Christos Kanellopoulos

The study of microbial mats in extreme environments is of high scientific interest from geological, ecological, and geomicrobiological aspects. These mats represent multilayer bio-structures where each taxonomic group dominates a specific vertical layering distribution resulting from its growth and metabolic activity. In the present study, microbial mats in a hot spring environment from Aedipsos (Euboea Island, Greece) resulting in the creation of thermogenic travertine, were studied through an interdisciplinary approach. The mineralogical composition was determined by optical microscopy, XRD, and SEM-EDS microanalysis, and the identification of Cyanobacteria was made primarily on morphological characteristics. The main mineral phase in the studied samples is calcite and, to a less extent, aragonite, with several trace elements in the mineral-chemistry composition, i.e., up to 1.93 wt. % MgO, up to 0.52 wt. % SrO, up to 0.44 wt. % Na2O, up to 0.17 wt. % K2O, and up to 3.99 wt. % SO3...

Native iron has been identified in an active thermogenic travertine deposit, located at Ilia area (Euboea Island, Greece). The deposit is forming around a hot spring, which is part of a large active metallogenetic hydrothermal system depositing ore-bearing travertines. The native iron occurs in two shapes: nodules with diameter 0.4 and 0.45 cm, and angular grains with length up to tens of μm. The travertine laminae around the spherical/ovoid nodules grow smoothly, and the angular grains are trapped inside the pores of the travertine. Their mineral-chemistry is ultra-pure, containing, other than Fe, only Mn (0.34–0.38 wt.%) and Ni (≤0.05 wt.%). After evaluating all the possible environments where native iron has been reported up until today and taking under consideration all the available data concerning the study area, we propose two possible scenarios: (i) Ilia’s native iron has a magmatic/hydrothermal origin i.e., it is a deep product near the magmatic chamber or a peripheral cool...

A new skarn, near Therapio village, in the Evros prefecture, is described in terms of mineralogy and petrogenesis. The skarn is developed in amphibolites in close relation with pegmatite veins. It is constituted of garnet, magnetite and quartz, while retrograde minerals are actinolite, and chlorite, along with sulfides and hematite, some of them also found in the host rock. The mode of skarn growth and its close relation with the pegmatite veins indicate the genetic relation between them. At the same time, the cataclastic structure of the garnets and the magnetite as well as the brittle structures, imply later tectonism. According to the field observations and the results of the laboratory study, the Therapio skarn is a result of the metasomatism due to the intrusion of the pegmatite veins into the protolite amphibolite.

A new occurrence of pyrophanite (MnTiO3) in Greece is described from the garnetclinopyroxene-wollastonite exoskarn of western Kimmeria. Hostrock of the pyrophanite-bearing skarn is amphibolite (retrogressed eclogites) of the Nestos suture zone in the Rhodope massif. In addition endo- and exo-skarns occur both in the Xanthi granodiorite and the surrouding marbles and consinst of diopside-vesuvianitequartz and wollastonite-garnet-calcite-quartz respectively. Pyrophanite formed in the prograde stage, together with garnet, pyroxene, wollastonite, titanite, zircon, rutile, thorite and ouranothorianite. Retrograde minerals are quartz, epidote, calcite, hematite, and sulfides. Chlorite-geothermometry revealed temperatures in the range from 300 to 350 oC for the retrograde event. Calcic garnets (andraditegrossular solid solutions) from the prograde amphibolite-hosted skarn are chemically zoned with either isotropic or anisotropic cores surrounded by non-cubic anisotropic rims, thus suggesti...

Epithermal-altered volcanic rocks in Greece host gem-quality amethyst veins in association with various silicates, carbonates, oxides, sulfides and halides. Host rocks are Oligocene to recent calc-alkaline to shoshonitic lavas and pyroclastics of intermediate- to acid composition. The amethyst-bearing veins occur in the periphery of porphyry-type and/or high-sulfidation epithermal mineralized centers in northern Greece (e.g. Sapes, Kirki, Kornofolia/Soufli, Lesvos island) and on Milos island in the active Aegean Volcanic Arc. Hydrothermal alteration around the quartz veins includes sericitic, K-feldspar (adularia), argillic, propylitic and zeolitic types. Precipitation of amethyst in the northern Greece occurrences, took place during the final stages of the magmatic-hydrothermal activity from near-neutral to alkaline fluids, as indicated by the presence of gangue adularia, calcite, smectite, chlorite, sericite, pyrite, zeolites (laumontite, heulandite, clinoptilolite), analcime and ...

