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Mineralogy, geochemistry and physical properties of bentonites from the Western Thrace Region and the islands of Samos and Chios, East Aegean, Greece

Published online by Cambridge University Press:  02 January 2018

E. Koutsopoulou ,
G.E. Christidis  and
I. Marantos
E. Koutsopoulou
Affiliation:
Institute of Geological and Mineral Exploration (IGME), Spyrou Loui 1, 13677 Acharnes, Greece
G.E. Christidis
Affiliation:
Technical University of Crete, School of Mineral Resources Engineering Chania, 73100 Greece
I. Marantos*
Affiliation:
Institute of Geological and Mineral Exploration (IGME), Spyrou Loui 1, 13677 Acharnes, Greece
*
*E-mail: [email protected]
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Abstract

Greece is a major bentonite producer, with Milos Island being one of the largest bentonite mining centres in the world. In addition to the bentonite deposits which are well known, various other occurrences exist in the islands of Chios and Samos, Eastern Aegean and in some areas of Thrace, in NE Greece. These bentonites are associated with volcanic activity and their age ranges from Lower Oligocene in Thrace, to Lower–Middle Miocene in Chios and to Upper Miocene in Samos. Although some of these materials have been utilized since ancient times (e.g. the Samian Earth), these bentonites have been mined only at a local scale. In this study the first data on the mineralogical and geochemical characteristics of these bentonites are presented.

The Samos bentonites of UpperMiocene age are medium–lowgrade (40–70% smectite) and crop out in the SE margin of the Karlovasi Basin formed at the expense of acidic pyroclastic flows mainly in a subaeriallacustrine environment. They consist mainly of Ca-rich medium–high-charge montmorillonite, opal-CT and sanidine with minor quartz and locallymordenite. The Chios bentonites of Lower–MiddleMiocene agewere formed at the expense of trachyandesitic tuffs in a lacustrine environment in the Neogene Basin at theSEpart of the island. They consist mainly of Ca,Mg-rich high-charge montmorillonite (33–75%), similar to the SAz-1, and opal-CT, minor plagioclase, chlorite, plagioclase, carbonates and traces of talc and serpentine. In Thrace, LowerOligocene pyroclastic flows, tuffs and lavas of acidic-intermediate compositionwere altered to zeolites and bentonites in the sedimentary basins of the Feres-Pefka, Skaloma and Sappes areas. The parent pyroclastic rockswere altered to Ca-rich and in places,Na-rich, dioctahedralmontmorillonite or Fe-rich beidellite (Sappes area) and with minor opal-CT,mordenite, quartz, plagioclase and, in places, illite. The bentonites are medium–high grade (50–58% smectite in Feres-Pefka, 74–86% in Skaloma and 29–40% in Sappes).

The bentonites havemoderate cation exchange capacity andmoderate/lowswelling index and viscosity and they are not suitable for the drilling and foundry industries. However, preliminary results show that after processing, most of the depositsmight be utilized in high added-value applications such as bleaching earths or in the synthesis of clay-based polymer nanocomposites.

Keywords

bentonitemontmorillonitebeidellitelayer chargelow-T hydrothermal alterationSamosChiosThrace
Type
Research Article
Information
Clay Minerals , Volume 51 , Issue 4 , September 2016 , pp. 563 - 588
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2016

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Footnotes

†

This work was originally presented during the Euroclay 2015 conference held in July 2015 in Edinburgh, UK.

