Synthetic zeolites from lignite fly ash and biomass ash for agricultural applications

The production of zeolites is one of the potential applications of fly ash production to obtain high value industrial products with environmental technology utilization. The synthesis of zeolite products from fly ash is analogous to the formation of natural zeolites from volcanic deposits or other high-Si-Al rocks,rich in amorphous phases, by the interaction of hot alkaline water on the glass fraction of the rocks. That zeolite development process may take thousands of years in order to form natural zeolites. In the laboratory, the process can be speeded up (to days or hours) for both volcanic and fly ash. Previous studies have demonstrated the utilization of lignite fly ash Na bearing synthetic zeolitic materials for the removal of heavy metals from wastewater, for mine-water treatment and as soil amendments in acid mining soils. Since K is considered as a nutritient in agriculture KOH was selected as an activation solution, in order to develop a K-rich synthetic zeolite suitable for utilization in agriculture. In the current study we are evaluating the results of the hydrothermal activation of lignite fly ash and biomass asses from Greece, by KOH in order to produce synthetic zeolites, for agricultural applications

Geological modelling for investigating CO2 emissions in Florina Basin, Greece

Published version also available at http://dx.doi.org/10.1515/geo-2015-0039This paper presents an investigation of naturally occurring CO2 emissions from the Florina natural analogue site in Greece. The main objective was to interpret previously collected depth sounding data, convert them into surfaces, and use them as input to develop, for the rst time, 3D geological models of the Florina basin. By also locating the extent of the aquifer, the location of the CO2 source, the location of other natural CO2 accumulations, and the points where CO2 reaches the surface, we were able to assess the potential for CO2 leakage. Geological models provided an estimate of the lithological composition of the Florina Basin and allowed us to determine possible directions of groundwater ow and pathways of CO2 ow throughout the basin. Important modelling parameters included the spatial positions of boundaries, faults, and major stratigraphic units (which were subdivided into layers of cells). We used various functions in Petrel software to rst construct a structural model describing the main rock boundaries. We then de ned a 3D mesh honouring the structural model, and nally we populated each cell in the mesh with geologic properties, such as rock type and relative permeability. According to the models, the thickest deposits are located around Mesochorion village where we estimate that around 1000 m of sediments were deposited above the basement. Initiation of CO2 ow at Florina Basin could have taken place between 6.5 Ma and 1.8 Ma ago. The NESW oriented faults, which acted as uid ow pathways, are still functioning today, allowing for localised leakage at the surface. CO2 leakage may be spatially variable and episodic in rate. The episodicity can be linked to the timing of Almopia volcanic activity in the area

Compaction of High-Ca Fly Ash-Al- and Al-Alloy-Composites: Evaluation of their Microstructure and Tribological Performance

In this study, highly calcareous and siliceous fly ash particles were utilized for the fabrication of Al- and Al-alloy-based MetalMatrix Composites (MMCs) by means of powder metallurgy. After compacting and sintering Al and Al/Si powders containing 10, 15, and 20wt. % ash particles, the homogenous (and with minimal amount of voids) microstructure of the produced composites was verified by means of Scanning Electron Microscopy (SEM). The composites were tested for their dry sliding wear behavior using a pin-on-disc machine against spheres of alumina. The worn surfaces of composites were then examined by using SEM and Energy Dispersive X-Ray Spectroscopy (EDS). It was shown that the addition of both types of FA enhanced the tribo-performance of Al, with the optimum metal powder replacement determined to the point of 15% wt., in the case of high-Si and 10% wt., in the case of high-Ca ash particles. Regarding alloy-matrix composites, although they generally presented worse tribological performance than pure Al/Si products, the additions of ashes up to 15% wt. resulted in only slight deterioration of the wear performance of composites

Hazard identification of the Mediterranean Temporary Mountain Pond ecosystems in Central Greece: Α Geo-environmental approach

