During our second meeting, on February 22nd 2019, we had the opportunity to host Margarita Melfou who graduated from the School of Geology at the Aristotle University of Thessaloniki and currently studies at the University of Lorraine in Nancy, France. Margarita was one of the 16 students who participated in the SEG Student Field trip in Chile between 11 and 19 January 2019, which emphasized on the alteration, mineralization, geochemistry, and structural settings of hydrothermal systems that occur in Northern Chile, stretching from Atacama, Copiapó to Antofagasta regions. The field trip included drill core reviews of the porphyry systems Cu-Mo, high-sulfidation Au-Ag-(Cu) epithermal, Cu-Au skarn-manto vein and Chilean “manto-type” Cu-Ag. Margarita referred to the geology of the projects they visited, the very positive experiences from the leaders and the mentors and the interaction with the other students. The presentation and the upcoming discussion motivated everyone to involve in SEG’s activities.
The meeting ended with the cutting of the vasilopita, revealing as lucky winner the undergraduate student, Sotirios Kechagias.
We would like to thank Margarita Melfou for her willingness to share her experiences and for the knowledge she shared with to us and wish her a successful career.
Figure 1. Margarita during her presentation for the SEG Student Field Trip 2019 in Northern Chile.
Vice-President of A.U.Th. S.E.G. Student Chapter
SGA Baltic Student Chapter guided tour by the AUTh SEG Student Chapter to selected ore mineralizations in Northern Greece
Between Friday August 31st and Monday September 3rd the AUTh SEG Student Chapter welcomed to Thessaloniki and offered a guided tour at selected Tertiary ore mineralizations of N. Greece to a number of members of the SGA Baltic Student Chapter (http://www.sga.agh.edu.pl/). Leaders of the visiting group were Krzysztof Foltyn and Slawomir Mederski the President and the Vice-President of the SGA Baltic Student Chapter respectively.
During the first ice-breaking day, a presentation meeting was held at the School of Geology, Aristotle University of Thessaloniki. The AUTh SEG student members had the opportunity to be informed on the geology and on the various types of ore deposits of Poland. In respect, the visiting students were introduced by Associate Professor Dr. Vasilios Melfos to the Oligocene-Miocene ore deposits and mineralization of the Serbo-Macedonian and Rhodope metallogenic province in Northern Greece, and by Christos Stergiou (PhD candidate) to the porphyry Cu-Au deposit of Vathi. At the end of the meeting the participants had some time spent on selected geological specimens both from Poland and Greece (Fig. 1a,b). The next day was devoted to relax and sightseeing at Thessaloniki city. The guest students had a chance to visit historical monuments of the city and be prepared for the next two field-trip days.
During the first field-trip day a joint group of students from both chapters visited two representative ore mineralization of the Kilkis ore district of the Serbo-Macedonian metallogenic province, under the guidance of Eftychia Petika (AUTh SEG SC President) and Christos Stergiou (Geologist MSc-PhD candidate) (Fig. 2a). The group explored the Vathi Cu-Au±U±Mo porphyry system which extends in an area of approximately 3 km2 and is hosted within qtz-monzonite dykes and a trachydacite porphyry. The participants got familiar with the hydrothermal alteration mineral assemblages and with the stockworks, sheeted, and D-type veins. Furthermore, some of them had the chance to collect some turquoise samples at the oxidation zone of the porphyry system. This is the only known turqoise locality in Greece. Later on that day the group visited the stibnite mineralization of Rizana. Greece hosts at least three significant, unexploited Paleogene-Neogene antimony mineralizations. At the Rizana area the ore mineralization is hosted in quartz veins crosscutting Paleozoic gneisses of the Vertiskos Unit and is related to a NW-SE trending shear zone. Stibnite is the main ore mineral, along with minor pyrite and arsenopyrite (Fig. 2b). Vaggelis Skoupras, a master student who studies the Rizana mineralization, guided the group around the ore bearing outcrops and the old mining excavations. Further he explained how this mineralization is related to the broader Neogene-Quaternary brittle geotectonic evolution of the Vertsikos unit.