References

Abdioglu, E. & Arslan, M. (2005) Mineralogy, geochemistry and genesis of bentonites of the Ordu area, NE Turkey. Clay Minerals, 40, 131–151.Google Scholar
Agha, M.A., Ferrell, R.E., Hart, G.F., Abu El Ghar, M.S. & Abdel-Motelib, A. (2013) Mineralogy of Egyptian bentonitic clays II: Geologic origin. Clays and Clay Minerals, 61, 551–565.Google Scholar
Aleksiev, B. & Djourova, E.G. (1975) On the origin of zeolite rocks. Comptes Rendus de l'Académie Bulgare de Sciences, 28, 517–520.Google Scholar
American Petroleum Institute (API) Specifications 13A (2006) Specification for drilling fluid materials.Google Scholar
Arslan, M., Abdioglu, E. & Kadir, S. (2010) Mineralogy, geochemistry and origin of bentonite in Upper Cretaceous pyroclastic units of the Tirebolu area, Giresun, Northeast Turkey. Clays and Clay Minerals, 58, 120–141.Google Scholar
Bellon, H., Grisollet, G. & Sorel, D. (1979) Age de l ’activite voleanique Neogene de I’ile de Chios (Mer Egee, Grece). ComptesRendusdel'AcademiedesSciences-Paris, 288, 1255–1258.Google Scholar
Besenecker, H. & Pichler, H. (1974) Die jungen Vulkanite der Insel Chios (östliche Ägäis, Griechenland). Geologische Jahrbuch, D9, 41—65.Google Scholar
Besenecker, H., Dürr, S., Herget, G., Jacobshagen, V., Kauffmann, G., Ladke, G., Roth, W. & Tietze, K.-W. (1968) Geologie von Chios (Ägäis). Ein Überblick. Geologica et Paleontologica, 2, 121–150.Google Scholar
Besenecker, H., Durr, S., Herget, G., Kauffman, G., Ludtke, G., Roth, W. & Tietze, K. (1971) Geological Map of Greece. Chios Sheet, 1:50.000. Institute of Geology and Mineral Exploration, IGME, Athens, Greece.Google Scholar
Bish, D.L. & Plötze, M. (2011) X-ray powder diffraction with emphasis on qualitative and quantitative analysis in industrial mineralogy. Pp. 35–76 in: Advances in the Characterization of Industrial Minerals (G.E. Christidis, editor). EMU Notes in Mineralogy, 9, Mineralogical Society, London.Google Scholar
Brun, J.P. & Sokoutis, D. (2007) Kinematics of the southern Rhodope core complex (North Greece). International Journal of Earth Sciences, 99, 109–138.Google Scholar
Burg, J.P., Ricou, L.E., Ivanov, Z., Godfriaux, I., Dimov, D. & Klain, L. (1996) Synmetamorphic nappe complex in the Rhodope massif. Structure and kinematics. Terra Nova, 8, 6–15.Google Scholar
Chapman, H.D. (1965) Cation-exchange capacity. Pp. 891–900 in: Methods of Soil Analysis, Part 2: Chemical and Microbiological Properties (C.A. Black, editor). American Society of Agronomy, Madison, Wisconsin, USA.Google Scholar
Cheliotis, I. (1986) Geology, mineralization and rock geochemistry of a volcanic-sedimentary formation in the Xylagani-Maronia area, NE Greece. Unpublished M.Sc. Thesis. University of Leicester, UK.Google Scholar
Christidis, G.E. (1998) Comparative study of the mobility of major and trace elments during alteration of an andesite and a rhyolite to bentonite, in the islands of Milos and Kimolos, Aegean, Greece. Clays and Clay Minerals, 46, 379–399.Google Scholar
Christidis, G.E. (2001) Formation and growth of smectites in bentonites: a case study from Kimolos Island, Aegean, Greece. Clays and Clay Minerals, 49, 204–215.Google Scholar
Christidis, G.E. (2006) Genesis and compositional het-erogeneity of smectites. Part III. Alteration of basic pyroclastic rocks. A case study from the Troodos Ophiolite Complex, Cyprus. American Mineralogist, 91, 685–701.CrossRefGoogle Scholar