Mediterranean Temporary Ponds (MTPs) are shallow water bodies which are characterized from a short wet period and their small size. MTPs of Europe have are under an effective protection status, as a result of their identification as a priority habitat (Annex I code 3170*) in the EU Directive 92/43/EEC (Habitats' Directive). These ponds are very delicate ecosystems regarding their hydrological and geochemical characteristics. Due to their small size, they are open to random destruction or other unpredictable dangers. Although small in size, MTPs are complex ecosystems where topography, soil, water and hydrological conditions and microorganisms are closely connected. The conservation and restoration of such ecosystems is very difficult because of their unique characteristics. The most common threats for MTPs include destruction of the hosting area through human and animal pressures, hydrological disturbance, fire and generally changes in ecological conditions resulting in an increase of competitive plants, nutrition influx, toxic contaminants and wastes, sedimentary deposit filling, exotic-invasive fauna and flora and negative effects from domesticated or hunted fauna. The study was carried out in the MTPs area of the National Forest Park of Mt. Oiti (GR2440004) and Mt. Kallidromo (GR2440006). Overall, the survey has included seven small and independent MTPs of high altitude in the areas of Mt. Oiti (Louka, Livadies, Greveno and Alikaina) and Mt. Kallidromo (Nevropolis, Mourouzos and Souvala). This study aims to present a dataset of the geo-environmental parameters in order to assess the potential hazards for these priority habitats. Furthermore, it is also worth mentioning that MTPs are unevenly studied, regarding their geological, hydrological, hydrochemical, geochemical and mineralogical characteristics and this work provides a first report on an integrated evaluation of these parameters regarding the qualitative and quantitative risk identification of the MTPs in Central Greece

Assessment of the impact of CO 2 storage in sandstone formations by experimental studies and geochemical modeling: the case of the Mesohellenic Trough, NW Greece

Representative sandstone samples from Mesohellenic Trough (NW Greece) were selected to investigate the geochemical reactions that occur when they come in contact with CO2 under representative in-situ conditions (T = 70 °C, P = 150 bar, 6 months reaction in batch experiments). Those sandstones consisted of predominant calcite and quartz, with lesser amounts of feldspars, chlorite, ankerite, dolomite, kaolinite, montmorillonite and muscovite. After reaction with CO2, the brine became acidic and was enriched in cations as a result of mineral dissolution. Minor mineralogical changes were observed that involved: a) the dissolution of carbonate minerals and b) the incongruent dissolution of chlorite to form clays and silica. The results related to these, have been linked with geochemical modelling using the PHREEQC code. Simulation results for a 10 ka time period predicted that chlorite was expected to dissolve completely within 100 years, leading to boehmite growth and increasing the mass of dolomite. Feldspars were expected to react at a later stage in the reaction sequence. Sensitivity tests were run to access the effect of various adjustable parameters on the outcome results. The geochemical experiments and modelling lend support to the view that Pentalofos and Tsotyli sandstone formations of the Mesohellenic Trough are suitable for the long-term storage of CO2 produced in the neighbouring lignite-fired power plants, at least in terms of mineralogy and geochemistry

Evaluating the effect of marine diagenesis on late Miocene pre-evaporitic sedimentary successions of Eastern Mediterranean Sea

Unidad de excelencia María de Maeztu MdM-2015-0552The microstructure and geochemical composition of foraminiferal tests are valuable archives for the reconstruction of paleoclimatic and paleoecological changes. In this context, the late Miocene Globigerinoides obliquus shells from Faneromeni section (Crete Island) were investigated through Scanning Electron Microscopy (SEM) imaging, Energy Dispersive System (EDS) analysis and X-Ray Diffraction (XRD) spectroscopy in order to evaluate their potential as paleoenvironmental archives in the eastern Mediterranean. Investigation of diagenetic features, in late Miocene sediments from the Faneromeni section, shows that carbonate precipitation and cementation occur in various lithologies, particularly in carbonate-rich portions, such as bioclastic or clayey limestones. We identified 3 different diagenetic stages (early, intermediate, advanced), as a function of taphonomy in the study area. The comparison of microstructural and geochemical characteristics reveals a sequence of preservation states with "glassy" to "frosty" to "chalky" shells, indicative of the progressive diagenetic alteration of late Miocene planktic foraminiferal calcite. The early diagenetic stage occurs during the Tortonian, and consists of intermediates between "glassy" and "frosty" individuals. Around the Tortonian/Messinian (T/M) boundary at the second diagenetic stage, planktonic foraminifera have a clear "frosty" appearance, showing a gradual high-Mg calcite (to dolomite) crystal overgrowth development and dissolution of biogenic calcite. During the late Messinian and progressively through the Messinian Salinity Crisis (MSC), planktonic foraminifera present a "chalky" taphonomy. The additional precipitation of authigenic high-Mg inorganic calcite and dolomite crystals in the exterior of the tests characterizes the advanced diagenetic stage. The measured amount of diagenetic Mg-rich (10-14% molar Mg on average) calcite and/or dolomite coatings is compatible with results obtained on modern eastern Mediterranean core-top sediments. The assessment of such a diagenetic alteration contributes to a more precise reconstruction of sea surface temperatures (SSTs) during the Neogene, such that only when the changing proportions of the texture are accounted for, would geochemical measurements and subsequent paleoenvironmental interpretations be more meaningful. However, further investigations should extend this approach to test the robustness of our findings across a range of taphonomies, ages and burial settings