A geochemical study of NW Euboea island ground waters was undertaken, in order to examine the possible effect of the chemical composition of the country rocks of the area as well as of the anthropogenic activities, to the concentration of environmentally important elements and chemical compounds in the groundwaters. NW Euboea consists of a great variety of rock types showing a wide range in mineralogical and chemical composition. The main groups of rocks occurring in NW Euboea are: i) various types of sedimentary rocks e.g. shale and chert formations, carbonate and clastic rocks, ii) ophiolitic rocks including peridotite, gabbro, serpentinite etc, and iii) epizonally metamorphosed basic igneous rocks, with schist and phyllite intercalations. A number of hot springs also occur in the area. The main anthropogenic activity in the area is the agricultural land use, as any significant industrial activity is absent. For that purpose, 45 water samples were collected and analyzed by Spectro...

 The metallic mineralization in Kontaros-Katsimouti area is an epithermal Pb-Zn Ag mineralization located along the NW-trending Kondaros-Katsimouti-Vani fault, NW Milos Island, Greece. It is hosted within propylitically and argillically altered dacitic flow dome and volcaniclastic sandstone and shows features typical of intermediate sulfidation deposits like colloform banding, cockade breccias and gangue adularia, Mnrich carbonates and amethystine quartz. The Kondaros-Katsimouti system evolves at higher elevation into the Vani Ag-Pb mineralization, which occurs proximal to the Vani manganese deposit. The metallic mineralogical assemblage at Kondaros-Katsimouti includes mainly galena and sphalerite and minor pyrite. Silver is present in the form of Ag-(Cd) rich tetrahedrite (up to 23.1 wt. % Ag) and polybasite included in galena. Bulk ore analyses indicate enrichment in W (up to 424 mg/kg) and Mo (up to 24 mg/kg), similarly to the other neighboring mineralizations in western Milos (e...

The Lapis Lacedaemonius (krokeatis lithos) is a well-known meta-volcanic rock of great historical importance. Petrographic observations, mineral chemistry data, as well as geochemical analysis of selected samples, reveal that these rocks are porphyritic metabasaltic rocks which have been significantly affected by saussuritization and also by restricted silicification processes. They represent subduction related calc-alkaline volcanic rocks which also appear in the adjacent Hellenic Triassic volcanic outcrops, and appear to be associated with the rift/drift phase within the Pindos oceanic realm. The unique features of the Lapis Lacedaemonius, when compared to geochemically similar volcanic rock outcrops, are mainly attributed to their distinct porphyritic textures, predominantly with microlithically textured groundmass along with the coarse grained plagioclase, and to saussuritization processes. The Lapis Lacedaemonius seems to have been formed in a sub-volcanic system closely associ...

Small occurrences of iron-oxide deposits at Sesi-Koropi in S. Hymittos, are hosted by an extensional brittle detachment zone between carbonate rocks of "Vari-Kirou Pira" and "Hymittos" units. Another low-angle fault separates a heterogeneous formation of schists, containing meta-ophiolitic blocks ("Lavrion" Unit), which is cut by high-angle normal faults that root in the detachment zone, reducing the total structural thickness of "Hymittos" marbles and bringing in contact the meta-ophiolitc lithologies with the "Vari-Kirou Pira" dolomites. Three mine caves were found along the detachment zone indicating that these iron deposits were possibly mined on a very small scale in the past. The mineralization is developed in a cataclastic zone a few meters thick (3-5m), forming thin rusty black encrustations and larger zones of alteration with a reddish to yellow brown hue. Scanning Electron Microscope (SEM) mineralogical study of the iron-or...