Christidis, G.E. & Dunham, A.C. (1993) Compositional variations in smectites derived from intermediate volcanic rocks. A case study from Milos Island, Greece. Clay Minerals, 28, 255–273.Google Scholar
Christidis, G.E. & Eberl, D.D. (2003) Determination of layer charge of smectites. Clays and Clay Minerals, 51, 644–655.Google Scholar
Christidis, G.E. & Huff, W.D. (2009) Geological aspects and genesis of bentonites. Elements, 5, 93–98.Google Scholar
Christidis, G.E. & Scott, P.W. (1996) Physical and chemical properties of the bentonite deposits of Milos Island, Greece. Transactions of the Institute of Mining and Metallurgy B, 105, B165–B174.Google Scholar
Christidis, G.E., Scott, P.W. & Marcopoulos Th. (1995) Origin of the bentonite deposits of eastern Milos, Aegean, Greece: geological, mineralogical and geo-chemical evidence. Clays and Clay Minerals, 43, 63–77.Google Scholar
Christidis, G.E., Scott, P.W. & Dunham, A.C. (1997) Acid activation and bleaching capacity of bentonites from the islands of Milos and Chios, Aegean, Greece. Applied Clay Science, 12, 329–347.Google Scholar
Christidis, G.E., Marcopoulos, Th. & Foscolos, A. (1999) Origin, physical and chemical properties of a bentonite deposit of Chios Island, eastern Aegean, Greece. Pp. 75–82 in: Clays for Our Future, Proceedings of the 11th International Clay Conference (H. Kodama, A.R. Mermut & J.K. Torrance, editors). 15-21 June 1997, Ottawa, Canada.Google Scholar
Christidis, G.E., Blum, A.E. & Eberl, D.D. (2006) Influence of layer charge and charge distribution of smectites on the flow behaviour and swelling of bentonites. Applied Clay Science, 34, 125–138.Google Scholar
Christofides, G., Pécskay, Z., Eleftheriadis, G., Soldatos, T. & Koroneos, A. (2004) The Tertiary Evros volcanic rocks (Thrace, Northeastern Greece): petrology and K/Ar geochronology. Geologica Carpathica, 55, 397–09.Google Scholar
Çiflikli, M., Çiftçi, E. & Bayhan, H. (2013) Alteration of glassy volcanic rocks to Na- and Ca-smectites in the Neogene basin of Manisa, Western Anatolia, Turkey. Clay Minerals, 48, 513–527.Google Scholar
Dabovski, Ch., Harkovska, A., Kamenov, B., Mavrudchiev, B., Stanisheva-Vassileva, G. & Yanev, Y. (1991) A geodynamic model of the Alpine magmatism in Bulgaria. Geologica Balcanica, 21, 3–15.Google Scholar
de'Genarro, M., Cappelletti, P., Langella, A., Perrotta, A. & Scarpati, C. (2000) Genesis of zeolites in the Neapolitan Yellow Tuff: geological, volcanological and mineralogical evidence. Contributions to Mineralogy and Petrology, 139, 17–35.Google Scholar
Del Moro, A., Innocenti, F., Kyriakopoulos, K., Manetti, P. & Papadopoulos, P. (1988) Tertiary granitoids from Thrace (Northern Greece): Sr isotopic and petrochemical data. Neues Jahrbuch für Mineralogie Abhandlugen, 159, 113–135.Google Scholar
Ekinci Şans, B., Esenli, F., Kadir, S. & Elliott, W.C. (2015) Geology, mineralogy and geochemistry of smectite-rich Eocene siliciclastics and pyroclastics of the İslambeyli formation in the Lalapasa region, NW Thrace, Turkey. Clay Minerals, 50, 459–483.Google Scholar
Eleftheriadis, G. (1995) Petrogenesis of the Oligocene volcanics from the Central Rhodope Massif (N. Greece). European Journal of Mineralogy, 7, 1169–1182.Google Scholar