On Monday September 3rd the group travelled to the eastern part of Northern Greece at the coastal area of Rhodopi county. We visited the Maronia Cu-Mo-Re-Au porphyry mineralization which is related with a porphyry microgranite (Fig. 3).. The group explored the sodic-potassic, the propylitic, the sericitic, and the argillic hydrothermal alteration zones of the system. Furthermore, along the Aegean seashore, we looked at on the A-, B- and D-type veins of the porphyry system, and collected samples of the quartz-molybdenite vein mineralization. In addition, the group visited the major supra-detachment fault of Marmaritsa which shapes the shoreline at an E-W trending direction. Finally, the group collected nice crystals of vesuvianite, garnet, pyroxene and other minerals at the skarn which is formed along the contact between the Maronia pluton and the surrounding marbles near the ancient ruins of Ismara.
The AUTh SEG SC Committee would like to thank all the members which willingly and exceptionally participated in this four-day event. Such meetings between student chapters are of great value; they do not only serve in educational means but they also promote collaboration and enhance the communication skills of the participating members.
Figure 1. a. Krzysztof Foltyn (President of the SGA Baltic Student Chapter) presenting the ore deposits of Poland. b. Associate Professor Vasilios Melfos discussing on the samples of selected ore mineralizations from Greece.
Figure 2. a. Christos Stergiou (center) explaining the metallogenic model of the Vathi Cu-Au±U±Mo porphyry system. b. Stibnite samples collected at the Rizana shear zone.
Figure 3. Members of the two students chapters at the Maronia porphyry system.
On Wednesday 14/02/2018 an event took place at the Aristotle University of Thessaloniki where the departments and curricula of the Aristotle University were presented to students of the 3rd Lyceum. The AUTh SEG Student Chapter also participated in the presentation of minerals and the personal information of the students both on the actions of the chapter and on the field of geology as well as geology in general.
AUTh SEG Student Chapter
Field trip at the Lavrion ore district, Attica, Greece
10th-11th February 2018
Members of the chapter that participated at the fieldtrip visiting the ancient theater of Thorikos (5th cent. BC), Lavrion
Submitted by: Sofia Christoforidou, Secretary
A total of nine postgraduate and undergraduate students, members of the AUTH SEG student chapter, participated at the field trip to the world-class Pb-Zn carbonate replacement ore deposit of Lavrion, in Attica, Southern Greece. They were accompanied by the Academic Advisor, Associate Professor Vasilios Melfos, who has published several papers about the Lavrion mineralization and is familiar with this deposit. This field trip was financially supported by the Municipality of Lavreotiki which covered our accommodation costs and the meals for two days.
Greece is located in southeastern Europe and the geological evolution is strongly related with the Alpine orogenesis. The collision between African and Eurasia plates and the subduction of the remnants of the Tethys oceanic plate in south Aegean, resulted in the famous Southern Aegean Active Volcanic Arc. The Miocene magmatism had an effective role at the formation of many ore mineralizations in the Attico-Cycladic massif. Lavrion has a very interesting geological history, which is related with the exhumation of the Attico-Cycladic massif. This exhumation is documented by the extensive Western Cyclades detachment fault system observed in many locations on the surface. The subsequent Miocene magmatism resulted in the deposition of several multi-elemental ore mineralization types.
Lavrion deposit covers an area of ~150 km2 and is famous for the exploitation of Pb-Ag-rich ore during the antiquity, mainly during the Classical period, from 6th to 4th cent BC (Conophagos 1980). However mining in the region has started already in the early 3rd millennium, and lasted until the 6th cent AD. It provided with silver the Athenians and as a result it had a direct and major effect on their power and on the “Golden Age” of the Athenian Democracy that followed. After the decline of Athens, the mines were closed and then operated again in the 19th century. The exploitation of the sulfide ores continued until the 1970s.
