www.geologia-croatica.hr ABSTRACT Comparative studies on hydrothermal alteration of submarine peperitic basalt occurrences related to the Triassic early rifting of the Neotethys were carried out in various parts of the Dinarides and Hellenides. The study areas included the displaced fragments of the Dina- rides in the Darnó Unit, NE Hungary, the Kalnik Mts. in Croatia and the Vares-Šmreka area in Bosnia and Herzegovina. In the Hellenides, similar environments were studied in the Stragopetra Mts., Greece. Jurassic pillow basalts formed in a back-arc-basin of the Neote- thys were also studied in the Szarvaskő Unit, NE Hungary, which also represents a dis- placed unit of Dinaridic origin. Within the submarine basaltic lava flows, six volcanic facies were distinguished. The hydrothermal alteration was characterised according to those fa- cies. The first process was the albitisation of the rock-forming plagioclase at ~300°C in all localities. During the higher temperature stage of the subsequent cooling, chloritisation in the ground mass is typical for all types of basalts, however chlorite and rarely quartz formed in the fractures and amygdales of the Triassic basalts, while chlorite, quartz and prehnite precipitated in the fractures of the Jurassic rocks. At lower temperatures of this cooling-re- lated process, calcite is a common mineral filling up the larger amygdales, jig-saw type fractures and other open spaces, but some epidote, pumpellyite, prehnite and laumontite also occur in the Triassic basalts. The late stage alteration (occurring at the lowest tempera- ture) is characterised by argillitisation at every locality. The observed hydrothermal altera- tion patterns also show slight differences according to the volcanic facies as a function of the distal/proximal setting in relation to the eruptive centres and the presence/absence of water-saturated and unconsolidated carbonate or siliciclastic sediments at the time of the emplacement of lava flows. The study revealed that the most important factors influencing mineralogy and zoning of hydrothermal alteration in these short lived local hydrothermal systems are the rapid cooling of the hydrothermal fluid, the dominance of the poorly evolved seawater as the source of hydrothermal fluid and the local, i.e. effective water/rock ratio, determined by the degree of fracturing in the rock. The mineralogical-textural peculiarities of the highly localised hydrothermal fluid/rock interaction in the studied submarine sea- mount type volcanoes are clearly different from the products of the large-scale hydrother- mal processes occurring at mid-oceanic ridges. Recognition of these differences is impor- tant in the evaluation of ore potential in the Neotethyan realm or other areas with occur- rences of submarine basaltic units. Keywords: submarine basaltic volcanism, submarine hydrothermal processes, minera- logy and geochemistry of submarine fluid/ rock interaction, fluid inclusions, chlorite thermometry Article history: Received November 09, 2015 Revised and accepted January 04, 2016 Avaliable online February 29, 2016 1. INTRODUCTION Correlation and comparison of the Triassic and Jurassic sub- marine basaltic units in the Darnó and Szarvaskő Units north- eastern Hungary, and similar occurrences in the Dinarides and Hellenides have been in the focus of several studies dur- ing past decades (see e.g. BUDA & KISS, 1980; BALLA et al., 1980; KUBOVICS 1984; BALLA, 1987; DOWNES et al., 1990; DOSZTÁLY & JÓZSA, 1992; HARANGI et al., 1996; JÓZSA, 1999; HAAS & KOVÁCS, 2001; SCHMID et al., 2008; ROBERTSON et al., 2009 and the references cited therein). The results of the most recent investigations suggest that the formation of the Triassic basaltic units found in NE Hungary and in the Dinarides and Hellenides can be related to the advanced stage of rifting of the Neotethys, while the Ju- rassic basalts occurring in the same mélange in NE Hungary have accumulated in a back-arc-basin or a marginal basin (HARANGI et al., 1996, AIGNER-TORRES & KOLLER, 1999, KISS et al., 2008, 2010, 2012, KOVÁCS et al., 2008, 2010, HAAS et al., 2011). These basaltic units of different ages were emplaced into unconsolidated sediments (Triassic – lime-mud, Jurassic – fine grained siliciclastics) as discussed in detail in KISS et al. (2010, 2011, 2012). doi:10.4154/gc.2016.0439-64 17 Figs. 7 Tabs. Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary, the Dinarides and Hellenides Gabriella B. Kiss1,*, Ferenc Molnár1,2 and Ladislav A. Palinkaš3 1Eötvös Loránd University, Faculty of Science, Department of Mineralogy, Pázmány P. stny 1/c, 1117 Budapest, Hungary (*corresponding author: G. B. Kiss e-mail: gabriella.b.kiss@ttk.elte.hu, telephone number: +36-1-372-2500 ext. 8333) 2present address: Geological Survey of Finland, PO. Box 96, FI-02151 Espoo, Finland 3University of Zagreb, Faculty of Science, Institute of Mineralogy and Petrology, Horvatovac 95, 10000 Zagreb, Croatia Vol. 69/1 40 Comparison of the characteristics of submarine hydrother- mal activities which affected these basaltic suites provides an additional tool to the correlation among the Triassic localities. Comparison of their overall characteristics to the Jurassic sys- tem offers an opportunity to investigate the effect of the geo- tectonic setting on the peculiarities of submarine hydrothermal processes. This aids recognition of the time- and environment- independent common characteristics of these hydrothermal systems. Submarine volcanism related hydrothermal systems at the oceanic ridges are quite well known and documented, especially because of the formation of economically important volcanogenic massive sulfide ore deposits (see e.g. FOUS- TOUKOS & SEYFRIED, 2007, PIRAJNO, 2009 and the refe- rences therein). As a contrary, submarine volcanism-related hydrothermal processes have scarcely been studied in other geodynamic settings, e.g. advanced stage of rifting. Distin- guishing between the features of submarine hydrothermal al- teration processes in the structurally-texturally similar basaltic rocks formed in different geotectonic settings is of obvious importance in mineral exploration. Here, we present the mine- ralogical-textural-geochemical characteristics and the tempo- ral and spatial evolution of the fluid/rock interaction in these submarine basaltic rocks. 2. REGIONAL SETTING The Darnó Unit The Darnó Unit (Fig. 1.) is part of the Bükk Unit, located within the Pelso Unit of the ALCAPA block (ALpine, CAr- pathian, PAnnonian, CSONTOS, 1995, SCHMID et al. (2008). It comprises an area of ca. 7km2 in NE Hungary (cen- tred on ~ N 47.936810, E 20.163246), in the vicinity of the city of Eger. According to the latest tectonic models, the Darnó Unit forms the uppermost nappe in the complex struc- ture of the Bükk Unit (which consists of four stacked nappes) (CSONTOS, 1995, CSONTOS, 1999, HAAS & KOVÁCS, 2001, KOVÁCS et al., 2008). The Darnó Unit consists of predominantly Triassic and sub- ordinately Jurassic submarine basaltic suites and associated Triassic and Jurassic sedimentary rocks. The magmatic suites are pillow basalt sequences, however, in the Triassic rocks, limey peperitic facies (i.e. unconsolidated sediment-lava mix- ing at the time of rock formation, SKILLING et al., 2002) also commonly occur (KISS et al., 2008, 2010, 2012, KOVÁCS et al., 2010). Recent geochemical and volcanological studies of these Triassic magmatic rocks suggest their emplacement oc- curred in an advanced rift-related tectonic setting. The whole Figure 1. Geological maps of the studied areas. A, Structural sketch map of the Circum-Pannonian Region and the Balkan Peninsula. B, Geo- logical sketch map of the Darnó and Szarvaskő Units. C, Geological sketch map of the area of Vareš. D, Geological sketch map of the area of Hruškovec. E, Geological sketch map of the Avdella Mélange. The studied localities are marked on each map. Kiss et al.: Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary... 41 unit is interpreted as an accretionary mélange complex (BAL- LA et al., 1980, BUDA & KISS, 1980, DIMITRIJEVIĆ et al., 2003, KOVÁCS et al., 2008, 2010, KISS et al., 2008, 2010, 2012). Signs of Alpine low grade metamorphism were ob- served nearby in the Bükk Mts. (see ÁRKAI, 2001 and refer- ences therein) and its effects on the Darnó Unit were docu- mented by MOLNÁR et al. (2015). The Szarvaskő Unit The Szarvaskő Unit (Fig. 1.) is also part of the Bükk Unit, within the ALCAPA block. It forms a nappe below the upper- most Darnó Unit, with outcrops mostly confined to a synform structure in the vicinity of the village of Szarvaskő (N 47.988742, E 20.332144) (CSONTOS, 1995, DOSZTÁLY et al., 1998). The Szarvaskő Unit consists of an incomplete Jurassic ophi- olitic sequence intercalated with some deep water siliciclastic sediments. Besides the well developed pillow basalt series with local siliciclastic peperite (KISS et al., 2011), gabbro and related plagiogranite, wehrlite, piroxenite and hornblendite also occur. However, other ultramafic rocks of true ophiolitic sequences are missing (SZENTPÉTERY, 1953, BALLA, 1984, DOSZTÁLY et al., 1998, PELIKÁN ed. 2005). The K-Ar age of the magmatic rocks is 165 +/- 5 Ma and 166 +/- 8 Ma according to ÁRVÁNÉ SÓS et al. (1987). BALOGH & PÉCSKAY (2001) obtained an Ar-Ar plateau age of 162.9 +/- 0.9 Ma for contact-metasomatic K-mica occurring along the intrusive contact of a gabbro intrusion and host sediments. KOHÚT & KISS (2013) reported 170 +/- 9 Ma based on chemical EMP dating of monazite of the plagiogranite associ- ated with the gabbroic intrusion. Current views suggest that formation of the incomplete ophiolitic sequence at Szarvaskő is related to the opening of a back-arc-basin or a marginal ba- sin (AIGNER-TORRES & KOLLER, 1999, CSONTOS, 2000, HAAS et al., 2011). Its differentiation from characteristic mid- oceanic ridge related rocks was also proven by KISS et al. (2011). ÁRKAI (1983), ÁRKAI et al. (1995), SADEK GHAB- RIAL et al. (1996), ÁRKAI (2001), PÉNTEK et al. (2006) and KISS et al. (2012) have also shown the occurrence of a very low and low grade Alpine regional metamorphism related al- teration mineral assemblage of Cretaceous age. Localities in the Dinarides The Kalnik Mts. (Fig. 1.) comprise two main tectonostrati- graphic units in the northern part of Croatia (centred on ~ N 46.150374, E 16.442340), in the Zagorje-Mid-Transdanubian Zone (ZMTZ) of the NW Dinarides. One unit is the strongly tectonised ophiolitic mélange, the other being the late Creta- ceous-Palaeogene flysch. The mélange mostly exhibits fea- tures characteristic of the Dinarides, and is therefore inter- preted as the most northwestern occurrence of the Dinaridic Ophiolite Zone (PAMIĆ & TOMLJENOVIĆ, 1998). The area of Vareš (N 44.161424, E 18.326386) (Fig. 1.) is located in Bosnia and Herzegovina, in the Central Dinarides. According to TRUBELJA et al. (2004) the Borovica-Vareš- Čeljanovići-Kalinovik Zone is part of the Palaeozoic-Mesozo- ic allochthonous series. Recently, HRVATOVIĆ (2006) inter- preted this zone as a part of the Dinaride ophiolitic mélange. Triassic pillow basalt series and the limey peperitic facies rocks are important constituents of both ophiolitic mélange oc- currences. In the Kalnik Mts., recent studies suggested a Neo- tethyan rifting related origin for the pillow basalts (PALINKAŠ et al., 2000, 2008, KISS et al. 2012). At Vareš, controversy surrounds interpretations of the origins of the rock. TRUBE- LJA et al. (2004) concluded subduction related