Fytikas, M., Irmocenti, F., Manetti, P., Mazzouli, P., Peccerillo, A. & Villari, L. (1984) Tertiary to Quaternary evolution of volcanism in the Aegean region. Pp. 687–699 in: The Geological Evolution of the Eastern Mediterranean (J.E. Dixon & A.H.F. Robertson, editors). Geolological Society of London Special Publication, 17, The Geological Society, London.Google Scholar
Gessner, K., Ring, U. & Gungor, T. (2011) Field guide to Samos and the Menderes Massif. Geolocical Society of America, Field Guide 23.Google Scholar
Ghiarra, M.R., Petti, C., Franco, E., Lonis, R.M., Luxoro, S. & Gnazzo, L. (1999) Occurrence of clinoptilolite and mordenite in Tertiary calc-alkaline pyroclastites from Sardinia (Italy). Clays and Clay Minerals, 47, 319–328.Google Scholar
Godelitsas, A., Gamaletsos, P. & Roussos-Kotsis, M. (2010) Mordenite-bearing tuffs from Prassa quarry, Kimolos Island, Greece. European Journal of Mineralogy, 22, 797–811.Google Scholar
Güven, N. (1988) Smectites. pp. 497–559 in: Hydrous Phyllosilicates (S.W. Bailey, editor). Reviews in Mineralogy, 19. Mineralogical Society of America, Washington, D.C. CrossRefGoogle Scholar
Hastie, A.R., Kerr, A.C., Pearce, J.A. & Mitchell, S.F. (2007) Classification of altered Volcanic Island Arc Rocks using immobile trace elements: development of the Th-Co discrimination diagram. Journal of Petrology, 48, 2341–2357.Google Scholar
Helvaci, C., Stamatakis, M., Zagouroglou, C. & Kanaris, J. (1993) Borate minerals and related authigenic silicates in northeastern Mediterranean Late Miocene continental Basins. Exploration & Mining Geology, 2, 1422.Google Scholar
Innocenti, F., Kolios, N., Manetti, P., Mazzuoli, R., Peccerilo, A., Rita, F. & Villari, L. (1984) Evolution and geodynamic significance of the Tertiary orogenic volcanism in NE Greece. Bulletin of Volcanology, 47, 25–37.Google Scholar
Ioakim, Ch. (1982a) Sratigraphic Study of the Drill-Hole Delta-Evros I. Geological Report of Delta Evros - I, D. Syrakopoulos, DEP Internal Report.Google Scholar
Ioakim, Ch. (1982b) Sratigraphic Study of the Drill-Hole Delta-Evros II. Geological Report of Delta Evros - 2, A. Katsaounis, DEP Internal Report.Google Scholar
Kanaris, I. (1981) Discovery of a Sedimentary Zeolitic Deposit in Thera Island. Unpublished Report, Institute of Geology and Mineral Exploration, IGME, Athens, 16 pp. (in Greek).Google Scholar
Kassoli-Fournaraki, A., Stamatakis, M., Hall, A., Filippidis, A., Michailidis, K., Tsirambides, A. & Koutles, Th. (2000) The Ca-rich clinoptilolite deposit of Pentalofos, Thrace, Greece. Pp. 193–202 in: Natural Zeolite for the Third Millenium (C. Collela & F.A. Mumpton, editors).Google Scholar
Kilias, A., Falalakis, G., Sfeikos, A., Papadimitriou, E. & Vamvaka, A. (2013) The Thrace basin in the Rhodope province of NE Greece - A tertiary supradetachment basin and its geodynamic implications. Tectonophysics, 595, 90–105.Google Scholar
Kirov, G., Fillipides, A., Tsirambides, A., Tzvetanov, R. & Kassoli-Fournaraki, A. (1990) Zeolite bearing rocks in Petrota area (Eastern Rhodope Massif, Greece). Geologica Rhodopica, 2, 500–511.Google Scholar
Kitsopoulos, K.P. (1997) The genesis of a mordenite deposit from Polyegos Island, Greece. Clays and Clay Minerals, 45, 632–648.Google Scholar
