequently occur. The mineral paragenesis is chl + ep + ser + rt ± ttn. Zone 4: Sericitization is the most characteristic alteration process in this zone; other alteration minerals are in subordi- nate amounts. The mineral paragenesis consists of ser ± chl. Whole rock chemical changes during metasomatic al- teration of the wall-rock to alteration halos were evaluated by GRANT’S (1986) method using the whole rock chemical Table III: Summary of the results of the fl uid inclusion study. Host mineral Type Number of Inclusions Phases (25 °C) φV Th (°C) V→L Tm(Ice) (°C) Salinity NaCl eq. mass % Cavity fi lling epidote P1 10 L+V 0.3–0.45 303–364 –0.7±0.3 0.4–1.6 PS 6 L+V 0.4–0.45 344–361 ~–0.8 ~1 P2 6 L+V ~0.15 201–214 –0.55±0.25 0.2–1.2 S – L – – – – Elongated epidote crystals P3 9 L+V ~0.1 163–186 –0.5±0.4 0.2–1.4 S – L – – – – Geologia Croatica 63/1Geologia Croatica 86 data (Table II). Isocon diagrams were constructed to com- pare the alteration halo with the unaltered wall-rock. Isocon analyses were undertaken using whole rock chemical data of the different metasomatic zones detailed above. This pro- cedure resulted in four isocon diagrams labelled from zone 1 to zone 4 (Fig. 9A.). In order to defi ne the best fi t isocon, TiO2 was used as an inert constituent for each isocon dia- gram. Titanium can be found in the altered domains as titan- ite and/or rutile in the pseudomorphs after biotite fl akes, in- dicating that the Ti content of the wall rock was not changed during the alteration process (Fig. 7; Table II). The most ob- vious characteristics of each isocon diagram are the signifi - cant gain of CaO in the alteration halo relative to the wall- rock. The amount of the gain is almost identical from the vein to the unaltered wall-rock (Figs. 9B, C, D, E). The con- tents of SiO2, Al2O3, Na2O and P2O5 behave very conserva- tively. They do not show any signifi cant change except for a minor gain of SiO2 (Figs. 9B, C, D) and Na2O close to the vein (Fig. 9B) and a minor loss of Al2O3 (Fig. 9B). Characteristic losses can be detected in concentrations of Fe2O3, MgO, MnO, and K2O. The Fe2O3 and MnO behave similarly; their concen- trations decrease gradually from wall-rock towards the vein, except closest to the wall rock where minor differences are observable. (Fig. 9B, C, D, E). The MgO content shows an intensive decrease towards the vein and only a little gain clos- est to the wall-rock. Signifi cant loss of K2O can be observed in the alteration halo (Fig. 9B, C, E), but a minor gain is de- tectable close to the unaltered wall-rock (Fig. 9D). Comparison of the results of the textural observations and isocon analyses may contribute to a better understand- ing of those processes that induced the characterized altera- tion patterns in the Baksa gneisses. Fi gu re 9: Isocon diagrams of an altered domain occur along propylitic veins. where Co refers to the concentration before, while Cf refers to the concen- tration after alteration. A) isocon diagram of metasomatic zone 1; B) isocon diagram of metasomatic zone 2; C) isocon diagram of metasomatic zone 3; D) isocon diagram of metasomatic zone 4. CM (dashed line) indicates constant mass-, while CV (dotted line) the constant volume line on the diagrams. A B C D Fintor et al.: Near vein metasomatism along propylitic veins in the Baksa Gneiss Complex, Pannonian Basin, Hungary Geologia Croatica 87 The most signifi cant alteration that occurs in great abun- dance from narrow margins along thin veins to massive al- terations of wall-rocks, are epidotization and chloritization of biotite. In some places, albite replacement after micas is also characteristic. In order to better explain the alteration processes, we present the most signifi cant element mass changes as a function of the original mass (Fig. 10). Here, the relative mass changes of elements (Mi f-Mi o)/Mi o) are rep- resented as a function of distance from propylitic veins. In the immediate few mm of the veins (Fig. 10, zone 1), micas (muscovite+biotite) are totally or partially replaced by albite (Fig. 4A). This phenomenon is most probably due to hydrothermal leaching that almost totally removed K, Fe, Mn, and Mg, from these areas (Figs. 9B, 10/zone 1). Simul- taneous to the decomposition of micas, albite crystals of the wall-rock were dissolved by the fl uid and were recrystallised in place of the micas. Using known compositions of reagent minerals (ÁRKAI et al., 1999; FINTOR, 2005) a relevant reaction equation (1) can be formulated based on constant Al: K Na Mg Fe Al Al Ti Si O OH muscovi 1.7 0.3 0.12 0.1 3.7 1.8 0.06 6.2 20 4( ) ( ) tte K Na Mg Fe Al Al Ti Si O OH bioti 0.9 0.1 2.1 2.5 0.9 2.7 0.2 5.3 20 4 + ( ) ( ) tte SiO quartz 1.087 Ca 7.043 Na 4.052 H 8.27 Na 2 2 + + + ++ + + 12 743. 