formation, while PAMIĆ (1984), KARAMATA et al. (2000) and KISS et al. (2012) presented observations strongly supporting a rift- related origin of the basaltic volcanism. Localities in the Hellenides The Avdella Mélange Formation (Fig. 1.) of Jurassic age oc- curs in NW Greece, within the Pindos Zone of the Hellenides. The mélange with basaltic and other magmatic and sedimen- tary blocks is one of the five main tectonostratigraphic units of the Pindos Zone. The accretionary mélange forms a nappe below the Pindos Ophiolites (JONES & ROBERTSON, 1991, RASSIOS & MOORES, 2006) occurring in the vicinity of the village of Avdella (N 40.007489, E 21.125159) in the Strago- petra Mts. Based on the geochemistry of the pillow basalt blocks, JONES & ROBERTSON (1991) argued that their formation took place in a mid-oceanic ridge environment, while KOVÁCS et al. (2010), KISS et al. (2012) and OZSVÁRT et al. (2012) suggested a Neotethyan rifting related origin and Triassic age (from fossil evidence in the limestones of the pe- peritic facies). Correlation possibilities The current geodynamic models correlate the Darnó Unit with the Triassic submarine basalt occurrences in the north- western parts of the Dinarides (DIMITRIJEVIĆ et al., 2003, HAAS & KOVÁCS, 2001, KOVÁCS et al., 2010, HAAS et al. 2011, KISS et al., 2008, 2010, 2012). Geological correla- tion summarised in DIMITRIJEVIĆ et al. (2003) and HAAS et al. (2011) also support the Dinaridic origin of the subma- rine magmatic and sedimentary rocks of the Szarvaskő Unit. However, results of KOVÁCS et al. (2010) and KISS et al. (2012) have also extended this correlation to localities in the Hellenides. Thus, the studied NE Hungarian, Dinaridic and Hellenidic units represent remnants of the Neotethyan accretionary com- plexes (DIMITRIJEVIĆ et al., 2003, HAAS et al., 2011). The NE Hungarian ones were transported from the northwestern Dinarides to the current position along the Mid-Hungarian Lineament by approx. 400 km of horizontal displacement du- ring the Alp-Carpathian collisional processes (CSONTOS & VÖRÖS, 2004, SCHMID et al., 2008). 3. STUDY METHODS Field studies were carried out in quarries and at outcrops of the Darnó Unit and Szarvaskő Unit (NE Hungary), Kalnik Mts. (N Croatia), Vareš area (Central Bosnia-Herzegovina) and in the Stragopetra Mts. (N Greece). Field recognition of volcanic facies and representative sampling of relatively fresh and hydrothermally altered rocks were the focus of field studies. Vol. 69/1 42 Thin-section petrographic study of samples with emphasis on observation of the distinctive textures of rocks and hydro- thermal alteration mineral assemblages was undertaken. An AMRAY 1830 SEM-EDS instrument with PV9800 type detec- tor at the Department of Petrology and Geochemistry of the Eötvös Loránd University was also used for the petrographic characterisation of mineral assemblages. EDS analyses were completed with focused electron beam with 20 kV accelera- ting potential, 1 nA beam current and 100s detection time. The instrument was calibrated using well known natural and syn- thetic standards. The average detection limits were 0.1 wt% for the analysed elements. X-Ray Powder Diffraction (XRPD, at the Department of Mineralogy of the Eötvös Loránd University) aided determina- tion of other mineral phases. A Siemens D-5000 type diffrac- tometer with Bragg-Brentano geometric emission (Θ-Θ work- ing method, Cu Kα (λ=0.154178 nm), secondary graphite crystal monochromator and scintillation detector was used to- gether with the EVA software (Bruker-AXS Diffrac Plus) for data analysis. Chlorite compositions from different textural settings facili- tated temperature determination of fluid/rock interaction via wavelength dispersive (WDS) electron microprobe analyses (EPMA). Calibrations by KRANIDIOTIS & MACLEAN (1987), CHATELINEAU & IZQUIERDO (1988) and ZANG & FYFE (1995) aided determination of chorite formation tem- peratures, depending on the measured Al(IV) and XFe values of the individual crystals. These methods bear about 20°C un- certainty of formation temperature estimation. The EPMA analyses of chlorite were performed at the Carleton University (Ottawa, Canada) and at the Masaryk University (Brno, Czech Republic). Elemental distribution maps of selected basalt sam- ples were prepared at the Eugen Stumpfl Laboratory of the University Centre of Applied Geoscience, University of Leo- ben, Austria. At the Carleton University, the quantitative ana- lyses of chlorite were completed using 15kv accelerating volt- age and a beam current of 20 nA. The detection limits were as follows: SiO2, TiO2, Cr2O3, MgO and Cl - 0.03 wt%; Al2O3, K2O, CaO and Na2O - 0.02 wt%; MnO, NiO and F - 0.04 wt%; FeO - 0.05 wt%. At the University of Leoben, elemental map- ping was performed in WDS mode, with 15 kV accelerating voltage and 10 nA beam current. At the Masaryk University, CAMECA SX 100 type instrument with 15 kV accelerating potential and a beam current of 10 nA was used for determina- tion of the major element compositions of chlorite. The detec- tion limits were as follows: 0.06 wt% for Na, 0.04 wt% for Si and V, 0.035 wt% for Al, 0.045 wt% for Mg and K, 0.03 wt% for Ca, Cr, Cl and Ti, 0.12 wt% for Ba, 0.08 wt% for Fe and Ni, 0.07 wt% for Mn and F and 0.2 wt% for Zn. A suite of reliable natural and synthetic minerals and compounds were used as calibration standards at all laboratories. Fluid inclusion petrography and microthermometry were carried out at the Department of Mineralogy, Eötvös Loránd University, on 80-100 μm thick, double polished sections of hydrothermal calcite from various volcanic and hydrothermal facies of basalt. Equipment was a Chaixmeca-type and Linkam FT-IR 600 type heating-freezing stage mounted on an Olym- pus BX-51 type polarizing microscope with 1000 x opical magnification capability. Precision of the microthermometric measurements was ±0.1 oC below 0 oC, and ±1 oC above it. CO2 and H2O synthetic fluid inclusions were used for all equip- ment calibration. Interpretation of microthermometric data in- volved using a macro program in MS Excel, developed in Vi- sual Basic environment by the first author, using the methods of HALL et al. (1988), NADEN (1996), POTTER & CLYNNE (1978) and ZHANG & FRANTZ (1987). Geochemical analysis of rock samples were carried out at the laboratory of the ALS Laboratory Group (Vancouver, Ca- nada) and in the geochemical laboratory of the Hungarian Geological Institute. Geochemical data (8 samples) were pub- lished in KISS et al. (2012) and 19 samples were analysed in this study. The ALS Laboratory used ICP-AES to determine the major elements, Pt, Pd and Au, and ICP-MS to analyse the trace elements. Detection limits and analytical procedures are described in the official booklet of ALS1. The Hungarian Geo- logical Institute analysed the major elements with ICP-AES, the trace elements with ICP-MS or ICP-AES, and Hg content with AAS. Detection limits and analytical procedures are de- scribed in the accreditation documentation of the laboratory2. Major and trace element data were interpreted using the Petro- graph software (PETRELLI et al., 2005). Mass transfer calcu- lations (MTC) were also performed, according to the method described in GRANT (1986), MACLEAN & KRANIDIOTIS (1987), BRAUHART et al. (2001) and ULRICH & HEIN- RICH (2002). 4. RESULTS Field study Six different volcanic facies can be distinguished in subma- rine lava flows: (1) coherent basalt, (2) closely packed pillow basalt, (3) peperitic pillow basalt, (4) in situ hyaloclastite breccia, (5) pillow fragmented hyaloclastite breccia and (6) isolated pillow breccia facies (PALINKAŠ et al., 2008, see also Fig. 16. below). The quarry at Hruškovec exposes all six distinguishable volcanic facies of a submarine lava flow (PALINKAŠ et al., 2008, KISS et al., 2008). It was therefore used as the basis of comparison for volcanological features in other similar subma- rine basaltic volcanic centres. Its characteristic features are summarised in the above referenced citations, and not repeated here. The closely packed pillow, peperitic pillow, in situ hyalo- clastite and the pillow fragmented hyaloclastite breccia facies were all detected in five studied quarries and several outcrops in the Darnó Unit. The studied quarry and the surveyed smaller natural and artificial outcrops in the Szarvaskő Unit expose three main volcanic facies: closely packed pillow, peperitic pillow and pillow fragmented hyaloclastite breccia facies. The quarry and several small outcrops in the Vareš-Smreka area expose the closely packed pillow facies and the peperitic pil- low facies. Three large artificial outcrops (a quarry and two roadcuts) and two smaller natural outcrops were studied in de- tail on the western, southern and southeastern slopes of the Stragopetra Mts. These exposures contain closely packed pil- 1available at: http://www.alsglobal.com/Our-Services/Minerals/Geochemis- try/Downloads 2accreditation number: NAT-1-1302/2012 Kiss et al.: Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary... 43 low facies, but the most abundant is the peperitic pillow facies. Petrography Detailed petrographic investigations, coupled with XRPD and SEM-EDS analyses as well as EPMA elemental mapping revealed mineralogical, pe- trographic and textural similarities and differences between the studied localities. Results are summarised in Table 1. and presented below, high- lighting the common and different features recognised in the four volca- nic facies occurring in the study area. The closely packed pillow facies The closely packed pillow facies, formed around the coherent pillows of the lava flow, as a moderately distal fa- cies in relation to the eruption centre (PALINKAŠ et al., 2008). They are composed of grey, greyish green, or reddish grey basaltic pillows 30-100 cm in diameter at every locality (Fig. 2A). The texture of the basalt is sphaeroli- tic, variolitic or interstertal. At the Tri- assic localities, the rock is composed mostly of altered plagioclase laths and 40-50% microcrystalline and glassy groundmass, while the occurrence of clinopyroxene laths is very rare (Fig. 2B,C). Porphyry texture occurs only rarely, when the weakly altered (argil- litised) plagioclase occur in two size groups: > 1 mm and 0.1 - 0.4 mm. The SEM-EDS studies proved that the pla- gioclase is predominantly albite in composition (Table 2, Fig. 3A). Ele- mental mapping by EPMA revealed that these crystals contain more Na and less Ca closer to the margins of the pillows (where sphaerolitic-vari- olitic texture dominates), than in their inner parts (where variolitic-interser- tal texture dominates) (Fig. 4A-I). The augitic pyroxene in the Triassic basalts is rather homogeneous (MORIMOTO, 1989; Table 3, Fig. 3B). Calcite, chlorite and opaque mine ral pseudomorphs after the 0.5-0.8 mm large olivine phenocrysts are common in the Triassic basalts. The groundmass is altered to chlorite, clay minerals, calcite, haematite and titanite. The XRPD analyses revealed the presence of chlorite-smectite, chlorite-illite interlayering, celadonite and smectite. Disseminated pyrite, Figure 2. Macroscopic and microscopic photos of the observed facies. A, Closely packed pillow with abundant, mostly calcite-filled jig-saw veins and a small amount of interpillow hyaloclastite breccia (Nagy-Rézoldal Quarry, Darnó Unit, Hungary). B, Intersertal textured Triassic basalt with small, chlorite filled amygdales (Nagy-Rézoldal Quarry, Darnó Unit, Hungary). C, Older, higher