Krohe, A. & Mposkos, E. (2002) Multiple generations of extensional detachments in the Rhodope Mountains (N. Greece): evidence of episodic exhumation of high-P rocks. Pp. 151–178 in: The Timing and Location of Major Ore Deposits in an Evolving Orogen (D.J. Blundell, G. Neubauer & A. Von Quant, editors). Special Publications, 204, The Geological Society, London.Google Scholar
Liati, A. (1986) Regional metamorphism and overprinting of the Rhodope zone, near Xanthi, (N. Greece). PhD thesis, University of Braunschweig, Germany, 186 pp.Google Scholar
Machiels, L., Garcés, D., Snellings, R., Vilema, W., Morante, F., Paredes, C. & Elsen, J. (2014) Zeolite occurrence and genesis in the Late-Cretaceous Cayo arc of Coastal Ecuador: Evidence for zeolite formation in cooling marine pyroclastic flow deposits. Applied Clay Science, 87, 108–119.Google Scholar
Magganas, A.C. (1988) Mineralogical, petrological and geochemical study of metabasic and meta-ultrabasic rocks of Circum-Rhodope belt in Thrace. Unpublished Ph.D. Thesis, University of Athens, Greece, 405 pp.Google Scholar
Marantos, I. (2004) Study of the Tertiary volcanic rocks alteration in the Feres basin Evros Prefecture, emphasising the genesis of zeolites and their possible applications. Unpublished Ph.D. Thesis, Technical University of Crete, Department of Mineral Resources Engineering, Greece, 261 pp.Google Scholar
Marantos, I., Kosharis, G., Perdikatsis, V., Karantassi, S., Michael, C. & Papadopoulos, P. (1997) A preliminary study on the zeolitic tuffs in the Komotini-Sappes tertiary basin, W. Thrace, N.E., Greece. Pp. 276–281 in: Natural Zeolites - Sofia ‘95 (G. Kirov, L. Filizova & O. Petrov, editors). Pensoft Publishers, Sofia.Google Scholar
Marantos, I., Kosharis, G., Perdikatsis, V., Karantassi, S. & Economou, G. (2002) Zeolitic alteration tuffs in the Skaloma-Darmeni-Nikites-Nea Santa area, Komotini Tertiary basin, Thrace, NE., Greece. P. 220 in: Zeolite ‘02, 6th International Conference: Occurrence, Properties and Utilization of Natural Zeolites (P. Misaelides, editor). Book of Abstracts.Google Scholar
Marantos, I., Koshiaris, G., Karantassi, S., Perdikatsis, V. & Christidis, G.E. (2004) Preliminary study of altered tertiary volcaniclastic rocks in the area of Asproula, Nea Santa, Rodopi perfecture, Thrace, NE Greece. Bulletin of the Geological Society of Greece, 35, 454–463.Google Scholar
Marantos, I., Michail, C. & Koshiaris, G. (2006) Study of the zeolitic alteration in Petrota Tertiary volcaniclastic rocks, Thrace area, NE Greece. Geoscience, 124-126.Google Scholar
Marantos, I., Markopoulos, Th. & Christidis, G.E. (2007) Zeolitic alteration in the Tertiary Feres volcano-sedimentary basin, Thrace, NE Greece. Mineralogical Magazine, 71, 327–345.Google Scholar
Marantos, I., Christidis, G.E. & Perdikatsis, V.C. (2008) Geochemical characteristics of the alteration of volcanic and volcanic clastic rocks in the Feres Basin, Thrace, NE Greece. Clay Minerals, 43, 575–595.Google Scholar
Marchev, P., Kaiser-Rohrmeier, M., Heinrich, C., Ovtcharova, M., von Quadt, A. & Raicheva, R. (2005) 2: Hydrothermal ore deposits related to post-orogenic extensional magmatism and core complex formation: The Rhodope Massif of Bulgaria and Greece. Ore Geology Reviews, 27, 53–89.Google Scholar
