P36 Copertina R OK C August 20-28,2004 Florence -Italy Field Trip Guide Book - P36 Associate Leader:Y

P36_copertina_R_OK C August 20-28,2004 Florence -Italy Field Trip Guide Book - P36 Associate Leader:Y. Yanev Leader: M.Fytikas 32 Volume n°4-fromP14toP36 GEOLOGICAL CONGRESS INDUSTRIAL MINERALS (GREECE), ANDRELATED AND ONMILOSISLAND RHODOPES (BULGARIA), VOLCANISM INTHEEASTERN PALEOGENE ANDRECENT Post-Congress nd INTERNATIONAL P36 3-06-2004, 10:08:22 The scientific content of this guide is under the total responsibility of the Authors

Published by: APAT – Italian Agency for the Environmental Protection and Technical Services - Via Vitaliano Brancati, 48 - 00144 Roma - Italy

Series Editors: Luca Guerrieri, Irene Rischia and Leonello Serva (APAT, Roma)

English Desk-copy Editors: Paul Mazza (Università di Firenze), Jessica Ann Thonn (Università di Firenze), Nathalie Marléne Adams (Università di Firenze), Miriam Friedman (Università di Firenze), Kate Eadie (Freelance indipendent professional)

Field Trip Committee: Leonello Serva (APAT, Roma), Alessandro Michetti (Università dell’Insubria, Como), Giulio Pavia (Università di Torino), Raffaele Pignone (Servizio Geologico Regione Emilia-Romagna, Bologna) and Riccardo Polino (CNR, Torino)

Acknowledgments: The 32nd IGC Organizing Committee is grateful to Roberto Pompili and Elisa Brustia (APAT, Roma) for their collaboration in editing.

Graphic project: Full snc - Firenze

Layout and press: Lito Terrazzi srl - Firenze

P36_copertina_R_OK D 3-06-2004, 10:06:53 Volume n° 4 - from P14 to P36

32nd INTERNATIONAL GEOLOGICAL CONGRESS

PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS

AUTHORS: Y. Yanev (Bulgarian Academy of Sciences, Sofia - Bulgaria), M. Fytikas (Aristotle University of Thessaloniki, School of Geology)

WITH PARTICIPATION OF: R. Ivanova (Bulgarian Academy of Sciences, Sofia - Bulgaria) T. Iliev (Bulgarian Academy of Sciences, Sofia - Bulgaria) S. Gier (Vienna University - Austria)

Florence - Italy August 20-28, 2004

Post-Congress P36

P36_R_OK A 3-06-2004, 10:15:46 Front Cover: Platy Ca-clinoptilolite grown on ﬁ ne K-clinoptilolite crystals on the wall of the pumice bubble (the black bar is 10µm); Jelezni-Vrata zeolitized tuffs deposit, Eastern Rhodopes. JEOL superprobe 735.

P36_R_OK B 3-06-2004, 10:15:48 PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Leader: M. Fytikas Associate Leader: Y. Yanev

In the Eastern Rhodope mountains, a huge and Athens (Greece). Travel will be by airplane and bus. extended volcanism developed during the Paleogene. The degree of physical effort is low. Temperatures: In Bulgarian territory, this fi eld trip will focus on two 22-30oC. points: a) different types of volcano-clastic products (ignimbrites, fall-out tuffs), and various volcanic FIRST PART: Eastern Rhodopes massifs (domes, lava fl ows etc), b) the transformation of these products, by hydrothermal activity or by a Regional geological setting quick cooling of the “border” lavas of the volcanic Author: Y. Yanev (Geological Institute, Bulgarian structures and products, into industrial minerals Academy of Sciences) (zeolites or bentonites), or by a quick cooling of the “border” lavas of the volcanic structures and products, Introduction we will visit a rhyolitic tuff ring with a diameter Paleogene volcanic activity in the Eastern Rhodopes of 1,700 m, a gigantic pumice deposit, some great (Harkovska et al., 1989; Dabovski et al., 1991; Yanev phreato-magmatic craters, spectacular lava –domes et al., 1998a) took place at the end of the Paleogene and fl ows, gigantic columnar dikes, and numerous collision between Eurasian (represented here by the hydrothermal craters. A great variety of hydrothermal Rhodopes terrain) and Apulian plates during the fi nal and industrial minerals were formed: bentonite, closure of the Thetys Ocean in the area. The blocking kaolin, barite, silica, alunite, sulpure, manganese, of the subduction during the continental collision, epithermal gold etc., together with an impressive and the following crustal thickening, led to orogenic geothermal fi eld. A huge industrial production uplifting, exhumation of metamorphic cores and the activity exists, producing more than 1 million tonnes formation of graben basins along their peripheries. of bentonite and 500,000 tonnes of perlite yearly. We Sedimentation, fi rstly continental, more recently will visit some of the most important and interesting marine, began in the Middle (?)–Late Eocene. The quarries. volcanic activity started after the beginning of the The duration of the fi eld trip will be 5 days; the sedimentation, lasting to differing extents in the departure point is Sofi a (Bulgaria), the arrival point different parts of the basin, and continued until the Volume n° 4 - from P14 to P36 n° 4 - from Volume

Figure A - Itinerary of the 1st day (dotted) of the P-36 excursion (for the 2nd day see Fig. B).

3 - P36

P36_R_OK 3 3-06-2004, 10:16:16 P36_R_OK 4

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas 3-06-2004, 10:16:18 PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Figure B - Simplified map of the Eastern Rhodopes volcanic area (Yanev, 1998) with the itinerary of the 1st (dashed line) and 2nd day (solid line); the stops (from St.1 to St.4) are also shown. In the corner: schematic stratigraphic

column of the Priabonian (Pr) and Early Oligocene (Ol1) phases. Key: (1) Neogene-Quaternary cover; Upper Oligocene: (2a) dykes (29-25.5 Ma) and (2b) volcano; Lower Oligocene: (3) acid dome-clusters of 3rd phase, (4) acid volcanoes of 2nd phase, (5a) acid explosive volcano and (5b) domes of the 1st phase; (6) Priabonian acid volcano; (7) intermediate volcanoes of different phases; (8a) acid tuffs and ignimbrites of different phases, (8b) Priabonian- Oligocene sediments; (9a) plutons and (9b) caldera faults; (10) crystalline basement. Volcanoes: (D) Dambalak, (H) Hisar, (K) Kostino (inferred), (P) Perperek, (S) Silen, (SL) St Ilia, (SK) Studen-Kladenetz, (Y) Yabalkovo; (U) Ustra dome-cluster; (BC) Borovitza caldera. Zeolitized tuffs deposits: BP, G, GK, L, M, Sh (see Fig. C). end of the Early Oligocene. fi eld trip (Stop 2). Only epiclastic and sedimentary The volcanic activity was of a cyclical character, that deposits (mudstones, sandstones, and limestones) are is, as 4 intermediate phases which alternated with 5 observed in the distal areas. The volcanoes developed acid phases (the 1st of which is Priabonian, and all during the 1st intermediate phase are located mainly the rest are Early Oligocene), which are traditionally in the northern volcanic region, these of the 2nd labeled as the 1st intermediate phase, 1st acid phase, phase – mainly in the southern region where the most etc. (Ivanov, 1960), and their age (according to Lilov important bentonite deposits are situated. The 3rd and et al., 1987) is indicated in Fig. B. The individual 4th phases are represented by one volcano each, as volcanoes are built up of the products of one or both are located in the southern region. (maximum) two phases (intermediate and acid), but the acid pyroclastics are normally distributed Acid volcanoes are of several types (Yanev, 1998): over the whole volcanic area and this creates a tuff rings, that produced only pyroclastic fl ows; picture of overall distribution of each phase. The dome volcanoes, built by intergrown domes with Eastern Rhodopes volcanic area has been divided pyroclastics in between and sometimes with short into two regions: northern, Borovitza, and southern and thick fl ows; dome clusters, often situated within – Momchilgrad-Arda (Fig. B). calderas, that do not form central volcanoes, but Deposits of perlite (Goranov et al., 1960; Yanev, each dome is a monogenic volcano. A transitional 1987), both of zeolitized (Alexiev et al., 1997; type between dome volcanoes and dome clusters Raynov et al., 1997) and adularized pyroclastics, has also been identifi ed (Studen-Kladenetz volcano, and some bentonite deposits are related to the acid Stop 3). The acid volcanics are mainly rhyolites, volcanism (Fig. C). The zeolite deposits are mainly trachyrhyolites to trachydacites, rarely – dacites. clinoptilolite, and just two are mordenite. The alunite Normally they contain phenocrysts up to 10% but and the most important bentonitized tuff deposits, as there are also domes very rich in phenocrysts (over well as some agate occurrences, associate with the 50%). The phenocrysts are of quartz (in more alkaline

intermediate volcanism. Only perlites, zeolitized and rocks quartz appears at SiO2>73%wt), oligoclase- bentonitized pyroclastics are currently exploited, and andesine (rarely more basic), sanidine, biotite and they are the objects of the present ﬁ eld trip. very rare – anortoclase. Amphibole (edenite or Mg- The intermediate volcanoes are shield-like or hornblende) is present in some volcanics, whereas stratovolcanoes, with diameters of up to 25-30 km, diopside has been found in others (crystallization and current elevation of up to 700-800 m. They are temperatures for the ﬁ rst are <710-720°C depending

built up of basaltic andesites and andesites, or by on SiO2 rock content, for the second – they are higher shoshonites, latites, and ultrapotassic latites. Single than 710-720°C; Yanev, 1998). The ground mass is ﬂ ows of basalts or trachybasalts are rarely present. granoblastic (in subvolcanic bodies), spherolitic, or Some of the volcanoes are intruded by monzonitoid felsitic, consisting of feldspar and quartz, or tridimite

plutons. The volcanic rocks contain phenocrysts (in (Dimitrov et al., 1984). Microlithes of feldspars and P14 to P36 n° 4 - from Volume quantities of up to 20-30%) of andesine-bytownite, biotite are also present. Water-containing (2-6%) enstatite, augite, biotite, Ti-magnetite, sometimes volcanic glasses (perlites), that are object of the – amphibole, and in more basic varieties – olivine. present ﬁ eld trip (Stop 3), formed in the periphery The texture of the matrix is pilotaxitic, hyalopilitic, of the lava bodies due to supercooling (Yanev, 1987). shoshonitic or trachytic. The lava and agglomerate Some hundred bodies of perlites are known in the ﬂ ows are interbeded by pumice to ash pyroclastics Eastern Rhodopes, and none of them consists of and epiclastics in proximal areas. The pyroclastics low-water glass (obsidian). This is one of the reasons are bentonitized and are the object of the present for considering perlites as directly resulted from the

5 - P36

P36_R_OK 5 3-06-2004, 10:16:28 P36_R_OK 6

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas into somepartsofthesouthernregion. They are of numerouspyroclastic fl region, theviolent explosions resultedingeneration Eastern Rhodopesvolcanism. Inthenorthernvolcanic acid EarlyOligocenephase tuffs aredeposited(now zeolitized-Stop4). the reefs,limestonesareabsent,andonlyfall-out alternating withlimestones,aretobefound.Nordof the reefs,onlyfall-out tuffs (presentlybentonitized), farther southward transportation,andtothesouthof of the Arda River. Coastalreefsprevented themfrom welded ignimbrites. They extended onlytothenorth pumice fl 1997): oneashfl pyroclastic fl inferred volcanic centerwas Kostino, fromwhichonly Early Oligocenephase is typicaloftheacidvolcanic activity. A progressive decreasinginthevolcanic explosivity have beeneroded. formed inthecaseofsubaerealeruptionprobably formation. The pumiceouspartsofthelava bodies lava fromintensive bubble growth andpumice or wereeruptedontheseabottom,whichprevented either atshallow depthinwater-containing sediments, obsidian hydration. The lava bodieswereemplaced cooling ofwater-containing lava, notfromadditional (4) alunitedeposits,(5)adularizedtuffs, (6)Paleogene volcanics andsediments,(7)crystallinebasement. JV, Jelezni-Vrata andM,Most-clinoptilolite;L,Liaskovetz andSh,Sheinovetz-mordenite), (2) bentonitizedtuffs, (3)zeolitizedtuffs deposits(BB,Belia-Bair, BP, Beli-Plast,G,Golobradovo, GK,Gorna-Krepost, Geren; HMS,Haskovo MineralSprings;S,Silenvolcano; SK,Studen-Kladenetzvolcano; T, Tatarevo; U,Ustra), (1) areaoftheperlitedeposits(D,Dambalak,Hisar, Perperek andSt.Iliavolcanoes; EB,EasternBororvitza;Gr, Figure C-Distribution oftheprincipalindustrialmineralsinEasternRhodopesPaleogene volcanic area.Key: ows whichdepositedlow- tomoderately- ows erupted(Yanev andBardintzeff, ow inthebasewas followed bytwo was mainlyexplosive, andthe ows, whichspreadeven isparoxysmalofthe The 1stacid The 2nd perlite deposit,Schupenata-Planina(Broken Hill), dome cluster(high-Sirhyolites),towhichthelargest ones, alsobelongstothisphase,aswelltheUstra Part oftheacidvolcanoes crowning theintermediate volume, andisrepresentedmostlybylava varieties. The 3rd acidEarlyOligocenephase and fl are locatedintheirnorthernfoot.Many aciddomes Perperek, andStuden-Kladenetzvolcanoes –Stop3), volcanoes (Hisarnearthetown ofKardjali–Stop1, phase (e.g.Dambalakvolcano, Stop2).Somesmall had developed duringtheformer2ndintermediate large latitevolcanoes alongthe Arda River valley that trachydacite lava domevolcanoes, whichtopthe this phaseisrepresentedbysometrachyrhyolite to after thecalderacollapse.Insouthernregion, domes withperliteperipherieswereemplaced Carpathians andUkraine).Numeroushigh-Sirhyolite the BalkanMountains,andprobablyasfar asinthe the EasternRhodopes(in Thrace, tothesouthof 1). The explosive products arespreadfar away from non-welded ignimbrites(presentlyzeolitized-Stop ignimbrites, andoutsidethecaldera–low-grade to fl caldera subsidence(30x15km). The pyroclastic the sameeruptionsthatledtonestedBorovitza accompanied bythickfall-out tuffs, producedby ow depositswithinthecalderaarehigh-grade ows have perliteperipheries. isofrestricted 3-06-2004, 10:16:30 PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

is connected. Acid epiclastics and limestones were and Lower Oligocene ultrapotassic latites (32-33.32