temperature quartz and prehnite filled cooling crack is cut by a younger, lower tempe- rature calcite vein in a Triassic basalt (RM-131 drillcore, Darnó Unit, Hungary). D, Porphyryc textured Jurassic basalt with coarse grained pyroxene showing compositional zonation. The rock is cut by a thin, cooling related calcite vein (Egerbakta Quarry, Szarvaskő Unit, Hungary). E, Chaotic mingling of basalt and pinkish limestone from a Triassic peperitic facies (Stragopetra, Greece). F, Chaotic mingling of basalt and limestone from a Triassic peperitic facies. The limes- tone contains basalt clasts, chloritised glassy shards as well as pieces of plagioclase laths (Báj- patak Quarry, Darnó Unit, Hungary). G, Pillow fragmented hyaloclastite breccia at a Jurassic basalt location (Egerbakta Quarry, Szarvaskő Unit, Hungary). H, Glassy basaltic clast in a Tri- assic hyaloclastite breccia. Textural variation from the glassy, through sphaerolitic till variolitic is observable, while the cementing hydrothermal material is mostly calcite (RM-131 drillcore, Darnó Unit, Hungary). Abbreviations: b: basalt, cal: calcite, chl: chlorite, g: glass, hem: haemati- te, l: limestone, m: matrix, pl: plagioclase, px: pyroxene, Q: quartz, preh: prehnite. Vol. 69/1 44 Triassic Jurassic C lo se ly p ac ke d pi llo w b as al t Rock Texture sphaerolitic, variolitic, rarely intersertal porphyric intersertal Main minerals plagioclase, rare clinopyro- xene (augite) plagioclase, clinopyroxene (augite) Other components pseudomorphs after olivine, pyrite, chalcopyrite, hematite, bornite, titanite pyrite, chalcopyrite Alteration Groundmass chlorite, chlorite-smectite and chlorite-illite interlayering, celadonite, smectite, calcite Plagioclase albite, partly atered to clay minerals albite Hydrothermal infillings amygdales, jig-saw veins, thin veinlets, former feeding channels, mineral bands of pyjamas-type pillows, inter- pillow hyaloclastite thin veinlets, interpillow hyaloclastite Hydrothermal minerals chlorite, quartz, calcite, lau- montite, haematite, epidote, prehnite chlorite, quartz, calcite, epi- dote, prehnite Pe pe ri tic p ill ow Rock Basalt similar, than in the closely packed pillow similar, than in the closely packed pillow Sedimentary rock red micritic limestone black aleurolite Sedimentary rock composition calcite, bioclasts, plagioclase, glassy shards, pyroxene quartz, chalcedony, albite (alteration products) Amount of sedimentary rock 50-70% 20-30% Alteration Groundmass haematite quartz, chalcedony, albite Hydrothermal infillings thin veinlets, jigsaw veins, amygdales thin veinlets Hydrothermal minerals calcite, chlorite, haematite, prehnite, laumontite calcite, quartz, chlorite, preh- nite, albite In si tu a nd pi llo w fr ag m en te d hy al oc la st ite Rock Breccia clasts pillow basalt, fractured basalt, glass shards, micritic limestone fractured basalt, glass shards Breccia matrix quartz, chlorite, calcite, preh- nite, pumpellyite quartz, chlorite, prehnite and pumpellyite Alteration Basalt clasts haematite, chlorite chlorite Table 1. Petrographical characteristics of the Triassic and Jurassic rocks. chalcopyrite, haematite (also pseudomorphs after pyrite) and bornite also occur in the basalt. Fluid/rock ineteraction processes and percolation of upheat- ed sea-water in the piles of Triassic basaltic lava flows, result- ed in precipitation of hydrothermal minerals filling the amyg- dales (0.1-5 mm in size), cooling of related jig-saw veins of 1-3 mm thickness, infilling of the 0.1-0.5 mm thin cross-cut- ting veins and former internal feeding channels of the lava. The interpillow hyaloclastite breccia is also cemented by hy- drothermal minerals (Fig. 2A, B, C). The thin veinlets and the smaller (0.1-1 mm) amygdales contain only the oldest mineral paragenesis, while the bigger (1-5 mm) amygdales, the mine- ral bands in the pyjama-type pillows, the former feeding cha- nnels, and the jig-saw type veins also contain the older hydro- thermal mineral phases along their walls, with younger mine- ral infillings of different composition in their central parts. The small amygdales are generally infilled with chlorite (Fig. 2B), but sometimes quartz also occurs. Larger amygdales are most- ly infilled with calcite and lesser amounts of chlorite and quartz. The thin veinlets contain chlorite, quartz, epidote, cal- cite and prehnite, whereas the jig-saw type veins are mostly infilled with a calcite-quartz-chlorite assemblage (Fig. 2C). The mineral bands of the pyjama-type pillows contain mostly calcite with a small amount of haematite, quartz, chlorite and laumontite. Infillings of the former feeding channels are most- ly calcite. The 0.5-5 cm glassy shards of the interpillow hyalo- clastite breccia are cemented with a mixture of chlorite, cal- cite, quartz, epidote and prehnite at all the studied localities. Alteration features in the Jurassic basalt slightly differ from the peculiarities of the Triassic basalt described above. It is generally characterised with a porphyric-intersertal texture and contains more clinopyroxene and lesser amounts of micro- crystalline and glassy groundmass (Fig. 2D). The weakly al- tered (argillitised) plagioclase and fresh pyroxene phenocrysts occur in two size groups: > 1 mm and 0.1 - 0.4 mm. The SEM- EDS studies proved that the plagioclase is predominantly Kiss et al.: Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary... 45 Table 2. Results of the SEM-EDS studies (plagioclase analyses). Na2O Al2O3 SiO2 K2O CaO Total Na Al Si K Ca Total Egerbakta Q. (Szarvaskő U.) porphyry albite mean (n=5) 10.79 19.77 69.04 b.d.l. 0.12 99.63 0.91 1.02 3.01 b.d.l. 0.01 4.94 st.dev. 0.39 0.16 0.37 b.d.l. 0.00 0.43 0.03 0.01 0.01 b.d.l. 0.00 0.02 groundmass albite mean (n=3) 10.70 19.90 68.79 b.d.l. 0.20 99.46 0.90 1.02 3.00 b.d.l. 0.01 4.93 st.dev. 0.28 0.16 0.21 b.d.l. 0.00 0.40 0.02 0.01 0.01 b.d.l. 0.00 0.02 Hruškovec Q. (Kalnik Mts.) groundmass albite mean (n=5) 9.92 20.01 69.23 b.d.l. 0.44 99.61 0.84 1.03 3.01 b.d.l. 0.02 4.90 st.dev. 0.33 0.26 0.38 b.d.l. 0.19 0.31 0.03 0.01 0.01 b.d.l. 0.01 0.02 Mély Valley Q. (Darnó U.) porphyry albite mean (n=6) 10.51 20.22 68.13 b.d.l. 0.54 99.40 0.89 1.04 2.98 b.d.l. 0.03 4.95 st.dev. 0.34 0.15 0.53 b.d.l. 0.17 0.29 0.03 0.01 0.01 b.d.l. 0.01 0.02 groundmass albite mean (n=4) 9.86 20.13 68.92 b.d.l. 0.67 99.58 0.83 1.03 3.00 b.d.l. 0.03 4.90 st.dev. 0.43 0.34 0.40 b.d.l. 0.09 0.28 0.04 0.01 0.01 b.d.l. 0.00 0.03 Nagy-Rézoldal Q. (Darnó U.) groundmass albite mean (n=2) 10.03 20.93 67.37 b.d.l. 1.48 99.81 0.85 1.08 2.95 b.d.l. 0.07 4.94 st.dev. 0.27 0.41 1.03 b.d.l. 0.61 0.25 0.03 0.02 0.04 b.d.l. 0.03 0.04 Stragopetra Mts. porphyry albite (n=1) 10.32 19.50 68.01 b.d.l. 2.19 100.02 0.87 1.01 2.98 b.d.l. 0.10 4.96 groundmass albite (n=1) 9.34 20.51 68.00 b.d.l. 1.64 99.49 0.79 1.06 2.97 b.d.l. 0.08 4.90 Vareš Q. porphyry albite mean (n=6) 10.11 20.06 68.91 b.d.l. 0.49 99.56 0.85 1.03 3.01 b.d.l. 0.02 4.91 st.dev. 0.55 0.18 0.50 b.d.l. 0.12 0.28 0.05 0.01 0.01 b.d.l. 0.01 0.04 ground- mass albite mean (n=2) 10.35 20.16 68.68 0.31 0.46 99.80 0.87 1.04 2.99 0.02 0.02 4.93 st.dev. 0.18 0.37 0.47 0.00 0.08 0.02 0.01 0.02 0.01 0.00 0.00 0.01 analyses are given in mass%, while the cation numbers are calculated for 8 oxygene b.d.l.: below detection limit; Q.: Quarry U.: Unit Egerbakta Quarry (Szarvaskő Unit) Nagy-Rézoldal Quarry (Darnó Unit) Vareš Quarry porphyry augite (zoned-1) porphyry augite (zoned-2) porphyry augite groundmass augite later diopside groundmass augite groundmass augite mean (n=2) st.dev. mean (n=2) st.dev. (n=1) mean st.dev. mean (n=2) st.dev. mean (n=4) st.dev. mean (n=4) st.dev. MgO 17.35 0.01 19.42 0.23 17.01 16.10 0.52 8.72 0.12 10.10 0.97 15.85 0.29 Al2O3 5.40 0.24 3.56 0.15 3.98 6.25 0.23 2.00 0.00 8.45 0.76 4.90 0.40 SiO2 50.71 0.18 52.77 0.13 51.87 49.66 0.81 51.68 0.67 43.11 1.10 50.87 0.21 CaO 20.22 0.19 18.41 0.42 20.28 19.53 0.19 24.06 0.62 21.84 0.26 20.24 0.50 TiO2 0.51 0.00 0.19 0.03 0.38 0.89 0.05 b.d.l. b.d.l. 5.31 0.53 1.07 0.10 Cr2O3 0.76 0.11 0.38 0.03 0.32 0.19 0.00 0.08 0.00 0.19 0.00 0.31 0.14 Mno 0.19 0.01 0.20 0.01 0.26 0.26 0.01 0.99 0.23 0.18 0.05 0.23 0.02 FeO 4.74 0.04 5.00 0.00 5.02 7.29 0.95 13.10 0.39 10.98 1.14 6.61 0.69 Total 99.86 0.17 99.92 0.46 99.12 100.05 0.42 99.57 0.33 100.01 0.69 100.01 0.20 Mg 0.95 0.01 1.05 0.01 0.93 0.89 0.02 0.50 0.00 0.58 0.05 0.87 0.02 Al 0.24 0.01 0.16 0.01 0.17 0.27 0.01 0.09 0.00 0.38 0.03 0.21 0.02 Si 1.86 0.01 1.91 0.00 1.91 1.83 0.01 1.99 0.03 1.65 0.02 1.87 0.01 Ca 0.80 0.01 0.71 0.01 0.80 0.77 0.00 0.99 0.03 0.90 0.02 0.80 0.02 Ti 0.01 0.00 0.01 0.01 0.01 0.03 0.01 b.d.l. b.d.l. 0.15 0.02 0.03 0.00 Cr 0.02 0.00 0.01 0.00 0.01 0.01 0.00 0.00 0.00 0.01 0.00 0.01 0.01 Mn 0.01 0.00 0.01 0.00 0.01 0.01 0.00 0.04 0.01 0.01 0.01 0.01 0.00 Fe 0.15 0.01 0.15 0.00 0.15 0.23 0.04 0.42 0.01 0.35 0.04 0.20 0.02 Total 4.02 0.01 4.00 0.00 3.99 4.02 0.01 3.98 0.01 4.01 0.01 3.99 0.01 analyses are given in mass%, while the cation numbers are calculated for 6 oxygene b.d.l.: below detection limit Table 3.Results of the SEM-EDS studies (pyroxene analyses). Vol. 69/1 46 type of infilling locality number of measure- ments* Th (mean,°C) scat- te ring (°C) Te (mean, °C) scat- te ring (°C) Tm (mean, C) scat- te ring (°C) salinity (NaCl equiv. wt%) scattering (NaCl equiv. wt.%) amygdales of the closely packed pillow Hosszú Valley Quarry (Darnó Unit) 18 101 11 -20.4 -2.73 0.36 4.54 0.55 Nagy-Rézoldal Quarry (Darnó Unit) 32 136 19 -21.6 0.65 -2.10 0.40 3.49 0.62 pyjamas-type closely packed pillow Hosszú Valley Quarry (Darnó Unit) 25 91 14 -21.3 0.82 -2.70 0.42 4.49 0.65 Mély Valley Quarry (Darnó Unit) 37 92 13 -22.2 0.82 -3.30 1.00 5.33 1.50 jig-saw veins of the closely packed pillow Hosszú Valley Quarry (Darnó Unit) 22 110 18 -21.3 -2.40 0.23 3.95 0.36 interpillow hyaloclastite breccia Hosszú Valley Quarry , earlier cal- cite (Darnó Unit) 10 98 16 -1.90 0.14 3.20 0.23 4 70 5 -2.00 0.17 3.40 0.28 pillow fragmented hyaloclastite breccia Hosszú Valley Quarry, later calcite (Darnó Unit) 27 88 13 -1.79 0.22 3.04 0.36 *: reveals to the no. of Th measurements. Te and Tm data may differ, see text for explanation. Th: homogenisation temperature Te: eutectic temperature Tm: final melting temperature Table 4. Results of the fluid inclusion study. albite in composition (Table 2, Fig. 3A), whereas the augite phenocrysts show compositional zoning due to slight variation in the Ca and Mg content (MORIMOTO, 1989; Table 3, Fig. 3B). Primary hydrothermal infillings are absent in the basalt, though the groundmass is altered to chlorite, clay minerals and calcite. Disseminated pyrite and chalcopyrite also occur in the altered ground mass. The XRPD analyses revealed the prese n- ce of chlorite-smectite, chlorite-illite interlayered clay mine- rals, celadonite and smectite. The Jurassic pillow basalt con- tains neither amygdales, nor jig-saw veins. Only a limited amount of hydrothermal mineral-cemented interpillow hyalo- clastite breccia and cooling related thin, short veinlets occur (Fig. 2D). The peperitic pillow facies The peperitic pillow facies, which formed where the lava rocks were mixed with water soaked sediment (PALINKAŠ et al., 2008, SKILLING et al., 2002), belong to the so-called blocky peperite subtype (SKILLING et al., 2002) at all the studied lo- calities. This volcanic facies is characterised by 10-50 cm large basalt fragments (sometimes of pillow shape) in the matrix (50- 70%), which is a reddish limestone of Triassic age (Fig. 2E), whereas it