The Triades-Galana Pb-Zn-Ag-Au mineralization is a shallow-submarine epithermal mineralization located along NE-trending faults, NW Milos Island, Greece. It is hosted in 2.5–1.4 Ma pyroclastic rocks and is genetically related to andesitic/dacitic lava domes. Mineralization occurs as breccias, quartz-barite galena veins and stockworks within sericite-adularia or kaolinitic altered rocks. The mineralization is enriched in Mo, W and base- and precious metals (e.g. Pb, Zn, Ag) similarly to the neighbouring mineralization at Kondaros-Katsimouti and Vani, indicating common source of metals from a deep buried granitoid feeding western Milos with metals and volatiles. Paragenetic relations suggest early deposition of pyrite, followed by famatinite, polybasite and Ag-rich tetrahedrite, and then by enargite, suggesting fluctuating sulfidation states during ore formation. The evolution from Sb- towards As-rich enrichment indicate a renewed magmatic pulse (probably in the form of magmatic gases...

In Edipsos area many hot springs occur, as a result of both active tectonic of the area and recent volcanism (Lichades volcanic center). A geochemical study of Edipsos hot groundwaters was undertaken, in order to assess the hydrochemistry of hot springs from Edipsos and re-evaluate the geothermal situation of the area. For that purpose, 12 water samples were collected and analyzed by Spectrophotometry for the main ions and by AAS, ICP-OES and ICP-MS for major and trace elements. The interpretation of the analytical data showed that the geochemistry of Edipsos hot groundwaters is controlled by three factors i) a deep magmatic source, ii) the chemical composition of the local rocks (ultramafic and carbonates) and iii) sea water. The application of chemical geothermometers is problematic because of the chemical composition of the hot groundwaters and especially the high participation of the sea water. The temperature which derives from the use of Na-K-Ca geothermometer is greater than ...

Ampelia area is a newly discovered area with geothermal interest and no surface manifestations (hidden resource). It is located in Farsala basin and belongs to the Enipeas graben. The geothermal anomaly is related with the E-W trending faults, which mainly control the basin development and the NNW-SSE trending faults of the area. The temperature values from the deep water boreholes (>200m depth) range from 20 to 41oC. The chemical composition of the studied groundwater samples varies in all chemical parameters. Most of the samples have affected by shallow cold aquifers (high E.C. and NO3- values). The most representative samples (T > 30oC) are from the deepest boreholes (hydrochemical type Na-HCO3), which cut the fractured crystalline basement, i.e. limestones, flysch and ophiolitic rocks. They present the highest pH values (pH > 8) and the lowest E.C. compared with the rest of the samples. Their Ni and Cr concentrations are very low, indicating that the groundwater is noti...

Alpinotype fissure-minerals in Thasos Island are hosted in gneisses, amphibolites, Mn-rich schists and calc-silicate layers, and marbles of the Carboniferous-Permian Pangeon Unit, which represents the lower tectonostratigraphic unit of the southern Rhodope metamorphic core complex. Alpinotype fissures crosscut metamorphic fabrics and are closely related to the exhumation processes of the core complex during the Oligocene-Miocene. Most mineralized fissures occur close to a major detachment fault, which separates gneisses from marbles and amphibolites. The mineralogy of the alpinotype fissures is closely related to the host rocks: amphibolite-hosted fissures include adularia, albite, quartz, titanite, apatite, actinolite, chlorite, calcite, hematite and rutile. Fissures in para- and orthogneisses- and in metapegmatites are characterized by smoky and clear quartz, adularia, muscovite and hematite. Fissures within spessartite-piemontite schists contain quartz, chlorite, spessartite, hem...

Natural CO 2 fields can be used to identify trapping mechanisms, the fate and the geochemical consequences of geologically stored CO 2 in shallow aquifers. The Florina Basin in Greece is regarded as a CO 2 naturally leaking analog due to millions of years of gas accumulation in a Tertiary sand formation. This research was conducted in order to identify the CO 2 fingerprints and to investigate and evaluate the factors controlling the groundwater quality in the basin. Leaking CO 2 is observed in the aquifers and at the surface. The basin is filled with clastic sediments. It can provide information regarding the fate of CO 2 and the possible impacts that can be used as reference in demonstration and industrial projects. Water sampling campaigns were conducted to determine the impact of the gas‐water long‐term interactions in the shallow aquifers. The CO 2 has increased the concentration (in relation to other water samples from the basin) of certain elements like Fe, Mn, Na, Cl, and Br but only in few cases exceeds the EU drinking limit. The chemistry of the groundwater in the Florina Basin aquifers was found to be controlled mainly by the CO 2 ‐water‐rock interactions due to the mineralogy of the aquifers (calcite and silicates including pyroxenes and chlorite). Metal attenuation processes have prevented the aquifers from brine contamination. Considering the Florina Basin is a natural analog for studying the leaking and migration pathways of stored CO 2 and that only minor affects have been identified in the groundwater chemistry, the conclusions of this research are promising for the possible usage of a basin of similar geology and lithology for deep CO 2 storage. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd

The Vani Ag prospect is a high-grade epithermal mineralization located along the NW-trending Kondaros-Katsimouti-Vani fault, NW Milos Island, Greece. The prospect is hosted in calc-alkaline dacite domes and volcaniclastic sandstones and represents the NW extension of the Pb-Zn-Ag-Mn Katsimoutis-Kondaros mineralization. It occurs proximal to the Vani exhalative manganese deposit. The Ag content of the prospect is derived from Ag-bearing phases (native silver, argentite/acanthite, silver halides and argentian covellite). Mineralogical evidence like the presence of skeletal habits of sulfides, presence of hydrothermal anglesite, covellite and silver halides that were formed after dissolution of the primary silver and lead-bearing minerals, verifies earlier work that mineralization along the Kondaros-Katsimoutis fault is the product of seawater oxidation and was formed in a submarine setting after reaction of hydrothermal fluids with seawater.

ABSTRACT A soil and vegetation survey was undertaken in NW Euboea Island, Greece. The objectives of the study were to establish the geochemical baseline of soil and identify the impact of local geology on threshold values of potentially harmful elements. The studied area is characterized by complex geology comprising metamorphic and ultramafic rocks as well as active hot springs. A total of 117 soil samples were collected from 89 sites at depths of 0–25 cm and 25–50 cm. Eighteen vegetation samples were also collected representing prevalent indigenous perennial species in the region. Soil samples from the present study were enriched in As, Ca, Cu, Mg, Ni with concentrations reaching 233 mg/kg, 38%, 336 mg/kg, 10.8%, 1560 mg/kg respectively. Factor analysis revealed three main factors controlling the chemical composition of soil reflecting the influence of ultramafic rocks (Cr, Ca, Mg, Ni), hot spring deposits (Ca, S, Sr, As) and paedogenesis processes (Fe, Co, V, Mn, Al). The first two of these factors showed significant spatial correlation with the geological features within the study area. Subsequently, baseline concentrations based on statistical and spatial data were estimated within sub-areas reflecting the influence of local geology in soil composition. Concentrations of potentially harmful elements in the plant tissues of indigenous perennial vegetation species showed a wide range of variation from below the detection limit up to 1700 mg/kg for Ni in the hyperaccumulator Alyssum chalcidicum demonstrating that plant species have adapted to the stressful conditions caused by high elemental concentrations in soil. The results of this study can be utilized in future studies at areas of similar geology by providing an objective basis for setting realistic threshold values for pollution assessment and remediation.

On Nisyros island as a result of the volcanic activity and active tectonic, a hydrothermal system develops and it is expressed by 5 types of surface manifestations: i) thermal springs, ii) fumaroles iii) hydrothermal craters, iv) hot grounds and v) mudpots. In general, a mudpot could be described as an acidic hot spring and fumarole with limited water which it is formed in high temperature geothermal areas. Water sample and depositions of mudpots collected, analyzed and studied from Stefanos hydrothermal crater, which is the only site on Nisyros Island, where mudpots occur. Mudpots water is very acidic (pH=2.4), with high sulfate concentration (1375mg/L), due to the H2S(gas) and temperature near the boiling point. As a result, elemental sulfur is found inside the depositions alongside with products of the hydrothermal alteration of the surrounding rocks. In the water and in the depositions were found high concentrations in several elements (e.g. in water: 55mg/L Fe; 19.5mg/L Zn, in ...