Michael, C. (2004) Epithermal systems and gold mineralization in western Thrace (North Greece). Bulletin of the Geological Society of Greece, 36, 416–23.Google Scholar
Michael, C., Katirtzoglou, C., Perdikatsis, V. & Constantinides, D. (1989) The polymetallic mineralization of the Pefka area, Evros county, Greece. Geologica Rhodopica, 1, 322–329.Google Scholar
Mposkos, E. & Liati, A. (1993) Metamorphic evolution of metapelites in the high-pressure terrane of the Rhodope zone, Northern Greece. The Canadian Mineralogist, 31, 401–424.Google Scholar
Papadopoulos, P. (1980) Geological Map of Greece. Ferres Sheet, 1:50,000. Institute of Geology and Mineral Exploration, IGME, Athens.Google Scholar
Papadopoulos, P. (1982) Geological Map of Greece. Maronia Sheet, 1:50,000. Institute of Geology and Mineral Exploration, IGME, Athens.Google Scholar
Papavassiliou, C. & Sideris, C. (1984) Geochemistry and Mineralogy of Tertiary Lavas of Sappai-Ferrai Area (W. Thrace) - Greece. Implications on Their Origin. Institute of Geology and Mineral Exploration, IGME, Geochemical Research, 4, 1–21.Google Scholar
Peccerillo, A. & Taylor, S.R. (1976) Geochemistry of Eocene calcalkaline rocks from Kastamonu area northern Turkey. Contributions to Mineralogy and Petrology, 68, 63–81.Google Scholar
Pecskay, Z., Eleftheriadis, G., Koroneos, A., Soldatos, T. & Christofides, G. (2003) K/Ar dating, geochemistry and evolution of the tertiary volcanic rocks (Thrace, Northeastern Greece). Pp. 1229–1232 in: Mineral Exploration and Sustainable Development (D. Eliopoulos, editor). Millpress, Rotterdam.Google Scholar
Pe-Piper, G. & Piper, D.J.W. (2007) Neogene back-arc volcanism of the Aegean: new insights into the relationship between magmatism and tectonics. Geological Society of America, Special Paper, 418, 17–31.Google Scholar
Pe-Piper, G. & Tsolis-Katagas, P. (1991) K-rich mordenite from Late Miocene rhyolitic tuffs, Island of Samos, Greece. Clays and Clay Minerals, 39, 239–247.Google Scholar
Polgari, M., Forizs, I., Mathe, Z., Toth, M. & Pecsi-Donath, E. (1995) Geoautoclave-type zeolitization in the Miocene rhyolite tuff, Mecsek Mts., SW Hungary. Pp. 227–240 in: Natural Zeolites - Sofia ‘95 (G. Kirov, L. Filizova & O. Petrov, editors). Pensoft Publishers, Sofia.Google Scholar
Raynov, N., Popov, N., Yanev, Y., Petrova, P., Popova, T., Hristova, V., Atanasova, R. & Zankarska, R. (1997) Geological, mineralogical and technological characteristics of zeolitized (clinoptilolitized) tuff deposits in the Eastern Rhodopes, Bulgaria. Pp. 263–275 in: Natural Zeolites - Sofia ‘95 (G. Kirov, L. Filizova & O. Petrov, editors). Pensoft Publishers, Sofia.Google Scholar
Skarpelis, N., Economou, M. & Michael, C. (1987) Geology, petrology and polymetallic ore types in a tertiary volcanosedimentary terrain, Virini-Pessani-Dadia, West Thrace (northern Greece). Geologica Balcanica, 17, 31–41.Google Scholar
Skarpelis, N., Marantos, I. & Christidis, G.E. (1993) Zeolites in Oligocene volcaniclastic rocks, Dadia-Lefkimi area, Thrace, Northern Greece: Mineralogy and cation exchange properties. Bulletin of the Geological Society of Greece, XXVIII/2, 305–315.Google Scholar
Solakius, N. & Tsapralis, V. (1987) Micropaleontological and Stratigraphic Analysis of Oligocene of Thrace, Greece. Unpublished Report, Institute of Geology and Mineral Exploration, IGME, Athens (in Greek).Google Scholar