00.9 0.1 1.1 2.9 8 5 Ca Al Si O albite 0.26 CaTiSiO titanite 2.6 K 2 + + ++ ..6 Fe Mg 6.026 H O 2 2 2 + ++ +2 22. Several researchers (e.g. RUBENACH, 2005; HOL- NESS, 2003; ENGVIK et al., 2008; DOLEJŠ & WAGNER, 2008) demonstrated that replacement of micas, (primarily muscovite and biotite) by albite, owing to fl uid infi ltration can play a signifi cant role in alteration of crystalline rocks. The hydrothermal solution ensured Ca2+ transport in the al- teration zone (Fig. 10, zone 1), and Ca2+ could be preserved as groups of small titanite crystals in the replacement albite or could be incorporated into albite. The appearance of ti- tanite indicates that the Ti content of biotite was immobile during hydrothermal leaching. Farther away from the veins, epidotization of biotite became dominant due to the Ca2+- containing fl uid infi ltrating the wall-rock. The continuous Ca addition in the whole altered zone is evidenced from Fig. 9, and 10. Epidotization of biotite releases K+ and Mg2+ ions that were removed by the hydrothermal fl uid (Fig. 9C, 10/ zone 2). Signifi cant depletion of Fe (Fig. 10, zones 1–3) in- dicates that during epidotization of biotite, a certain amount of iron had been removed by the fl uid as Fe2+. The small euhedral titanite grains that occur around and inside repla- cive epidote indicate that formation of epidote could not con- sume all of the Ca2+ transported by the fl uid, hence Ca2+ was in excess during metasomatism of the wall-rock (Fig. 10). In addition, titanite also contains Si, i.e. a certain amount of silica must also have been released from biotite during the alteration. Knowing the composition of all initial reactants and fi nal products, the following reaction equation (2) can be constructed (biotite from ÁRKAI et al., 1999; epidote from FINTOR, 2005): K Na Mg Fe Al Al Ti Si O OH biotite 1.9 0.1 2.1 2.5 0.9 2.7 0.2 5.3 20 4( ) ( ) + 3.. . . . . 33 1 2524 1 5652 2 2 2 3 0 7 12 Ca H Ca Al Fe Si O OH epidote 0.2 3 + ++ ( ) + CaTiSiO titanite Fe 2.1 Mg 1.9 K Na 5 2+ + + + + + + + + 1 4044 0 1 0 4 2. . . 0044 1 0348H SiO (aq) H O4 4 2+ . Epidotization of biotite is a well-known process espe- cially in metasomatic alterations caused by granitic and gran- odioritic intrusions (e.g. JACOBSEN & MCCARTHY, 1976; SINGLETON, 1979; KLEMD & BARTON, 1988; ŠARIČ, et al., 2009). From comparison of the former equation with Fig. 10 (zone 2), it is obvious that not all of the potassium had been removed from this part of the vein margin. It is likely that this defi cit most probably resulted from musco- vite that had not suffered epidotic or chloritic alteration and its replacement by albite became weak in the zone 2. How- ever, sericitization became more intensive from zone 2, and a signifi cant amount of potassium that was released during dissociation of biotite could be incorporated into sericite. Towards the unaltered wall-rock, epidotization became less effective and chloritic alteration became predominant. In a few locations of this region chlorite-pseudomorphs contain Fi gu re 10: Diagram representing the relative mass changes of elements in order of these elements original mass as a function of distance from the propylitic veins. Dotted horizontal line at zero value indicate TiO2 as the inert (constant mass) constituent. Geologia Croatica 63/1Geologia Croatica 88 sagenite rutile inclusions, which support the immobility of titanium in the altered rocks, but indicate that calcium and silica were insuffi cient to form titanite in these domains. The Mg content in this zone (Fig. 10/zone 3) increases most obviously due to the predominance of chlorite and a lesser epidote content. The signifi cant increase in the