deposited during this phase in the distal area. Ma; SiO2=57.14-59.34, Na2O=2.01-2.67, K2O=5.20- In the southern region, the products of the above 6.20%wt), from the periphery of the Borovitza mentioned phases are covered by alluvial deposits in caldera. The Priabonian latites (hydrothermally an E-W trending valley more than 70 km long (called altered in many places) are also exposed along the Paleo-Arda). These are rhyolite conglomerates at road to the town of Kardjali. They host the large the base, cross-bedded sandstones and mudstones Spahievo Pb-Zn-Au ore district (including some covered by the products of the Silen rhyolite volcano, deposits of alunites, turquoise, etc.). Flysch deposits which was formed during the 4th acid phase. This from the deepest parts of the Priabonian basin, with volcano is composed of E-W aligned domes with submarine slides and intralayer deformations, are perlite peripheries. Probably during this phase, and exposed between the village of Chernoochene and also during the Late Oligocene, the metamorphic the town of Kardjali. They are covered by limestones, basement and the overlaying volcanic products were also Priabonian in age (in the distance on the left), intruded by subvolcanic rhyolite bodies and 130o- or by the pyroclastic fl ow deposits of the 1st Early trending dyke swarms. Oligocene acid phase (seen on the right). The proposed genetic model for the Eastern Rhodopes volcanism is discussed in Yanev et al. (1998a) and DAY 2 Yanev (2003). The bentonitized tuffs of the Dobrovoletz deposit Field itinerary are exposed to the east of Kardjali, eastwards of the road (in front of the Pb-Zn metallurgic factory), at the DAY 1 beginning of the trip. They are covered by pyroclastic fl ow deposits (three fl ow units), and fall-out tuffs of Beginning from Sofi a (Fig. A), the fi eld trip route the 2nd acid phase described in Stop 1. The lowest crosses the Pliocene Sofi a depression (fi lled with lake fl ow deposit is NW-dipping and laminated, probably deposits, and rich in thermal mineral springs), and as a result of passing over a barrier (here – coral the Ihtiman crystalline terrain, with numerous Upper reefs), similarly to the pyroclastic fl ow deposit Cretaceous granites belonging to the Srednogorie in VTTS (Alaska), as described by Fierstein and volcanic island arc system (Dabovski et al., 1991). Hildreth (1992). Then our route crosses the area of the Epithermal porphyry-cupper deposits, associated with Jelezni-Vrata zeolite deposit. the Cretaceous magmatism, can be seen on the left. About 80 km from Sofi a, the road enters the Upper Stop 1: Thracian depression, fi lled with Paleogene marine Zeolite deposit “Jelezni-Vrata” (“iron door”) and Neogene lake deposits laying over volcanic Authors: Y. Yanev, R. Ivanova. and Tz. Iliev arc products. The road goes to the north of Plovdiv, (Geological Institute, Bulgarian Academy emplaced on hills built up by Upper Cretaceous of Sciences). monzonites. At the village of Gorski-Izvor (215 km from Sofi a), we enter the Eastern Rhodopes volcanic The deposit is located 4 km to the east of Kardjali (Fig. area (Fig. B): the northernmost and the oldest 1-1) on the Arda River bank, and occupies an area of (Bartonian) latites of Yabalkovo volcano (Yanev et about 16 km2, close to the trahcydacite volcano Hisar,

al., 1998b) can be seen on the left, and Priabonian which is capped by a dome ﬂ ow (SiO2= 66.54-68.57,

latites (1st intermediate phase) are exposed to the Na2O=3.7-4.31, and K2O=5.64-6.42). The complex

south of Gorski-Izvor village. latite-trachydacite volcano Dambalak (trachybasalts P14 to P36 n° 4 - from Volume

Rhyolite domes (age 29.5-30.4 Ma; SiO2=70.34- to latites with SiO2 = 50.85 - 62.26, Na2O = 1.86 -

75.90, Na2O=2.43-3.80, K2O=4.78-5.04%wt - Yanev 4.50, and K2O = 2.0 - 4.02 %wt; trachydacites having

and Pecskay, 1997), with perlite periphery (the ﬁ rst SiO2 = 70.65 - 71.85, Na2O = 3.64 - 4.11, and K2O perlites were described in Bulgaria by Bontscheff, = 5.26 - 5.79%wt) are located on the opposite bank 1897), are crossed near the village of Haskovo Mineral of the Arda River (Fig. B). The deposit includes Springs. They are located in the eastern periphery of the zeolitized (clinoptilolitized) explosive products the Borovitza region. The mountains visible into the (non-welded to low-grade ignimbrites and fall-out distance on the right are built of Priabonian latites tuffs), of the 2nd acid phase. The deposit has been

7 - P36

P36_R_OK 7 3-06-2004, 10:16:34 P36_R_OK 8

Volume n° 4 - from P14 to P36 P36 - P36 tuffs ofthe2ndintermediatephase;(5)1stacid(6)Priabonianlimestones.. epiclastics), (2)fall-outtuffs and4thpyroclasticflow, (3)lower threepyroclasticflows; (4)epiclasticsandbentonitized on scale1:10000).Key: pyroclasticrocks ofthe2ndacidphase:(1)depositscover (upperpyroclasticflows and Figure 1.1-GeologicalmapofJelezni-Vrata (Stop 1)andBelia-Bairzeolitizedtuffs deposits(mappedby Yanev in1963 Leader: M.Fytikas deodorant, etc.(Raynov etal.,1997). supplement inanimalhusbandry, asamineralsoil, for oxygenenrichmentinmetallurgy, asadietary be usedasasorbent(inclusive ofradionuclides), 1968; Djourova and Aleksiev, 1990),andassuchcan deposit hasbeenfoundbyProf.B. Alexiev (Alexiev, binding properties. As azeoliteraw materialthe addition forlighteningandimproving thecement- material isusedinthecementindustry–asaclinker exploited over thelast50years,asminedraw also present. The pumiceisreplacedbyclaymineral, (probably oflatite),andadularizedperliteclastsare Plagioclase, rarelyK-feldspar, denselava fragments 2), consistingmainlyofalteredpumicefragments. ash tolapilli-sizedpumicetuffs (thesameasatStop the bottomtotop):(1)yellow bentonitizedlatite the Dambalakvolcano, representedhereby(from products ofthe2ndintermediatephaseeruptedby The zeolitizedpyroclastics areunderlayedbythe Geological background unit of11oxygens(asH The structuralformulaofI/S,basedona Table 8.3,MooreandReynolds, 1997),isabout15%. after solutionwithethyleneglycol(accordingtothe reﬂ of thedifference betweenpositionsofthesmectite illite inthemixed layersisestimatedonthebasis of mixed-layered illite/smectite. The quantityof and adularia(Fig.1-2). The <2µfractionconsists zeolites (clinoptiloliteandlessmordenite),calcite ﬁ coats theclastsandwalls ofthesmallcavities calcite, smectite,andceladonite,astheceladonite fragments arealsopresent. The matrixconsistsof pyroxene, sanidine,andbiotite.Singlealteredpumice blocks (upto50cm),andfreecrystalsofplagioclase, clasts canbeupto5-10cm),gradingupwards into contain roundedlatiteclasts,upto1cminsize(single analyses). (2)Brightgreenlatiteepiclastics. They (Ca (Si lled withsilica,andreplacesbiotitephenocrysts ection at5and8.5°2 3.977 0.092 Al Na 0.023 0.025 O K 10 0.123 )(OH) ) (Al 2 (average from8microprobe θ ,andnear16to17°2 2 O isnotconsidered),is: 1.241 Mg 0.368 Fe 3+ 0.361 3-06-2004, 10:16:36 Ti θ , and 0.027

) PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Figure 1.2 - SEM images of bentonitized latite pumice tuff: left, pumice fragment (the tube-like bubbles are still perfectly seen) completely replaced by smectite; right, clinoptilolite and rhomb-like adularia enclosed by smectite.

in the lava fragments. Clinoptilolite and adularia in the central voids montmorillonite, carbonate or have also been detected. Coral reefs (with horizontal celadonite is developed. Perlite clasts might have been dimensions from several to 100 m), can be seen zeolitized prior to their transportation and deposition within the epiclastics, as one large reef is located in as an element of the pyroclastic fl ows. The matrix the southern part of the quarry (on the dam bank). is clay-carbonatic, and contains microfossils and The cross-section of the products of the 2nd acid zeolitized vitroclasts. Blocks derived from both the volcanic phase, starting from the bottom, is the underlaying tuffs and coral reefs can often be seen. In following: the uppermost 0.5 m the breccia fast depletes in large 1. A bed (up to 1 m thick) of layered pale green fall-out blocks, and grades into the non-welded to low-grade tuffs, composed by fi ne-lapilli clasts. In many places, ignimbrites of the 1st fl ow, which is locally laminated. it is cut and deformed by the overriding pyroclastic This basal breccia can be interpreted as either lag- fl ow (layer 2a). It consists of crystalloclasts (quartz, breccia resulted from the collapse of the dense part feldspars, biotite, and amphibole) 0.2-1.2 mm in size, of the eruptive column (Druitt and Sparks, 1982), and little lithoclasts (spherolitic rhyolites and perlites), then transported as a pyroclastic fl ow or lahar (mud and pumices (0.15-0.6 mm) with spherical bubbles. fl ow, composed of clasts derived from the volcano The matrix consists of fi ne acute glass shards as rarely slope, and covered by the following pyroclastic fl ow). microfossils can also be seen. All glass shards and There is no hematization of the underlaying tuffs, pumice clasts are replaced by zeolites, accompanied which is indicative of “cold” transport and deposition by clay minerals. Celadonite, giving the greenish of the described breccia. color of the rocks, is formed in the central voids of the 2b. the two following fl ows have hematized basal shards and along the bubble walls in the pumice. parts up to 1 m thick (as the hematization also affects 2. Non-welded to low-grade ignimbrites, deposited the top of the underlaying deposits). By contrast, from by three pyroclastic fl ows (Fig. 1-1), each 7-10 m the lowermost fl ow, they show no internal lamination, thick. Individual fl ow units are separated by either since they fl owed on an already fl attened surface. few-centimeter thick layers of fossils containing The three fl ow deposits are pale pink in color (due to epiclastics (Djourova and Aleksiev, 1990) or co- the montmorillonite accompanying zeolites), and are ignimbrite ash layers. low-grade to non-welded ignimbrites (resulted from Volume n° 4 - from P14 to P36 n° 4 - from Volume their deposition in a shallow marine environment), 2a. a 1-2 m thick layer of basal latite breccia (clast poorly sorted, and rich in fi ne-grained pumice (0.47- size is 5-10 cm, rarely up to 1 m) lies in the base of 0.75 mm in size). The main component of their basal the lowest fl ow deposit. Many clasts of spherolitic part (Fig. 1-3, left) is crystallolithoclastic, including rhyolites, perlites, and pumice (0.15-0.6 mm), mainly crystalloclasts (0.15-1.5 mm) of quartz (rich as well as acute crystalloclasts (0.2-1.2 mm) of in melt inclusions), sanidine, plagioclase, and biotite quartz, plagioclase, sanidine, and biotite fl akes are as well as lithoclasts (up to 0.5 cm in size) - mainly also presented. All glassy clasts are zeolitized, as pumice and rhyolite, with less perlite and latite. The