Dichotomy of The Messada Pluton, Serbo-Macedonian Massif, Greece: From Rifting to Subduction

The Messada pluton is a mafic intrusion that is located about 12 km SW of Serres town, (Macedonia Greece) that intrudes the two mica, biotite and the augen gneisses of the Vertiskos formation (Serbo-Macedonian massif). The aim of this study is to investigate, define and evaluate the geochemical characteristics of the pluton in order to determine the geotectonic environment in which the parental magma has been formed. The Mesada pluton is a mid to coarse grained intrusion presenting petrographic variety from diorite and quartz diorite to tonalite and granodiorite. The variety in petrography reflects its chemical inhomogeneity in major and trace elements. It is suggested that parts of pluton have been formed by distinctly different types of magmas originated in diverse geotectonic settings. Those parts of quartz diorite and tonalite composition, present similar geochemical characteristics, LILE/HFSE ratios and negative Nb, but no Ti anomalies in their primitive mantle normalized trace elements spider grams. They exhibit higher HFS values than those of granodioritic composition. Moreover, their ORG normalized spider grams not only suggest that they have been evolved by a common parental magma, but also present the typical characteristics of a “ crust dominated” within plate pluton that may have been formed in an early stage during rifting, prior to a subsequent subduction episode. This interpretation may be in accordance with the suggestion for the Gondwanian origin of the more silicic Triassic rift related meta-granites (e. g. Arnea plutonic complex) of the Serbo-Macedonian massif. In contrary; the parts of Mesada pluton of granodioritic composition, exhibit a calc-alkaline to high K calc-alkaline magmatic suite and present higher LILE/HFSE and LREE/HREE ratios, related to a higher crustal component contribution for the magma genesis. Furthermore, their primitive mantle normalized spider grams’ present negative anomalies at Nb and Ti. These characteristics indicate that those granodioritic parts have been formed by the crystallization of a calk-alkaline magma, produced by the partial melting of lower crust, lithospheric mantle and asthenospheric mantle components, in a volcanic arc geo-tectonic setting. Their geochemical characteristics have close similarities to those of the collision related granitoids that have intruded the SerboMacedonian during Tertiary

A comparative study in the geochemistry of the trace and the rare earth elements in tertiary granites in Central Macedonia, related or not, with known mineralizations: definition of the geotectonic environment for the granites' genesis

