Papers by Vasilios Melfos
Proceedings of SPIE, Apr 26, 2012
The sanctuaries of Demeter and Asklepios are part of the Dion archaeological site that sits among... more The sanctuaries of Demeter and Asklepios are part of the Dion archaeological site that sits among the eastern foothills of Mount Olympus and covers roughly 100 hectares. The excavations finds from this area are dated since the Hellenistic, Roman and Early Christian times. The main building materials are limestones and conglomerates. Sandstones, marbles, and ceramic plinths were also used. The materials consist mainly of calcite and/or dolomite, whereas the deteriorated surfaces contain also secondary and recrystallized calcite and dolomite, gypsum, various inorganic compounds, fluoroapatite, microorganisms and other organic compounds. Cracks and holes were observed in various parts of the stones. The most proper approach to select effective methods for the structural and surface consolidation, the cleaning, the protection and the overall conservation of these structures is the knowledge of the processes contributing to their deterioration. The influence of the water presence to the behavior of the materials was examined by in situ IR thermometer measurements. Temperature values increased from the lower to the upper parts of the building stones and they significantly depend on the orientation of the walls. The results indicate the existence of water in the bulk of the materials due to capillary penetration. To confirm these observations measurements of the following physical characteristics of the building materials have been studied: open porosity, pore size distribution, water absorption and desorption, capillary absorption and desorption. The existence of water in the bulk of the materials due to capillary penetration, the cycles of wet-dry conditions, correlated with the intensive surface and underground water presence in the whole surrounding area, lead to partial dissolution-recrystallization of the carbonate material and loss of the structural cohesion and the surface stability.
EGU General Assembly Conference Abstracts, Apr 1, 2017
RawMat 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Bulletin of the Geological Society of Greece, 1998
Geochemistry Geophysics Geosystems, Jun 1, 2021
Subduction-associated plate boundaries are unstable and their location, structure, and morphology... more Subduction-associated plate boundaries are unstable and their location, structure, and morphology depend on factors such as rates of convergence and subduction, dip of the subducting slab, or subduction of volcanic chains or ridges (e.g., Cross & Pilger, 1982; Royden, 1993). The upper plate may be eroded, which leads to landward-directed migration of the arc magmatism away from the trench (e.g., Jicha & Kay, 2018). Alternatively, the subducting slab retreats which causes migration of the trench and the magmatic arc but also back-arc extension in the upper lithospheric plate (Faccenna et al., 2001). The Aegean region is an example where subduction migrated during the past ∼90 million years due to the accretion of oceanic and
Bulletin of the Geological Society of Greece, Jan 24, 2017
Inorganic arsenic (As) is a naturally occurring metal, present in various ecosystems. However, it... more Inorganic arsenic (As) is a naturally occurring metal, present in various ecosystems. However, it can also be added to an aquatic system by anthropogenic activities. The aim of the present study is to determine the total As content in the Palea Kavala river (NE Macedonia, Northern Greece). The correlation between As content and some chemical and physico-chemical parameters of the samples was also examined. Research demonstrated significant As concentrations in the water and the sediments of the river. No correlation was found between As and pH, Fe, Mn in the water samples. Concerning the sediment samples, positive correlation was revealed for As with Fe and Mn content, while negative correlation was revealed between As and pH. This is probably indicative of a higher arsenic mobility in the Palea Kavala river water than in sediments. Since no anthropogenic activities were observed in the river's catchment area, elevated As concentrations are probably due to the lithology of the broader area and especially the presence of extended ore mineralizations including As-bearing sulphide minerals. However, the research in the study area is in progress since a more detailed evaluation of the local sources of As and mechanisms of As release is required.