9 - P36

P36_R_OK 9 3-06-2004, 10:16:41 P36_R_OK 10

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas types (mainlyquartz,sanidineOr amount ofcrystalloclaststheabove-mentioned in size);ignimbrites(Fig.1-3,right),containingsmall deposits graduallygradeintopumice(upto1.8mm matrix isclay-zeolite,invery smallquantities. These (2) latiticclast,(3)feldshpars and(4)quartzclastsinthezeolitizedmatrix.||N.Thebaris0.5cm. colored): left,thebasalpartandright,middleofpyroclastic flow deposits.Key: (1)zeolitizedpumice clast, Figure 1.3-Microphotographiesofignimbritesamples from Jelezni-Vrata zeolitedeposit(thesamplesareartificially enclose glassshards. The ripple-marksarerichinrose 1-4), canbeseenlocallywithinthetuffs asallthey of psilomelanwithdifferent Mn/Baratios(Fig. 6 cmindiameter, and1-2cm-sizedblacknodules (Fig. 1-4).Claylensesandnodules,concretions5- (mainly ofquartzandfeldspars)but rarelypumice consist ofacuteglassshardsandtiny crystalloclasts with ripple-marksofvermicular andothertypes. They out tuffs, 5-7mintotalthickness,palepinkcolor, 3. Thinly-bedded (layersupto5cmthick)ashfall- Fuhrman andLindsley, 1988). (according tothetwo-feldspar geothermometerof the 3rdfl shards. The lava temperatureincreasesfromthe1stto small quantitiesandconsistsofash-sizedglass spindle- totube-like bubbles. The matrixisinvery rhyolites). The pumicecontainsbothsphericaland amount oflithoclasts(felsiticandspherolitic magnetite, rarelytitaniteorzircon);andvery small plagioclase An ow andis700,720740°C,respectively 18.8-39.5 Or 2.0-6.5 , biotite,alittleamphibole, 66.4-72.9 Ab 26.2-32.6 , top oftheunderlayingfall-out tuffs (paragraph5). have uneven boundarieswith,orinterbedthe enriched inbiotite-pyroxene latiteclasts. They pyroclastic fl ignimbrites isidenticaltotheseoftheunderlaying pyroclastic fl 6. Several meters-thick,notwellindividualized, these unitsispresentedin Table 1-1. mined inthequarry. The whole-rockchemistry of them (paragraphs2-4ofthedescribedsection)are deposits, aswellthefall-out tuffs locatedbetween The topmostlevel ofthe2nd,3rdand4thfl parts. 10 cmthick).Smallcoralreefsappearintheupper color andmorethicklybedded(thelayersareupto those describedinparagraph3,but grayishwhitein 5. Fall-out tuffs (morethan30-40mthick)similarto contain lensesenrichedinchloritizedbiotite. rounded. They aregraytopalegreenincolor, and in coarse-grainedpumiceclasts(1-2cmsize),often compared withthelower fl bottom. They arealsolow-grade tonon-welded,but by the4thfl 4. The ignimbrites(morethan20mthick)deposited montmorillonite. ow deposits. The compositionofthese ow deposits,but someofthemare ow have uneven, locallyhematized ow deposits,areenriched 3-06-2004, 10:16:44 ow ow PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Upwards, with no clear boundary, they grade into gmelinite (?) are detected in the lower pyroclastic latite epiclastics. fl ow unit, and needles of mordenite – in the 4th fl ow 7. The latitic epiclastic rocks are poorly-sorted and unit. The quantities of the glass replacing minerals locally thickly-bedded. They contain varying types and crystalloclasts are presented in Table 1-2: the of latite clasts (inclusively red in color resurgent highest quantity of the clinoptilolite is registered in ones), up to 5-10 cm in size, great amounts of pumice the fall-out tuffs, and this of the crystalloclasts – in clasts, and single rhyolite and perlite fragments. The the 1st fl ow deposit. crystalloclasts of feldspars, pyroxene, and biotite are The shape of both vitro- and pumice clasts is fully not very abundant. The matrix is almost lacking, but preserved (Fig. 1-4). Most often they are zonally sometimes zeolites have crystallized between the replaced: a thin montmorillonite or illite fi lm is formed clasts. They also contain lenses (up to 10-15 m long) along their outlines, as well as along the bubble walls of bioclastic limestones and coral reefs, very often in the pumice; the periphery of the shards is replaced silifi cated. Latite epiclastics are more than 100 m by tiny clinoptilolite crystals with K as the main thick. exchangeable cation; the inner part of the vitroclasts The inferred vent region for these pyroclastic fl ow is replaced by heulandite-type platy crystals (1-2 to deposits is Borovitza caldera (Yanev and Bardintzeff, 10-12 µm, rarely up to 20 µm in size, photo on the 1996), located 25 km to the northeast of the deposit. front cover page), with Ca as the most abundant The pyroclastic fl ows stopped at the northern foot exchangeable cation. The clay minerals form very of the Dambalak volcano that had risen during the small drops between the clinoptilolite crystals. These former 2nd intermediate phase. The lamination of the minerals give the characteristic color of the zeolitized lowermost fl ow (to the NW) and deformations in its tuffs – celadonite gives the grey color of the lower base are indicative of the fl ow direction. Moreover, layer, and the Fe-poor montmorillonite provides the ignimbrites contain quartz crystalloclasts, the pink and white color of the other zeolitized while the lavas produced by the closely located pyroclastic rocks. The opal-CT is hard to recognize, acid volcanoes Hisar and Dambalak do not contain as it forms only globules or irregular grains between quartz phenocrysts (Yanev, 1998). The cone of the the clinoptilolite crystals in the vugs. The ignimbrite trachydacite volcano Hisar, rising just next to the matrix is replaced by the cryptocrystalline aggregate quarry, is built up of coarse block and ash fl ow of the above mentioned minerals. deposits wedged into the fi ne-grained fall-out tuffs. Impact structures of blocks erupted from this volcano Data obtained from the bore-hole exploration of are preserved in the tuffs of the zeolite deposit. The a neighboring area (Belia-Bair deposit), show the latite epiclastics covering the deposit materials have following average composition (calculated on the some of the features of the lag-breccia (Druitt and base of 42 samples), from a 90 m thick section: Sparks, 1982), which derived from collapse of the clinoptilolite 52.8%, montmorillonite 7.8%, illite dense part of the eruptive column and was deposited 4%, opal-CT 4.3%, calcite 0.9%, adularia (including close to the volcano vent (e.g. during the acid activity sanidine) 17.4%, quartz 4.6%, plagioclase 7.5%; CEC of the Dambalak volcano). On the other hand, these measured in 5 samples varies from 88 to 129 meq/ epiclastics can be deposited from dense mud fl ows, 100g (Raynov et al., 1997). The exchangeable cations dragging a mixture of latite fragments (including of the clinoptilolite (Table 1-3) change gradually bombs), and loose acid tephra down from the fl anks from the 1st fl ow unit to the fall-out tuffs: Ca and Na of the same volcano. The presence of the coral reefs is decrease, K increases. The clinoptilolite passes from somehow indicative of the second hypothesis. K-Na type in the 1st fl ow, to a Na-K one in the fall- out tuffs. Zeolitization The zeolitization of the volcanic glass from the P14 to P36 n° 4 - from Volume All glassy shards (vitroclasts and pumices), thick pyroclastic successions, is low-temperature constituting the pyroclastic rocks and the matrix of alteration occurring in a slightly alkaline environment the epiclastic rocks, are replaced by clinoptilolite, of an open hydrological system. However, whether accompanied by opal-crystobalite-trydimite (opal- this alteration is a diagenetic process (i.e. <200°C) CT), Ca-montmorillonite, illite (celadonite has been (Sheppard and Hay, 2001; Utada, 2001), or resulted identifi ed only in the lower pyroclastic layer) and from the alteration of low-temperature hydrothermal probably adularia. Small quantities of lomontite and solutions circulated throughout the highly permeable

11 - P36

P36_R_OK 11 3-06-2004, 10:16:47 P36_R_OK 12

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas the left,onsouthernbankofriver. trachydacite lavas (2ndand3rdacidphases),riseson Dambalak (2ndintermediatephase),crowned by distance ontheright. The Lower Oligocenevolcano covered byPriabonianlimestones,isseeninthe crossing the Arda River, themetamorphicbasement, route goesontoStop2.Leaving behindthetown and After Stop1wewillgobacktoKardjali,whenceour 1997), isaquestionstillopentodebate. pyroclastic deposits(Gogishvili;1980;Rainov etal., sheet (SiO of theLower Oligocenevolcano Dambalak. A latite of thetown ofKardjali(Fig.B), inthewesternfoot This bentoniteoutcropislocated4kmtothesouth crystalloclasts. Thewhitebaris100µm. (white, 6-6.7;grey, 9-13).(1)quartzand sanidine cemented bypsilomelanwithdifferent Mn/Baratio replaced byplatyK-clinoptilolitecrystals(black) and in thezeolitizedashtuff: vitroclastswithcentralvoids Figure 1.4-Back scatteredelectronimageofMnnodule of Petrology, Vienna University). Bulgarian Academy ofSciences)andS.Gier(Institute Authors: Y. Yanev, R.Ivanova (GeologicalInstitute, Bentonite outcrop Stop 2: 2 =57.60, Na 2 O=3.82, K 2 O=3.71%wt), the basisofaformulaunit11oxygens(H The structuralformulaoftheclayiscalculatedon might beduetothepresenceofvermiculite layers. glycerol solutionofpreviously Mg-saturatedsamples 1997). Incompleteexpanding ofsmectiteafter (according tothe Table 8.3,MooreandReynolds, 16° 2 estimated onthebasisofpositionapproximately presence ofabout10%illitelayersinthesmectiteis 2-2) consistsmostlyofsmectite,illite,andzeolite. A and adularia(seeFig.1-2). The clayfraction<2µ(Fig. altered, andreplacedmainlybyclayminerals,calcite, of plagioclasearevery scarce.Pumiceiscompletely adularized perlite,anddenselatiteclasts.Fragments mainly ash-sizedpumiceclasts(Fig.2-1),single due totechnicalreasons. The bentonitizedtuffs contain (located eastward ofKardjali),thatcannotbevisited corresponds tothebentonitedepositDobrovoletz In characterandstratigraphicposition,theoutcrop layers, areexposed ontheeasternscarpofroad. of Stop1),withseparatelimeconcretionsorthin Bentonitizedlatiteashtuffs (thesameasatthebase clinopyroxene, and Ti-magnetite microliths. not considered):(Ca ( Fe phenocrysts ofdiopside-augite(Wo to thenorth. The latitecontainssmallamountof having afi matrix, containingplagioclase(An periphery An rises ontheright. After thevillageofJinzifovo, the epiclastics (Fig.1-1). The trachydacitevolcano Hisar same zeolitizedpyroclastics andtheircover ofmixed “Jelezni-Vrata”, ourtripcontinueslokingatthe and leaving behindthealreadyvisiteddeposit Kardjali (Fig.B),astheway toStop1isthesame, The afternoonroutestartsagain fromthetown of conditions. composition thattakes placeunderslightlyacidic temperature alterationoffi It issupposedthatclaymineralsresultfromlow- feldspar, plagioclase,quartz,andmicacrystals. fossils. They consistofsmectite,calciteandtiny K- of sedimentaryorepiclasticorigin,richincalcareous free crystals.Somelayersarefi biotite, andplagioclasemicrocrystals),thesame layers containalsolatiticfragments(withamphibole, 7 microprobeanalyses). The lime concretionsand IV Al=2.45, Mg 3+ 0.337 θ smectiterefl Ti 0.019 nely columnarjointedbase,isvisible ) (Si 74-80 # 70), andplagioclase(core An Or 3.887 ection oftheEG-solvated sample 1-2 Al ), enclosedwithinaglassy 0.102 0.113 Na ne ashorpumiceoflatite O 10 0.040 )(OH) ne-grained mudstones K 0.197 56 2 42 (average from Or ) (Al En 5 ), ortho-and 42-43 1.107 ), biotite 3-06-2004, 10:16:48 Mg 81 2 O is Or 0.637 4 , PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Table1.1 - Major elements content (%wt) of the zeolitized alternation (caused by fault displacements) of Sample 1803 1804 1805 1806 1807 tuffs, epiclastics, and limestones, deposited during the 1st, 2nd and 3rd volcanic phases, Loca- 1st 2nd 3rd fall- 4th fl ow can be observed going uphill above Perperek tion fl ow fl ow fl ow out village. These products are covered by rhyolite

SiO2 73.30 73.32 73.46 70.91 70.62 conglomerate sandstones and clays, deposited in a river valley (called Paleo-Arda) more than TiO2 0.14 0.13 0.10 0.10 0.15 70 km long and 1-4 km wide, which developed Al O 11.14 11.53 10.14 10.72 11.56 2 3 at the end of the Oligocene volcanic activity.

Fe2O3 1.38 1.19 0.41 0.84 1.55 The Priabonian sediments appear again in MnO 0.01 0.00 0.01 0.04 0.01 the vicinity of the Miladinovo village. The MgO 0.39 0.32 0.25 0.40 0.40 subvertical pale green zeolitized ignimbrites of the 1st acid phase (the Lyaskovez mordenite CaO 1.31 1.20 1.20 1.51 1.63 deposit) are exposed in the area of the

Na2O 1.85 1.45 0.79 1.64 2.13 Lyaskovetz village. The products of the same K O 3.66 3.56 4.21 2.44 2.94 volcanic phase are exposed uphill above the 2 village, but here they are clinoptilolized, and P O 0.12 0.08 0.09 0.07 0.11 2 5 displaced by normal faults. Afterwards the

H2O 5.95 5.64 8.48 10.62 8.14 route crosses the eastern margin of the Silen

Somme 99.25 98.42 99.14 99.29 99.24 volcano (SiO2=75.13-76, Na2O=3.5-3.6,

K2O=4.84-5.15%wt), which developed during R-ray fl uorescence analyses (“Eurotest”, Sofi a) the 4th volcanic phase. It lies on the Paleo- Arda alluvial deposits and is also associated road crosses the Chifl ik fault-fl exure zone. The upright with perlites. Then the road again crosses layers are fall-out tuffs (with clear ripple-marks), and the deposits fi lling the Paleo-Arda valley (here E-W thin ignimbrite deposits, similar to these seen at Stop oriented), as well as the underlying tuffs of the 2nd 1. The mountain massif on the left is crowned by acid volcanic phase, and the sediments, epiclastics, pale green zeolitized ignimbrites, and fall-out tuffs and latites of 2nd intermediate phase, within which of the 1st acid phase (Stop 4); the epiclastics from Stop 3 is located. the cover of Stop 1 are visible on the right. The trachyrhyodacite volcano Perperek (SiO =70.78-72, 2 Stop 3: Na2O=2.92-4.45, K2O=4.53-6.62%wt) rises near the village of the same name, as the fl at tops seen on the Perlite Deposit “Golobradovo” left are fan-like lava domes squeezed out from the Author: Y. Yanev (Geological Institute, Bulgarian vents of this volcano (Yanev et al., 1968). A repeated Academy of Sciences).

Table 1.2 - Mineral quantities (in %wt) of the zeolitized pyroclastics, Jelezni-Vrata deposit Sample number Cl CT Ad Sm Il Q Pl Mu Others and pyroclastic +S unite 1803 - 1st fl ow 42 12 17 1 8 16 3 - lomontite gmelinite (?) 1804 – 2nd fl ow 38 15 14 1 10 16 3 2 P14 to P36 n° 4 - from Volume 1805 – 3rd fl ow54136251513 1806 – fall-out 57 10 196115- gmelinite (?) 1807 – 4th fl ow45106781211- Based on XRD, DTA and comparison of the whole-rock and mineral chemistry (analyzed by R. Pravchanska and P. Petrova, Geological Institute). Cl,clinoptilolite; CT, cristobalite-tridimite; Ad+S, adularia +sanidine; Sm, smecite; Il, Illite; Q, quartz; Pl, plagioclase; Mu, muscovite.