The present thesis deals with a comparative study in the geochemistry of the trace and the rare earthelements in tertiary granitoids in central Macedonia, related or not with known mineralizations andthe definition of the geotectonic environment of the granite magma genesis.The objective of the thesis is the study of the trace and the rare earth elements’ geochemistry of• the Stratoni granodiorite and the Stratoni – Olympias aplites and pegmatites that are relatedwith the notorious mass sulfide and precious metal mineralizations,• the Megali Panagia’s granitoids that include the diorite to granite porphyries of Tsikara andSkouries which is associated with the homonym Cu-Au ore deposit and• the Jerissos’, Mesada’s, Stefanina’s and Mesolakkia’s plutons which are not related with anyknown mineralizations.This study aims to give a comprehensive account on the determination of the granites of the studyarea, which, even if are not related with any known ore deposits, they have common geochemicalcharacteristics of the Large Ion Lithophile Elements (LILE), the High Field Strength Elements(HFSE) and the Rare Earth Elements (REE) with those that are related.Specifically, the study is focused on:• the definition of the geochemical characteristics of each pluton,• the determination of the geotectonic environment in which the granite magma has been formed,• the determination of the common geochemical characteristics of the granites that are associatedwith known mineralization,• the comparison of the above geochemical characteristics, with those of the granites’ that are notassociated with any known ore deposits.The studied granites presented petrographic variety, that included diorites, monzodiorites, quartzdiorites, quartz monzodiorites, tonalites granodiorites, granites, pegmatites and aplites.The Jerissos granite is of Mid Eocene age, which till now It hasn’t been associated with anymineralization and has the same age with the Sithonia and Ouranoupolis Plutons in SE Chalkidikipeninsula. It is consisted by different petrographic types, biotite granite, two mica granite and biotiegranodiorite.The Stratoni plouton is a fine to coarse grained magmatic intrusion composed by quartz diorite,quartz monzodiorite, tonalite and granodiorite to granitite petrographic types, but the granodioritetype is the dominant. In Stratoni – Olympias area there exist a wide network of aplitic andpegmatitic dykes that usually have been identified as aplite-pegmaties.The Skouries porphyry close to the Megali Panagia village is a granodiorite to tonalite porphyryintrusion. South-eastern of the Skouries porphyry, the great porphyry intusion that occupies thecentral part of the Tsikara mountain is a granodioritic to tonalitic porphyry. That porphyry issurrounded by a more mafic igneous rock, partly porphyritic, mainly of quartz monzodioritecomposition.The Mesolakkia granite is a coarse grained, partly porphyritic pluton of monzodiorite granodioriteand granite composition. During the fieldwork, a gossan formation of some tens of square meters,has been identified in the southern edge of the pluton.The pluton of the Mesada region is a mid to coarse grained mafic magmatic intrusion of dioriteand quartz diorite to tonalite and granodiorite composition. The Stefanina pluton is a mid-grained pluton of monzodiorite to diorite composition. Occasionallyit is being crosscut by pegmatite dykes. At the western part of the pluton, close to the border withthe ultrabasic rocks, a highly altered rock with porphyritic texture, presenting evidence of coppermineralization, has been identified during the fieldwork.Sampling was carried out during fieldwork, taking care to include fresh rock samples from anydifferent petrographic types of its pluton. The bulk rock chemical analyses were implemented bythe X-ray Fluorescence analytical method (XRF) in the Laboratory of the Department of Geology,University of Leicester, UK. The major elements analyses were performed