potas- sium content (Fig. 10 zone 3) can be attributed to more fac- tors. Sericitization is the most intensive in this zone; while muscovite is almost unaltered in this part of the alteration zone, except for minor sericitic recrystallization. Although chloritization of biotite is very intensive towards the unal- tered wall-rock, more and more unaltered biotite relics occur in the chloritized domains that also conserve potassium. In zone 4, those components that display the most sig- nifi cant mass depletion elsewhere (Fig. 10, zones 1–3) reach their mass values characteristic of the unaltered wall-rock (Fig. 10, zone 4). Here, the major alteration mineral is seric- ite with a few chlorite fi lled cavities. The high Ca-content (Fig. 10, zone 4) of the zone is most probably due to the pres- ence of cavity-fi lling epidote, which occurs very frequently in the alteration zones, and in the unaltered wall-rock. 5.2. Palaeohydrology The euhedral albite crystals on the cavity walls, and the well- developed growth zonation of the cavity fi lling epidote (Fig. 4D), indicate that these minerals precipitated in an open space system. The secondary porosity was most probably caused by hydrothermal leaching of the circulating fl uid, which is one of the most effective processes in the metaso- matic regime (PUTNIS, 2002). Effective leaching is sup- ported by the signifi cant turbidity of feldspars in the altered margins, because this texture can develop by fl uid infi ltra- tion (PARSONS & LEE, 2000; WALKER et al., 1995). The primary (P1, P2) and pseudosecondary (PS) fl uid inclusions of cavity fi lling epidote, display a uniform physicochemical character, which is a dilute aqueous-electrolyte solution with- out any volatile components. Both the composition (0.2–1.6 mass% eq. NaCl) and the range of Th values (200–360 °C) indicate a fl uid identical to that found in the primary fl uid inclusions of vein fi lling diopside (0.7–2.9 eq. mass % NaCl, Th: 308–362 °C), and epidote (0.2–1.2 eq mass% NaCl, Th: 206–359 °C), of the Ca-Al-silicate veins (FINTOR et al., 2009) that are bordered by the metasomatised zone. Based on the previous assumptions, it could be stated that an inter- connected cavity system existed in the margins that was in connection with the veins. Hence the migrating fl uid pene- trated the cavity system resulting in epidote precipitation. Although the chemical character of the P3 assemblage (0.2– 1.4 mass% eq. NaCl), indicates a similar fl uid type to that found in P1 and P2, the lower Th values (160–200 °C) indi- cate that trapping of this fl uid type occurred later than the main phase of hydrothermal alteration. Taking into consid- eration that any unambiguous evidence for heterogeneous entrapment, or post-entrapment modifi cations of inclusions, including leakage/refi lling or irreversible change of inclu- sion volume etc. could not be found, the wide Th range (200– 364 °C) may be explained by subsequent entrapment of pri- mary and pseudosecondary FI in a cooling hydrothermal fl uid regime. Such an important drop in temperature (~200 °C) that can be observed between P1 (Th: 303–364 °C) and P3 (Th: 160–200 °C) assemblages, can be imagined if the heat effect of an immediate magmatic source caused a short lived fl uid fl ow with a very low fl uid/rock ratio and the am- bient rock temperature was ~180 °C. The existence of an interconnected fl uid circulation re- gime between the veins and the metasomatized domains in- dicates that the same pressure conditions (~88 MPa, FIN- TOR et al., 2009), which were established in the case of the Ca-Al-silicate veins, can be applied in the case of fl uids mi- grating into the cavities. Based on this approach, the trapping temperature of fl uid that entered the rock mass was in the 250–480 °C range similar to that which could have been ob- served in the Ca-Al-silicate veins (FINTOR et al., 2009). This is in accordance with such a kind of alteration in a hy- drothermal metasomatic regime (ROBB, 2005). Based on the observed mineral paragenesis, the esti- mated temperature range and the type of element mobiliza- tion, the studied alteration process belongs to the propylite metasomatic family based on the nomenclature of ZHA- RIKOV et