is a fine grained, black siliciclastic rock in peperites of Jurassic age. The so-called fluidal peperite subtype (SKIL- LING et al., 2002) is locally present (Fig. 2E) and the transition from the closely packed pillow to the peperitic facies also oc- curs in the Triassic localities. The sedimentary material forms not only the matrix of the basalt fragments, but infiltrates into the cooling cracks of the basalt or forms a chaotic mixture with it (Fig. 2F). Where mixing of the volcanic material with uncon- solidated sediments is the most chaotic, a high amount hydro- thermal minerals, such as calcite, quartz, chalcedony, chlorite, pumpellyite and laumontite is present as vein- or cavity-filling. The texture of the Triassic limestone is generally micritic, but it locally contains bioclasts and weakly preserved Radiola- rians, as well as fragments of Bivalve shells. The carbonate matrix characteristically contains disseminated minerals and fragments of basaltic origin (mostly plagioclase laths, glassy shards, rarely pyroxene, Fig. 2F). The limestone also contains disseminated, fine grained (below 3 µm) haematite laths and plates. The siliciclastic sedimentary rock in the Jurassic peperites is completely altered to a fine grained mass of albite-quartz-chal- cedony, but the original sedimentary textural features are pre- served and resemble aleurolite. In both cases, the mineralogical and textural features of ba- salt fragments admixed to the sediments are very similar to the basalt of the closely packed pillow facies, though more glassy parts, as well as haematitisation are more common in the Trias- sic basalts. The thin hydrothermal veinlets contain calcite, prehnite, quartz and chlorite in both occurrences. In addition, albite also occurs in the Jurassic peperite. The amygdales in the Triassic basalt contain calcite, chlorite and haematite, while the jig-saw veins are filled mostly with calcite, with some chlorite, laumontite and prehnite. The in situ hyaloclastite breccia and the pillow fragmented hyaloclastite breccia facies In the in situ hyaloclastite breccia facies only observed in lo- calities of Triassic age, smaller fractured basalt pillows (20-30 cm), and slightly disproportional pillow fragments, are cement- Kiss et al.: Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary... 47 ed by hydrothermal calcite and cogenetic chlorite and pyrite. Glassy basalt shards and occasional pieces of reddish limestone fragments also occur. This facies forms close to the seafloor, immediately around the closely packed pillow facies (PALINKAŠ et al., 2008). It is a transitional facies between the closely packed pillow and the more distal pillow fragmented hyaloclastite breccia facies. The latter is observed at both Trias- sic and Jurassic localities and it contains more matrix and less and smaller basalt fragments than the in situ breccia (Fig. 2G). The hydrothermal cement is composed of quartz, chlorite, cal- cite, prehnite and pumpellyite. Basalt in both breccia facies is characterised with the same features as described above, how- ever, more glassy textures are also common (Fig. 2H). The ba- salt is often strongly chloritised, but in the case of the Triassic ones, haematitisation also occurs. Fluid inclusion study Fluid inclusion studies were performed on calcite from the hy- drothermal infillings. Microthermometric data from some Tri- assic and Jurassic localities are summarised in earlier publica- tions (KISS et al., 2008, 2011, 2012). Here we present micro- thermometric data for the jig-saw veins, interpillow hyaloclas- tite breccia, the pillow fragmented hyaloclastite breccia and some new closely packed pillow occurrences. Interpretation is based on these new data together with that previously pub- lished. In all cases, the calcite often shows a spongy texture, mak- ing observation of the peculiarities of fluid inclusions difficult. Primary fluid inclusions are characterised by a negative crystal shape and are very rare, occurring in isolation in the inclusion poor parts of calcite or in populations of randomly distributed inclusions forming ‘3D clouds” in some parts of the host mine- rals, far from the cleavage-plane related secondary fractures. The size of primary inclusions is generally between 4 - 10 µm, while the phase ratio with 95-90% liquid phase and 5-10% va- pour phase appear to be constant, suggesting homogenous en- trapment from a homogenous parent fluid. The small size of the inclusions, as well as the generally occurring metastable melt- ing during freezing runs resulted in a low amount of microther- mometry data. Figures 5-8. and Table 4. present the results obtained from the amygdale filling calcite, the mineral bands of the pyjama- type pillows, the jig-saw veins, the interpillow hyaloclastite breccia as well as the pillow fragmented hyaloclastite breccia of the Triassic localities. Chlorite thermometry Temperatures of fluid-rock interaction were estimated on the basis of chlorite thermometry from samples of Triassic and Ju- rassic age. Compositions of chlorite occurring in the ground- mass of basalt, forming pseudomorphs after olivine, infilling amygdales and veins and confined to the cement of the interpil- low and the pillow fragmented hyaloclastite breccia, were de- termined by electron microprobe analyses. Results indicate that all chlorite samples belong to the Type I, Mg-chlorite group, defined by ZANE & WEISS (1998). Table 5. shows the compo- sitions and calculated formation temperatures of chlorite crys- tals of different textural positions (CHATELINEAU & IZQUI- ERDO, 1988 and ZANG & FYFE, 1995). Geochemical features of the fluid/rock interaction The results of the analyses for most major elements (Ca, Mg, Na, K, Fe, Mn) as well as some precious and base metal trace elements (e.g. Au, Cu, Zn) and the LILE group of trace ele- ments show highly variable amounts and scattering on the spider diagram. In contrast, Si, Al, Cr, Ti, the HFS and REE group of trace elements do not scatter significantly, when comparing the less and more altered samples in our database (Table 6 and Fig. 9 A, B, C, D). As a consequence, the spider diagram of the REE shows two narrow, distinguishable fields of results, one for the Trias- sic and one for the Jurassic basalts (Fig. 9 C, D). Enrichment in LREE, thus a higher La/Sm ratio (above 1) is characteristic for the Triassic basalts, while a lower La/Sm ratio (around or below 1) is typical for the Jurassic basalts indicating their dif- ferent origins (WILSON, 1989). This topic has been exhaus- tively discussed in previous publications (see e.g. KISS et al., 2011, 2012 and references therein), therefore the data is eva- luated herein terms of the fluid/rock interactions, with dai- grams presented only for comparison with the earlier results. Discrimination diagrams based on rather immobile ele- ments by PEARCE & CANN (1973) and MESCHEDE (1986) prove the different geotectonic position of the basaltic rocks of Triassic and Jurassic ages (Fig. 9EF). Enrichment in the incompatible elements in the Triassic basalt shows relatively low partial melting, which together with the high Zr/Y ratio (generally above 4) supports the idea that this basalt is not related to mid-oceanic ridges (SUN & MCDONOUGH, 1989). Geochemical analyses of the peperitic limestone are shown in Table 7. Mass transfer calculation (MTC, GRANT, 1986, MA- CLEAN & KRANIDIOTIS, 1987, BRAUHART et al., 2001, ULRICH & HEINRICH, 2002), which is widely accepted in ore deposit exploration, can also efficiently be used for quan- titative modelling of element mobilisation occurring during submarine hydrothermal fluid-rock interaction processes. The calculations may be done on different scales; within a single pillow (from its centre to its margin), within a volcanic facies (from less to more altered parts) and for comparison of two or more volcanic facies. The present study shows the prelimi- nary results of these calculations; a few examples for all these different scales. According to the MTC method, after determining the freshest samples in the data set, the most immobile compo- nents have to be determined. In the present study, we used the isocon method and thus Y, Zr, Nb and TiO2 were found to be the most immobile components. Then the residual composi- tions of the altered samples were calculated, followed by de- termination of the gains/losses of mass. Only data sets origi- nating from the same locality (thus rocks from the same pro- toliths) were compared and used for MTC calculations (Fig. 10). Generally, a decrease in SiO2, CaO and the analysed me- tals and a slight increase in Na2O and K2O are observable in- dependently of the scale of observation. Special features may be also identified (e.g. the amount of mass transfered is sig- nificantly higher when heading to the peperitic facies; see Fig. 10). Vol. 69/1 48 Hosszú Valley Quarry (Darnó Unit) Mély Valley Quarry (Darnó Unit) ground- mass chlorite chlorite in amyg- dales chlorite in the ma- trix of the pillow fragmented hyalo- clastite breccia chlorite in pseudo- morphs after olivine chlorite in the matrix of the inter- pillow hyaloclastite breccia chlorite in thin veinlets of the closely packed pil- low facies (type 1) chlorite in thin veinlets of the closely packed pil- low facies (type 2) (n=1) mean (n=2) st.dev. mean (n=6) st.dev. mean (n=2) st.dev. mean (n=6) st.dev. mean (n=8) st.dev. mean (n=4) st.dev. SiO2 29.03 30.16 0.15 29.86 0.30 30.86 1.15 30.35 1.64 29.57 0.84 33.35 1.48 TiO2 0.08 0.02 0.01 0.04 0.04 0.51 0.70 0.02 0.00 0.08 0.02 0.11 0.01 Al2O3 17.56 17.00 0.14 18.09 0.21 17.42 0.36 19.61 0.89 19.20 0.54 18.56 0.55 Cr2O3 0.11 0.02 0.00 0.01 0.01 0.02 0.00 0.01 0.01 0.08 0.02 0.11 0.02 FeOT 18.65 17.92 0.20 20.39 0.22 19.39 1.45 13.77 0.73 17.26 0.54 15.69 0.48 MnO 0.38 0.45 0.01 0.29 0.03 0.26 0.07 0.61 0.04 1.53 0.09 1.62 0.16 MgO 19.59 19.70 0.29 18.79 0.27 18.62 1.16 21.44 0.81 18.92 0.93 18.19 0.23 CaO 0.33 1.37 0.18 0.38 0.12 1.54 1.59 0.44 0.10 0.55 0.42 0.42 0.09 Na2O 0.05 0.06 0.07 0.06 0.02 0.10 0.05 0.05 0.02 n.a. n.a. n.a. n.a. K2O 0.06 0.05 0.00 0.07 0.02 0.13 0.06 0.37 0.59 0.03 0.01 0.09 0.04 V2O3 b.d.l. 0.05 0.01 0.02 0.01 0.01 0.00 0.01 0.01 n.a. n.a. n.a. n.a. NiO 0.02 0.08 0.06 0.05 0.03 0.05 0.00 0.21 0.05 n.a. n.a. n.a. n.a. ZnO b.d.l. 0.17 0.06 0.13 0.07 0.16 0.06 0.15 0.09 n.a. n.a. n.a. n.a. Cl 0.02 0.02 0.00 0.01 0.00 0.01 0.00 0.02 0.01 0.02 0.01 0.02 0.01 F b.d.l. b.d.l. b.d.l. 0.01 0.01 0.05 0.00 0.01 0.01 n.a. n.a. n.a. n.a. Total 85.88 87.00 0.45 88.13 0.45 89.06 0.98 86.99 1.73 87.24 0.46 88.13 1.83 Cation numbers calculated for 14 oxygene: Si 3.01 3.08 0.00 3.04 0.03 3.10 0.06 3.03 0.09 3.00 0.07 3.29 0.07 Al (IV) 0.99 0.92 0.00 0.96 0.03 0.90 0.06 0.97 0.09 1.00 0.07 0.71 0.07 Total (IV) 4.00 4.00 0.00 4.00 0.00 4.00 0.00 4.00 0.00 4.00 0.00 4.00 0.00 Al (VI) 1.16 1.13 0.00 1.20 0.02 1.16 0.06 1.33 0.13 1.30 0.09 1.45 0.06 Ti 0.01 0.00 0.00 0.00 0.00 0.04 0.05 0.00 0.00 0.01 0.00 0.01 0.00 Cr 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.01 0.00 Fe 1.62 1.53 0.03 1.73 0.02 1.63 0.15 1.15 0.08 1.47 0.05 1.29 0.05 Mn 0.03 0.04 0.00 0.03 0.00 0.02 0.01 0.05 0.00 0.13 0.01 0.13 0.01 Mg 3.03 3.00 0.02 2.85 0.04 2.79 0.22 3.19 0.18 2.87 0.15 2.68 0.07 Ca 0.04 0.15 0.02 0.04 0.01 0.16 0.17 0.05 0.01 0.06 0.04 0.04 0.01 K 0.01 0.01 0.00 0.01 0.00 0.02 0.01 0.05 0.07 0.00 0.00 0.01 0.01 Na 0.01 0.01 0.01 0.01 0.00 0.02 0.01 0.01 0.00 n.a. n.a. n.a. n.a. V b.d.l. 