in fussed beads whilethe trace elements analyses’ were performed in pressed pellets. The chemical analyses of selectedsamples, for the REE and for the U, Ta, Hf and Cs as well, were carried out by the instrumentalneutron activation method in the Institute of Nuclear Technology and Radio Safety, National Centrefor Scientific Research “DEMOKRITOS”. The microprobe analyses for the determination of themineral chemistry were obtained by E.M.P.A. equipped with a WD system in the Laboratory of theDepartment of Geology, University of Leicester, UK.The variety in petrography presented by the studied plutons reflects their chemicalinhomogeneousness in major elements. In any case, the Stratoni, Megali Panagia, MesolakkiaStefanina intrusions the Stratoni – Olympias aplite-pegmaties and at least parts of Jerissos andMesada plutons, have many common geochemical characteristics. They have been formed by calcalkalineto high K calc-alkaline to magmas and they are characterized by high LILE/HFSE καιLREE/HREE ratios. Their primitive mantle normalized spidergrams present negative anomalies atNb and Ti. These characteristics indicate that these plutons that have been crystallized from calkalkalinemagmas, produced in a volcanic arc geotectonic environment, by the partial meltingof crustal, lithospheric mantle and asthenospheric mantle components.The Stratoni pluton, the Megali Panagia intrusions, the Mesolakkia granitoid, the granite andgranodiorite parts of the Jerissos pluton and the granodiorite parts of the Mesada pluton, havecommon geochemical characteristics with the pre-plate collision granites (that means VolcanicArc Granites) and with the post- collision granites (post-COLG). The commonalities in theirnormalized trace elements’ spidergrams are so strong that even a common origin for the granitemagma could be suggested. As long the tertiary magmatism is related with massive sulphide andporphyry copper ore deposits, the Mesolakkia pluton and the granodiorite parts of the Mesadapluton can be related to mineralization just similar to the Stratoni and Megali Panagia graniticintrusions.Moreover, the Stefanina pluton exhibits also common geochemical characteristics, presenting, highLILE/HFSE and LREE/HREE rations and negative Nb and Ti anomalies, that indicate a highcrust/mantle ratio in the formation of its parental magma. The geotectonic environment for themagma formation was a volcanic arc environment. As there is a significant number of commongeochemical characteristics in trace and rare earth elements of the Stefanina pluton with the abovementioned calk-alkaline plutons the possibility that this pluton can be related to mineralization, likethe above mentioned granitic intrusions could be suggested.The Stratoni – Olympias aplite-pegmaties and Stefanina pegmaties are characterized, at least partly,either as syn-collisional (syn-COLG), or as post collisional (post-COLG), or as volcanic arcgranites (VAG). Whereas the unaltered Stratoni aplite-pegmaties and the Stefanina graniticpegmatites are presenting geochemical characteristics of syn-collisonal granites, thesecharacteristics could also be attributed to their formation during the late stages of a granitemagma fractional crystallization process. The later suggestion is the most favourable as theStratoni aplite-pegmaties have been considered, geochemicaly, to be formed at the latest stages ofthe granite magma crystallization. Due to the fact that, Stefanina pegmatites have similargeochemical characteristics with the former, it is suggested that they could also had been formed atthe latest stages of the magma crystallization process. Different parts of Jerissos granite have been formed by sequential intrusions of diverse types ofgranite magmas. Even though its parts of granite and granodiorite composition have been formed ina post- collision geotectonic environment, the parts of adamellite composition have been formed bymagma in a syn-collision environment.Moreover, parts of Mesada pluton have been formed by different types of magmatic intrusions thathave been produced in a diverse geotectonic environments. Those parts of quartz diorite andtonalite composition have been formed by a “crust dominated” magma, originated in a withinplate environment.