13 - P36

P36_R_OK 13 3-06-2004, 10:16:51 P36_R_OK 14

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas having arelative weightfrom60upto500kg/m expanded perlite isanartiﬁ Application deposits have notbeenexploited. the expanded perliteanditshighFecontent,these the 1980s.Becauseofrelatively highdensityof performed duringthe1970sandatbeginning of perlite depositsassociatedwiththisvolcano was A twofold trenchanddrill-holeexploration ofseveral found andﬁ et al.,1987;Georgiev etal.,2003). The perliteswere perlites oftheCholderenSummitis32-33Ma(Lilov phase. The K-Arageofthetrachyrhyolitesand Studen-Kladenetz whichbelongsto2ndacidvolcanic and isconnectedwiththeLower Oligocenevolcano (perlites) islocated20-25kmtotheeastofKardjali, The depositofwater-bearing volcanic glasses Introduction uphill fromthebus stopatGolobradovo village. The stopislocated750mawayand about80-90m Note: monomineral wetanalyses heating at300-350 Natural perlitesaremainlyused(afterpreliminary (according tothetypeofproducts),withgood by fast heatingat1200-1300 (accordingDjourova and Alexiev, 1990) Table1.3 -Chemistryofthezeolites oainfo lwout Fall- flow SiO flow location 1st3rd Sample 65 56 15 29 52 4.98 26 13.68 22 36 4.84 46 K % 18 Na % 13.54 5.10 Ca % 12.76 Si/Al L.O.I. K g .804 0.51 2.83 0.43 2.22 Na 0.48 CaO 2.10 MgO Fe Al TiO 2 2 2 .544 4.49 4.43 3.65 O 2 O O .714 0.80 1.41 O 2.47 2 2 3 3 rstly describedbyGoranov etal.(1960). .304 0.49 11.19 0.07 0.45 65.79 11.47 0.07 0.33 11.09 65.71 0.06 66.66 ° C) forexpanded perlite production cial pumicematerial, ° C. Practically, the tuff 3

numerous smallerdomes(having diametersfrom and producinghyaloclasticfl with acomplex structure(upto3x1kminsize), direction, andiscomposedofseveral large domes, (Fig. 3-1). The volcano iselongatedinanE-W volcano Geology oftheStuden-Kladenetz these bodiesareemplacedonanareaofabout20km tens, toseveral hundredsofmeters),andsills. All properties (0.04kcal/mh fi glass andceramicindustries. production) representsthefraction<2.5mm–in elements, andthewaste (40%resultingfromthe used mainlyasalightfi body ofthevolcano interfi to thesouthofStuden-Kladenetzvolcano. The the St.Iliavolcano (2ndintermediatephase),located parts oftwo latitesheetsfromthenorthernfootof latite pyro- andepiclastics,aswellofthefrontal 1998). The volcano basementisbuilt ofsediments, that ofadomevolcano andadome-cluster(Yanev, i.e. thevolcano morphologyistransitionalbetween reproofi Figure 2-1-Bentonitizedtuffs; (1)pumice clast.||N. ng, aswellheatandsoundinsulating ller ofprefabricated building o C). The expanded perliteis ngers withtheexplosive ows (upto1kmlong), The baris0.25cm. 3-06-2004, 10:16:52 2 , PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

products of the 2nd acid phase, having a thickness of 50-70 m (these latter being pumice and perlite tuffs, corresponding to the zeolitized tuffs of Jelezni-Vrata deposit – Stop 1), with epiclastics (70 m thick), and with the overlaying limestones (130 m thick). The epiclastics are of acid composition, silty, sandy to granule. Only in the central and western parts of the volcano are they of mixed composition (containing rounded perlite, trachyrhyolite, latite, and gneiss clasts up to 20-30 cm in size, and enclosed by an ash-pumice matrix), poorly-sorted to chaotic. The domes are emplaced at different levels: only in the volcano basement (in the Figure 3.1 - Geological sketch map of Studen-Kladenetz central parts), in tuffs and mixed epiclastics, and in volcano (Yanev, 1987): (A) Golobradovo (Stop 3), the limestones (in the central and western parts). (B) Svetoslav and (C) Konevo perlite deposits. In the corner: schematic cross sections of (A) and (C). The volcanic domes have a zonal structure: a core Key: (1) trachyrhyolite dome with perlite periphery, built up of red ﬂ ow-banded trachyrhyolites, and a (2) perlite breccia, (3) acid tuffs and latite-trachyrhyolite periphery – of black to gray perlites. The later form epiclastics; white arrows indicate the hyaloclastic flows. lens-, sickle-, or ring-like bodies. The trachyrhyolite/ perlite transition could be of two types (Yanev, 1987): 1) alternation of trachyrhyolite and perlite layers or Volume n° 4 - from P14 to P36 n° 4 - from Volume

Figure 2.2 - XRD-patterns of the oriented clay fraction of the bentonitized latite ash tuff after different treatments. N – air-dried, EG – ethylene glycol saturation. Inset: Mg+Gly – first Mg-, then glycerol saturation K – K saturation; d-values in Å. S – smectite, I – illite, Z – zeolite.

15 - P36

P36_R_OK 15 3-06-2004, 10:16:55 P36_R_OK 16

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas dome, (4)Smalldomeand(5)North-easterndome. A-A andB-B–crosssectionsshown atthebottom. exposed partofthesillanddottedline–schematic positionoftheperlite/trachyrhyolite transitionzone),(3)Central The grayareaisperliteandtheblack oneistrachyrhyolite. Key: (1)Odjak-Kayadome,(2)sill(dashedline-not Figure 3.2-GeologicalmapoftheGolobradovo perlitedeposit(Stop3)(mappedby Yanev in1975onscale1:10000). 3-06-2004, 10:17:00 PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Figure 3.3 - Microphotographies of the Golobradovo deposit: left, deformation of the Fe-oxide microlithe flow bands in the glassy matrix (1) by the trahyrhyolitic spheruloids (2) (the bar is 0.25cm); right, two generations spherolites (1st and 2nd) in trachyrhyolite spheruloid with diameter 10cm (perlite / trachyrhyolite transition zone (the bar is 0.25 cm). || N.

lenses; 2) areas of trachyrhyolite spheres, enclosed fast increase of the cooling rate towards the dome by a perlite matrix. In the fi rst case, the layers are up periphery, to 10-15 cm thick, as the thickness of trachyrhyolite • products of the partial crystallization of parts of layers gradually decrease (to a few mm), towards the already litifi ed glass (devitrifi cation), perlite periphery, and fi nally disappear. Alternatively, • products of subliquidus immiscibility, in which the the perlite layers thin towards the trachyrhyolite core. super-cooled water-containing lava (the presence of Along their strike. the trachyrhyolite layers (as well water in acid lavas has been proved by Hervig et as the perlitic) grade into wedges and disappear i.e. al., 1989) splits into two immiscible liquids. One the two rock varieties interfi nger laterally with one of them is rich in water, and after cooling, produces another. The trachyrhyolite spheres (spheruloids perlites; the other dry melt crystallizes, and generates - Yanev, 1970), in the second type of transition, are trachyrhyolite layers or spheruloids. Available up to 10-15 cm in diameter, and have a spherolitic petrologic data are in agreement with this hypothesis texture. (see below). At the perlite periphery, the spheruloids gradually Dome-connected fl ows consist of gray hyaloclastic decrease in number, and fi nally, they also disappear. (Svetoslav and Konevo deposits). Their emplacement In the Golobradovo deposit, the trachyrhyolite/perlite in an marine environment is marked by the coral reefs

transition is mostly a combination of these two types: grown on them. Tens of meters in size trachyrhyolite P14 to P36 n° 4 - from Volume lineally-arranged trachyrhyolite spheruloids, stuck bodies, enclosed by the above-described transition onto trahyrhyolite layers. Vesicles (from several zones, are also present within the fl ows. The mm up to 10-15 cm in size), are observed only in the hyaloclastic fl ows grade into massive perlites towards trachyrhyolite spheruloids and layers. Some of them the necks, as the trachyrhyolite/perlite transition are partly-fi lled with opal-chalcedony aggregates. is an alteration of layers (Konevo deposit), or an There are three hypotheses on the genesis of the interfi ngering between perlite and trachyrhyolite trachyrhyolite layers and spheruloids (Yanev, 2000): wedges (Svetoslav deposit). The sill (made up of • products of suppressed crystallization, due to the Golobradovo deposit), consists of black massive

17 - P36

P36_R_OK 17 3-06-2004, 10:17:03 P36_R_OK 18

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas glass-like appearance. The shapeof crystals withinachalcedony matrix),andhave a (Yanev, 1987,Popov etal.,1989) previous works, ithasbeendescribedasperlitefl perlites, andalsocontainstrachyrhyolitebodies.In tuffs aresilifi horizontal. At thecontactwithperlites,hosting perpendicular tothecoolingsurfaces, i.e.mostoften or pentagonalcolumns(20-25cmindiameter) perlites exhibit columnarjointing,withhexagonal typical ofsubaeriallyerupteddomesareabsent. The as cryptodomes.Dome-roundingcolluvialbreccias, bottom, i.e.they cooledatshallow subvolcanic level volcano basement, about50-60mbelow volcano the sedimentary, epi-andpyroclastic rock from the one neck-connectedthicksill. (trachyrhyolite/perlite ratiois1:5to1:4),aswell size), having blacktodark grayperliteperipheries three onesare240x150,220x80and160x60min deposit includesadozensmalldomes(thelarger periphery oftheStuden-Kladenetzvolcano. The (Fig. 3-2). This depositislocatedintheeastern Geology oftheGolobradovo deposit (2) intheperlite/trachyrhyolite transitionzone(Smalldome).Theperlitematrixiseroded. Figure 3.4-Trachyrhyolite spheruloids(1)withmenisci(arrows) locatedonthetrachyrhyolite “layer”; cied andzeolitized(platyclinoptilolite The domes the sill intrude isL- ow ow fl trachyrhyolite layers). The trachyrhyolitesshow clear trachyrhyolite transition(spheruloids“grown” on and 40x130minsize,displayingcombinedperlite/ in itslower parts),andtwo subvertical bodies20x50 numerous smalltrachyrhyolite“lenses”(especially structure ofthesilliscomplicatedbypresence but angled(along theChalderestream). The internal uneven sillbottom,thecolumnsareoftennotvertical, cm) orarebrecciatedinthelobofsill.Dueto exhibit columnarjointing(columndiameteris12-20 on bothbanksoftheChalderestream. The perlites body inthedeposit.Itisalmostentirelyexposed varies from80to25m)i.e.thisisthelargest perlite direction, andis350x200minsize(thethickness outcropping partofthesilliselongatedinaSW-NE hosting sedimentaryandepiclasticrocks. The eastern includes two large “lenses” (tensofmetersinsize) 150 mwideatathicknessofabout20-30m,and interfi (Cholderen Summit).Closetotheneck,perlite neck located200mtothe WNW ofthesilloutcrop shaped inplanarview. Itisprobablyconnectedtoa ow bandingandparalleljointing. ngers withtrachyrhyolites.Here,thesillis 3-06-2004, 10:17:06 PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Petrographic characteristics The alkali contents in transitional zones change The perlites consist of phenocrysts up to 1-2 mm in gradually from the trachyrhyolite core to the perlite periphery (Fig. 3-5): in the trachyrhyolite layers, size and matrix. The phenocrysts are of sanidine (Or59.4- # Na, K, and Rb decrease gradually, in perlite ones, 66Ab33-40), plagioclase (An22-25-Or6-7), biotite (Mg 31- IV Na increases, K does not changes signiﬁ cantly, 38, Al 2.46-2.55 with 0.3% F), less augite (Wo40En23- and Rb decreases. Thus, Na and Rb contents in the 25), and microphenocrysts of quartz (Yanev, 1998); the accessory minerals are magnetite, apatite, and zircon. perlite periphery and trachyrhyolite layers become The magma temperature, calculated using the two- equal. The additional hydration cannot explain these feldspar geothermometer of Fuhrman and Lindsley gradual changes, which most probably are due to the (1988), is 776oC. The matrix is of dark volcanic glass immiscibility (Marakushev and Yakovleva, 1980; with perlitic cracks, and numerous, mainly feldspar Yanev, 2000). The earlierly generated smaller spheres microlites, and dendrite-like crystallites. They are in the spheruloids (Fig. 3-3) have almost equal

arranged in bands curving around the phenocrysts contents of Na and K (Na2O=4.35, K2O=4.69%wt), and spheruloids (Fig. 3-3, left), which is one of the while the hosting larger spheres (2nd generation),

indicators of their origin from immiscible liquids show the signiﬁ cant predominance of K (Na2O=3.39, (Roedder, 1979). The spheruloids have a spherolitic texture, and often enclose (Yanev, 1970, 2000) an earlier generation of spherolites (Fig. 3-32, right). The spheruloids that lay on the trachyrhyolite layers have menisci (Fig. 3-4), that is “unequivocal evidence for immiscibility” (Hanski, 1993).

The trachyrhyolites contain the same phenocrysts as perlites, but their matrix is of felsitic or locally axiolitic texture, consisting of feldspar and tridimite microcrystals (Dimitrov et al., 1984). Their colour is red (at a depth of several tens of meters – gray), caused by the superfi cial oxidation of microlithic magnetite dispersed in the matrix. Some of the spheruloids which contain latitic enclaves having diffuse outlines, and are composed of a glassy matrix with microlithic plagioclase and pyroxene, indicating a process of magma-mixing (Yanev, 1998). Chemical composition Both perlites and trachyrhyolites are rich in alkalies (Table 3-1), and an obtained K/Na ratio of 1.5 is typical of most Eastern Rhodopes acid volcanics (Yanev et al., 1983). The normative composition of perlite is: quartz 29%, K-feldspar 44%, and albite 27% (Yanev and Zotov, 1995). Compared with trachyrhyolites (water free base, Table 3-1), perlites have a lower content of SiO , higher K, and lower Na 2 P14 to P36 n° 4 - from Volume contents, and, relatively, a much higher K/Na ratio. Figure 3.5 - Na2O, K2O (%wt) and Rb (ppm) contents Since Na cation hydrates easily compared with K, due (fl ame photometry, analyzed by B. Karadjova) of the to its smaller size and is relatively leached to a greater perlite (solid circles and solid lines) and trachyrhyolite (crosses and dashed lines) layers in the transition zone degree, the lower Na contents are widely considered along two profi les across the Central dome periphery as evidence supporting the hypothesis of a later perlite (left, to the trachyrhyolite core, right, to the perlite hydration (Noble, 1967; Steward, 1979). However, in periphery). Bottom, schematic cross section of the perlite, the Eastern Rhodopes, in perlites, the correlation trachyrhyolite transition (p, perlite and r, trachy-rhyolite). between water content and K/Na ratio is negative The arrows indicate the trace (Yanev, 1987, 1994). element analyzed samples (Table 3-2).