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 n.a. n.a. n.a. n.a. Ni 0.01 0.03 0.02 0.02 0.01 0.02 0.00 0.07 0.02 n.a. n.a. n.a. n.a. Zn b.d.l. 0.05 0.02 0.04 0.02 0.05 0.02 0.04 0.03 n.a. n.a. n.a. n.a. Total (VI) 5.91 5.88 0.01 5.88 0.02 5.84 0.12 5.82 0.07 5.84 0.07 5.62 0.06 vacancy 0.09 0.12 0.01 0.12 0.02 0.16 0.12 0.18 0.07 0.16 0.07 0.38 0.06 XFe 0.34 0.32 0.01 0.37 0.00 0.35 0.02 0.26 0.01 0.32 0.01 0.31 0.00 Mg+FetTot 4.65 4.54 0.00 4.58 0.05 4.42 0.38 4.34 0.26 4.33 0.19 3.97 0.11 Al+vacancy 1.25 1.26 0.00 1.33 0.04 1.32 0.18 1.51 0.20 1.46 0.15 1.82 0.12 Nomencla- tura of Zane and Weiss (1998): Type 1. 1 1. 1. 1. 1. 1. Name* Mg Mg Mg Mg Mg Mg Mg Thermo- metry: T (oC) (C&I-1988) 256 233 2 252 30 259 22 167 23 T (oC) (Z&F-1995) 221 5 216 0 Table 5. Results of the EPMA quantitative analyses of the chlorite crystals. Analyses are given in mass% *: Mg: magnesium chlorite Thermometry based on C&I-1988: Chatelineau and Izquierdo, 1988; Z&F-1995: Zang and Fyfe, 1995 **: though slightly differers from the criteria of the given method, based on Frimmel (1997) the data still can be used for calcula- tions. (n.a.: not available; b.d.l.: below detection limit, st.dev.: standard deviation) ***: only one analyses fit into the criteria of the thermometry methods, therefore mean and standard deviation were not calculated. Kiss et al.: Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary... 49 Nagy-Rézoldal Quarry (Darnó Unit) Stragopetra Mts. chlorite in small (only chlorite filled) amygdales chlorite in small amygdales groundmass chlorite chlorite in pseu- domorphs after olivine chlorite in thin veinlets of the closely packed pillow facies chlorite on the rims of the big amygdales chlorite on the rims of the jig-saw veins chlorite in thin veinlets of the closely packed pillow facies mean (n=13) st.dev. mean (n=3) st.dev. mean (n=3) st.dev. mean (n=3) st.dev. mean (n=2) st.dev. mean (n=3) st.dev. mean (n=3) st.dev. mean (n=3) st.dev. SiO2 30.53 0.42 30.60 0.25 31.33 1.85 28.94 0.30 29.73 0.73 29.60 0.64 30.10 0.90 26.97 1.74 TiO2 0.02 0.01 0.01 0.00 0.03 0.01 0.02 0.01 0.02 0.00 0.01 0.00 0.02 0.00 0.02 0.00 Al2O3 16.78 0.42 17.19 0.15 17.09 0.88 18.46 0.45 17.82 0.54 18.14 0.51 18.12 0.77 17.26 0.68 Cr2O3 0.09 0.05 0.03 0.01 0.08 0.01 0.11 0.04 0.03 0.01 0.03 0.01 0.02 0.01 0.01 0.00 FeOT 20.74 0.42 20.98 0.25 22.88 1.40 24.08 0.51 23.41 0.04 23.57 0.09 23.72 0.27 23.25 1.36 MnO 0.32 0.05 0.34 0.04 0.26 0.07 0.26 0.03 0.30 0.04 0.26 0.05 0.28 0.04 0.57 0.02 MgO 16.67 0.35 16.63 0.14 16.60 0.16 16.24 0.53 17.04 0.66 16.68 0.35 16.49 0.86 15.14 0.47 CaO 0.31 0.03 0.33 0.01 0.40 0.13 0.21 0.03 0.27 0.02 0.22 0.04 0.24 0.04 2.23 2.03 Na2O n.a. n.a. n.a. n.a. 0.10 0.08 0.03 0.02 0.06 0.01 0.01 0.00 0.06 0.01 0.06 0.05 K2O 0.01 0.01 0.02 0.01 0.05 0.03 0.09 0.06 0.04 0.00 0.03 0.01 0.15 0.21 0.14 0.13 V2O3 n.a. n.a. n.a. n.a. 0.03 0.02 0.03 0.02 0.01 0.01 0.02 0.01 0.02 0.01 0.03 0.01 NiO n.a. n.a. n.a. n.a. 0.07 0.04 0.05 0.01 0.04 0.01 0.06 0.01 0.06 0.04 0.05 0.02 ZnO n.a. n.a. n.a. n.a. 0.14 0.12 0.10 0.09 0.08 0.06 0.08 0.08 0.06 0.00 0.15 0.07 Cl 0.01 0.01 0.02 0.01 0.02 0.01 b.d.l. b.d.l. 0.02 0.00 0.02 0.00 0.01 0.00 0.02 0.01 F n.a. n.a. n.a. n.a. b.d.l. b.d.l. b.d.l. b.d.l. b.d.l. 0.00 b.d.l. b.d.l. b.d.l. b.d.l. 0.01 0.00 Total 85.46 0.94 86.13 0.02 89.05 0.44 88.58 0.77 88.79 0.71 88.66 0.49 89.25 0.27 85.82 1.31 Cation numbers calculated for 14 oxygene: Si 3.20 0.03 3.18 0.02 3.18 0.16 2.99 0.01 3.05 0.04 3.04 0.05 3.07 0.08 2.91 0.12 Al (IV) 0.80 0.03 0.82 0.02 0.82 0.16 1.01 0.01 0.95 0.04 0.97 0.04 0.93 0.08 1.09 0.12 Total (IV) 4.00 0.00 4.00 0.00 4.00 0.00 4.00 0.00 4.00 0.00 4.00 0.00 4.00 0.00 4.00 0.00 Al (VI) 1.27 0.03 1.29 0.01 1.23 0.04 1.23 0.06 1.20 0.04 1.23 0.03 1.24 0.06 1.11 0.14 Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cr 0.01 0.00 0.00 0.00 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe 1.82 0.02 1.82 0.03 1.94 0.14 2.08 0.03 2.01 0.02 2.02 0.02 2.02 0.04 2.10 0.12 Mn 0.03 0.00 0.03 0.00 0.02 0.01 0.02 0.00 0.03 0.00 0.02 0.00 0.02 0.00 0.05 0.00 Mg 2.60 0.04 2.58 0.02 2.51 0.01 2.50 0.06 2.60 0.07 2.55 0.04 2.50 0.12 2.44 0.05 Ca 0.03 0.00 0.04 0.00 0.04 0.01 0.02 0.00 0.03 0.00 0.02 0.00 0.03 0.00 0.26 0.24 K 0.00 0.00 0.00 0.00 0.01 0.00 0.01 0.01 0.01 0.00 0.00 0.00 0.02 0.03 0.02 0.02 Na n.a. n.a. n.a. n.a. 0.02 0.01 0.01 0.00 0.01 0.00 0.00 0.00 0.01 0.00 0.01 0.01 V n.a. n.a. n.a. n.a. 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ni n.a. n.a. n.a. n.a. 0.02 0.01 0.02 0.00 0.01 0.00 0.02 0.00 0.02 0.01 0.02 0.01 Zn n.a. n.a. n.a. n.a. 0.04 0.04 0.03 0.03 0.02 0.02 0.02 0.02 0.02 0.00 0.05 0.02 Total (VI) 5.76 0.02 5.76 0.01 5.79 0.09 5.88 0.03 5.88 0.00 5.86 0.02 5.85 0.04 5.99 0.13 vacancy 0.24 0.02 0.24 0.01 0.21 0.09 0.12 0.03 0.12 0.00 0.14 0.02 0.15 0.04 0.01 0.13 XFe 0.41 0.00 0.41 0.00 0.43 0.02 0.45 0.00 0.43 0.01 0.44 0.01 0.44 0.01 0.43 0.02 Mg+FetTot 4.42 0.05 4.40 0.02 4.46 0.15 4.58 0.09 4.61 0.05 4.57 0.03 4.53 0.10 4.54 0.17 Al+vacancy 1.51 0.05 1.53 0.02 1.44 0.13 1.35 0.09 1.32 0.05 1.37 0.03 1.39 0.07 1.11 0.27 Nomencla- tura of Zane and Weiss (1998): Type 1. 1. 1. 1. 1. 1. 1. 1. Name* Mg Mg Mg Mg Mg Mg Mg Mg Thermo- metry: T (oC) (C&I-1988) T (oC) (Z&F-1995) 174** 25 185** 4 221*** 223 2 212 4 213 9 215 9 240 26 Table 5. Results of the EPMA quantitative analyses of the chlorite crystals. Analyses are given in mass% *: Mg: magnesium chlorite Thermometry based on C&I-1988: Chatelineau and Izquierdo, 1988; Z&F-1995: Zang and Fyfe, 1995 **: though slightly differers from the criteria of the given method, based on Frimmel (1997) the data still can be used for calcula- tions. (n.a.: not available; b.d.l.: below detection limit, st.dev.: standard deviation) ***: only one analyses fit into the criteria of the thermometry methods, therefore mean and standard deviation were not calculated. Vol. 69/1 50 D ar nó U ni t Sz ar va sk ő U ni t L oc al ity B áj -p at ak N or th Q ua rr y H os sz ú Va lle y Q ua rr y M él y Va lle y Q ua rr y R es zé l R id ge Q ua rr y R M -1 36 dr ill co re E ge rb ak ta Q ua rr y R es zé l R id ge N or th , va lle y Sz ar va sk ő vi lla ge (n at ur al o ut cr op s) R M -1 36 dr ill co re R oc k ty pe cl os el y pa ck ed pi llo w pe pe ri tic ba sa lt cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w (p ro ve n Tr ia ss ic ) ce nt re o f a pi llo w tr an si tio n zo ne o f a pi llo w m ar gi n of a pi llo w pe - pe ri tic ba sa lt pr ov en T ri - as si c pi llo w ba sa lt cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w pe pe ri tic ba sa lt cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w pr ov en Ju ra ss ic pi llo w ba sa lt Sa m pl e 1* 2* 1* 2* 1* 1* 2* 3* 4* 1* 1* * 2* * 3* 1* * 2* 1* 2* * 3* * 4* * 5* * 1* Si O 2 46 .6 42 .2 37 .8 4 40 .2 41 .0 33 .4 38 .4 51 .6 47 .1 47 .8 54 .3 53 .6 53 .2 51 52 .3 47 .8 49 .4 50 .3 46 .7 49 .3 47 .5 A l 2O 3 15 .6 14 .8 20 .7 53 20 .4 16 .7 23 .2 12 .6 16 .8 18 .8 21 .2 13 .9 5 13 .7 5 15 .8 16 .4 5 15 .7 15 .8 14 .5 13 .9 5 14 .8 14 .4 5 22 .4 Fe 2O 3 3. 01 3. 02 8. 35 7. 66 4 2. 79 6. 85 5. 38 2. 35 7. 23 6. 85 9. 11 8. 66 9. 38 10 1. 98 3. 61 11 .8 10 .9 12 .6 5 11 .6 4. 67 Fe O ** * 6. 15 4. 54 n. a. n. a. 8. 93 1. 78 2. 09 2. 10 n. a. 1. 58 n. a. n. a. n. a. n. a. 6. 08 7. 38 n. a. n. a. n. a. n. a. 4. 47 C aO 8. 72 10 .2 12 .1 10 .9 23 7. 72 11 .5 14 .4 5. 96 4. 80 3. 18 7. 6 7. 76 4. 74 7. 09 7. 48 10 .0 10 .1 8. 19 6. 63 10 .3 5 4. 21 M gO 5. 46 4. 32 2. 14 1. 83 5 5. 60 5. 64 6. 10 4. 70 4. 28 2. 64 5. 69 6. 58 5. 99 5. 03 6. 28 6. 96 6. 84 6 7. 48 6. 73 4. 37 N a 2O 2. 53 3. 98 3. 21 0 3. 23 3. 77 3. 16 4. 17 7. 47 6. 17 4. 64 5. 04 5. 25 6. 32 5. 57 5. 29 2. 54 3. 33 4. 19 3. 05 3. 29 4. 85 K 2O 0. 51 1 0. 92 9 1. 31 1. 94 4 0. 23 9 <0 .2 <0 .2 0. 26 4 1. 12 3. 56 0. 03 0. 01 <0 .2 0. 05 <0 .2 0. 37 7 0. 17 0. 04 0. 13 0. 16 <0 .2 C r 2O 3 n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. 0. 02 0. 03 n. a. 0. 02 n. a. n. a. 0. 04 0. 03 0. 03 0. 04 n. a. Ti O 2 2. 10 2. 00 1. 89 0 2. 02 8 1. 86 0. 64 5 0. 72 8 1. 02 2. 10 1. 37 0. 82 0. 79 0. 82 3 1 0. 82 6 1. 62 1. 66 1. 56 1. 29 1. 58 1. 43 M nO 0. 11 2 0. 10 1 0. 10 0 0. 09 6 1. 22 0. 11 8 0. 12 6 0. 08 1 0. 07 7 0. 02 9 0. 16 0. 15 0. 14 5 0. 14 0. 14 6 0. 18 0 0. 18 0. 19 0. 69 0. 18 0. 25 8 P 2O 5 0. 25 8 0. 33 2 0. 36 3 0. 60 8 0. 26 0 <0 .1 5 <0 .1 5 <0 .1 5 0. 29 1 0. 27 5 0. 07 0. 04 <0 .1 5 0. 07 <0 .1 5 <0 .1 5 0. 16 0. 17 0. 1 0. 15 <0 .1 5 Sr O 0. 02 6 0. 03 5 0. 02 4 0. 02 4 0. 01 5 0. 02 4 0. 03 3 0. 03 7 0. 07 4 0. 01 6 0. 01 0. 01 0. 01 5 0. 01 0. 01 7 0. 01 3 0. 03 0. 03 0. 01 0. 03 0. 01 7 B aO 0. 00 7 0. 01 1 0. 01 6 0. 01 7 0. 00 6 <0 .0 05 <0 .0 05 0. 00 7 0. 01 6 0. 01 2 0. 01 <0 .0 1 0. 00 6 <0 .0 1 0. 00 8 <0 .0 05 <0 .0 1 0. 01 <0 .0 1 <0 .0 1 <0 .0 05 C n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. 0. 1 0. 04 n. a. 0. 06 n. a. n. a. 0. 01 0. 04 0. 46 0. 02 n. a. S n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. 0. 03 0. 05 n. a. 0. 01 n. a. n. a. 0. 1 0. 02 0. 04 0. 06 n. a. A g n. a. n. a. <0 .2 <0 .2 n. a. n. a. n. a. n. a. <0 .1 n. a. <1 <1 <0 .1 <1 <0 .1 0. 29 <1 <1 <1 <1 n. a. B a 62 .7 98 .5 14 3. 3 15 2. 3 53 .7 <4 4. 8 <4 4. 8 62 .7 14 3. 3 10 7. 5 76 .6 48 .8 53 .7 65 .9 71 .7 <4 4. 8 10 .9 56 .5 70 .8 14 .2 <4 4. 8 C d 0. 11 0 <0 .1 0 <0 .0 6 <0 .0 6 <0 .1 0 0. 27 4 0. 20 1 <0 .1 0 <0 .0 6 <0 .1 0 n. a. n. a. <0 .0 6 n. a. <0 .0 6 <0 .0 6 n. a. n. a. n. a. n. a. 0. 15 3 C e 30 .6 26 .1 37 .4 47 .0 40 .9 5. 71 6. 30 6. 84 27 .0 23 .4 6. 4 6. 8 3. 83 12 .2 4. 91 12 .9 16 15 .4 16 .4 18 .9 10 .5 C o 47 .5 42 .6 36 .7 28 .0 43 .8 44 .5 41 .9 36 .3 49 .4 27 .5 33 .4 36 .5 42 .8 34 41 .2 50 .8 46 .2 40 .4 66 .7 56 .3 36 .8 C r 19 4 18 5 17 2 18 5 26 3 61 8 37 5 50 7 31 1 91 .5 11 0 24 0 15 3 10 0 16 9 23 8 27 0 19 0 22 0 33 0 80 .8 C s 0. 42 6 0. 44 3 1. 20 1. 76 0. 53 1 1. 56 1. 04 0. 79 0 4. 06 7. 27 0. 08 0. 05 <0 .2 5 0. 13 <0 .2 5 0. 47 0. 56 0. 3 1. 5 0. 72 0. 32 8 C u 50 .7 38 .5 20 .2 19 .6 56 .2 47 .0 99 .6 74 .5 40 .8 1. 15 61 44 62 .3 62 62 .6 51 .7 72 41 11 6 92 55 .2 D y 4. 87 4. 32 5. 61 7. 54 5. 50 2. 07 2. 21 2. 62 5. 22 3. 29 3. 85 3. 71 2. 68 4. 25 3. 28 5. 87 7. 3 6. 65 6. 27 8. 46 4. 62 E r 2. 99 2. 81 3. 42 4. 57 3. 46 1. 36 1. 48 1. 93 3. 14 2. 12 2. 42 2. 33 1. 68 2. 67 2. 11 3. 52 4. 56 4. 25 4 5. 34 3. 15 E u 1. 73 1. 51 1. 54 2. 19 2. 20 0. 55 2 0. 60 3 0. 62 0 1. 52 1. 11 0. 81 0. 88 0. 46 1. 04 0. 63 1. 31 1. 63 1. 67 1. 64 2. 01 0. 97 3 G a n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. 15 .6 13 .2 n. a. 19 .3 n. a. n. a. 20 .9 20 .4 22 .8 25 .8 n. a. G d 7. 02 6. 17 5. 39 7. 59 8. 12 2. 37 2. 51 2. 71 4. 79 4. 76 2. 87 2. 91 1. 83 3. 53 2. 32 4. 36 5. 92 5. 26 5. 21 6. 88 5. 07 H f n. a. n. a. 3. 72 4. 23 n. a. n. a. n. a. n. a. <0 .5 n. a. 1. 3 2. 1 <0 .5 5. 3 <0 .5 <0 .5 5. 5 4. 7 3. 7 6 n. a. H o 1. 07 0. 96 1. 16 1. 58 1. 21 0. 45 5 0. 48 2 0. 64 8 1. 17 0. 68 8 0. 81 0. 76 0. 60 0. 92 0. 78 1. 35 1. 53 1. 39 1. 33 1. 88 1. 08 L a 13 .5 11 .0 17 .8 22 .4 12 .2 2. 24 2. 31 2. 41 10 .4 9. 54 2. 3 2. 5 1. 38 4. 6 1. 80 4. 44 5. 4 5. 5 6. 9 6. 2 3. 93 L u 0. 45 5 0. 38 7 0. 42 3 0. 61 2 0. 51 1 <0 .2 5 <0 .2 5 0. 29 4 0. 38 0. 28 7 0. 34 0. 31 0. 25 0. 36 0. 29 0. 50 0. 6 0. 55 0. 54 0. 72 0. 46 8 M o 0. 77 7 0. 88 1 1. 10 1. 28 0. 70 4 <0 .2 5 <0 .2 5 <0 .2 5 <0 .2 0. 21 8 <2 <2 <0 .2 <2 0. 49 5 <0 .2 <2 <2 <2 <2 0. 37 2 N b 12 .0 12 .6 23 .3 25 .1 7. 02 1. 10 1. 28 1. 76 13 .0 5. 19 0. 9 1. 4 <0 .2 5 2. 1 <0 .2 5 1. 75 3. 5 3. 2 2. 8 4 2. 98 N d 19 .1 17 .3 19 .0 26 .8 23 .5 4. 29 4. 85 5. 73 18 .0 15 .6 5. 6 6 3. 72 8. 4 4. 93 11 .1 13 .7 13 .1 12 .5 16 .7 9. 