Αντικείμενο της παρούσας διατριβής είναι η μελέτη της γεωχημείας των λιθόφιλων ιχνοστοιχείωνμεγάλης ιοντικής ακτίνας (LILE), των ιχνοστοιχείων υψηλού δυναμικού πεδίου (HFSE) καθώς καιτων στοιχείων της ομάδας των σπανίων γαιών (REE), Τριτογενών γρανιτικών σωμάτων τηςΚεντρικής Μακεδονίας που σχετίζονται ή μη, με γνωστή μεταλλοφορία και ο προσδιορισμός τουγεωτεκτονικού περιβάλλοντος γένεσης του μητρικού μάγματος των γρανιτικών σωμάτων.Τα πλουτώνια σώματα που μελετήθηκαν εμφανίζουν ποικιλία πετρογραφικών τύπων.Περιλαμβάνουν διορίτες, μονζοδιορίτες, χαλαζιακούς διορίτες, χαλαζιακούς μονζοδιορίτες,τοναλίτες, γρανοδιορίτες, γρανίτες, πηγματίτες και απλίτες.Ο γρανίτης της Ιερισσού είναι ένα μεσόκκοκο έως χονδρόκοκκο γρανιτικό σώμα αποτελούμενοαπό, βιοτιτικό γρανίτη, διμαρμαρυγιακό γρανίτη, και βιοτιτικό γρανοδιορίτη. Η ηλικία του είναιΜέσο-Ηώκαινική, ανάλογη με εκείνη των γρανιτικών σωμάτων της Σιθωνίας και τηςΟυρανούπολης στη νοτιοανατολική Χαλκιδική.Το μαγματικό σώμα του Στρατωνίου, είναι ένας λεπτόκοκκος έως αδρόκοκκος πλουτωνίτηςΟλιγοκαινικής ηλικίας με σύσταση που ποικίλει από χαλαζιακή διοριτική έως και γρανιτική.Επικρατεί ο μεσόκοκκος γρανοδιοριτικός πετρολογικός τύπος. Η ευρύτερη περιοχή ΣτρατωνίουΟλυμπιάδας χαρακτηρίζεται από την ύπαρξη ενός πυκνού δικτύου απλιτοπηγματιτικών φλεβών.Ο πορφύρης των Σκουριών, στην περιοχή της Μεγάλης Παναγιάς, είναι μια γρανοδιοριτικής έωςτοναλιτικής σύστασης διείσδυση. Νοτιοανατολικά των Σκουριών, η μεγάλη πορφυρική διείσδυσηπου καταλαμβάνει το κεντρικό τμήμα του όρους Τσικάρα είναι επίσης, ένας γρανοδιοριτικός έωςτοναλιτικός πορφύρης. Ο πορφύρης αυτός, περιβάλλεται από βασικότερο πέτρωμα, ενίοτεπορφυριτικό, ως επί το πλείστον χαλαζιακής μονζοδιοριτικής σύστασης.Το γρανιτικό σώμα της Μεσολακκιάς, είναι ένα συμπαγές αδροκρυσταλλικό, ενίοτε πορφυρικόπέτρωμα, κατά τόπους μονζοδιοριτικής, γρανοδιοριτικής και γρανιτικής σύστασης. Κατά τηδιάρκεια της εργασίας υπαίθρου, στο πλαίσιο της παρούσας διατριβής, εντοπίστηκε ζώνησιδηρούχου καλύμματος “gossan”, εκτάσεως μερικών δεκάδων τετραγωνικών μέτρων, στο νότιοτμήμα του πλουτωνίτη.Ο πλουτωνίτης της Μεσάδας. είναι μια μεσόκοκκη έως αδρόκοκκη βασική διείσδυση, με σύστασηπου κυμαίνεται από διοριτική έως τοναλιτική.Ο πλουτωνίτης των Στεφανινών, είναι ένας μεσόκοκκος πλουτωνίτης, μονζοδιοριτικής έωςδιοριτικής σύστασης που κατά θέσεις, διασχίζεται από πηγματιτικές φλέβες. Κατά τη διάρκεια τηςεργασίας υπαίθρου εντοπίστηκε στην δυτική περιοχή του πλουτωνίτη έντονα εξαλλοιωμένοςλιθολογικός σχηματισμός με πορφυρικό ιστό και ενδείξεις χαλκούχου μεταλλοφορίας.Κατά την εργασία υπαίθρου, η δειγματοληψία έγινε με τέτοιο τρόπο ώστε να περιληφθούν, όσοήταν δυνατό, δείγματα υγιούς πετρώματος, από όλους τους διαφορετικούς πετρογραφικούς τύπουςκάθε γρανιτικού σώματος. Οι χημικές αναλύσεις για τα κύρια στοιχεία και τα ιχνοστοιχεία όλωντων δειγμάτων έγιναν με τη μέθοδο της φθορισμομετρίας ακτίνων Χ (XRF) στο Εργαστήριο τουΤμήματος Γεωλογίας του Πανεπιστημίου του Leicester της Αγγλίας. Οι χημικές αναλύσειςεπελεγμένων δειγμάτων, για τα στοιχεία της ομάδας των σπανίων γαιών (REE) και για τα στοιχείαU, Ta, Hf και Cs, πραγματοποιήθηκαν με τη μέθοδο της ενόργανης νετρονικής ενεργοποίησης(INAA) στα εργαστήρια του Ε.ΚΕ.Φ.