Native iron has been identified in an active thermogenic travertine deposit, located at Ilia area (Euboea Island, Greece). The deposit is forming around a hot spring, which is part of a large active metallogenetic hydrothermal system depositing ore-bearing travertines. The native iron occurs in two shapes: nodules with diameter 0.4 and 0.45 cm, and angular grains with length up to tens of µm. The travertine laminae around the spherical/ovoid nodules grow smoothly, and the angular grains are trapped inside the pores of the travertine. Their mineral-chemistry is ultra-pure, containing, other than Fe, only Mn (0.34–0.38 wt.%) and Ni (≤0.05 wt.%). After evaluating all the possible environments where native iron has been reported up until today and taking under consideration all the available data concerning the study area, we propose two possible scenarios: (i) Ilia's native iron has a magmatic/hydrothermal origin i.e., it is a deep product near the magmatic chamber or a peripheral cooling igneous body that was transferred during the early stages of the geothermal field evolution, from high temperature, reduced gas-rich fluids and deposited along with other metals in permeable structural zones, at shallow levels. Later on, it was remobilized and mechanically transferred and precipitated at the Ilia's thermogenic travertine by the active lower temperatures geothermal fluids; (ii) the native iron at Ilia is remobilized from deep seated ophiolitic rocks, originated initially from reduced fluids during serpentinization processes; however, its mechanical transport seems less probable. The native iron mineral-chemistry, morphology and the presence of the other mineral phases in the same thermogenic travertine support both hypotheses.

We herein report the discovery of active cinnabar-depositing hydrothermal vents in a submarine setting at Paleochori Bay, within the offshore southeastern extension of the Milos Island Geothermal Field, South Aegean Active Volcanic Arc. Active, low temperature (up to 115 • C) hydrothermal venting through volcaniclastic material has led to a varied assemblage of sulfide and alteration mineral phases in an area of approximately 1 km2. Our samples recovered from Paleochori Bay are hydrothermal edifices composed of volcaniclastic detrital material cemented by pyrite, or pure sulfide (mainly massive pyrite) mounts. Besides pyrite and minor marcasite, the hydrothermal minerals include cinnabar, amorphous silica, hydrous ferric oxides, carbonates (aragonite and calcite), alunite-jarosite solid solution and Sr-rich barite. Among others, growth textures, sieve-textured pyrite associated with barite, alunite-jarosite solid solution and hydrous ferric oxides rims colloform-banded pyrite layers. Overgrowths of arsenian pyrite layers (up to 3.2 wt. % As and/or up to 1.1 wt. % Mn) onto As-free pyrite indicate fluctuation in As content of the hydrothermal fluid. Mercury, in the form of cinnabar, occurs in up to 5 µm grains within arsenian pyrite layers, usually forming distinct cinnabar-enriched micro-layers. Hydrothermal Sr-rich barite (barite-celestine solid solution), pseudocubic alunite-jarosite solid solution and Mn-and Sr-enriched carbonates occur in various amounts and closely associated with pyrite and/or hydrous ferric oxides. Thallium-bearing sulfides and/or sulfosalts were not detected during our study; however, hydrous ferric oxides show thallium content of up to 0.5 wt. % Tl. The following scenarios may have played a role in pyrite precipitation at Paleochori: (a) H2S originally dissolved in the deep fluid but separated upon boiling could have reacted with oxygenated seawater under production of sulphuric acid, thus causing leaching and dissolution of primary iron-rich grains from the volcaniclastic components of the sediments and resulting in precipitation of pyrite; (b) the iron may also have been derived by the near-neutral reduced hydrothermal brines and precipitate metal sulfides as a result of cooling, mixing with seawaters; the necessary iron content to form sulfides is mostly derived from primary iron-rich components of the basement; (c) biological activity may have resulted in pyrite deposition (e.g. sulfur is provided by a biogenic reduction of marine sulphate). The mineralogy of hydrothermal precipitates considered in the present study resemble hydrothermal products from other shallow water venting areas elsewhere: Lihir and Ambitle Islands, Papua New Guinea, Kraternaya Bight, Kuriles, Russia, Punta Mita and Bahía Concepción, Mexico and Punta Banda at Baja California. The Paleochori vents contain the first documented occurrence of cinnabar on the sea floor in the Aegean area and provide an important link between offshore hydrothermal activity and the mercury-depositing mineralizing system on Milos Island. An interplay between bacterial activity, pH, Eh, temperature, precipitation rate and iron concentration resulted in precipitation of As-pyrite with interlayered cinnabar, hydrous ferric oxides enriched in thallium, alunite-jarosite solid solution and carbonates.