There are four mineralization types in Lavrion: porphyry type, skarn type, vein type and carbonate replacements (Voudouris et al. 2008a,b; Bonsall et al. 2011; Melfos and Voudouris 2017). The porphyry Mo-W mineralization occurs as sheeted quartz veins and stockworks cutting the late Miocene granodiorite stock in the Plaka area. The mineralization consists of pyrite, molybdenite, chalcopyrite, pyrrhotite and minor scheelite. Quartz, hydrothermal biotite, K-feldspar, amphibole and sericite are gangue minerals. The granodiorite was intensely altered to potassic, sodic, propylitic, and sericitic assemblages, locally with silicification.
The Pb-As-Sb-Cu-Ag rich banded Filoni 80 vein with epithermal affinities trending ESE-WNW, is up to 2 m thick and up to 1 km long (Voudouris et al. 2008a). This vein includes early deposition of pyrrhotite followed by arsenopyrite, löllingite, pyrite, marcasite, a Cu-Bi bearing assemblage including lillianite homologues, pyrargyrite, chalcopyrite, Bi-bearing tetrahedrite/tennantite, bournonite, lead sulfantimonides and finally by galena and native arsenic. Quartz, siderite, fluorite and calcite are the main gangue minerals.
The carbonate-replacement Pb-Zn-Ag mineralization is the most economically important in the Lavrion district and occurs in the form of stratabound lenses, bedded replacements (mantos), and chimneys up to tens of meters in length, in the Kamariza and Sounion areas (Voudouris et al. 2008a,b; Bonsall et al. 2011). According to Voudouris et al. (2008a,b), Bonsall et al. (2011), and Berger et al. (2013) the ore deposits in Lavrion are genetically related to the Miocene Lavrion granitoids, and ore formation occurred under extensional kinematic conditions. The carbonate-replacement and vein mineralogy is dominated by pyrite, arsenopyrite, sphalerite, chalcopyrite and galena, with various silver sulfosalts and native gold and quartz, fluorite, calcite and sericite gangue. Skarn deposits also occur around the Lavrion granodioritic body, and consist of early magnetite followed by pyrrhotite, pyrite, arsenopyrite, sphalerite, chalcopyrite, galena, bismuthinite, tetradymite, and native bismuth. Extensive zones of supergene mineralization occur above the primary mineralization zones.
The field trip
On Saturday 10th February 2018, the first day of the field trip, the members of the AUTH SEG student chapter met Hercules Katsaros, Vasilios Stergiou and Konstantinos Voukelatos, all inhabitants of the Lavrion city. Mr. Voukelatos had been working for over 20 years in this gallery as a miner. Our guests are very experienced in entering the abandoned underground mines of Lavrion, which form a very complicated underground system with modern galleries cutting the ancient narrow galleries and shafts. We were informed by Nikos Leloudas, one of the best skilled cave specialists in Greece, about the safety instructions and we all entered the Plaka underground mine (Fig. 1). The entrance in this mine is permitted by the authorities. Plaka mine is also known as ‘‘Vein 80’’ or ‘‘Filoni 80’’, and was opened in mid-1950’s along the major Pb-As-Sb-Cu-Ag rich banded vein. This vein is up to 2 m thick and 1 km long.
Figure 1. The members of the AUTH SEG student chapter in front of the Plaka underground mine, together with the academic advisor, V. Melfos, H. Katsaros, N. Leloudas and K. Voukelatos.
The students had an experience with the ore minerals including galena, tennantite, arsenopyrite, pyrite, bournonite and many lead sulfo-antimonides. We examined the textures and the relation of the vein with the host metamorphic rocks, e.g. marble and schist. At the deepest parts of the gallery we had the opportunity to observe the detachment fault. The galena-rich ore was concentrated underneath the fault, at the footwall, forming a breccia with a thickness up to 3 m (Fig. 2). This was the ore which was mined in this part of the Plaka mine. It was an amazing experience entering this gallery and we realized many geological events which are not visible at the surface.