European Journal of Mineralogy, Jun 2, 1997
Ore Geology Reviews, Apr 1, 2015
Although metals are produced from a wide variety of deposit types within these trends, gold has b... more Although metals are produced from a wide variety of deposit types within these trends, gold has been recovered mostly from disseminated, sediment-hosted Carlin-type deposits since the 1960s (John et al., 2003). In 2004, Nevada accounted for over 80 percent of United States gold production and nearly a tenth of world gold production, behind only South Africa and Australia (Price and Meeuwig, 2005). The Battle Mountain-Eureka trend consists of 10 mining districts, three of which are located in the northern Shoshone Range in Lander County (Hilltop, Lewis, and Bullion; Figs. 1, 2). These districts were organized shortly after the 1859 Comstock Lode discovery and include over 140 mines and prospects (Stewart and McKee, 1977). Unlike Carlin-type deposits, mineralization within the northern Shoshone Range occurs mostly as vein-and fracture-fill in siliceous and siliciclastic rocks. Between 1902 and 1936, more than 33 Koz gold (placer and lode), 5 Moz silver, 3 Mlbs. lead, and 1 Mlbs. copper were produced solely from underground workings within the Hilltop, Lewis, and Bullion districts accounting for 59, 27, 49, and 8 percent, respectively, of total Au, Ag, Pb, and Cu production from all 15 mining districts within Lander County during that time (Vanderburg, 1939). Other commodities including mercury, antimony, turquoise, fluorspar, barite, and manganese were also produced from the Hilltop, Lewis, and Bullion districts. Since 1936, mining operations in the northern Shoshone Range have largely ceased. However, considerable interest in exploring and reevaluating the inactive mines within the Hilltop, Lewis, and
Bulletin of the Geological Society of Greece, Jul 28, 2017
The Olympias tailings of NE Chalkidiki, Greece represent the mine wastes produced by the benefici... more The Olympias tailings of NE Chalkidiki, Greece represent the mine wastes produced by the beneficiation of the Pb-Zn-Au-Ag ore deposit, which is hosted within the carbonate rocks of the Kerdylia Unit. In the present study X-Ray diffraction (XRD), scanning electron microscopy (SEM), optical microscopy, chemical analyses and pH measurements were conducted to determine the tailings mineralogy and chemical composition. The results indicated that they consist of gangue (quartz, rhodochrosite, calcite, dolomite, feldspars, micas, kaolinite and actinolite) and sulfide minerals (pyrite, arsenopyrite, sphalerite, chalcopyrite and galena), reflecting the source ore and its host rock composition, accompanied by traces of Fe-oxides (magnetite, hematite), Fe-oxyhydroxides (goethite) and Mn-oxides, often enriched in Zn and Pb and in some cases Fe, Sb and As. Secondary sulfates (gypsum, jarosite) and surface efflorescent salts (ferrohexahydrite, hexahydrite, halotrichite) have also been recognized. The Olympias tailings are generally unoxidized, generating an alkaline environment. However, variations in composition result in the formation of restricted separate phases, such as thin layers and lenses of oxidized material that generates an acidic environment. In terms of precious metals content, the Olympias tailings are enriched in Au (up to 12 g/t) and Ag (up to 20 g/t).
Acta Carsologica, May 31, 2021
UDC 551.435.84(495) Georgios Lazaridis & Vasilios Melfos: Morphological features and formation co... more UDC 551.435.84(495) Georgios Lazaridis & Vasilios Melfos: Morphological features and formation conditions of The Almopia Speleopark caves (Loutra Almopias, N. Greece) The Almopia Speleopark caves are located at the Almopia basin in northern Greece, at the foothill of Voras Mountain, and are formed in the Maestrichtian limestones of the Pelagonian zone. They are studied on the basis of their meso-and microscale morphology as well as their horizontal pattern, in order to investigate the character of the forming aquifer. Emphasis is given on the morphological description of the Loutra Almopias Cave. Cave morphology is dominated by the presence of cupolas, rock bridges, ridges and "windows", abrupt terminations of fracture guided passages, pendants, rising channels, pseudonotches, false-floors and spongework. Speleogens indicate a speleogenesis due to slowly natural convecting hot water bodies. Phreatic calcite from the Varathron Cave is analyzed on the basis of the fluid inclusions in order to investigate the physicochemical conditions of the convecting water bodies. This has shown that the calcite was formed at temperatures ranging between 120 and 189 ºC, with a peak around 150 ºC. The fluids were dominated by NaCl of very low salinities (0.2-1.0 wt% NaCl equiv.), showing probably the incorporation of meteoric waters.