65 N i 11 1 11 2 75 .5 64 .3 76 .1 38 7 24 0 21 1 14 3 46 .1 37 83 54 .4 47 60 .4 64 .7 69 61 29 2 95 44 .7 Pb 0. 54 <0 .2 5 <0 .6 <0 .6 4. 55 <0 .2 5 <0 .2 5 <0 .2 5 <0 .6 6. 19 <5 <5 <0 .6 <5 <0 .6 <0 .6 n. a. n. a. n. a. n. a. 1. 74 Pr 4. 29 3. 63 4. 77 6. 51 5. 28 0. 87 8 0. 99 1 1. 16 3. 90 3. 53 n. a. 1. 06 0. 63 1. 69 0. 86 2. 11 2. 61 2. 45 2. 39 3. 11 1. 82 R b 7. 30 12 .4 26 .9 36 .0 3. 54 0. 85 1. 46 2. 31 28 .1 10 7 0. 7 0. 6 <0 .2 5 0. 8 <0 .2 5 5. 89 4. 8 1. 1 4. 4 5. 8 1. 05 Sm 5. 08 4. 72 4. 59 6. 28 6. 15 1. 42 1. 56 1. 91 4. 96 4. 10 2. 02 2. 07 1. 66 2. 73 1. 83 3. 89 4. 52 4. 01 3. 84 5. 47 3. 45 Ta bl e 6. R es ul ts o f t he g eo ch em ic al a na ly se s ( ba sa lt) . Kiss et al.: Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary... 51 D ar nó U ni t Sz ar va sk ő U ni t L oc al ity B áj -p at ak N or th Q ua rr y H os sz ú Va lle y Q ua rr y M él y Va lle y Q ua rr y R es zé l R id ge Q ua rr y R M -1 36 dr ill co re E ge rb ak ta Q ua rr y R es zé l R id ge N or th , va lle y Sz ar va sk ő vi lla ge (n at ur al o ut cr op s) R M -1 36 dr ill co re R oc k ty pe cl os el y pa ck ed pi llo w pe pe ri tic ba sa lt cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w (p ro ve n Tr ia ss ic ) ce nt re o f a pi llo w tr an si tio n zo ne o f a pi llo w m ar gi n of a pi llo w pe - pe ri tic ba sa lt pr ov en T ri - as si c pi llo w ba sa lt cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w pe pe ri tic ba sa lt cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w cl os el y pa ck ed pi llo w pr ov en Ju ra ss ic pi llo w ba sa lt Sn 1. 00 0. 53 7 3. 71 2. 39 3. 24 <0 .5 <0 .5 <0 .5 3. 74 <0 .5 n. a. n. a. 4. 76 n. a. 3. 19 4. 16 n. a. n. a. n. a. n. a. 0. 55 7 Sr 21 9. 9 29 6. 0 20 2. 9 20 2. 9 12 6. 8 20 2. 9 27 9. 0 31 2. 9 62 5. 7 13 5. 3 12 5 87 .2 12 6. 8 13 0. 5 14 3. 8 10 9. 9 31 9 29 3 18 2 39 1 14 3. 8 Ta 0. 93 8 0. 99 3 5. 97 6. 28 0. 58 0 <0 .2 5 <0 .2 5 0. 13 3 1. 20 0. 38 4 0. 1 0. 1 <0 .2 5 0. 1 <0 .2 5 <0 .2 5 0. 2 0. 2 0. 2 0. 3 <0 .2 5 T b 0. 88 8 0. 78 9 0. 91 1. 28 0. 99 8 0. 35 9 0. 35 7 0. 40 3 0. 85 0. 57 6 0. 57 0. 55 0. 36 0. 62 0. 44 0. 91 1. 1 0. 99 0. 97 1. 29 0. 74 2 T h 1. 29 1. 24 1. 77 1. 89 0. 65 2 0. 42 <0 .2 5 <0 .2 5 3. 48 3. 52 0. 36 0. 3 2. 62 n. a. 2. 63 2. 61 0. 39 0. 44 0. 31 0. 46 0. 30 T l <0 .1 0 <0 .1 0 0. 10 6 0. 16 8 <0 .1 0 <0 .1 0 <0 .1 0 <0 .1 0 <0 .1 0. 42 0 <0 .5 <0 .5 <0 .1 <0 .5 <0 .1 <0 .1 <0 .5 <0 .5 <0 .5 <0 .5 <0 .1 0 T m 0. 47 5 0. 42 9 0. 46 2 0. 67 9 0. 56 5 0. 22 6 0. 25 1 0. 30 6 0. 49 0. 32 5 0. 37 0. 31 0. 26 0. 36 0. 33 0. 57 0. 66 0. 6 0. 56 0. 79 0. 51 2 U 0. 37 1 0. 52 5 0. 50 0 0. 50 3 <0 .2 5 <0 .2 5 <0 .2 5 0. 44 5 0. 62 0. 69 6 0. 1 0. 06 0. 42 0. 16 <0 .2 5 <0 .2 5 0. 14 0. 14 0. 09 0. 14 <0 .2 5 V 31 7 30 3 19 9 19 4 36 7 16 4 14 8 12 6 n. a. 14 7 25 6 23 0 n. a. 29 2 n. a. n. a. 34 9 33 5 30 0 43 3 33 7 W <0 .2 5 <0 .2 5 <0 .2 5 <0 .2 5 0. 64 <0 .2 5 <0 .2 5 <0 .2 5 0. 85 <0 .2 5 <1 n. a. 0. 90 n. a. 0. 87 0. 81 n. a. n. a. n. a. n. a. 0. 72 Y 27 .6 24 .7 26 .6 36 .5 32 .7 12 .5 13 .0 16 .0 27 .2 17 .8 20 20 .8 13 .5 23 .4 18 .1 30 .9 40 .2 37 .1 35 .4 48 .8 27 .5 Y b 2. 61 2. 38 3. 16 4. 06 3. 15 1. 25 1. 38 1. 77 2. 79 1. 78 2. 33 2. 21 1. 67 2. 52 2. 11 3. 47 4. 3 3. 86 3. 69 5. 01 2. 89 Z n 81 .8 68 .7 85 .6 70 .4 98 .2 58 .1 72 .2 38 .9 68 .3 78 .8 70 64 65 .1 90 66 .5 92 .5 10 9 95 12 0 13 5 86 .7 Z r 16 1 15 7 12 9 13 6 14 0 42 .0 49 .1 69 .8 13 0 10 8 45 72 39 .3 21 5 38 .1 97 .0 21 2 17 8 13 3 23 2 94 .2 A s n. a. n. a. 8. 48 9. 11 n. a. n. a. n. a. n. a. 4. 28 n. a. 3. 5 2. 4 62 .1 0. 9 2. 88 <0 .6 0. 2 0. 2 2. 8 0. 1 n. a. B i <0 .2 5 <0 .2 5 <0 .2 5 <0 .2 5 <0 .2 5 <0 .2 5 <0 .2 5 <0 .2 5 <0 .2 5 <0 .2 5 0. 05 0. 01 <0 .2 5 0. 04 <0 .2 5 <0 .2 5 0. 03 0. 01 0. 01 0. 01 <0 .2 5 H g n. a. n. a. 0. 00 4 0. 00 2 n. a. n. a. n. a. n. a. 0. 01 5 n. a. 0. 02 8 0. 00 8 0. 00 9 0. 01 6 0. 00 8 0. 00 8 0. 00 8 0. 01 2 0. 02 0. 01 1 n. a. Sb 0. 66 1 <0 .1 0 <1 <1 0. 65 8 0. 49 1 0. 26 6 0. 23 1 1. 39 1. 87 0. 06 <0 .0 5 6. 95 <0 .0 5 2. 50 4. 73 <0 .0 5 0. 07 0. 19 <0 .0 5 0. 23 9 Se n. a. n. a. <0 .6 <0 .6 n. a. n. a. n. a. n. a. <0 .6 n. a. 0. 6 0. 6 6. 06 0. 8 <0 .6 <0 .6 0. 8 0. 8 0. 8 0. 6 n. a. Te n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. 0. 02 <0 .0 1 n. a. <0 .0 1 n. a. n. a. 0. 01 <0 .0 1 <0 .0 1 <0 .0 1 n. a. A u n. a. n. a. <0 .0 02 <0 .0 02 n. a. n. a. n. a. n. a. <0 .0 02 n. a. 0. 00 3 <0 .0 01 <0 .0 02 0. 00 6 <0 .0 02 <0 .0 02 0. 00 8 0. 00 1 <0 .0 01 <0 .0 01 n. a. Pt n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. <0 .0 2 <0 .0 05 n. a. <0 .0 2 n. a. n. a. 0. 06 <0 .0 2 <0 .0 05 <0 .0 05 n. a. Pd n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. <0 .0 2 0. 00 1 n. a. <0 .0 2 n. a. n. a. 0. 07 <0 .0 2 0. 00 1 <0 .0 01 n. a. O s n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. <0 .0 1 n. a. n. a. <0 .0 1 n. a. n. a. <0 .0 1 <0 .0 1 n. a. n. a. n. a. R u n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. <0 .0 5 n. a. n. a. <0 .0 5 n. a. n. a. <0 .0 5 <0 .0 5 n. a. n. a. n. a. Ir n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. <0 .0 01 n. a. n. a. <0 .0 01 n. a. n. a. 0. 00 1 <0 .0 01 n. a. n. a. n. a. R h n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. <0 .0 05 n. a. n. a. <0 .0 05 n. a. n. a. <0 .0 05 <0 .0 05 n. a. n. a. n. a. _H 2O 0. 88 1. 52 0. 15 0. 19 0. 38 0. 69 0. 61 0. 25 n. a. 0. 78 n. a. n. a. n. a. n. a. 0. 27 0. 25 n. a. n. a. n. a. n. a. 0. 76 +H 2O 5. 44 3. 77 3. 96 4. 52 5. 66 4. 21 4. 09 3. 10 n. a. 4. 07 n. a. n. a. n. a. n. a. 3. 30 3. 00 n. a. n. a. n. a. n. a. 3. 82 C O 2 2. 45 7. 73 4. 07 2. 29 3. 72 8. 59 11 .1 4. 15 n. a. 1. 92 n. a. n. a. n. a. n. a. 0. 21 4 <0 .0 2 n. a. n. a. n. a. n. a. 1. 15 L O I n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. n. a. 3. 13 3. 05 n. a. 3. 42 n. a. n. a. 2. 24 3. 22 5. 68 2. 32 n. a. Z r/ Y 5. 8 6. 4 4. 8 3. 7 4. 3 3. 4 3. 8 4. 4 4. 8 6. 1 2. 3 3. 5 2. 9 9. 2 2. 1 3. 1 5. 3 4. 8 3. 8 4. 8 3. 4 L a/ Sm 2. 7 2. 3 3. 9 3. 6 2. 0 1. 6 1. 5 1. 3 2. 1 2. 3 1. 1 1. 2 0. 8 1. 7 1. 0 1. 1 1. 2 1. 4 1. 8 1. 1 1. 1 R es ul ts o f m aj or e le m en t a na ly se s a re g iv en in o xi de % , w hi le m in or a nd tr ac e el em en ts a re g iv en in p pm . *: T he m ea su re m en ts w er e do ne in th e la bo ra to ry o f t he H un ga ria n G eo lo gi ca l I ns tit ut e. ** : T he m ea su re m en ts w er e do ne in th e la bo ra to ry o f t he A LS L ab or at or y G ro up . ** *: W he re F eO is n ot g iv en , t he re th e to ta l F e is g iv en in F e 2O 3. n. a. : n ot a va ila bl e Ta bl e 6. R es ul ts o f t he g eo ch em ic al a na ly se s ( ba sa lt) . Vol. 69/1 52 Darnó Unit Locality Báj-patak N Q. Reszél Ridge Q. Rock type red limestone (peperitic facies) red limestone (peperitic facies) Sample 1* 1* SiO2 26.7 7.64 Al2O3 5.08 5.17 Fe2O3 29.5 43.2 FeO** 5.85 n.a. CaO 13.7 22.5 MgO 3.22 1.05 Na2O 0.230 0.564 K2O <0.2 <0.2 TiO2 0.093 0.124 MnO 0.116 0.085 P2O5 0.277 0.317 SrO 0.006 0.014 BaO <0.005 0.005 Ag n.a. <0.25 Ba <44.8 44.8 Cd 0.244 <0.06 Ce 6.13 5.17 Co 8.48 22.0 Cr 14.5 7.29 Cs 1.61 <0.625 Cu 6.10 <0.2 Dy 0.91 0.59 Er 0.55 0.34 Eu 0.365 0.13 Gd 1.27 0.56 Hf n.a. <1.25 Ho 0.188 <0.125 La 4.10 2.89 Lu <0.25 <0.125 Mo 1.60 <0.2 Darnó Unit Locality Báj-patak N Q. Reszél Ridge Q. Rock type red limestone (peperitic facies) red limestone (peperitic facies) Nb 0.203 <0.625 Nd 3.42 3.34 Ni 62.8 136 Pb <0.25 14.3 Pr 0.761 0.80 Rb 0.81 <0.625 Sm 0.824 0.73 Sn <0.5 3.61 Sr 50.7 118.4 Ta <0.25 <0.625 Tb 0.144 <0.125 Th <0.25 2.63 Tl <0.10 <0.25 Tm <0.10 <0.125 U 0.545 <0.625 V 281 n.a. W <0.25 0.88 Y 6.27 2.74 Yb 0.45 0.28 Zn 54.6 71.0 Zr 10.3 11.3 As n.a. 17.5 Bi <0.25 <0.625 Hg n.a. 0.012 Sb 0.412 13.5 Se n.a. 2.38 Au n.a. <0.002 _H2O 0.85 n.a. +H2O 3.04 n.a. CO2 11.1 n.a. Table 7. Results of the geochemical analyses (limestone). Analyses of the major elements are given in oxide%, while minor and trace elements are given in ppm. *: The measurements were undertaken in the laboratory of the Hungarian Geological Institute. **: Where FeO is not given, the total amount of Fe is given as Fe2O3. n.a.: not available 5. DISCUSSION Temporal evolution of fluid-rock interactions The submarine basaltic rocks of Triassic and Jurassic ages from localities in this study area were not formed in a typical mid-oce- anic ridge setting (AIGNER-TORRES & KOLLER, 1999, BAL- LA et al., 1980, BUDA & KISS, 1980, CSONTOS, 2000, KO VÁ- CS et al., 2008, 2010, KISS et al., 2008, 2010, 2011, 2012), thus, widely used models for hydrothermal fluid circulation in ophiolitic sequences of oceanic ridges (see e.g. FOUSTOUKOS & SEY- FRIED, 2007, PIRAJNO, 2009, BODNAR et al., 2014 and refe- rences therein) can not be applied to their hydrothermal systems. The Triassic and Jurassic basalts studied here were affected by hydrothermal alteration on slightly different scales. Hydrothermal alteration minerals are more abundant in the Triassic than the Ju- rassic localities, but all occurrences can be categorised into three main groups, according to the model of HART (1973); (1) pri- mary hydrothermal alteration, (2) cooling related hydrothermal alteration and (3) low-temperature hydrothermal alteration. This classification is followed in the discussion below. Using this scheme for evaluation of all the available data, the characteristics of the single processes and the importance of the medium (i.e. seawater or unconsolidated sediment) can also be determined. Primary hydrothermal alteration Primary alteration is present at each studied locality, represented by albititisation of rock forming plagioclase. This took place im- Kiss et al.: Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary... 53 Figure 3. Classification diagrams based on the results of the SEM-EDS analyses. The composition of the studied plagioclase (A) and pyroxene (B) grains are shown. Figure 4. Results of the EPMA elemental mapping in a single thin section. Plagio- clase laths contain more Na and less Ca at the margin of the pillows (A-C), than ca. 1.5 cm closer to the middle (D-F) and ca. 3 cm closer to the middle (G-I). The section is from a Triassic basalt (RM-131 drillcore, Darnó Unit, Hungary). mediately after solidification of the submarine basaltic flows, as albitisation characterises both the groundmass plagioclase and the porphyric plagioclase. This process could occur around 300°C, according to HART (1973). Cooling related hydrothermal alteration The textural characteristics of the basalt (sphaerolitic, varioli- tic or intersertal texture; skeletal crystal plagioclase, high amount of glassy/microcrystalline material) as well as the composition of the clinopyroxene (high Ca, Al and Fe content, NISBET & PEARCE, 1977) suggest a very rapid cooling of the basaltic lava. This together with the known geotectonic po- sition (i.e. the absence of a deep-seated long-lasting heat- source), have obvious effects on the possibilities of the fluid/ rock interaction. Thus, only very rapid, cooling related hydro- thermal processes took place and protracted fluid convection Vol. 69/1 54 did not develop. However, some difference between the Trias- sic and the Jurassic localities can be observed, as signs of rapid cooling are less dominant in the Jurassic basalts (intersertal textures with smaller amounts of microcrystalline material are more common). Chloritisation of the ground mass and the formation of the dif- ferent hydrothermal mineral infillings (cooling cracks, amygda- les, mineral band of the pyjamas-type pillow, matrix of the hyalo- clastite breccia) have taken place