In Greece, several areas are presenting geothermal anomaly, which is controlled by the tectonic setting of each area, such as active graben and continental rift systems and in many cases these anomalies are related also to the recent volcanism. Two of these areas are the northwestern Euboea Island and the neighboring part of the mainland, i.e. eastern Sperchios area, Greece. These areas include several hot springs and active thermogenic travertine deposits, which are the surface manifestations of a geothermal system, recognized as having one of the highest geothermal gradient in Greece, just after the south Aegean active volcanic arc areas. Field surveys verified the presence of hot springs with fluid temperature over 82 oC. Geological, geochemical and isotopic data, alongside with drilling data suggest the presence of several medium and low enthalpy geothermal resources in these areas. Until now, the only use of these renewable energy resources is limited to thermal bath / spa therapies. Taking under consideration the geological, geomorphological, climate characteristics, the economic activities of the local societies, and the existing infrastructure, we suggest a series of targeted geothermal direct use applications that could be easily applied in these areas. Their application will have multiple positive socio-economic effects to national and regional level, resulting to the sustainable development of the areas, through the exploitation of a renewable energy resource i.e. the geothermal energy.

The Mn-Ba-Pb deposit at Aspro Gialoudi in NW Milos is shown to be a fossil inhalative-exhalative hydrothermal deposit that represents the deepest part of the Vani succession at the western extremity of the main Vani manganese deposit. The geology of the Vani-Aspro Gialoudi area is characterized by Upper Pliocene-Lower Pleistocene dacitic and rhyodacitic lava domes, which are overlain by the Vani volcaniclastic unit considered to be part of the 2.66–1.44 Ma magmatic event at Milos Island. The presence of in-situ and intrusive hyaloclastite breccias surrounding the coherent lava domes at Aspro Gialoudi and Vani areas indicates submarine emplacement for the domes. The dacitic-rhyodacitic domes are variously altered (mainly propylitic and/or argillic alteration, silicified and in some cases locally exhibiting adularia alteration). Both Aspro Gialoudi and main Vani deposit are located proximal to fault systems: the main Vani manganese deposit is adjacent to the NW-trending Kondaros-Katsimouti-Vani Dome fault, whereas the Aspro Gialoudi deposit is adjacent to the relatively minor NE-trending fault on the west coast of Milos. At Aspro Gialoudi, mineralization took place in a subseafloor and/or seafloor environment and is characterized by a stratabound Mn-barite-rich deposit mainly within a package of propylitized intrusive hyaloclastites and within the overlying sandstones. Banded epithermal veins trending NE-SW and composed of chalcedonic silica/quartz + barite + Mn-oxide + sulfides crosscut the dacitic lavas, the hyaloclastites and the overlying volcaniclastic sequence at Aspro Gialoudi and are considered to represent the feeder zones of the manganese-barite mineralization. Within the veins, early sulfide (galena-sphalerite) barite and quartz deposition is followed by manganese oxides and aragonite, thus resembling the epithermal-style Pb-Zn-Ag-Mn mineralization across the NW-trending Katsimoutis-Kondaros-Vani fault. Mineralization in Aspro Gialoudi and Vani deposits seems to be controlled by alternating cycles of deposition of sulfides and hydrothermal manganese oxides within the faults. Manganese deposition in both deposits formed in a similar manner, namely by transport of hydrothermal fluids through the adjacent fault systems into a reservoir of volcanoclastic sandstone and hyaloclastites to produce a deposit initially consisting of principally of pyrolusite and occasionally ramsdellite, which were subsequently replaced by cryptomelane, hollandite, coronadite and hydrohaeterolite. Precipitation of hydrothermal manganese oxides took place very quick and under microbial Mn(II) oxidation. Compositional data show that metallic elements most enriched in the Aspro Gialoudi and Vani manganese deposits relative to the average continental crust, lie in the sequences Pb > Cd > Mn > As > Sb > Zn > W > Tl > Ba > Cu > Mo > Co > Bi and As > Sb > Pb > Mn > Tl > Cd > Zn > W > Cu > Ba > Mo > Co, respectively. Mineralogical and geochemical (e.g. REE) data from both Aspro Gialoudi and main Vani deposit are taken to indicate mainly a seawater source for the hydrothermal fluids. These two deposits are genetically and spatially related to base- and precious metal intermediate-sulfidation epithermal mineralization. They formed successively by similar processes and are considered to be integral parts of the same hydrothermal system.