Although the weather was rainy, after exiting the underground mine, we continued and visited the Plaka porphyry system where we observed the granodiorite intruding the metamorphic rocks along the detachment fault. The alteration zones and the characteristic minerals for each zone were examined carefully.
Figure 2. The group, including the members of the AUTH SEG student chapter, in the Plaka underground mine where the brecciated galena-rich ore was extracted at the foot wall of the detachment fault.
In the second day of our fieldtrip, on Sunday 11th Febrauary 2018, the members of the AUTH SEG student chapter visited several sites of ancient mining, ore processing and metallurgy, around Thorikos. Thorikos was an ancient Greek city in southern Attica, close the mines of Lavrion, where lead and silver have been mined since the prehistoric times. Mycenaean tholos tombs (15th century BC) and a Late Mycenaean installation (12th century BC) were probably connected with the mines in this area. There is also a theatre, dated in 525–480 BC, which is one of the first theaters in ancient world. This shows the wealth of the Thorikos citizens, which is attributed to the rich mines of Lavrion.
It is remarkable that the ancient Athenians had realized in Thorikos the occurrence of exploitable ore exactly below the detachment fault and they developed the proper techniques to open large underground mines. We therefore recognized the high geological knowledge of ancient Greeks, who focused on the ore occurrences along or below the Western Cyclades detachment fault or between the Lower Marble and the schist of the Kamariza unit.
We also visited the carbonate-replacement Pb-Zn-Ag mineralization at the “3rd kilometer” mine, which has been the most economically important in Lavrion district since the classical period. It occurs in the form of stratabound lenses to bedded replacement (mantos) and chimneys, up to tens of meters in length.
The members of the AUTH SEG student chapter in front of an ancient ore washing table at Thorikos of Lavrion.
We would like to thank the Municipality of Lavreotiki which covered our accommodation costs and the meals for two days and especially the Mayor Mr. D. Loukas. Special thanks are also due to H. Katsaros, V. Stergiou, K. Voukelatos and N. Leloudas who joined our student chapter and took care about our safety in the underground mine of Plaka. They also showed us several significant parts of the mine with geological importance.
The students who participated: Eftychia Petika, Sofia Christoforidou, Fivos Kiniklis, Eftychia Peristeridou, Sofia Ketikidou, Vaggelis Tataris, Vaggelis Skoupras, Margarita Melfou, Vaggelis Katsis.
Field-trip to epithermal and VMS mineralizations of the Rhodope Metallogenic Province (Greece-Bulgaria)
Field-trip to epithermal and VMS mineralizations of the Rhodope Metallogenic Province (Greece-Bulgaria)
On 15th and 16th October 2016 the AUTH SEG Student Chapter organized a field trip in Southern Bulgaria and Northeastern Greece (Fig. 1). A group of 20 members of the chapter, using 2 nine-seat vehicles and one car, visited a number of ore deposits of the Rhodope Metallogenic Province. The field trip was organized by Efi Petika, 2015-16 Chapter’s secretary, with the guidance of the Assistant Professor Vasilios Melfos, Academic Advisor of the chapter. In total 12 undergraduate students, 6 MSc students and 2 PhD students participated at this field trip.
The field trip was focused on three significant ore deposits of Southern Rhodope Core Complex and on the abandoned processing plant of the Kirki mine (Thrace, Greece). The Tertiary Rhodope Metallogenic Province belongs to the Western Tethyan Metallogenic Belt and spreads to Bulgaria and Greece hosting several major ore deposits of various types. The AUTH SEG student chapter visited Ada Tepe, a sedimentary-hosted low-sulfidation epithermal gold deposit that in the present is operated by “Dundee Precious Metals”, the Perama Hill deposit, a high- and intermediate-sulfidation Au-Ag-Te-Se epithermal system owned by “Eldorado Gold”, the Xylagani Mesozoic gold-bearing Fe-Cu VMS deposit and the abandoned processing plant near Kirki of Alexandroupolis (Fig .1). The field trip was a great opportunity for the students to visit deposits of a great scientific importance, near our host Aristotle University of Thessaloniki. Furthermore, they got familiar with the regional geology, the ore deposit types and their ore paragenesis, and had the chance to explore the specific metallogenic and the structural control processes of these deposits.