Journal of Radioanalytical and Nuclear Chemistry, Jan 28, 2019
The 238 U, 226 Ra, 210 Pb, 228 Ra, 228 Th and 40 K concentrations have been measured beside to ra... more The 238 U, 226 Ra, 210 Pb, 228 Ra, 228 Th and 40 K concentrations have been measured beside to radon emanation factor due to sample granulometric using γ-spectrometry. The radiological hazards of zeolitic rocks application in the environment as soil improvements, diet supplements and building materials have been studied. No γ-radiation hazards occur for soil improvements since up to 0.13 mSv year −1 estimate. No radiation hazards arise for diet supplements since 0.21 μSv day −1 g −1 of zeolite intake is estimated. Instead, the application as cement and bricks give external annual effective dose up to 1.19 mSv, while the internal radiation rises to 3.45 mSv.
HAL (Le Centre pour la Communication Scientifique Directe), Aug 12, 2022
Minerals
In the present study, rough emerald single crystals and rough emeralds in the host rock from the ... more In the present study, rough emerald single crystals and rough emeralds in the host rock from the ruins of Alexandria and from the Mount Zabargad in Egypt, preserved in the collection of the museum of the Ecole des Mines (Mines Paris—PSL) since the late 19th or early 20th century, are investigated. All samples were characterized by non-destructive spectroscopic and chemical methods during a week-long loan to the LFG. Raman, FTIR and UV-Vis-NIR spectroscopy revealed that Egyptian emeralds contain H2O molecules accompanied by relatively high concentrations of alkali ions and are colored by chromium and iron. Additionally, EDXRF showed that the emeralds from Egypt contain up to 84 ppm Rb and low amounts (below 200 ppm) of Cs. Inclusions and parts of the host rock were also observed under optical microscope and analyzed with Raman spectroscopy. Tube-like structures, quartz, calcite, dolomite, albite and phlogopite are associated minerals, and inclusions are identified in these historic e...
The dataset contains whole rock geochemical data of Oligocene to Miocene volcanic and plutonic ro... more The dataset contains whole rock geochemical data of Oligocene to Miocene volcanic and plutonic rocks from the Aegean region, Greece. The samples originate from outcrops in northeast Greece near Alexandropoulos and from the island of Limnos. Major and trace elements were measured using X-ray fluorescence spectrometry (XRF) and Quadrupole Inductively Coupled Plasma Mass Spectrometry (ICP-MS), respectively. The Sr and Nd isotopes were measured using thermal ionization multi-collector mass spectrometry (TIMS). All analyses were carried out at the GeoZentrum, Friedrich-Alexander-Universität in Erlangen. The data complement published geochemical data of magmatic rocks of the Aegean, which reveal a migration of the magmatic activity from NE to SW during the past 30 Ma.