19 - P36

P36_R_OK 19 3-06-2004, 10:17:10 P36_R_OK 20

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas nanoagreggates (<15nm)–25%,Fe hematite nanoaggregates (15-30nm)–17%,wustite perlites: magnetitemicroliths(>30nminsize)–32%, the following distribution ofFeintheGolobradovo room temperature,77°and4.2°K(Fig.3-6),show measurements (Dormannetal.,1989)performedat ions intheglassstructure(signalatg=4.3).Mösbauer in nanocrystals(signalatg=3.2),andmuchlessas of thealumo-sillicatemelts. trachyrhyolites isLi,cation-stimulatingcrystallization they form. The onlytraceelementprevailing inthe texture becauseofthefavorable metal-oxygenbonds K that theGolobradovo perlitescontainFe found byEPRspectroscopy (Calasetal.,1988), possibilities foritsuseintheglassindustry. Itwas defi A specialmodifi al., 1989). resulted frompresenceofwater molecules(Zotov et due tothetetrahedralringsexpansion thatmighthave Si,Al-O-Si,Al angleinvolcanic glassesis10°larger, feldspar glasses(Taylor andBrown, 1979),but the of theGolobradovo perliteissimilartothatofthe been measured(in Å): Si,Al-O forming ions,arrangedin6-memberedrings,have al., 1989),thefollowing distancesbetweennetwork X-ray radialdistribution functionanalysis(Zotov et disordered inmedium-andlong-rangeorder. Using up toadistanceofabout8 Å, respectively), andare short-range order(i.e.upto2-3neighboringions,or the syntheticalkalialumo-silicateglasses,show only the nanostructureofvolcanic glasses,whichlike X-ray- andspectroscopicmethodsallow aview on Perlite nanostructure Ti formation (Yanev, 1994,andreferencestherein)i.e. crystallochemical propertiesregarding theglass especially of Ti, Mn,Cs,andRb,becauseoftheir are higherthantheseinthetrachyrhyolite layers, 3-2) intheperlitelayersfromtransitionalzone, The contentsofalmostalltraceelements(Table stages (Yanev, 2000). explained byoccurrenceofimmiscibility, but intwo Mn O-O Si,Al-Si,Al presence ofFeOnanoaggregates intheglassstructure the glassstructure–17and9%,respectively. The 2 4+ O=6.62%wt, Yanev, 1970),whichalsocanbe nes theperlitecolorand,consequently, the 2+ isaglass-formingcation;Cs 2 , Zn =5.265, andtheangleis153°. The nanostructure 2+, andPb 1 = 3.15,Si,Al-O er cationisFe,asitsvalence state 2+ aremodifi 2 =4.12, Si,Al-Si,Al er cationsintheglass 1 =1.62, O-O + , Rb 2+ + andFe , aswell 3+ , mainly 1 =2.68, 2 , and 3+ in bands at3588,3233cm therein). The perlitespectrumischaracterizedby et al.,1984; Yanev andZotov, 1996,andreferences groups andtwo groupsofmolecularwater (Dimitrov Golobradovo perlitesshowed thepresenceofOH- bonded totheglassstructure.Infraredstudiesof glasses exists asmolecularwater andhydroxylgroups expanding. Itisknown (Scholze,1959)thatwater in The water presentinperlitesisthemaincausefortheir glass structure. and themainpartofFeisascationsbondedto perlites containlessblacknano-andmicrocrystals, have colloidsize–Kocik etal.,1983). The gray coloring isofcolloidtype(thecoloredcompounds is responsibleforitsbluishshade. Thus, theperlite perlite resultsfromrapidevaporation ofthelittleH 1200-1300°C, Fig.3-7).Hence,theexpansion of corresponding totheperliteexpansion (e.g.about not escapetotally, even duringheatingattemperatures groups entertheglassstructure. The OH-groupsdo the molecularwater dissociates,andadditionalOH- glass. Itissupposedthatduringdehydration,apartof only structurally-bondedOH-groupsremaininthe takes placeatabout600°C. Above thistemperature, evaporation occursat320°C,andthetotalwater loss show thatthemostsignifi The TGA-curves (Fig.3-8,Bagdassarov etal.,1999) distances O-Hofallwater speciesare0.94-0.97Å. water, 2.8 Å (icetypeH-bond)and3.1 Å. The glasses tobeabout2.9 Å, andthoseofthemolecular distance R(O...O)oftheOHgroupsinvolcanic (Yanev andZotov, 1996)theaverage hydrogenbond glass (having viscosityof10 as wellofapartOH-groupsfromthesoftened this, they canbe usedasafi groups molecularwater), and3450cm is indicative ofthereductionconditionsat T remaining (after300-350 position inthe3000-3600cm the OH-groups),respectively. The absorptionband density (144kg/m obtained fromtheGolobradovo deposit have ahigh Technical characteristics. (Bagdassarov and Dingwill,1994). color. The presenceofFe Fe contentsinperlite(1.65wt%),defi mineral phases/structuralFe(2.85),andtotalhigh of blacknano-andmicrocrystals,thehighratio e.g. duringtheperlitecooling. The highcontents 5025 cm OH-groups); andinNIR(Fig.3-7)-52605155- -1 (ofthemolecularwater) and4535cm 3 of0.2-2.5mmfraction).Despite o 2+ -1 C preheatingoftheperlite), (combinedbandsoftwo ionsintheglassstructure ller inconcrete,asa2.5- 8 Expandedperlites -10 cant molecularwater -1 interval hasrevealed 7 Pa) heatedabove T -1 ne itsblack (bandofthe 3-06-2004, 10:17:13 g point, -1 (of 2 O g

PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36 0.26 1.43 0.47 3.70 5.30 3.78 5.41 1.03 0.11 0.02 0.11 0.02 0.57 0.25 0.46 98.97 12.50 75.68 12.75 NE dome(5) trachyrhyolite SK-327 Core rhyolite Little dome (4) perlite trachy- 1.64 0.88 0.50 0.39 0.60 0.95 0.87 0.47 0.58 0.90 0.86 0.46 0.78 1.07 0.95 1.05 tot) 3 O transition zone 2 rhyolite . n.d. 0.05 0.06 0.27 n.d. 0.05 0.06 0.27 n.d. 0.01 0.01 0.03 n.d. 0.01 0.01 0.03 1.92 1.84 2.19 1.42 0.78 1.37 0.98 0.97 3.065.88 2.45 4.50 2.74 6.00 3.60 5.10 3.226.19 2.54 4.67 2.89 6.34 3.65 5.17 0.14 0.12 0.15 0.11 0.15 0.12 0.16 0.11 0.74 1.32 0.93 0.96 99.49 100.27 99.67 99.71 70.3312.89 75.30 69.75 11.37 74.47 74.18 13.13 12.24 74.0013.56 78.07 73.67 11.79 75.56 13.87 12.42 2.00tot 0.75 1.01 0.94 4.45tot 2.18 4.11 0.63 2.10tot perlite trachy- SK-796 794 793 SK-325 core periphery rhyolite Central dome (3) om the Golobradovo deposit, Studen-Kladenetz volcano deposit, Studen-Kladenetz volcano om the Golobradovo 99.56 99.48 70.1313.06 74.73 11.78 73.4613.68 76.19 12.01 perlite trachy- transition zone rhyolite 0.24 0.80 0.31 0.15 2.31 1.50 2.18 1.45 0.63 0.52 0.64 1.10 2.866.62 3.64 5.46 2.80 6.10 3.60 5.21 2.996.91 3.65 5.48 2.93 6.39 3.67 5.31 0.14 0.12 0.13 0.13 0.03 0.01 0.030.15 0.02 0.12 0.14 0.13 0.03 0.01 0.03 0.02 1.15 0.76 1.23 1.03 0.23 0.80 0.30 0.15 3.60 0.07 3.64 0.84 1.20 0.76 1.29 1.05 0.60 0.52 0.61 1.08 0.40 0.26 0.45 0.55 0.52 0.72 1.13 0.37 0.50 0.72 1.08 0.36 Perlite sill (2) G-73 769 768 SK-337 periphery and FeO) and R-ray ﬂ uorescence (analyses with total Fe as Fe and FeO) and R-ray ﬂ 3 O 2 . n.d. n.d. n.d. n.d. 1.67 0.75 3.40 5.69 3.55 5.94 0.14 0.15 0.72 1.74tot 1165 perlite perlite trachy- . n.d. n.d. 0.32 1.66 1.19 3.09 5.12 3.29 5.46 0.11 0.12 0.30 1.12 5.18 4.2tot 1.20 69.0313.30 71.07 13.04 70.14 74.70 13.49 12.88 73.5814.18 74.25 13.62 73.24 75.01 14.09 12.93 100.20 99.93 99.76 99.94 1.75tot 1.67tot 1.86tot Volume n° 4 - from P14 to P36 n° 4 - from Volume perlite dome (1) Odjak-kaya C) average o C) o o O 2 (1050 3 3 3 3 (105 - + 2 2 5 5 2 2 O O O O O O 2 2 O O O O O/Na 2 2 2 2 O O 2 2 2 2 2 2 2 Water fry base Water SiO Total H FeO MgO CaO Volcanic body Volcanic Na K P K P Fe TiO Fe TiO SiO FeO Al H Al K MgO CaO Na Rock variety Position in the dome periphery periphery Analysis n Table 3.1- Major elements content (%wt) in the trachyrhyolites and perlites fr 3.1- Major elements content (%wt) in the trachyrhyolites Table Note: wet chemistry analyses (analyses with Fe

21 - P36

P36_R_OK 21 3-06-2004, 10:17:15 P36_R_OK 22

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas perlites withalower density-102 kg/m example, ofthe Svetoslav deposit)gives expanded et al.,1989).For comparison,theperlitebreccia(for MPa anddensity of490kg/m 5.0 mmfractionhasahighcompressive strength:16.8 (1996) andafterexpandingat1300 (sample G73)before (top,accordingto Yanev andZotov Figure 3.7-Nearinfra-redspectraofGolobradovo perlite according toDormannetal.(1989). (sample G73)atthreedifferent temperatures(in°K) Figure 3.6-MössbauerspectraofGolobradovo perlite From Stop3,wegobackbythesameroadto 27.0 MPa and470 kg/m 3 at60secexpanding (Popov 3 at30secexpanding, or o C (bottom). 3 . the 1stacidphase,inwhichStop4islocated. Both slopesarecrowned byzeolitized pyroclastics of outcropped alongthevalley ofthePerperekRiver. travel totheNEinPriabonian fl Chifl Hf, Co, V, Ta -NNA; Nb-colorimetry Ti, Mn–R-ray fl uorescence; REE,Cs, Th, U, Sc, Li, Pb,Zn,Cu,Ni-atomicabsorbtion;Rb,Sr, Ba,Zr, trachyrhyolite (Golobradovo deposit) Table 3.2-Trace elementcontents(inppm)ofperliteand b1. 18.2 4.2 0.5 18.4 0.7 5.8 5.2 0.5 3.4 0.7 9.8 6.3 49.5 4.1 Nb 0.70 11.5 Ta 4.8 62.2 V 1.03 0.85 Co 0.30 Hf 5.8 7.7 1.22 Sc 131 0.30 U 64.0 Th 8.4 19 11 155 Lu 70.8 Yb 25 35 Tb 32 Eu 8 181 34 Sm 714 38 Ce 201 La 507 >70 845 Ni 32 234 Cu 74 Zn 7.75 107 49 Pb 3.66 29.25 Mn Ti 235 2.65 Zr Ba trachyrhyolite Sr Cs perlite Rb Li Rock variety Analyses n ik village(Fig.B),fromwherewecontinueto o 9 794 793 yc deposits ysch 3-06-2004, 10:17:17 PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Stop 4: identifi ed. A huge oval hall, apparently left roofl ess, (facultative) – Thrace holly HILL (from 18th was discovered in the palace. At the center of this century B.P. to 14th century A.D.): Castle and open space, a magnifi cent round altar was sculpted sanctuary, cut in the zeolitized pyroclastics. from the rock (2 m in diameter, and rising 3 m above Byzantine castle “PERPERICON” the fl oor level). At least two oracles of momentous signifi cance for human history can be connected with Geological remarks (author Y. Yanev). this altar. When Octavian, father of Augustus, came The holy hill, which represents an archeological site, is upon the Holy Mount of Dionysus, he consulted the built up by low-to medium-grade fi ne-grained pumice oracle about his son, and the Thracian prophets said ignimbrites, deposited from the pyroclastic fl ows of to him that his son was to rule the world, for, as the the 1st acid phase. The supposed vent area of these wine was spilt onto the altar, the smoke rose up above volcanics (Yanev and Bardintzeff, 1996), is located the top of the shrine and even into the heavens, as about 15 km to the west of Stop 4, in the region of had happened when Alexander the Great himself had the village of Kostino (Fig. B). The pyroclastics are sacrifi ced upon that same altar. Wine and fi re were zeolitized, and are perfect building stone, having been used to deliver the prophecy: wine was spilt onto the completely preserved for as long as 25 centuries. altar and the height of its fl ame signifi ed the prophetic The enormous zeolite deposits of Gorna-Krepost and Most are located in front of the hill on the NE slope of the river, where the same pyroclastics are also zeolitized. The average mineral composition (calculated on the basis of 101 and 120 samples of both deposits) is: 84% and 78% clinoptilolite, 4.5% and 5.3% montmorillonite, 1.4% and 2.5% celadonite and illite (giving the pale green color of the rocks), 1.9% and 2.5% opal-CT, 0.2% and 0.6% calcite, 7.5% and 6.4% cristallo- and lithoclasts; C.E.C (measured in 5 samples) is 100-133 and 80-128 meq/100g, for Gorna-Krepost (Raynov et al., 1997). The thickness of the zeolitized pyroclastics there reaches 110 m.

Historical remarks (according to web-site www.perperikon.bg). The earliest traces of human civilization discovered so far at Perperikon were dated to the late Neolithic Period, 6th-5th millennium BC, but the earliest pits hewn in the rock were dated to the Figure 3.8 - Results of TGA (1, in wt%), DTG (2, in late 5th - early 4th millennium BC. During the late 0,1mg/min) and DSC (3, in mW) of Golobradovo perlite Bronze Age, in particular, 18th-12th century BC, and (sample G73) obtained in a thermal gravitational later during the early Iron Age (11th-6th century BC), balance with heating rate of 5 K/min (according to Bagdassarov et al., 1999). Perperikon saw its ﬁ rst heydays as a Trachian cult center, as the ﬁ rst period probably coincided with the answer. A throne hall, 30 m long, with massive throne peak of the Mycenaean and Minoan civilizations. At carved out in the tuffs, and a sewer system draining that time, a citadel (Acropolis) was built, whose stone the rainwater into two large cisterns (12/5/6 m), have walls are 2.8 m thick and which surround numerous

also been found in the palace. Many basins on two P14 to P36 n° 4 - from Volume temples and civil buildings with monumental portals levels, carved in the rocks, are found around the hill, (the ground ﬂ oors are entirely carved in the rocks). probably used as winepresses (“sharapani”). A giant palace, being also a temple of Dionysus (it is known that Thracian rulers possessed both This cult center was revived and enhanced after secular and religious authority), enclosed by 2.5-2.6 Thrace was conquered by the Romans (in 45 AD). m thick stone walls, is attached to the citadel. 50 During the 4th century, Perperikon was captured and chambers, having an area of 17 000 m2, built on seven burned by the Goths, but in the 5th century, the city levels, across a gradient of approximately 30 m, are became a center of Christianity. Later, the main city