during this cooling related al- teration. Although the mineral paragenesis may be similar to that Figure 5. Results of the fluid inclusion study obtained from Triassic amygdale filling calcite. Figure 6. Results of the fluid inclusion study obtained from the calcite of the mineral bands of Triassic pyjamas-type pillow. Kiss et al.: Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary... 55 usually connected to low-grade Alpine metamorphism, the obvi- ous textural features (e.g. the cooling cracks do not cross-cut the pillow boundaries) and also the observed fluid characteristics (T, X, see e.g. in KISS et al., 2011) help to distinguish different steps of the submarine hydrothermal process from the later low-grade metamorphic overprint (Figs. 11-15). However, the cooling-rela- ted mineral paragenesis is slightly different in the Triassic and Jurassic basalts at the studied localities. The Triassic basalts are generally characterised by chlorite with some quartz and prehnite in the early high temperature alteration stage, and abundant cal- cite, together with rare epidote, prehnite, zeolite and pumpellyte formation at the lowest temperatures. In contrast, the Jurassic lo- calities are abundant in the high temperature products of chlorite, quartz and prehnite, and only a low amount of lower temperature calcite and pumpellyite occur (Figs. 11-15). On the basis of chlorite thermometry (Table 5), chloritisation of the ground mass, pseudomorph formation after olivine, as well as formation of some thin, cooling related veinlets, took place at around 180-280°C. This kind of chlorite is associated with some calcite, quartz, prehnite, pumpellyite and epidote, and their forma- tion was the earliest step of the cooling-related processes. Infilling of the smaller and larger amygdales in the Triassic basalts and some thin veins in both basalts, together with the onset of mineral precipitation in the matrix of the interpillow and pillow fragmented hyaloclastite breccia, collectively represent the next step of the cooling-related fluid/rock interactions. Temperatures around 200 °C are characteristic for the small, chlorite or chlorite- quartz filled amygdales, for precipitation of chlorite along the walls of larger amygdales and in thin veins, as well as for the Figure 7.: Results of the fluid inclusion study obtained from Triassic jig-saw vein filling calcite. Figure 8. Results of the fluid inclusion study obtained from the calcite of the matrix of Triassic hyaloclastite breccias. Vol. 69/1 56 earliest precipitation of chlorite grains in the matrix of hyaloclas- tite breccias (Table 5). The fluid inclusion study revealed that the homogenisation temperatures and salinity values are similar to those from the cal- cite-filled amygdales, pyjama-type pillows and jig-saw veins of some other Darnó Hill locations, and others at Vareš and the Stragopetra Mts. (KISS et al., 2012). Combining all the data pre- sented in KISS et al. (2012) and here (Figs. 5-8, Table 4), suggests that the lowest temperature stages of the cooling-related fluid/rock interactions can be related to precipitation of calcite in the amyg- dales, jig-saw veins, former feeding channels, mineral bands of the pyjama-type pillows and in the cement of the hyaloclastite breccia. As the homogenisation temperature corresponds to the minimum formation temperature in the case of the homogenous state of the parent fluid, the exact formation temperatures can be calculated if the pressure conditions of the entrapment of the in- clusions are known. In these submarine systems, the pressure is determined by the depth of the seawater. For the Triassic locali- ties, 1.5 km water depth is proven at Vareš-Smreka from a combi- nation of chlorite thermometry and fluid inclusion data (KISS et al., 2012), while a maximum of 4 km depth is assumed for the Darnó area (BALLA et al., 1980). Those pressures result in around 10-20 °C correction of the homogenisation temperatures. Howe - ver, in the case of the Jurassic localities, deeper water (~4-6 km) is indicated by the combination of chlorite thermometry with fluid inclusion data (KISS et al., 2011), resulting in a 20-28 °C correc- tion of the homogenisation temperature data. Applying this cor- rection to the Triassic basalts, the highest temperature conditions for precipitation of calcite existed in the amygdales (~100-180 °C), whereas the lowest temperature conditions characterised the jig-saw veins (~70-140 °C) and the feeding channel and pyjama- type pillow infillings as well as from the hyaloclastite breccia ma- trix (~80-150 °C) (Figs. 11-14). The rather wide range (together Figure 9. Results of the geochemical analyses. A, B: N-MORB normalised trace element spider diagram of the Triassic (A) and Jurassic (B) basalts. C, D: Chondrite normalised REE spider diagram of the Tri- assic (C) and Jurassic (D) basalts, note the clear difference observable between them. E: Discrimination diagram of PEARCE & CANN (1973), showing different fi- elds of origin for the Triassic and Jurassic localities. F: Discrimination diagram of MESCHEDE (1986), showing different fields of origin for Triassic (mostly within- plate basalt) and Jurassic (mostly island- arc and N-MORB) localities. Kiss et al.: Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary... 57 with the significantly lower temperature, in relation to the chlorite formation temperatures) can result from very rapid cooling, i.e. a significant difference can be observed from the margin to the cen- tre of a single amygdale or vein. In contrast, the formation tem- perature range of the cooling crack calcite in the Jurassic basalt is narrower at approx. 130-170 °C (KISS et al., 2011). Another important characteristic parameter of the processes is the salinity of the parent fluid (see Figs. 5-8 and Table 4). For the Triassic samples, the fluid inclusion salinities were 3.3-5.6 NaCl equiv. wt%, which is around, and just a bit higher, than seawater salinity. The slightly higher salinities may be caused by the effect of the fluid-rock interactions on the composition of upheated sea- water (NEHLIG, 1991). This process is a good explanation for the salinity increase in the thin veins, or amygdales (especially along their walls), where the effective local water/rock ratio is lower. However, it also explains the fact that in the case of the different hyaloclastite breccias (where the local water/rock ratio is obvi- ously higher), the salinity is always similar to the seawater value (Fig. 16). In contrast, the results of the thin cooling cracks found in the Jurassic basalts correspond to 4.95-9.07 NaCl equiv. wt% (KISS et al., 2011), thus a lower water/rock ratio is expected (NE- HLIG, 1991), which may explain (together with the observed higher formation temperatures) the slightly different mineral para- genesis. The results of our studies can be compared with the characte ri- stics of the hydrothermal system at Hruškovec, where a complete submarine volcanic lava flow is known (see above, PALINKAŠ et al., 2008). There, a maximum of 150 °C as homogenisation tem- perature and seawater salinity is characteristic of the relatively distal facies in relation to the eruptive centre, while up to 250 °C homogenisation temperature, boiling of fluids and up to 23 NaCl equiv. wt% salinities (which may be caused by boiling of the modified seawater, see e.g. PIRAJNO, 2009 and BODNAR et al., 2014) are typical in the central zones of the lava flow (BOROJEVIĆ et al., 2000, Borojević pers. comm.). Therefore, the fluid inclusion data fully supports the results of the volcanic facies analysis of KISS et al. (2008, 2010, 2012), i.e. the presence of only distal fa- cies at the presently studied, strongly tectonised localities. Figure 10. Results of the mass transfer calculations. Gains and losses of mass of major elements within a single pillow, from core to rim (A), from more central to more distal parts of the same closely packed pillow facies (B), between the closely packed and peperitic pillow facies (C), between the closely packed pillow ad pillow fragmented hyaloclastite breccia facies (D) and gains and losses of mass of trace elements (E). Abbreviations: BPÉ: Báj-patak Quarry, RT: Reszél-tető Quarry, HV: Hosszú Valley Quarry, NR: Nagy-Rézoldal Quarry, cl. packed: closely packed pil- low facies, hyal. br. fac.: pillow fragmented hyaloclastite breccia facies. Vol. 69/1 58 The low temperature hydrothermal alteration The low temperature hydrothermal alteration in the submarine basaltic mounds is the result of the long-lasting seawater-rock interaction at temperatures below 70 °C. According to HART (1973), formation of K-rich smectites is characteristic of this low temperature process. Studies by PICHLER et al. (1999), ALT & TEAGLE (2003) and SCHRAMM et al. (2005) also confirmed this together with occurrences of celadonite, sapo- nite, iron oxy-hydroxides and rarely, illite-smectite and chlorite- smectite interlayered clay minerals. Iron oxy-hydroxides occur at all localities studied, but it can- not be stated clearly, whether their occurrence is part of this low temperature alteration process, or to later processes (e.g. to weathering). However, the presence of abundant phyllosilicates can be related to this low temperature hydrothermal process as chlorite-smectite interlayered clay minerals occur both in the groundmass and in some amygdales of basalt. As well as the presence of chlorite-illite interlayered clay minerals, celadonite and smectite were also detected in the basalt at all the studied localities. Figure 11. Mineral precipitation sequence according to the volcanic facies at the Darnó Unit, Hungary. Figure 12. Mineral precipitation sequence according to the volcanic facies at the Kalnik Mts., Croatia. Kiss et al.: Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary... 59 Geochemical features of fluid/rock interaction As shown in the previous studies, the major and trace element characteristics of basaltic rocks from the studied localities sup- port a different origin for the Triassic and Jurassic basalts; i.e. a rifting related (within-plate basalt) origin for the Triassic exam- ples (KISS et al., 2012) and a subduction related origin for the Jurassic basalts (KISS et al., 2011). However, submarine hydro- thermal processes certainly have strong effects on the geoche- mical composition of these rocks (see e.g. HART, 1973, WIL- SON, 1989, KARAMATA et al., 2000, etc), especially if the basalt interacted not only with the seawater, but also with the unconsolidated sediment. The latter may have significant effects also, though it has not been previously studied in detail (see e.g. MUKHERJI, 1972). Therefore the significant scattering of re- sults for a few elements (e.g. Ca, Mg, Na, K, Fe, Mn, Au, Cu, Zn, Pb, and LILE group, Fig. 9 A, B) can be explained by the mobility of those elements during hydrothermal processes. Traces of component mobilisation Using the MTC method, component mobilisation during the submarine hydrothermal processes were quantitatively mo- delled. Although the number of available analyses does not allow generalised conclusions to be drawn, some preliminary interpretations can be made based on observed variations. Slightly different mobilisation patterns were seen at dif- ferent scales (Fig. 10 A-D). Within a single pillow, from the centre to its margin, or within the closely packed pillow fa- cies from less to more distal parts, the amount of CaO de- creases, while the amount of Na2O increases. Both show