Ore Geology Reviews, 2022
Abstract The Pefka Cu-Au-Te-In-Se and nearby St Philippos Pb-Zn-Bi-Sn-Ge-Ga-In vein- and breccia-... more Abstract The Pefka Cu-Au-Te-In-Se and nearby St Philippos Pb-Zn-Bi-Sn-Ge-Ga-In vein- and breccia-type deposits in western Thrace, Greece, display strong similarities, but also differences in terms of mineralization style, ore mineralogy, and chemistry, and host rock compositions. The Pefka mineralization consists of two crosscutting vein systems with high sulfidation (HS)- and intermediate-sulfidation (IS) assemblages hosted by andesitic lavas and is unusually enriched in In (up to 700 ppm), Te (>1000 ppm), Se (>100 ppm), and Cu (>1 wt%). The main In-carriers are roquesite (CuInS2) and In-bearing tennantite-(Cu) which contains up to 6.5 wt% In, substituting into the C site. Roquesite is associated with enargite and arsenosulvanite/colusite, as part of the HS assemblage at Pefka. Selenium-bearing galena and a large suite of tellurides including calaverite, sylvanite, petzite, kostovite, empressite, tellurantimony, and coloradoite, in addition to native tellurium, account for the marked tellurium and selenium enrichment in the ores from Pefka. Tellurides and native gold were introduced together at Pefka and accompany the precipitation of Te-bearing minerals of the tetrahedrite group, such as “stibiogoldfieldite” and “arsenogoldfieldite”, and Cu-excess varieties of tetrahedrite and tennantite. However, the bulk of telluride deposition is associated with normal, fully substituted tetrahedrite-tennantite varieties. The St Philippos deposit is associated with a brecciated fault zone hosted by Eocene sandstones and Oligocene quartz-feldspar porphyry dikes. It is enriched in a large suite of incompatible elements, including Bi (>2000 ppm), Sn (>100 ppm), U (up to 200 ppm), Pb (>1 wt%), Zn (>1 wt%), Mo (up to 62 ppm), Ge (>100 ppm), Ga (up to 466 ppm) and In (up to 222 ppm), contrasting with the element suite defining the nearby Pefka deposit. The main carrier of In, Ga, and Ge is sphalerite (and wurtzite) with In-rich zones in sphalerite containing up to 6.1. wt% In. Germanium and Ga in sphalerite reach concentrations of up to 0.27 and 0.32 wt%, respectively. Sphalerite from the St Philippos deposit is extremely Fe-poor ( Both deposits are characterized by early high-temperature (>300 °C) and HS fluid conditions, followed by IS assemblages as temperatures waned. Rhyolitic oxidized magmas are considered to be the sources of metals in the St Philippos deposit; however, their anomalous W, Sn, U, and Bi contents suggest a contamination by crustal rocks. The Cu-Au-Te signature of the Pefka deposit is compatible with a genetic relationship to less fractionated andesitic magmas, although a possible contribution of In from rhyolitic magmas could explain the high In contents of the ore. However, other factors, as for example different metal-deposition mechanisms resulting in metal zonation around causative porphyry centers at depth, may also account for the observed metal endowment in these two deposits. The Sn-Te-In-(Ge-Ga) element association at Pefka and St Philippos is unusual in that it has been previously reported from only a few other places in the world (e.g., Capillitas deposit, Argentina, and the Kawazu deposit, Japan). We conclude based on this exotic mineralization-style that the northeastern part of Greece represents an area of great potential for the exploitation of critical metals and metalloids.
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Papers by Vasilios Melfos
The area of interest is monitored by a network of 20 different permanently installed GPS stations. The processing of the primary geodetic data is based on the triangulation of the GPS stations. In particular, the total of 20 different GPS stations were combined each other, forming different sets of three stations. Each set leads to a triangle formation, while each station is located on a triangle vertex. The recorded geodetic data of a GPS station is combined with the other two stations geodetic data, calculating the maximum horizontal extension and rotation of the triangle centroid, representing the triangle. Based on the aforementioned procedure, 399 different triangles were constructed within the study area, providing 399 different maximum horizontal extension and rotation values.
Based on the extracted maximum horizontal extension values, the interpolation method was applied, leading to the construction of a map, including 50 nano-strain step contours, while the maximum and minimum values are 543.5029 and 2.1114 nano-strains, respectively. The exact ore mineralization locations were highlighted onto the aforementioned map in order to be examined their relationship to the maximum extension values. The extracted results show that the majority of ore mineralization locations are included into the medium to maximum horizontal extension areas. This proves the fact that several tectonic structures related to the ore mineralization formation are relatively active or not active in the present. Especially, at the southern part of the study area, ore mineralization localities exhibit remarkably higher maximum horizontal extension values, as a result of active since Oligocene fault zones of Stratoni-Varvara, Megali Panaghia-Gomati, Sochos and Mygdonia. Finally, the presented GPS rotational data are in agreement with the published palaeomagnetic data for the study area. In particular, counter-clockwise and clockwise rotations appear at the northern and the southern part respectively. Α transition zone of zero rotation values is observed between the two parts, enclosing probably a tectonic structure, separating the counter-clockwise and clockwise rotation blocks.