The field trip started early in the morning, on Saturday 15th October 2016, with three vehicles from Thessaloniki (Greece) to Krumovgrad (Bulgaria). After approximately 5 hours we arrived at the offices of “Dundee Precious Metals” in Krumovgrad. At our arrival the chief geologists of the company, Yaroslav Dintchev and Tsvetana Jeleva, waited for us and lead us to the presentation room, where we attended a presentation by Y. Dintchev about the activities of the mining company, the regional geology, the mining history of Ada Tepe deposit and its metallogenic and structural characteristics. Ada Tepe is a sedimentaryhosted detachment-associated low-sulfidation epithermal gold deposit. It is hosted in Maastrichtian–Paleocene sedimentary rocks above a detachment fault at the contact with the underlying Paleozoic metamorphic rocks. Dating of the ore mineralizing processes revealed older ages than the adjacent magmatic rocks. Gold mineralization is located in: (1) a massive, tabular ore body above the detachment fault; and (2) open space filling ores along predominantly east–west oriented listric faults. The ores are zones of intensive silicification and brecciation synchronous with the detachment faulting.
After the end of the presentation session, we discussed our questions and then visited the drilling cores (Fig. 2) where we could observe the ore minerals (including visible gold!), the ore textures (breccias, colloform, bladed and banded textures), the hydrothermal alterations (mainly alunite) and the host rocks.
After fruitful discussions with the two geologists we moved to the Ada Tepe hill with the company’s vehicles. We were excited with the prehistoric gold mines since 3rd millennium BC. The mineralization with an intense silification was formed at the hanging wall of a long impressive detachment fault (Fig. 3). At this point, T. Jeleva explained us the regional geology and presented the Au and Ag grades of the deposit. We were also informed by the company geologists that the AUTH SEG student chapter was the last group visited the Ada Tepe Hill at the present situation, as in the following days the company started the infrastructures for the open pit!
Our last stop in Krumovgrad area was about a silica sinter and the breccia in the sinter mixed with sandstone of a low-sulfidation system. We really appreciate the effort of Y. Dintchev and T. Jeleva, who spent more than 6 hours with our chapter to present and explain all the details of the Ada Tepe ore deposit. We also thank the staff and the Directors of “Dundee Precious Metals” in Krumovgrad who helped in many ways this field trip in Bulgaria (Fig. 4).
Next day, on Sunday 16th October, we drove from Krumovgrad to Komotini in Greece, and then to Perama Hill deposit (Fig. 1) owned by “Eldorado Gold”. It is a high- and intermediate-sulfidation Au-Ag-Te-Se epithermal system located at the eastern margin of the Petrota graben. The mineralization forms ore veins in the Oligocene silicified and argillicaltered andesite (33.1 and 30.8 Ma) and oxidized Au-rich mineralization in the overlying Eocene sedimentary rocks (Fig. 5, 6). The mineralization consists mainly of enargite-luzonite, tennantite, Au-Ag tellurides, and native gold. The deposit evolved from an early stage silicapyrite rock and argillic alteration followed by the deposition of sulfide-, sulfosalt- and telluride-bearing quartz-barite veins and stockworks.
The proven and probable reserves are 975,000 oz Au @ 3.13 g/t and the measured and indicated resources 1,382,000 oz Au @ 3.46 g/t, whereas the inferred resources are 554,000 oz Au @ 1.96 g/t (Eldorado Gold 2016).We would like to thank “Eldorado Gold” for the permission to visit Perama Hill and for the continuous support of the AUTH SEG student chapter activities.