Ε. «ΔΗΜΟΚΡΙΤΟΣ». Πραγματοποιήθηκαν τέλος,ορυκτοχημικές αναλύσεις σε πετρογραφικά παρασκευάσματα, με τη χρήση ηλεκτρονικούμικροαναλυτή, εξοπλισμένου με σύστημα σκέδασης μήκους κύματος (WDS), στο Εργαστήριο τουΤμήματος Γεωλογίας του Πανεπιστημίου Leicester,. Η πετρογραφική ποικιλία που παρουσιάζουν τα μελετηθέντα πλουτώνια σώματα, αποτελείέκφραση της ανομοιογένειας στη χημική τους σύστασή σε κύρια στοιχεία. Σε κάθε περίπτωσηόμως, οι διεισδύσεις του Στρατωνίου, της Μεγάλης Παναγιάς, της Μεσολακκιάς, των Στεφανινών,οι απλιτοπηγματίτες της περιοχής Στρατωνίου – Ολυμπιάδας, και τουλάχιστον τμήματα τωνπλουτωνιτών της Ιερισσού και της Μεσάδας, παρουσιάζουν πολλά κοινά γεωχημικάχαρακτηριστικά. Πρόκειται για ασβεσταλκαλικά έως ασβεσταλκαλικά υψηλού Κ πετρώματα πουχαρακτηρίζονται από υψηλούς λόγους LILE/HFSE και LREE/HREE. Τα κανονικοποιημένα ωςπρος πρωταρχικό μανδύα διαγράμματα ιχνοστοιχείων τους εμφανίζουν αρνητικές ανωμαλίες σταστοιχεία Nb και Ti. Τα χαρακτηριστικά αυτά δείχνουν ότι τα πλουτώνια σώματα έχουν προέλθειαπό ασβεσταλκαλικό μάγματα που δημιουργήθηκαν κατά την υποβύθιση ωκεάνιας πλάκας κάτωαπό ηπειρωτική σε περιβάλλον ηφαιστειακού τόξου με τη συμμετοχή φλοιού, μανδύα από τακατώτερα τμήματα της λιθόσφαιρας, (λιθοσφαιρικού μανδύα) και ανώτερου μανδύα από τηνασθενόσφαιρα, (ασθενοσφαιρικού μανδύα).Τα γεωχημικά χαρακτηριστικά που παρουσιάζουν οι πλουτωνίτες του Στρατωνίου, της ΜεγάληςΠαναγιάς, της Μεσολακκιάς, τα γρανιτικής και γρανοδιοριτικής σύστασης τμήματα τουπλουτωνίτη της Ιερισσού και τα γρανοδιοριτικής σύστασης τμήματα του πλουτωνίτη της Μεσάδαςείναι κοινά για τα γρανιτοειδή που δημιουργούνται σε περιβάλλον ηφαιστειακού τόξου (VAG),κατά την υποβύθιση ωκεάνιας πλάκας κάτω από ηπειρωτική (πριν από τη σύγκρουση) και για ταγρανιτοειδή που δημιουργούνται μετά από τη σύγκρουση των πλακών (post COLG). Οι ομοιότητεςείναι τέτοιες που μπορεί να πιθανολογηθεί ακόμη και κοινή μαγματική προέλευση τωνπλουτωνιτών. Καθώς δε, ο τριτογενής μαγματισμός παρουσιάζει σύνδεση με τις μεταλλοφορίεςσυμπαγών θειούχων μεταλλευμάτων καθώς και πορφυρικών συστημάτων Cu, να συνδέονται μεμεταλλοφορίες αντίστοιχες με αυτές του Στρατωνίου και της Μεγάλης Παναγιάς.Ο πλουτωνίτης των Στεφανινών παρουσιάζει πολλά κοινά γεωχημικά χαρακτηριστικά, όσον αφοράτα ιχνοστοιχεία και τα στοιχεία της ομάδας των σπανίων γαιών, με τους υπόλοιπουςασβεσταλκαλικούς πλουτωνίτες και χαρακτηρίζεται από υψηλή συμμετοχή υλικού από τον φλοιόστα μητρικό του μάγμα. Το γεωτεκτονικό περιβάλλον δημιουργίας του μάγματος, προέκυψε ότιήταν περιβάλλον ηφαιστειακού τόξου (VAG). Τα κοινά γεωχημικά χαρακτηριστικά πουπαρουσιάζει ο πλουτωνίτης των Στεφανινών με τους προηγούμενους οδηγούν στην πιθανολόγησηότι κι αυτός μπορεί να σχετίζεται με μεταλλοφορίαΟι απλιτοπηγματίτες των περιοχών Στρατωνίου - Ολυμπιάδας και των Στεφανινών,χαρακτηρίζονται εν όλω ή εν μέρει, είτε ως συνορογενετικοί (syn-COLG), είτε ωςμεταορογενετικοί που δημιουργούνται μετά από τη σύγκρουση των πλακών (post-COLG) είτε ωςγρανίτες ηφαιστειακού τόξου (VAG). Αν και οι μη εξαλλοιωμένοι απλιτοπηγματίτες τουΣτρατωνίου και οι γρανιτικοί πηγματίτες των Στεφανινών εμφανίζουν γεωχημικά χαρακτηριστικάσυν-ορογενετικών γρανιτοειδών, τα χαρακτηριστικά αυτά είναι παρόμοια με εκείνα πουπαρουσιάζουν και τα μαγματικά πετρώματα που δημιουργούνται κατά τα τελευταία στάδιακλασματικής κρυστάλλωσης. Καθώς οι απλιτοπηγματίτες του Στρατωνίου, προέκυψε ότιπιθανότατα, αποτελούν απολήξεις του πλουτωνίτη, φαίνεται ότι πρόκειται για τη δεύτερηπερίπτωση. Το αντίστοιχο πρέπει να ισχύει και για τους γρανιτικούς πηγματίτες των Στεφανινώνπου παρουσιάζουν όμοια γεωχημικά χαρακτηριστικά με τους προηγούμενους.Τμήματα του πλουτωνίτη της Ιερισσού, έχουν δημιουργηθεί από διεισδύσεις διαφορετικών τύπωνμαγμάτων. Σε αντίθεση με τα γρανιτικής και γρανοδιοριτικής σύστασης τμήματα του πλουτωνίτη,το αδαμελιτικής σύστασης τμήμα του, φαίνεται ότι προέρχεται από μάγμα που δημιουργήθηκεκατά τη σύγκρουση των πλακών (syn-COLG).Όσον αφορά τον πλουτωνίτη της Μεσάδας, προέκυψε ότι, τμήματα του προέρχονται απόδιεισδύσεις μαγμάτων, που είχαν δημιουργηθεί σε εντελώς διαφορετικά γεωτεκτονικάπεριβάλλοντα. Τα χαλαζιακής διοριτικής και τοναλιτικής σύστασης τμήματα του πλουτωνίτη, είναιπροϊόντα κρυστάλλωσης μάγματος, που είχε δημιουργηθεί σε γεωτεκτονικό περιβάλλον εσωτερικού πλακών. Πρόκειται μάλιστα, για τον τύπο μάγματος του εσωτερικού των πλακών πουχαρακτηρίζεται από την επικράτηση φλοιικών χαρακτηριστικών (crust-dominated)