results have been included in an informative table for future comparison of raw materials found in excavations in ancient cities and settlements. The studied quarries are located at: Mt Tisaion, Mt Pelion in the village
Makrinitsa, the Goritsa hill, ancient Demetrias, the area from Nea Anchialos to Cape Angistri, Velestino, Mikrothives and Mikro Perivolaki. The rocks extracted in these quarrying areas are mainly marbles and also travertine, limestone, dolomite and basalt.
The most important and extended ancient mining area is “Asimotrypes” at the central part of the mountain. Along a steep valley, 8 ancient and 3 modern (20th cent.) mining adits are found. Four trial excavation trenches in three of the mining galleries did not yield any ceramic material to allow relative chronology of the mining activity.
The archaeometallurgical excavation at the Valtouda metallurgical area provides a useful tool for understanding the metallurgical activity, especially during Roman times at the study area. Archaeological and geological information gained by this study will help to understand the metals chain production in this mining and metallurgical area.
Το βιβλίο αυτό αναφέρεται στην καταγραφή των σημαντικότερων μεταλλοφόρων κοιτασμάτων της Ελλάδας και στις συνθήκες γένεσής τους σε σχέση με τη γεωτεκτονική εξέλιξη των Ελληνίδων. Έμφαση δίνεται στη γεωλογία, στην τεκτονική, στα πετρώματα ξενιστές και στην ορυκτολογική και γεωχημική σύσταση των κοιτασμάτων αυτών. Τα κεφάλαια του παρόντος βιβλίου αναφέρονται στη σύντομη ιστορική αναδρομή της μεταλλευτικής δραστηριότητας στην Ελλάδα, από τα προϊστορικά χρόνια έως σήμερα, στη γεωτεκτονική εξέλιξη και μεταλλογένεση, καθώς και στην ταξινόμηση των ελληνικών κοιτασμάτων στις διαφορετικές μεταλλογενετικές επαρχίες. Περιγράφονται τα ορθομαγματικά κοιτάσματα Cr σε οφιολιθικά συμπλέγματα, τα ηφαιστειογενή κοιτάσματα συμπαγών σουλφιδίων και τα μεταμορφωμένα κοιτάσματα Mn, όλα Μεσοζωικής ηλικίας. Επίσης, παρουσιάζονται οι μαγματικές-υδροθερμικές μεταλλοφορίες που συνδέονται με τον μαγματισμό του Καινοζωικού και που εντοπίζονται κυρίως στα δύο σημαντικά μεταμορφικά συμπλέγματα της Ελλάδας, της Ροδόπης και Σερβομακεδονικής στα βόρεια και της Αττικοκυκλαδικής στα νότια. Αυτές οι μεταλλοφορίες περιλαμβάνουν τα κοιτάσματα που φιλοξενούνται σε μαγματικές διεισδύσεις, τα κοιτάσματα τύπου skarn, τα κοιτάσματα από αντικατάσταση ανθρακικών πετρωμάτων και τα κοιτάσματα πορφυριτικού και επιθερμικού τύπου. Αναπτύσσονται επίσης οι πολυμεταλλικές φλέβες του Καινοζωικού σε μεταμορφωμένα πετρώματα, τα κοιτάσματα Fe, Mn, Zn από οξείδωση θειούχων μεταλλοφοριών, τα λατεριτικά κοιτάσματα Fe-Ni, τα κοιτάσματα βωξίτη με αλουμίνιο, τα προσχωματικά κοιτάσματα Au, Pt και REE, καθώς και τα σύγχρονα μεταλλοφόρα πεδία στο ενεργό ηφαιστειακό τόξο του Νοτίου Αιγαίου και στην Κεντρική και Βόρεια Ελλάδα. Στο τέλος του βιβλίου γίνεται μία ανασκόπηση σχετικά με την παρουσία των σπάνιων και κρίσιμων μετάλλων στα κοιτάσματα της Ελλάδας, ενώ στο τελευταίο κεφάλαιο δίνονται λεπτομερή γεωλογικά και κοιτασματολογικά στοιχεία δύο σημαντικών μεταλλογενετικών περιοχών της Νοτιοανατολικής Ευρώπης, δηλαδή της ΒΑ Χαλκιδικής και του Λαυρίου.