Our next stop was at the abandoned hydrometallurgy plant of the Kirki Pb-Zn sulfides mines, where numerous old tailing ponds and mine wastes (Fig. 7) have caused permanent problems due to acid mine drainage and the subsequent contamination of the ground water. The Kirki flotation plant operated between 1973 and 1992, without any
Environmental Impact Assessment. It comprises eight tailings ponds close to the factory at morphologically favorable locations, requiring the minimum earthworks. They were excavated along valleys or in the flat areas surrounding the two main streams (Kirkalon and Eirini streams), without taking into consideration the effects of surface water flow. We had the opportunity to see the details of the effects caused from mine wastes and hydrometallurgy products left in situ without any environmental consideration by the state and the local authorities.
Our last target was the Xylagani Mesozoic gold-bearing Fe-Cu volcanogenic massive sulfide (VMS) deposit (Fig. 8). The mineralization shares many common features with the Cyprus-type mineralizations. It is hosted in Mesozoic meta-volcanic rocks (lavas and tuffs) which belong to the Circum Rhodope belt and have been metamorphosed to very low to low grade stage. Lensoidal silicified mineralized bodies are hosted in the metavolcanic rocks. On the basis of textural features, five types of mineralization are recognized: thin layered, disseminated, disseminated to massive and massive sulfide (pyrite or chalcopyrite-pyrite) mineralization as well as quartz veins poor in sulfides. The ore mineral assemblage consists of framboidal pyrite, pyrite, chalcopyrite, sphalerite, galena, pyrrhotite, tennantite and gold. The main gangue minerals are quartz, white mica and chlorite. VMS deposits are not so common in Greece and they are mostly of Mesozoic age. The students were introduced by the academic advisor, V. Melfos, who studied this mineralization for his PhD in early 1990’s and showed the various mineralization textures and types and their relation to the host rocks.
This field trip was a conclusion for the second year of operation of AUTH SEG student chapter. The Executive Committee would like to thank the Society of Economic Geologists for the overall support and trust provided through the 2014-2015 academic year. In addition we would like to exceptionally thank the Student Chapter Stewart R. Wallace Funding Program of the Society of Economic Geologists for the provided financial support regarding the field trip expenses. Special thanks are due to “Dundee Precious Metals” and “Eldorado Gold” for the permission to visit Ada Tepe and Perama Hill deposits, respectively.
Figure 1. Simplified map displaying the distribution of the ore deposits within the Rhodope and the Serbomacedonian metallogenic provinces in the southern Balkan peninsula. RM Rhodope Massif, SMM Serbomacedonian Massif, CRB Circum Rhodope Belt, AZ Axios (Vardar) Zone, SG Srednogorie Zone. 1. Ada Tepe; 2. Perama Hill; 3. Kirki; 4. Xylagani.
Figure 2. Drill cores from the Ada Tepe at the “Dundee Precious Metals”.
Figure 3. The AUTH SEG Student Chapter in front of the hanging wall of the detachment fault of the Ada Tepe deposit accompanied by the geologists Yaroslav Dintchev and Tsvetana Jeleva.
Figure 4. The AUTH SEG Student Chapter in front of the “Dundee Precious Metals” offices in Krumovgrad, Bulgaria.
Figure 5. The AUTH SEG student chapter in front of the Au-bearing quartz-barite veins crosscuting Eocene sandstones at the Perama Hill deposit of “Eldorado Gold”.
Figure 6. The Au-bearing sandstones of Perama hill deposit that host part of the ore mineralization.
Figure 7. The AUTH SEG student chapter with the academic advisor, Prof. V. Melfos, standing on a tailing pond with acid drainage of the abandoned hydrometallurgy plant at the Kirki mines.
Figure 8. Members of the AUTH SEG student chapter investigating the ore mineralization textures at the Xylagani VMS deposit.
Submitted on behalf of
the AUTh SEG Student Chapter Executive Committee by