Srodofl, I. & McCarty, D.K. (2008) Surface area and layer charge of smectite from CEC and EGME/H2O-retention measurements. Clays and Clay Minerals, 56, 155–174.Google Scholar
Stamatakis, M.G. (1989a) Authigenic silicates and silica polymorphs in the Miocene saline-alkaline deposits of the Karlovasi basin, Samos Island, Greece. Economic Geology, 84, 788–798.Google Scholar
Stamatakis, M.G. (1989b) A boron-bearing potassium feldspar in volcanic ash and the tuffaceous rocks from Miocene lake depositis, Samos Island, Greece. American Mineralogist, 74, 230–235.Google Scholar
Stamatakis, M.G., Hall, A. & Hein, J.R. (1996) The zeolite deposits of Greece. Mineralium Deposita, 31, 6, 473–81.Google Scholar
Stamatakis, M.G., Hall, A., Lutat, U. & Walsh, J.N. (1998) Mineralogy, origin and commercial value of the zeolite-rich tuffs in the Petrota-Pentalofos area, Evros County, Greece. Estudios Geologicos, 54, 315–322.Google Scholar
Sun, L., Ling, C.Y., Lavikainen, L.P., Hirvi, I.T., Kasa, S. & Pakkanen, T.A. (2016) Influence of layer charge and charge location on the swelling pressure of dioctahedral smectites. Chemical Physics, 473, 40–45.Google Scholar
Theodoropoulos, D. (1979) Geological Map of Greece. Neon Karlovasi Sheet, 1:50.000. Institute of Geology and Mineral Exploration, IGME, Athens.Google Scholar
Tsirambides, A., Filippidis, A. & Kassoli-Fournaraki, A. (1993) Zeolitic alteration of Eocene volcaniclastic sediments at Metaxades area, Thrace, Greece. Applied Clay Science, 7, 509–526.Google Scholar
Tsolis-Katagas, P. & Katagas, C. (1989) Zeolites in pre-caldera pyroclastic rocks of the Santorini volcano, Aegean Sea, Greece. Clays and Clay Minerals, 37, 497–510.Google Scholar
Velde, B. (1984) Electron microprobe analysis of clay minerals. Clay Minerals, 19, 243–247.Google Scholar
Vlahou, M., Christofides, G., Eleftheriadis, G., Pinarelli, L. & Koroneos, A. (2006) Tertiary volcanic rocks from Samothraki island (north Aegean, Greece): Sr and Nd isotope constraints on their evolution. pp. 283—304 in: Post-collisional Tectonic and Magmatism in the Mediterranean Region and Asia (Y Dilek & S. Pavlides, editors). Geolological Society of America Special Paper, 409.Google Scholar
Vougioukalakis, G., Fytikas, M., Kolios, N. & Francalanci, L. (2009) Cenozoic volcanic activity in Greece. Acta Vulcanologica, 21, 71–86.Google Scholar
Winchester, J.A. & Floyd, P.A. (1977) Geochemical discrimination of different magma serries and their differentiation products using immobile elements. Chemical Geology, 20, 325–343.Google Scholar
Yanev, Y., Innocenti, F., Manetti, P. & Serri, G. (1998) Upper Eocene-Oligocene collision-related volcanism in Eastern Rhodope (Bulgaria)-Western Thrace (Greece): petrographic affinity and geodynamic significance. Acta Vulcanologica., 10, 279–291.Google Scholar
Yildiz, A. & Kuscu, M. (2007) Mineralogy, chemistry and physical properties of bentonites from Basören, Kütahya, W. Anatolia, Turkey. Clay Minerals, 42, 399–14.Google Scholar
Zielinski, R.A. (1982) The mobility of uranium and other elements during alteration of rhyolite ash to mont-morillonite: A case study in the troublesome formation, Colorado, USA. Chemical Geology, 35, 185–204.Google Scholar