23 - P36

P36_R_OK 23 3-06-2004, 10:17:22 P36_R_OK 24

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas the daybefore. depression andtheroutebacktoSofi of Haskovo, whereweentertheNeogene Thracian sediments outcropalongtheroaduptotown meq/100g (Raynov etal.,1997). The Priabonian CEC (measuredin5samples)vary from90to150 CT, 0.6%calcite,10.5%crystallo-andlithoclasts; monmorillonite, 2.9%illiteandceladonite,1%opal- the zeolitizedpyroclastics is:80%clinoptilolite,6.2% composition (calculatedonthebaseof56samples) (Beli-Plast deposit)isnearhere. The average mineral for obtaining70mthickzeolitizedfall-out tuffs coarse-grained baseofapyroclastic fl 2nd phase(theupperpartofthe“mushrooms”is are formedwithinthezeolitizedpyroclastics ofthe the road,several-meters highrock“mushrooms” the ridgetonorthofPerperekRiver, along these areBeli-Plast,Gorna-KrepostandMost. At large zeolitedepositslocated. Fromnorthtosouth, of the1stacidphaseareexposed, andwherethree NW-SE trendinggraben,wherezeolitized pyroclastics Priabonian volcano. Itscentralpartsarecrossedbya interbedded bylatiteseruptedonestrongly-eroded sediments, whichatthevillageofStremtsiarecutand After Stop4,ourroutecrossesthesamePriabonian Christian. century, thesettlementsnearPerperikon remained was conqueredbyOttoman Turks, but uptothe17th – Perperek. At theendof14thcentury, thetown of thecitadel(“Perperikon”) andofthenearbyriver “perpera”, andthatmightbethesourceofnames Priabonian sediments).Laterthecoinwas named mine, locatedjustfew kmaway (withinthesilicifi and refi is thoughtthatthenameconnectedtomelting I Comnenusin1082 AD, andcalled“hyperpyron” (it 1/3 carats,struckbytheByzantineEmperor Alexius It issupposedthatthegoldusedforcoinsof21 signifi found inoneofthegrave chambers). The town had wood, believed tobefragmentsofthe True Cross,was (a cruciformpendantreliquary, containingpiecesof center, withlarge monasterycomplex andnecropolis regional governor of Achridos andalsoasepiscopal at thefootofPerperikon, whichwas theseatof of theByzantineprovince of Achridos was located Milos hasbeenawell-known island sinceancient General Information SECOND PART: MilosIsland cant importanceduringthe11th-14thcenturies. ning ofgoldbyfi re) camefromthegold a isthesameas ow). The quarry ed 4 “ The fi the museumofLouvre,inParis. statue of“Venus” was foundandthentransferredto island becamemorefamous after1820,whenthe its namecomesfromtheancienthero“Milos”. The times, duetoitslocationandhistory. Mostprobably a lotoffi In Plakathereisalsoanarchaeologicalmuseumwith of “Thalassítra”,whichwas built inthe13thcentury. “Korphiatissa”. Insidethecastle,thereischurch manage the30-minuteclimb,andvisitchurchof hill, whileabeautifulview isavailable forthosewho The ruinsofaFrankishcastlearevisibleontopthe fl “Plaka”, theoldcapitalofMilosisbuilt onarather mineralogical collection. quarry activities ontheislandandexhibiting arich in Adamas, giving importantinformationaboutthe Mining andGeologicalInterestisalsoinoperation old hand-carved wooden temples. The Museumof with remarkablepost-Byzantineiconsandvery the ruinsofancienttown ofFlakopí arelocated. built onthenortheasternpartofisland,nearwhich “Pollonia”, apicturesqueformerfi Christian era. catacombs thatdatebacktothebeginning ofthe Nearby, thereisthevillage“Tripití”, withthefamous the Romanwalls, thetheatreandbaptistery. Roman mosaics(nearaplacecalled“Tramithia”), Near thetown, thevisitorcanseewonderful the greatestinterest. minerals, photographs,andhistoricaldocumentsof collection offolkartifacts, samplesoftheisland’s periods ofMílos. The Folklore Museumhasa After Philakopi declined,theDoriantown of“ exporting mainlytoolsandweaponsmadeofobsidian. established awell-developed commercialactivity, Aghia Triada(13 interesting sightsofthetown arethechurchesof The capitalandportofMilosis“Adamas”. The most island today. Venetians, Turks, andeven pirates,areevident inthe the RomanandByzantinetimes. Traces ofFranks, Spartan domination,andenduredthetribulations of War (431-404B.C.),was laterrebuilt underthe bay. Itwas destroyed duringthePeloponnesian was founded.KlimaislocatedatthemouthofMilos at lava fl Philakopi th milleniumtill800B.C..Milosatthattimehad rst known settlementoftheislandwas nds fromvarious historicandprehistoric ow. Itsarchitectureistypically Cycladic. ”, whichthrived intheperiodfrom th century)and Aghios Charalambos, shing village,is 21-06-2004, 10:04:45 Klima ” PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Regional Geologic Setting Milos was affected by an extensive volcanism, Author: M. Fytikas (Aristotle University of which was more or less continuously active. Phreatic Thessaloniki, School of Geology) explosions took place until recent and historic times (Angelier et al., 1977; Fytikas et al., 1984; Fytikas et Introduction al., 1986; Traineau & Dalabakis, 1989). The volcanic island of Milos is situated in the SW The volcanic succession of Milos overlies the part of the Cyclades Islands group, and is a relatively Mesozoic metamorphic rocks and the Neogene small but signifi cant portion in the central part of the limestones (Fig. 3). It comprises a thick (up to South Aegean Active Volcanic Arc (SAAVA). 700m) (Fytikas & Marinelli, 1976) compositionally The SAAVA extends from the Greek mainland in and texturally diverse Upper Pliocene-Pleistocene the west, through the islands of the Dodecanese in succession of calc-alkaline volcanic rocks, that the east (Fig. 1). It was formed during the Pliocene- record a transition from a relatively shallow, but Quaternary, as a consequence of the northward dominantly below-wave-base submarine setting, to subduction of the African Plate beneath the Aegean a subaerial one. The felsic-intermediate volcanic microplate, and is still active (Fytikas, 1977; Fytikas succession comprises syn-volcanic intrusions, lava et al., 1986; Markopoulos & Katerinopoulos, 1986). domes and volcanoclastic rocks, which host several The Arc is no more than 20km wide, and its outer signifi cant epithermal gold deposits. The growth part extends from Crommyonia, through Methana, and development of submarine felsic volcanoes Aegina, Poros, Milos, Santorini, to Nisyros and are diffi cult to observe, while records of phreatic western Kos (Fytikas et al., 1984). eruptions are extremely restricted. Volcanism occurred concurrently along the arc The most recent attempts to describe the volcanic (Fytikas et al., 1976; Innocenti et al., 1979; Fytikas et succession on Milos were those of Fytikas & al., 1984), beginning at the end of the Early Pliocene Marinelli, 1976; Angelier et al., 1977; Fytikas, 1977; (4,5 Ma), and continuing up to today (McKenzie, Fytikas et al., 1984; Fytikas, 1979. 1978; Mercier 1989; Pe-Piper et al, 1983; Fytikas et The following formations have been distinguished: al., 1984). a) Volcano-sedimentary rocks, consisting of Milos is almost totally built up of volcanic rocks. pyroclastic material, pumice fl ows, tuffs, and tuffi tes. Outcrops of the pre-volcanic units are observed in the It is a thick (>120m) succession of felsic, pumice- southern part of the island, and consist of a crystalline rich, submarine units (Angelier et al., 1977; Fytikas basement and of a neogene sedimentary formation et al., 1986), which represent the earliest volcanic (Fig. 2). activity (Middle-Late Pliocene). The metamorphic basement of Alpine age belongs b) Domes and lava fl ows. The effusion of lavas, the to the South Cyclades Unit, and consists of re- composition of which is rhyolitic to andesitic, was crystallized metasediments, such as clay stones, accompanied by the ejection of pyroclastic material, sandstones and limestones, mainly under greenschist and the emission of glowing avalanches (Late facies conditions (Durr et al., 1978). Blue-schist facies Pliocene-Early Pleistocene). also were identifi ed. Fragments of metamorphic rocks c) Lavas from the recent volcanic activity. Their occur often as xenoliths in phreatic eruption, and composition is rhyolitic to rhyodacitic. They are the more rarely in pyroclastic products. products of a mainly eruptive activity, which resulted in the deposition of successive layers of lava, pumice, Geological Evolution and cinders. During the subduction in the Tertiary, Milos Island d) “Green lahar”. A strange, chaotic formation, was submerged. This procedure lasted until the Early consisting of angular fragments of metamorphic Volume n° 4 - from P14 to P36 n° 4 - from Volume Oligocene. The intense erosion of the metamorphic rocks and, more rarely, volcanic pebbles. The fi ne basement resulted in the formation of a plane surface, bonding material is usually of volcanic origin. In a creating a part of the Aegean continental shelf during few cases, though, it is the product of the alteration of the Oligocene and Miocene. the metamorphic rocks. The limited thickness of the Neogene sequence e) Rhyolitic products of a tuff ring in fall and surge (Upper Miocene-Lower Pliocene), and the absence deposits, together with important lava fl ows of the of clastic material, indicate an uplift of the area for same composition, are the younger deposits (90 ka). extended periods (Fytikas, 1977; Markopoulos & f) Tuffi tes, which indicate the end of the volcanic Katerinopoulos, 1986). activity. During the Middle and Late Pliocene, the area of 25 - P36

P36_R_OK 25 21-06-2004, 10:04:47 P36_R_OK 26

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas ranging from5%to11%;theNa invariably greater than1%,withnormative anorthite b. High-Carhyolites by biotite. minerals; femicmineralsareessentiallyrepresented quartz-sanidine sequenceofcrystallizationsialic petrographical observations suggestaplagioclase- around 2-3%,andtheNa lower than1%,thuswithnormative anorthiteof a. Low-Ca rhyolites distinguished: particularly signifi rocks (rhyolitesmorerecentthan1Ma),seems The variability inthechemistryofmoreevolved strongly corrodedquartzaresporadicallyobserved. occasionally rimsofclinopyroxene; biotiteand hornblende appearswidelyspreadandthereare plagioclase, orthopyroxene, andclinopyroxene; dacitic rocks,thephenocrystsarecharacterizedby the samephasesformingphenocrysts.In contains avariable amountofglass,togetherwith are sporadicallypresent. The groundmassalways microphenocrysts. Unstableolivin andhornblende clinopyroxene, orthopyroxene, andmagnetite represented byzonedplagioclase,generallyaugitic the lessevolved rocks,phenocrystalsaretypically some rhyoliticmembersarecompletelyglassy. In Nearly allthevolcanic productsareporphyritic;only completely absentandbasalticandesitesarerare. rocks areandesites,dacites,andrhyolites;basalts Milos belongtothecalc-alkalineassociation.Most As mentionedabove, thevolcanic formationson the volcanic rocks Petrology andChemistryof evolved tosubaerialones,covering a timespan Milos islandwithsubmarineeruptions,whichlater The volcanic activity began inthewesternpartof Conclusions on Volcanology magma chamber, whichfedthevolcanic activity. suggests thelackofany majorzonation,withinthe as regards boththemajorandtraceelements. This homogeneity withineachindividual eruptive system, systems. Systematicsamplingshowed reasonable is observed intheHalepaandFyriplakaeruptive is typicalofthe Trachilas complex, whereasthesecond The fi older products. minerals arebiotiteandamphibole,presentonlyin and quartz,sanidinebeingtypicallyabsent;femic sialic phenocrystsarerepresentedbyplagioclase rst ofthetwo distinctgroups(low-Ca rhyolites), cant. Two maingroupscanbe , showing CaOcontentsusually : theserocksshow CaOcontents 2 O/K 2 O ratio<1;the 2 O/K 2 O ratio>1; interaction processeswiththecrustrocks. and ofshortlife,thereforeavoiding consistent of modestvolume, andbeingrelatively shallow seems toberelatedmultiplefeedingsystems,each the crustrocks. The as allowing forimportantprocessesof assimilation of relatively longperiod(about1,5millionyears)aswell been relatively large, permittingitsexistence fora stability. The volume ofthisdeepchambermusthave boundary, basicallyoutside the rangeofplagioclase in adeeppartofthecrustoratcrust-mantle fi phase rst and younger(Pleistocene)phasesofactivity. The suggest different trendsfortheolder(Pliocene) In conclusion,allthecollectedandanalyzeddata subordinated. plagioclase, inwhichcontaminationwas decidedly due tothefractionalcrystallizationdominatedby members iscompatiblewithprocesses,mainly and isotopicaldata,theoriginofmoreevolved According tothepetrographical,geochemical, decreased involume. of activity (LatePleistocene),andprogressively then becameexclusively rhyoliticduringalaterphase evolved products. The compositionofthevolcanics magma, startingwiththeemplacementofmore (Early Pleistocene)was fedbyanew inputofdeep part oftheisland. The subsequent cycle ofactivity surface toformdomesandpyroclastics inthewestern of magmaoriginatedseparately, eachrising tothe relatively deepinthecrust,fromwhichsmallmasses been interpretedasevidence forafeedingsystem, by theplagioclaseinfractionationprocess,have of practicallycoeval eruptions,theminorroleplayed central volcanic structures, thedifferent composition and fractionalcrystallization. The absenceoflarge originated fromacomplex processofcontamination ratios available, suggestthatthisrockassociation and traceelementvariations, togetherwiththeisotopic characterize thePliocenevolcanic cycles. The major with acleardominanceoftheintermediatemembers, Products rangingfrombasicandesitestorhyolites, 0,1 millionyearsbeforepresent(Fyriplaka Volcano). tensional tectonics. The latestvolcanism isdatedat in thecentralpartofMilos.Itwas affected bystrong volcanic activity reduced,andbecameconcentrated subaerial orsubmarinedomes(1,8-1,0Ma). Then, the deposited jointlywiththeextrusion ofsubordinate island, wheresubmarinepyroclastic productswere igneous activity moved tothenortheasternpartof from 3,5to2,0m.y. beforepresent.Subsequently, isrelatedtoamainfeedingsystemset younger phase , ontheotherhand, 3-06-2004, 10:17:27 PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Figure 1 - Geodynamic situation of Greece and the location of Milos Island on the Aegean volcanic arc (Papazachos, Papazachou, 2001) This different evolution of the feeding system in the new geotectonic situation, the area was also inﬂ uenced two main phases of volcanic activity on Milos is by further intense tectonic activity during the Pliocene interpreted as a consequence of consistent variations and Quaternary. Milos presents an interesting seismic in the stress ﬁ eld affecting the crust. In fact, during activity, which indicates the neotectonic and active Late Pliocene times, this sector of the Arc was character of the tectonic structures. The study of the Volume n° 4 - from P14 to P36 n° 4 - from Volume affected by a relatively weak tensional tectonic tectonic situation of the island has substantially helped regime, as observed in the Aegean area, where a towards a better understanding of the volcanological compressional episode has been described at the situation, the stratigraphy, and the recent and active Pliocene-Pleistocene boundary (Mercier, 1981). thermal conditions. The ascension of magma is attributed to a strong Tectonic-Neotectonic activity tensional tectonic regime. The effects of such tectonics The tectonic structures in the area of Milos were have been mapped by Fytikas on a scale of 1:25.000 mainly affected by the Alpine orogenesis. Due to the (IGME, Geological Map of Milos Island, 1977). A