al. (2007). As chemical compositions of pyrite in both the pure sulphide veins (TARNAI, 1998) and the Ca- Al-silicate veins is identical concerning the Co/Ni ratio (FIN- TOR et al., 2009), both vein types were formed due to post- magmatic hydrothermal processes and the studied veins represent real propylites. According to the “T-qualitative pH diagram” of metasomatic families (Fig. 11) (ZHARIKOV et al., 2007), propylite is stable around ~260–410 °C tempera- ture and ~4.5–7 pH range, (grey shaded area on Fig. 11). As the dissociation of water is also temperature dependent, the neutral pH value becomes 5 at around 250 °C. Hence the Fi gu re 11: Diagram illustrating a fragment of the general T-qualitative pH fi elds of the metasomatic families (modifi ed after ZHARIKOV et al., 2007). The dot-dash line separates acidic and neutral alkaline-alkaline families (with and without quartz). Dashed lines indicate the possible temperature range of the metasomatic alteration. The grey shaded fi eld represents the possible metasomatic family indicated by mineral paragenesis. The hatched area indicates a metasomatic paragenesis without quartz. (Aeg-am meta- somatic rock refers to aegirine-amphibolite metasomatic rock; qtz-fp m–r* refer to quartz-feldspar metasomatic rock). Fintor et al.: Near vein metasomatism along propylitic veins in the Baksa Gneiss Complex, Pannonian Basin, Hungary Geologia Croatica 89 observed mineral assemblage is stable at neutral-weakly al- kaline conditions, which is in good agreement with observa- tions in many other fl uid-rock interaction systems where al- bite, epidote, and chlorite are stable (BIRD et al., 1984; GIGGENBACH, 1981; BIRD & HELGESON, 1980). The total lack of a quartz phase in the metasomatic col- umn indicates that the peak temperature condition of altera- tion was above ~340 °C, because quartz free propylite only exists at the 340–400 °C temperature range (ZHARIKOV et al., 2007) (hatched area on Fig. 11). This estimation is co- herent with the fl uid inclusion microthermometry data. We can ascertain from the observed characteristics that the fl uid circulated in propylitic veins (FINTOR et al., 2009), and caused signifi cant propylitic alteration in the adjacent rocks. The composition of the metasomatic column can be summarized as ab+ep+chl+ttn+rt+ser. The same phases can be found inside the propylitic veins (FINTOR et al., 2009). The indications of sulphide ores in the studied well (TAR- NAI, 1997; 1998), and the similarities of the observed pro- pylitic metasomatite with other fi elds where signifi cant ore mineralization is associated with this type of alteration (KU- LIKOVA et al., 2007; TASSINARI et al., 2008; ABIA et al., 2003) indicates further investigation of the area. 6. CONCLUSIONS 1. The fl uid circulated in the propylitic veins and caused metasomatism of the wall-rock with transport of consid- erable amount of Ca2+ toward the adjacent rocks. The hy- drothermal leaching almost totally removed the K, Fe, Mg, and Mn basic ion content of the wall rock. 2. The characteristic mineral parageneses of individual meta- somatic zones of the metasomatic column indicate that the altered wall rock is related to the propylite metasomatic family. The combined mineral assemblage of the metaso- matic column is: ab+ep+chl+ttn+rt+ser. 3. The pervasive hydrothermal leaching in the wall-rock re- sulted in signifi cant volume loss and secondary porosity in the altered domains. The fl uid migration took place not only in the veins but also in the margins along them, and penetrated a great distance into the adjacent rocks along interconnected cavities. 4. The peak temperature range of the metasomatism was around 360–480 °C, and the alteration occurred as a result of a near neutral, or weakly alkaline hydrothermal solution. 5. The similarities of the studied propylitic mineral assem- blages (both in the veins and in the wall-rock) with those that are characteristic in the case of many hydrothermal ore deposits, indicates further research in this topic would be useful. ACKNOWLEDGEMENT The authors would like to thank the Hungarian Research Fund (No. K60768) for providing fi nancial support. 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