The Triades-Galana Pb-Zn-Ag-Au mineralization is a shallow-submarine epithermal mineralization located along NE-trending faults, NW Milos Island, Greece. It is hosted in 2.5–1.4 Ma pyroclastic rocks and is genetically related to andesitic/dacitic lava domes. Mineralization occurs as breccias, quartz-barite-galena veins and stockworks within sericite-adularia or kaolinitic altered rocks. The mineralization is enriched in Mo, W and base-and precious metals (e.g. Pb, Zn, Ag) similarly to the neighbouring mineralization at Kondaros-Katsimouti and Vani, indicating common source of metals from a deep buried granitoid feeding western Milos with metals and volatiles. Paragenetic relations suggest early deposition of pyrite, followed by famatinite, polybasite and Ag-rich tetrahedrite, and then by enargite, suggesting fluctuating sulfidation states during ore formation. The evolution from Sb-towards As–rich enrichment indicate a renewed magmatic pulse (probably in the form of magmatic gases) in the hydrothermal system. Silver is present in the structure of sulfosalts (up to 66.2 wt.% in polybasite-pearceite, 15.1 wt.% in tetrahedrite and 60 wt. % in pyrargyrite). Boiling processes (as evidenced by the presence of adularia accompanying intermediate-sulfidation ore) and mixing with seawater (presence of hypogene lead chlorides) and contemporaneous uplift, contributed to ore formation.

Small occurrences of iron-oxide deposits at Sesi-Koropi in S. Hymittos, are hosted by an extensional brittle detachment zone between carbonate rocks of "Vari-Kirou Pira" and "Hymittos" units. Another low-angle fault separates a heterogeneous formation of schists, containing meta-ophiolitic blocks ("Lavrion" Unit), which is cut by high-angle normal faults that root in the detachment zone, reducing the total structural thickness of "Hymittos" marbles and bringing in contact the meta-ophiolitc lithologies with the "Vari-Kirou Pira" dolomites. Three mine caves were found along the detachment zone indicating that these iron deposits were possibly mined on a very small scale in the past. The mineralization is developed in a cata-clastic zone a few meters thick (3-5m), forming thin rusty black encrustations and larger zones of alteration with a reddish to yellow brown hue. Scanning Electron Microscope (SEM) mineralogical study of the iron-ore deposit indicated that hema-tite is the primary iron-oxide mineral extensively replaced by goethite. Goethite appears with the typical colloidal form within voids showing typical open-space filling type microstructures. According to field evidence and the tectonic macro-structure of the area, the mineralization is associated with hydrothermal fluid circulation along the brittle detachment zone between meta-ophiolitic lithologies and carbonate rocks. Similar type iron-oxides mineralization in cataclastic zones were observed along other detachment zones in northern and southeastern Hymittos Mt. and further south towards Lavrion. This suggests that this type of mineralization is not local but has a broader development and regional implications for the tectonic evolution of the central and SE Attica.