27 - P36

P36_R_OK 27 3-06-2004, 10:17:29 P36_R_OK 28

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas island (Fig.4). volcanism, structuresandgeothermalsituationofthe major Plioceneepisodes,thusinfl the olderNW-SE faults, whichcorrespondtothe the ENE-WSWdirection,andareintersectedby which aremorecommonineasternMilos,follow circulation ofthermalfl to thefacilitation ofbothvolcanic activity andthe neotectonic evolution ofthearea,andconsequently The lastphaseplayasignifi general NW-SE direction 3. Quaternary:intense 2. Post-Pliocene: SW direction. 1. Pliocene: can bedistinguished: by Simeakis(1985),threephasesoftectonicactivity According tothedetailedneotectonicstudyofMilos that thetectonismisstillactive today. historic andconstructionsundertheseashow The frequentearthquakes andthesinkingofpre- observed bothinthefi dense gridoffaults, grabens,andhorstscanbeeasily boreholes aremarked (Fytikas,1977;1989). Rhyolitic complexes (UpperPleistocene),(9)Productsofphreaticactivity, (10) Alluvium. Thelocationsofthedeep Pliocene), (4)Complexdomesandlavaflows, (5)Pyroclasticseries(lower Pleistocene).(6),(7)Lava domes.(8) Transgressive marinesediments(UpperMiocene-Lower Pliocene),(3)Basalpyroclasticseries(Middle-Upper Figure 2-Simplifiedgeologicalmapoftheisland:(1)Metamorphicbasement(Middle-UpperPleiocene),(2) distensional compressional eld andinaerialphotographs. uids. The mostrecentfaults, extensional tectonics tectonicswithageneralNE- phase uencing greatly the cant roleinthe witha large shallow magmachambers(Fytikasetal.,1986). rate ofthedeepmagma,prevented theformationof eruptive ratethat,beingcomparablewiththefeeding petrogenetic history, istoberegarded astheresultofa magmas, above allhomogeneous,andwith adistinct activity, characterizedbysmallvolumes ofevolved rise toshallow levels. The Pleistocenevolcanic more intenselyactive, allowing deepmagmasto From thePleistocene,tensionaltectonicsbecame acted asafi at depth(probablythebottomofcrust),which accumulation andstagnationofcalc-alkalinemelts The mildextensional regime favored the formation ofshallow magmachambers. The activity the development ofwhichisattributed tothe phase tectonismandthegreatgeothermalanomalies, is relatively recent,andisconnectedtoPleistocene part ofMilos. The ageofthehydrothermalactivity phreatic explosions, etc),areevident inthebiggest (fossil andactive thermalmanifestations,cratersof The resultsofthewidespreadhydrothermal activity Hydrothermal activity lter systeminsuchageodynamic context. 3-06-2004, 10:17:32 PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Figure 3 - Schematic geological profile across Milos island (Fytikas et al., 1989). has let to the creation of several mineral deposits, both Geothermal situation by transformation and deposition. Extensive geothermal exploration has been carried The most important effect of this, is the transformation out in Milos since 1971 until today. It was started by of the volcanics into clay minerals. Depending on the Institute of Geological and Mineral Exploration local conditions, we have “bentonization” in the (IGME), and the Public Power Corporation (PPC) deeper hot environment, and “kaolinization” in the during the years 1971-1976. shallower ones (Fytikas & Marinelli, 1976). This exploration program included 60 shallow (40- The temperature of the hydrothermal phases formation 80m) slim thermometric wells, all around Milos, from was initially around 100°C. As the permeability of the which the mean geothermal gradient was defi ned surface volcanites was reduced by “self-sealing”, (Fytikas, 1977; Fytikas, 1989). The observed gradient due to the thermal transformations, a progressive is high everywhere, but particularly in some areas of uplift of the isotherms took place. Thus, the presence the central and eastern parts of the island, and its mean of a good “cover”, and hot hydrothermal fl uids at values are greater than 8°C/10m, in other words 24 or shallow depths, resulted in the occurrence of phreatic more times higher than the world average. explosions. By making simple considerations, the From the iso-gradient map (Fig. 5) that was produced, temperature necessary for such explosions for the two main geothermal areas were distinguished: the craters north of Zephyria has been estimated to be Zephyria plane and the Adamas area, while some 325°C. This estimation was later verifi ed by the minor anomalies were observed in the western measurements in 5 production wells in the same area. part of Milos. Southwards of Zephyria, where On the island several but small thermal manifestations there are outcrops of the crystalline basement and P14 to P36 n° 4 - from Volume can be observed: fumaroles, hot springs, hot grounds, superfi cial thermal manifestations, a strong anomaly submarine gas escapes. They are mainly located in the is expected. central and eastern part of Milos, and occasionally on In the framework of this program, two deep the sea bottom. The maximum measured temperature exploration-production wells were drilled: MZ-1 in of the fumaroles is 101°C, of the hot grounds, 100°C the Zephyria area (max. depth 1101m), and MA-1 (30cm below surface), and of the hot springs, 76°C. in the Adamas area (1163m). Both wells produced a mixture of steam and liquid, proving the existence of

29 - P36

P36_R_OK 29 3-06-2004, 10:17:37 P36_R_OK 30

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas 150m) low enthalpy (80-100 in Milos,whichwillexploit thevery shallow (80- Recently, anew geothermalprojecthasbeenstarted the desalinationofseawater. to theenvironmental noise(mainlyanH problems, but mainly becauseofthelocalopposition was terminatedin1986,duetoseveral operational geothermal power plant(2MW)inZephyria,which In 1985,PPCstartedtheoperationofapilot 1200m. maximum temperatureof318°Catadepth1150- values ofmorethan1700KJ/kgr, thusrevealing a during theproductiontestsonMILOS-2in1984gave b, 1982). The resultsoftheenthalpy measurements et al.,1982; Vrouzi, 1985;ENELandPPC,1981a, MILOS-2 (1381m),andMILOS-3(1017m)(Cataldi drilled intheZephyriaplain:MILOS-1(1180m), During theyears1980-1982,threenew wellswere 1095m inMA-1(Fytikasetal.,1976). at adepthof932minMZ-1,and250°C a geothermalreservoir withatemperatureof310°C as 60 can beeasilylostbyheatingattemperaturesaslow sheet ofwater betweenthe1:1layerunits,which octahedral one).Halloysite containsanadditional (i.e. consistingofatetrahedrallayerfollowing an are hydrous Al-silicates, with1:1layerstructure deposits iskaolinateand/orhalloysite. Bothminerals The mainmineralphasepresentinthekaolin Kaolin deposits (Fig. 6). related asfar astheirmodeofformationisconcerned the alterationoforiginalvolcanic rocks,arenot main typesofindustrialmineraldepositsformedby solfataras. However, bentonitesandkaolins,thetwo present todayintheformofthermalsprings,mainly the volcanic andhydrothermalactivity, whichisstill rocks intheislandofMilosiscloselyassociatedwith The formationofdepositsindustrialmineralsand of Milos Industrial MineralsandRocks Ti- andFe-oxides,micas,feldspars,smectites, and the formationofdeposits. They usually include rock andthegeologicalprocessesprevailing during materials, anddependsonthetypeofparent deposits affects thephysical propertiesoftheraw The presenceofothermineralphasesinthekaolin of Milos. Both kaoliniteandhalloysite arepresentinthekaolins o C (conversion totheanhydrous7A-halloysite). o C) geothermalfl 2 S smell). uids for kaolinite, isvery diffi CT, thegrainsizeofwhichisvery similartothatof as aluniteisconcerned,but theseparationofOpal- The gradeofthepoordepositscanbeimproved asfar silica sulphatecontentsdonotcausebigproblems. is themanufacture ofwhitecement,wherethehigh industries. The majorapplicationoftheMiloankaolin fi content, rendersthemunsuitableforcoatingsand Milos, mainlyduetotheiropalinesilicaandalunite The relatively poorqualityofthekaolindeposits smaller than1µ.). ± haliteFe-oxides.Kaoliniteisfi associated withquartz,christobalite±alunitebarite The mainphaseiskaoliniteand/orhalloysite, (faults, tectoniccontacts). or lenses,andarecontrolledbystructuralcriteria acid conditions(Ph=4-5). The depositsformpockets hydrothermal alterationofvolcanoclastic rocksunder primary kaolin,andhave beenformedinsitubythe The kaolindepositsofMilosbelongtothecategory of be easilyconverted tosulphuricacidonfi applications, becauseSO Milos deposits,causefurtherproblemsinceramic Sulphates like alunite,whicharevery commoninthe paper industry. cause rheologicalproblemsintheapplications characteristics ofthematerials,whilesmectites fi especially thoseconcerningtheirapplicationsas deteriorate thephysicalpropertiesofdeposits, various polymorphsofsilica;andsulphates,which Like thekaolindeposits,bentonitescontainavariety these raw materials arebasedonthem. properties ofthebentonites,andmany applicationsof exchange capacity andswellingarevery important causing swellingofthesmectitelayers.Cation capacity. The exchangeable cationsarehydrated, exchangeable, imparting thecationexchange by theso-calledinterlayercations. The latterare lead toacharge defi tetrahedral andoctahedralsheets. These substitutions are characterizedbycationsubstitutionsinboththe However, unlike talcandpyrophyllite, smectites smectites) andtalc(trioctahedralsmectites). with structuressimilartopyrophyllite (dioctahedral sheet “sandwiched”betweentwo tetrahedralsheets), phase. Smectitesare2:1layersilicates(anoctahedral Bentonites containsmectiteasthemajormineral Bentonite deposits llers. Onlysmallquantitiesareconsumedbythese llers. The coarse-grainedphasesaffect theabrasion cult. cit, whichiscounterbalanced 3 -2 isreleased. The lattercan ne-grained (fl ne-grained ring. 3-06-2004, 10:17:39 akes PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

of clay and non-clay minerals, the presence of Miloan bentonites are predominantly Ca, Mg-rich. which depends on the type of the parent rock and Na-activation is applied to improve their performance geological processes which prevailed during their in their various different industrial applications. formation. The most common accessory minerals The bentonite deposits of eastern Milos are more are feldspars (both K-feldspar and plagioclase), or less stratiformed, i.e. they are controlled mainly zeolites, various forms of silica polymorphs (with by stratigraphic and tectonic criteria. The presence the most common representative phase being opal- of authigenic K-feldspar in the dissolution of CT), kaolinite and/or halloysite, mixed layered clay cavity-fi llings, and/or pore linings in several minerals, (most commonly, illite/smectite and less deposits, indicates that sometimes the alteration of commonly, chlorite/smectite), and various sulphates the parent volcanoclastic rocks took place at very and sulphides. low temperatures. Furthermore, the hypothesis for The bentonites of Milos consist principally of the hydrothermal genesis of the deposits (mainly smectite (smectite contents of up to 95%). They pyroclastics, but also lavas in origin) is the most contain authigenic and pyrogenetic K-feldspars, probable, at higher temperatures (150-180oC) and pyrogenetic plagioclase, opal-CT, zeolites, sulphates under alkaline pH conditions. On the contrary, it is (gypsum, alunite, jarosite, barite), sulphides possible that some of the Miloan bentonites were (pyrite and/or marcasite), Fe-oxides and Ti-oxides formed by the devitrifi cation of volcanic glass in a (mainly brookite). Smectites have a very variable marine environment at low temperatures. Several composition, which is determined to some extent by deposits contain opaline-silica beds, which are not the composition of the parent rocks; Beidellite and associated with hydrothermal activity, but are by- montmorilonite are present. Cheto and Wyoming products of the devitrifi cation of volcanic glass. Small type montmorillonites are present in the Miloan bodies of non vitrifi ed or partly vitrifi ed galls are also bentonites but they do not co-exist. Also, beidellites present. do not co-exist with Wyoming montmorillonites. The Almost all bentonite deposits have been affected by Volume n° 4 - from P14 to P36 n° 4 - from Volume

Figure 4 - Map showing the thermal gradient contours (dashed lines) along with the main visible faults (thin solid lines). The thick solid lines represent the faults obtained by the interpretation of the terraced gravity data (Tsokas,1996).