Fossilized Bacteria in Fe-Mn-Mineralization: Evidence from the Legrena Valley, W. Lavrion Mine (Greece)

The primary mineralization in the famous Lavrion mine in the Lavreotiki area, Attica (Greece), associated with a granodiorite intrusion of Upper Miocene age and composed of massive sulphide Pb-Zn-Ag ores [sphalerite, pyrite and galena (B.P.G)], has been extensively studied. The present study is focused on thin, hard, dark brown to black Fe-Mn crusts (a few mm to cm in thickness) in the Legrena valley, SW Lavreotiki, aiming to provide new insights on that type of Fe-Mn-mineralization. The scanning electron microscope (SEM)/energy dispersive spectroscopy (EDS) data presented revealed the presence of fine rounded fragments, resembling nodules (up to 200 μm) and fossilized bacteriomorphic Fe-Mn-oxides/hydroxides, within brecciated and foliated zones of carbonate rocks. They exhibit unusual features when compared to the common massive Fe-Mn mineralization with regards the following: (a) the extensive occurrence of bacteriomorphic Fe-oxides/hydroxides and their micro-textures; and (b) the minor elements (K, Na, P, S, Ca, As and Cl). The occurrence of abundant bacteriomophic Fe-Mn-oxides/hydroxides in the samples from the Legrena valley may reflect their catalytic role in the redox reactions during ore-forming processes. The characteristic features of that type of Fe-Mn mineralization seems to be the result of multistage supergene processes superimposed over initial hydrothermal stages. Such a multistage remobilization and precipitation of metals along open space surfaces on karstified carbonates during a subsequent stage of their initial precipitation may be widespread in the Attica region, Greece