Ampelia area is a newly discovered area with geothermal interest and no surface manifestations (hidden resource). It is located in Farsala basin and belongs to the Enipeas graben. The geothermal anomaly is related with the E-W trending faults, which mainly control the basin development and the NNW-SSE trending faults of the area. The temperature values from the deep water boreholes (>200m depth) range from 20 to 41 o C. The chemical composition of the studied groundwater samples varies in all chemical parameters. Most of the samples have affected by shallow cold aquifers (high E.C. and NO3-values). The most representative samples (T > 30 o C) are from the deepest boreholes (hydrochemical type Na-HCO3), which cut the fractured crystalline basement, i.e. limestones, flysch and ophiolitic rocks. They present the highest pH values (pH > 8) and the lowest E.C. compared with the rest of the samples. Their Ni and Cr concentrations are very low, indicating that the groundwater is not in contact with the ultramafic rocks from the ophiolite sequence. According to silica chemical geothermometers for the most representative samples, the expected temperature values of a potential geothermal reservoir range from ~ 60 to 100 o C. Περίληψη Η περιοχή της Αμπελίας είναι μια νέο-ανακαλυφθείσα περιοχή, η οποία παρουσιάζει γεωθερμικό ενδιαφέρον, χωρίς να παρουσιάσει επιφανειακές γεωθερμικές εκδηλώσεις. Εντοπίζεται στη λεκάνη των Φαρσάλων και ανήκει στο τεκτονικό βύθισμα του Ενιπέα. Η γεωθερμική ανωμαλία συνδέεται με τα ρήματα διεύθυνσης Α-Δ, που ελέγχουν την δημιουργία της κοιλάδας και τα διασταυρούμενα σε αυτά ρήγματα διεύθυνσης ΒΒΔ-ΝΝΑ. Οι θερμοκρασίες από τις βαθιές γεωτρήσεις (> 200 μ) κυμαίνονται από 20 έως 41 o C. Η χημική σύσταση των δειγμάτων παρουσιάζει έντονες διαφοροποιήσεις. Τα περισσότερα δείγματα έχουν επηρεαστεί από κρύους επιφανειακούς υδροφόρους (υψηλές τιμές E.C. και NO3-). Τα πιο αντιπροσωπευτικά δείγματα με T > 30 o C προέρχονται από βαθιές γεωτρήσεις που αναπτύσσονται και μέσα στο τεκτονισμένο κρυσταλλικό υπόβαθρο (ασβεστόλιθοι, φλύσχης, οφιολιθικά πετρώματα). Τα δείγματα αυτά παρουσιάζουν τις υψηλότερες τιμές pH (pH > 8) και τις χαμηλότερες τιμές E.C. Επίσης, παρουσιάζουν πολύ χαμηλές συγκεντρώσεις Ni και Cr, ενδεικτικό ότι δεν είναι σε επαφή με τα υπερβασικά πετρώματα των οφιολιθικών σχηματισμών. Βασιζόμενοι σε πυριτικά χημικά γεωθερμόμετρα και εστιάζοντας κυρίως στις τιμές των πιο αντιπροσωπευτικών δειγμάτων εκτιμάται ότι η θερμοκρασία ενός πιθανού γεωθερμικού ταμιευτήρα στην περιοχή πρέπει να κυμαίνεται από ~ 60 έως 100 o C. Λέξεις κλειδιά: γεωθερμική ενέργεια, γεωχημεία θερμών υπόγειων νερών, συγκεντρώ-σεις ιχνοστοιχείων και ιόντων, Ανατολική Θεσσαλία, Ελλάδα.

This paper presents a new garnet-magnetite-bearing skarn hosted within metasomatised amphibo-lites, in the Kimi Unit of the Rhodope metamorphic complex, near Therapio village Evros prefecture. The skarn is described in terms of mineralogy and petrogenesis.
The Therapeio skarn occurs is developed in amphibolites in close relation with pegmatite veins. It is constituted of  the prograde assemblage garnet, magnetite, apatite, and bornite, while retrograde min-erals amphibole, barite, allanite, galena, chlorite, quartz along with sulfides and hematite. Some of them are also found in the host rock. 
According to the field observations and the results of the laboratory study, the Therapio skarn is a result of the metasomatism due to intrusion of the pegmatite veins into the protolite amphibolite.

ABSTRACT The soil geochemistry was studied in the area of Atalanti, Greece, an area characterized by presence of mafic and ultramafic rock members of an ophiolite complex. The objectives of the study were to evaluate their impact on soil chemistry and to establish the geochemical baseline of soil with respect to elements derived from the ophiolite rocks. A total of 118 agricultural soil samples were collected and found to be enriched in Ca (7.6 %), Co (31 mg/kg), Cr (230 mg/kg), Cu (37 mg/kg), Mg (2.9 %) and Ni (330 mg/kg) relative to the median values of both European and Greek soils. Soil baseline concentrations of the ophiolite derived elements (Cr, Ni, Co) were estimated within two sub-areas and the variation in their concentration was assessed along two toposequences characterised by different intensity of weathering of parent rock. Differences in groundwater chemistry were also demonstrated for the aquifers developing within the two subareas. The results of this study can be utilized in future studies on serpentine soil in temperate climate by providing an objective basis for setting realistic threshold values for pollution assessment and remediation.