Το βιβλίο αυτό αναφέρεται στην καταγραφή των σημαντικότερων μεταλλοφόρων κοιτασμάτων της Ελλάδας και στις συνθήκες γένεσής τους σε σχέση με τη γεωτεκτονική εξέλιξη των Ελληνίδων. Έμφαση δίνεται στη γεωλογία, στην τεκτονική, στα πετρώματα ξενιστές και στην ορυκτολογική και γεωχημική σύσταση των κοιτασμάτων αυτών. Τα κεφάλαια του παρόντος βιβλίου αναφέρονται στη σύντομη ιστορική αναδρομή της μεταλλευτικής δραστηριότητας στην Ελλάδα, από τα προϊστορικά χρόνια έως σήμερα, στη γεωτεκτονική εξέλιξη και μεταλλογένεση, καθώς και στην ταξινόμηση των ελληνικών κοιτασμάτων στις διαφορετικές μεταλλογενετικές επαρχίες. Περιγράφονται τα ορθομαγματικά κοιτάσματα Cr σε οφιολιθικά συμπλέγματα, τα ηφαιστειογενή κοιτάσματα συμπαγών σουλφιδίων και τα μεταμορφωμένα κοιτάσματα Mn, όλα Μεσοζωικής ηλικίας. Επίσης, παρουσιάζονται οι μαγματικές-υδροθερμικές μεταλλοφορίες που συνδέονται με τον μαγματισμό του Καινοζωικού και που εντοπίζονται κυρίως στα δύο σημαντικά μεταμορφικά συμπλέγματα της Ελλάδας, της Ροδόπης και Σερβομακεδονικής στα βόρεια και της Αττικοκυκλαδικής στα νότια. Αυτές οι μεταλλοφορίες περιλαμβάνουν τα κοιτάσματα που φιλοξενούνται σε μαγματικές διεισδύσεις, τα κοιτάσματα τύπου skarn, τα κοιτάσματα από αντικατάσταση ανθρακικών πετρωμάτων και τα κοιτάσματα πορφυριτικού και επιθερμικού τύπου. Αναπτύσσονται επίσης οι πολυμεταλλικές φλέβες του Καινοζωικού σε μεταμορφωμένα πετρώματα, τα κοιτάσματα Fe, Mn, Zn από οξείδωση θειούχων μεταλλοφοριών, τα λατεριτικά κοιτάσματα Fe-Ni, τα κοιτάσματα βωξίτη με αλουμίνιο, τα προσχωματικά κοιτάσματα Au, Pt και REE, καθώς και τα σύγχρονα μεταλλοφόρα πεδία στο ενεργό ηφαιστειακό τόξο του Νοτίου Αιγαίου και στην Κεντρική και Βόρεια Ελλάδα. Στο τέλος του βιβλίου γίνεται μία ανασκόπηση σχετικά με την παρουσία των σπάνιων και κρίσιμων μετάλλων στα κοιτάσματα της Ελλάδας, ενώ στο τελευταίο κεφάλαιο δίνονται λεπτομερή γεωλογικά και κοιτασματολογικά στοιχεία δύο σημαντικών μεταλλογενετικών περιοχών της Νοτιοανατολικής Ευρώπης, δηλαδή της ΒΑ Χαλκιδικής και του Λαυρίου.