good correlation with the macroscopically and microscopi- cally observed alteration intensity of the studied samples. A slight increase of K2O is detected only on larger scales, from less to more distal parts of a single facies or between less and more distal facies, in relation to the centre of the lava flow. Figure 13. Mineral precipitation sequence according to the volcanic facies at Vareš, Bosnia and Herzegovina. Figure 14. Mineral precipitation sequence according to the volcanic facies at Stragopetra Mts., Greece. Vol. 69/1 60 However, a decrease of SiO2 was observed in all studied cas- es. These changes may be explained by the petrographically observed mineral paragenesis modifications, e.g. the albitisa- tion of anorthite during primary hydrothermal alteration (change in Na2O and CaO content) or the formation of K-rich clay minerals (change in K2O and SiO2 content) during low temperature alteration. Important conclusions can be drawn regarding the metal content at the studied localities. Copper, zinc and cobalt com- monly decrease, from the less distal (thus less altered) to the Figure 15. Mineral precipitation sequence according to the volcanic facies at the Szarvaskő Unit, Hungary. Figure 16. Schematic model of a submarine lava flow (PALINKAŠ et al., 2008) and the results of the affecting hydrothermal processes. Kiss et al.: Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary... 61 more distal (thus more altered) parts of either a single pillow or the volcanic centre (Fig. 10 E). Tracing the effects of the different steps of the hydrother- mal processes was possible at several scales from a single pillow to an outcrop, raising the question of whether these phenomena are also present at microscopic (thin section) scale. The EPMA elemental mapping revealed, that at such a scale, the plagioclase crystals contain more Na and less Ca closer to the margins of the pillows (sphaerolitic-variolitic texture), than in their inner parts (variolitic-intersertal tex- ture), thus the relative enrichment of Na and depletion of Ca in the more altered parts is obvious (Fig. 4). The geochemical effects of the interaction with the uncon- solidated sediment The slight differences in the hydrothermal mineral paragen- eses (i.e. higher amount of infilling hydrothermal minerals and also, more mineral species, see Figs. 11-15) draw atten- tion to the observation of the effects of unconsolidated sedi- ment on the elemental compositon of the basalt. Based on the preliminary MTC calculations, more intensive component mobilisation can be recognised in the peperitic facies com- pared to other facies (see the greater amounts of gains/losses of mass on Fig. 10 C). Hence the geochemical analyses sup- port the earlier petrographical assumption, i.e. the presence of water saturated, unconsolidated sediment strengthens the effect of hydrothermal alteration in the basaltic rocks. How- ever, it was found that the limestone in the peperitic facies is enriched in Co, Zn, Ti and Ni, in relation to a typical lime- stone (Fig. 17, LEVINSON, 1974). Thus, where lime mud was present during the submarine hydrothermal processes, the metals escaping from the basalt did not (or not only) dis- solve in the seawater, but were also captured in the sediment. Determination of the water/rock ratio Although at the submarine basaltic eruption centres ‘unlimi- ted’ amounts of seawater is available for the fluid/rock inter- action processes, obviously the amount of water taking part effectively in the hydrothermal processes is lower, mostly depending on the available interaction surface. The study of the mineral paragenesis, as well as results of the fluid inclu- sion study have drawn attention to the importance of this lo- cal water/rock ratio (see above). Using the numerical results of the MTC calculations and the method described by SHIKAZONO et al. (1995), this effective water/rock ratio can be approximated. The results of the calculations support the earlier interpretations; at the closely packed pillow facies of the studied Triassic localities a higher water/rock ratio (15- 20) occurred, while at the studied Jurassic localities a lower ratio was obtained (5-10). This fact also supports the conclu- sion, that this local, effective water/rock ratio is a determining factor in these kinds of submarine hydrothermal systems. The general peculiarities of the hydrothermal process The observed main phases of the fluid/rock interaction pro- cesses, as well as the general features of mineral precipitation and the chemical changes are rather similar at both Triassic and Jurassic localities. In both cases the development of a small scale, rapidly cooling, and slightly modified/evolved seawater dominated system can be reconstructed. This is dif- ferent from the typically large scale fluid circulation systems of the mid-oceanic ridges (see e.g. NEHLIG, 1991, FOUS- TOUKOS & SEYFRIED, 2007, PIRAJNO, 2009, BODNAR et al., 2014 and references therein). In addition to the main peculiarities listed above, other evidence can also be collected, including the absence of high temperature fluids, differences in the fluid composition properties and the lack of sulfate and sulfide phases. The clear difference from the large scale sub- marine hydrothermal systems also seems to be obvious in oth- er rifting related submarine basaltic-sedimentary successions e.g. the low temperature, seawater dominated hydrothermal processes in the Mecsek Mts., Southern Hungary (JÁGER et al., 2012). The observed slight, but important differences in the studi- ed small-scale hydrothermal systems are also obvious. How- ever, these differences in the texture, hydrothermal alteration mineralogy and fluid properties can be connected to the differ- ent position of the studied blocks in relation to the centre of the lava flow (i.e. different volcanic facies), particularly and prac- tically by the different local, effective water/rock ratio (Fig. 16). Therefore, we conclude, that the features of the hydrother- mal processes are typical to the volcanic facies and vice versa the observed characteristics may help in the spatial reconstruc- tion of the original lava flow. The distinction between the volcanogenic massive sulfide deposit forming i.e. large scale, and the non-extended, i.e. small scale hydrothermal systems is also economically crucial, as the latter does not tend to contain significant ore deposits. The afore-mentioned characteristics may help in distinguish- ing these different types of ore-productive and barren hydro- thermal processes. 6. CONCLUSIONS Submarine hydrothermal alteration of Triassic, advanced rift- ing related pillow basalt at different localities from the Dina- rides, as well as from displaced fragments of the Dinarides and the Hellenides were compared with the alteration of Ju- rassic, back-arc/marginal-basin opening related pillow basalt series. The study aimed to complete the earlier less detailed knowledge on the general characteristics of the non-extended, submarine basaltic complex related hydrothermal systems. The study revealed that the most important determining fac- tors of these small scale hydrothermal systems are the ex- tremely rapid cooling of the hydrothermal fluid, the dominance Figure 17. Selected trace element spider diagram of the studied pepe- ritic limestones, showing enrichment in relation to typical limestones (LEVINSON, 1974). Vol. 69/1 62 of the slightly modified seawater as a hydrothermal fluid and the dependence on the local, effective water/rock ratio (i.e. dis- tal/proximal position within the lava flow). The observed fea- tures are typical of the volcanic facies, thus may also help in the identification of the spatial relationships within a subma- rine lava flow. The overall characteristics of these local, sub- marine basaltic volcanic centre related hydrothermal systems are markedly distinct from the typical mid-oceanic ridge or back-arc-basin opening related, volcanogenic massive sulfide deposit forming large scale hydrothermal systems (see e.g. NEHLIG, 1991, FOUSTOUKOS & SEYFRIED, 2007, PIRA- JNO, 2009 and BODNAR et al., 2014 and references therein). Three main phases of submarine hydrothermal processes were distinguished and characterised: the primary hydrother- mal processes, which took place at around 300 °C and caused the albitisation of the plagioclase; the hydrothermal alteration processes, during cooling from 300 °C to ~50-70 °C, resulting in the formation of the groundmass chlorite and all the other vein, cavity and amygdale filling hydrothermal minerals; and the low temperature hydrothermal processes below ~50-70 °C, resulting in formation of argillic alteration and iron oxy-hy- droxides. Based on detailed observation of the textural features and the use of different geothermometry methods, more steps can be distinguished within the cooling related phase of the fluid/rock interaction process. Firstly the groundmass altera- tion product chlorite and the infilling minerals of the thin vein- lets formed, which were followed by precipitation of the small and later the bigger amygdale infilling minerals. Later still, the infillings of the former feeding channel, and the mineral band- ing of the pyjama-type pillows precipitated, which was fol- lowed by the formation and filling of the jig-saw veins. At the highest temperatures (300-150 °C) mostly chlorite, quartz and prehnite formed, while calcite, laumontite and pumpellyite are more common at lower temperatures (150-70 °C). Thus, at those localities, where the higher temperature phases were lon- ger lasting (e.g. the studied Jurassic ones), minerals from the first group are dominant, while in the other localities, charac- terised by dominantly lower temperatures (e.g. the studied Tri- assic localities), minerals from the latter group are more typi- cal. Component mobilisation during the different major phases and smaller steps of the hydrothermal processes were also traced. Based on the EPMA elemental mapping and mass transfer calculations, the gains and losses of mass during the fluid/rock interaction were followed at different scales (from microscopic to outcrop scale). The water-saturated sediment of the peperitic facies has strengthened the alteration efficiency of the hydrothermal processes. During the progressive altera- tion, the amount of Cu, Zn and Co decreased, thus these metals dissolved into the seawater, but in the peperitic facies, they were also captured in the limestone. Acknowledgment Federica ZACCARINI (University of Leoben, Austria), Peter JONES (Carleton University, Ottawa, Canada) and Zsolt BENDŐ (Eötvös Loránd University, Budapest, Hungary) are thanked for their assistance with the EPMA and SEM-EDS analyses. The University Centre for Applied Geosciences (University of Leoben) is thanked for the access to the Eugen F. STUMPFL Electron Microprobe Laboratory. Todor SE- RAFIMOVSKI (University “Goce Delčev”-Štip, Macedonia) and an anonymous reviewer are thanked for their constructive comments, improving the original version of the manuscript. This work was supported by the Hungarian-Croatian Science and Technology Agreement Project no. 07/CRO to F. MOLNÁR and L. A. PALINKAŠ, by the OTKA (HNSF) research grant no. T 49633 to F. MOLNÁR and by the AÖU research grant no. 85öu11 to G. B. KISS and F. ZACCARINI. REFERENCES AIGNER-TORRES, M. & KOLLER, F. (1999): Nature of the magma source of the Szarvaskő complex (NE-Hungary).– Ofioliti, 24, 1–12. 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