31 - P36

P36_R_OK 31 3-06-2004, 10:17:40 P36_R_OK 32

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas glyceride oils. shown thatthey cansuccessfullydecolorizeedible opal-CT. Detailedacidactivation experiments have brightness isnotlow (75-85%),they containabundant their qualityisratherpoor, becausealthoughtheir are presentineasternMilostheareaofKomia, but applications, asanimallitters,etc. White bentonites in iron-orepelletization,civil engineering drilling industry, asabindingagent in thegreensands, The Miloanbentonitescanbeusedsuccessfullyinthe May andOctober. The active periodofbentoniteextraction isbetween sodium carbonate,andfi under atmosphericconditions,thenactivated by tonnes peryear. The raw materialisdriedinfl Mining Co.”, withaproductionofmorethan850.000 operating company inMilosis“Silver andBariteOre order ofseveral tensofmillionstonnes. The major exact reserves arenotknown, but they areofthe great producerofsuchhydrothermalproducts. The Greece, duemainlytotheMinoanbentonite,isa and sulfa-tones. “Ankeria”, intheformofsulfurousthermalsprings alteration isstillvisibletodayinthedepositsof hydrothermal activity. The infl Figure 5-ContoursofthegeothermalgradientonMilosisland(oC/10m)(Fytikas,1977). nally byair-heating burners. uence ofhydrothermal at areas specifi at approximately2,5milliontonnesofbarites,witha tonnes/year. The actualreserves have beenestimated Today, barite extraction hasdroppedto30.000-50.000 the benefi exploration began in1934andwas associatedwith Milos, intheformofveins fi Barite depositsarepresentprincipallyineastern Barite deposits beautiful volcano-sedimentary formation.Onthe in MilosIsland(Vani-marine deposits), ina Barite withmanganesearealsointerestingdeposits product ofthehydrothermalalteration-reaction. associated entirelywiththeSideposition,but arethe silicifi silicifi The illitisationreactionreleasesSi,whichcauses formation ofK-bentonitetakes place(sub-bentonite). way, thequalityofbentonitesdeterioratesand and subsequentillitizationofthebentonite.Inthis barite isprobablyassociatedwithK-metasomatism probably inthe Tsantili deposit),theemplacementof of bentonites.Inseveral locations(e.g. Agrilies and that theirformationmightpostdatethe their specialrelationshipwithbentonites,indicate The geologicalcharacteristicsofbaritedeposits,and ed rocksobserved inMilosarenotnecessarily cation tothesurrounding rocks. Therefore, the c gravity of3,5gr/cm ciation ofsilver asaby-product(baritine). 3 . lig als Their faults. lling 3-06-2004, 10:17:45 PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

north-west part of Milos island, in the area of Cape hydroheteroaerolite), took place. The oxides of the Vani, a manganese and barite mineralization is second stage are characterized by the presence of Ba, present. The “occurrence” lies in a series of Upper Pb, K, Zn, and As. Pliocene volcanoclastic materials with marine fossils The third stage is defi ned by the formation of (Argyropoulos 1966, Schmidt 1966, and Fytikas quartz + barite ± sulphide veins and carbonates + 1977), and it is divided into two phases. quartz ± sulphides. The geochemical analysis of the The fi rst phase contains ramsdellite and pyrolusite, metalleogenic third phase, indicates that carbonates while the second phase contains coronadite- were placed in these veins at a temperature of 180oC, cryptomelane-hollandite and hydrohetaerolite. and that their formation required the mixing of the The main mineral phases are as previously cited. The mineralized fl uids with seawater. accessory mineral phases are: arsenosiderite, barite, Generally, the formation of the manganese and barite galena, pyrite, and sphalerite. took place rapidly through the hydrothermal activity According to Liakopoulos (1987), the three main in the area of Cape Vani, probably after the submarine stages of Mn-minerals genesis can be distinguished: formation of the volcano-sedimentary sequence. The During the fi rst stage, Mn-solutions are discharged hot fl uids penetrated to the previous formations by

under submarine conditions, forming the MnO2 vertical fractures, and migrated along the bedding minerals pyrolusite + ramsdelite. This stage is plane of the sediments, where they emerged accompanied by the emplacement of very ﬁ nely (Liakopoulos et al, 2001). disseminated barite in the tuffs. In the second stage, formation of the isostructural Perlite deposits Mn-oxides (coronadite, cryptomelane-hollandite, and The volcanic centers of Milos Island have created very Volume n° 4 - from P14 to P36 n° 4 - from Volume

Figure 6 - Sketch map with the locations of the industrial minerals of Milos

33 - P36

P36_R_OK 33 21-06-2004, 10:05:12 P36_R_OK 34

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas very high. glass. The suppliesofallperlitetypesinMilosare to thepumiceousperlite,indicatinghydrationof vesicles increases andglassdecreasesfromthehard texture, tothe pumiceous one. The proportionof have beenidentifi (Koukouzas andDunham,1994). Various textures biotite, opaqueminerals,vesicles, andglass The perliteofMilosconsistsquartz,feldspars, entered inthemassduringitsconsolidation. river) water, andthatthewater was eitherdepositedor magmatic massabsorbedthesuspended(sea-,lake- or understood sofar. The simplesthypothesisisthatthe submagmatic temperatures,hasnotbeenfully The hydrationmechanismoftheacidmagmaunder case oftheFyriplakaand Trahilas cones. activity, formedconesofperliticlapillis,asinthe Perlitic volcanic products,createdalsobyeruptive Vounalia, etc). lava fl substances was removed. Suchdomesandperlitic initial eruptive activity, themainbulk ofitsvolatile viscous acidmagmaticmaterial,fromwhich,afterthe is natural,sincetheactivity was fedbyintensively types, andformlava domesandthicklava fl the eruptive-effusive perlitesprevail over theother the extrusive andtheeffusive. Inany ofthesecases, basic processesofvolcanic activity: theeruptive, The perliteformationsaresettledwithallthree of eachvolcanic center. secondary mineralsisstable,asitinalltheproducts The chemicalcompositionofboththemainand generally glassy. plagioclases orbiotite-amphibole. The basicmassis rich inCa,andrarelycontainphenocrystalsof rhyolites of Tsigrando-Fyriplaka andChalepaare plagioclase, andbiotitephenocrystals,whilethe Trahilas centerhasproducedlow Carhyolitesand 1986). rhyolites ofMilosisgiven in Table 1(Fytikasetal, The chemicalcompositionofthemostimportant fl Bonbarda, andDemenegaki volcanic domesand perlitic lavas, areencounteredattheHondro Vouno, interesting outcropsofrhyolites,andinplaces, ring coneandlava fl cone andlava fl lava domeandfl the hydrothermalalterations,andformedChalepa & Fytikas,1991). The perlites,werenotinfl massive depositsofrhyoliticperlites(Argyropoulos ows. ows predominateinMilos(Chalepas, Trachilas, ows (0,34Ma),andtheFyriplakatuff ows (1,2Ma),the Trachylas tuff ring ed, rangingfromthehardperlite ows (0,09Ma).Smallerandless uenced by ows. This 2001). with epithermalmineralisation(Plimer&Nethery, hydrothermal eruptionpipesoccurred,associated mud pools.Minorbarite-argentian galenaveins and steaming grounds,siliceoussinters,andboiling site ofhydrothermaleruptions,whileothersformed rocks. Someoftheepithermalveins indicatethe replacements of5Maevaporates andcarbonate zones. Rareepithermalsystemsaremassive siliceous precious metals,andtothere-depositionofbonanza of epithermalsystemsledtothedissolution gold systemsbycrack-sealmechanisms. The collapse temporally telescopedquartz-adularia-Fe,sulfi structurally controlled,andprecipitatedspatially The large-scale geothermal systemsinMiloswere Epithermal golddeposits volcanic product. of thousandstonnesthisinterestingindustrial Two bigGreekcementcompaniesproducehundreds on thepyroclastic formationsoutcroppingthere. important puzzolanedepositswerediscovered, laying In thesouthwesternpartofMilosIsland,very Puzzolan deposits perlite. Milos isthesecondworld’s largest producerof is calculatedatabout500,000tonnes/year. For that, is heldonlybytheSilver andBariteCompany, and In therecentyears,perliteproductioninMilos other perlites,duetotheirsmallquantity. be lessimportant,duetotheirquality, andalsoallthe Megatons. The Chalepasperlitesareconsideredto 184 Megatons, andtheFyriplakareserves, 884 The Trachilas perlitereserves areestimatedtohold northwestern partoftheisland,wherepyroclastic If thereisenoughtime,willbeavisittothe exhibition ofmineral miningtools. facilities existing there,as wellasseeinganimportant mining situationinMilos,usingtheappropriate of watching apresentationonthegeologicaland the Museum,groupwillhave the opportunity Apollonia) areorganized forthe1 of Adamas, andtotheindustrialplantsof Voudia (near Introductory visitstotheGeological-MiningMuseum Arrival atMilos(noonorafternoon). Field itinerary DAY 3 st dayinMilos.In 3-06-2004, 10:17:55 de- PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

Figure 7 - Itinerary Sketch Map formations of Sarakiniko and Bombarda, and the deposited it at the fl ames of the cone in a reverse- dacitic-andesitic lava domes and fl ows can be grating sequence. A lot of older lavic lithics can be observed. observed. The ancient village, the Roman theatre and the paleo- Christian (2nd century AD) catacombs are built on the Stop 3: pyroclastic formations of the area. Trachilas perlite quarry (mine). In Plaka, the group could visit the mediaeval castle In the internal part of the cone, the rhyolitic lavas, that and some very old and interesting churches, which are fl ow in a northwest directionto the seashore line, are constructed on the volcanic domes. to be found. The lava has a typical perlitic structure, and it is DAY 4 one of the best quality perlites existing in the world. Departure from Adamas The exploitation is open-style; they use explosives and create continuous terraces. Some interesting Stop 1: rehabilitation work exists. Thiafes. 600m northwards of Adamas downtown, there is Stop 4: a solfatara and hot ground fi eld, with gas and soil Sarakiniko. temperatures at 100oC. The hot area is a result of the Natural erosion has created an impressive intersection of two important faults (N-S and E-W landscape, with pumice falls and fi ne-grained acid directions). Its size is 15000m2 . (white) pyroclastics. Marine fossils (Echinoderms, At a borehole drilled there, the temperature at the Lamellibranches, Brachiopods, etc), typical of a bottom (72m), was 138oC, and a water-steam mixture shallow marine environment, are abundant in the P14 to P36 n° 4 - from Volume was produced. Deposits of S are visible in many area. The collapse of the fi ne-grained tuffi tes, and spots. the presence of faults and fractures on the white formations, helped the deposition of hydrothermal Stop 2: products inside these tectonic cracks. Kaoline Trachilas tuff ring. formations are also present, as well as some gigantic The external deposits of the Trachilas tuff ring are pumice-stones (sometimes with a diameter bigger visible in detail. Numerous explosions caused the than 5m). fragmentation of the original rhyolitic magma, and

35 - P36

P36_R_OK 35 21-06-2004, 10:05:37 P36_R_OK 36

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas which formedsubmarinedacitic-crypto-domes. hyaloclastites arelinked totheadjacentvolcanism, white lithicscomefromthepumiceformation. The were formedinashallow marineenvironment. Some colored hyaloclastiteswithpseudo-pillows, which Above thisrhyoliticformation,therearegray- origin. chemical composition. This formationisofmarine are someimeshigherthan2m,andhave aconstant mixed withvery smallpiecesofpumice. The pumices together withafi pumices have formedadepositupto50mthick, outcrops ofthepumicefl Near theprehistoricsettlementofPhylakopi, typical Phylakopi. Stop 5: mushroom-like form. barite, saturatingthealteredvolcanites ina metal-bearing rocks,consistingofmicrocrystalline and wells.Onecanmake outfromthesurface the the otherorehasbeenexcavated, usingsmalltunnels In thisstop,wewillseetheBaritinemine,fromwhich Picridou. Stop 9: silisifi that causedbentonitization,kaolinitization,and and toobserve thedetailsofhydrothermalactivity it iseasytoseetheentiregeologicalcross-section, mine (>2kmlongand200mdeep)intheworld. Here, could bethelargest opencast(stripmining)bentonite which, togetherwiththeothertwo neighboringones, and Tsantili), we willarrive atthe Angeria quarry, Passing throughotherbentonitemines(AsproChorio, Angeria andotherquarries. Stop 8: preparation ofthemineral. be abletoseetheair-drying ofbentoniteandthe of theSilver andBariteCompany. The visitorswill The roadpassesnearthefacilities andinstallations Vudia area. Stop 7: Stop 6: road. can beclearlyobserved nearthe Adamas-Apollonia (pentagonal columnarlavas, breccia,andmud-fl The external partofthedaciticcrypto-dome Kalogeros. cation.

ne-grained volcanic ashmatrix, ow formationexist. Big ow), Stop 12: explosion musthave beenvery superfi pieces ofweatheredwhitevulcanite. The pointofthe to 20m),whiletheirribsconsistofbeddedangular external diameteroftheirrimisgenerallysmall(up overlapping theother, aresituatedinthisarea. The with eachother, andsometimesoneiswithinor Several smallphreaticcraters,whichareincontact Aghii Theodori. Stop 11: been about325 and resultedintheformationofcrater, musthave hydrothermal activity, whichcausedtheexplosion the crater. Itwas estimatedthatthetemperatureof the surface aftertheexplosion whichinitiallycaused limestone (morethan1meterindiameter),cameupto Pieces ofthebasement,withinterspersedfragments with adiameterofabout600m,islocatedinthisarea. A large andwell-preserved phreaticexplosion crater, Aghii Anargyri. Stop 10: alteration ofexplosion intensity),–anditsalmost layers, continuallyvarying insize (periodical crater’s structure–whichismadeupofpyroclastic external sideof the new crater, wecanobserve the In theprofi Fyriplaka dome. Stop 14: the kaolins. formation. Very recent“greenlahar”depositsoverlay were formedbelongstotheoldfi volcanic formationfromwhichthekaolindeposits area, producinggoodqualitykaolin. The original An importantkaolinopenmineisoperatinginthe Filli (kaolinquarry). Stop 13: since every otherpossibilityhasbeenexcluded. however, usedthistermasbeing themostverisimilar, composition isnotofatypicallahar. We have, is chaotic,ungraded,ofstablethickness,but its well-mixed withinthesamematrix. The formation green rocks,andpiecesoflimestoneorvulcanite,all 90% ofwhichcomprisesangularmetamorphosed mudfl In Filli,wewillexamine asignifi Filli (green lahar). ow withconsiderablestratigraphicimportance, le ofaperlite minewhichislocatedinthe o C. cnl extended cantly cial. n pyroclastic ne 3-06-2004, 10:18:02 PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

total lack of matrix, together with the stability in sheeting of the lavas is characteristic of this type of its composition (rhyolitic, perlitic), etc. Taking into volcano. account its enormous diameter (1700m), the fragility of its products, and their glass-like structure, it can be Stop 3: said that Fyriplaka is probably a submarine volcano of Provatas acid hyaloclastits. However, all the above-mentioned The Neogene sediment sequence starts with a could be attributed to the abrupt contact between the multicolored basal conglomerate, and continues with seawater and the magma inside the faulted basement, marine deposits of marls, limestone, sandstones, etc. and, thus, the crater could have been formed on dry The area is characterized by impressive extensional land but near the sea. Its age is approximately 0.5 faults, dipping to the north, which have created the m.a.. Inside the Fyriplaka crater, another smaller unique morphology of the area. Many marine fossils and similar crater exists, as well as various lava can be found here. fl ows of the same composition and a peculiar lahar, which mainly consists of pyroclastic materials from Stop 4: the biggest crater. The lava fl ows have moved in Kipoi various different directions (however, mainly towards The volcanic dome of Chalepa has produced very well the NW), governed by whatever obstruction they preserved thick lava fl ows of rhyolitic-rhyodacitic confronted that eventually forced them to form small composition. The lava fl ow extends to the south and hills (which the natives call Vounalia). arrives at the actual shoreline. The lava structure and its well-developed phenocrystals are clearly visible. Stop 15: Paleochori. Stop 5: In the Paleochori area, we can observe the Xylokeratia metamorphic basement, some kaolin quarries, and the Following the road near the southern coast and going upper part of the Pyriplaka deposits. There is also a west, we pass through the Neogene deposits and beautiful beach for an optional brief swimming stop. volcanic formations of various origins: andesite lava On that particular beach, there is a certain spot fl ows, breccias from collapsed domes, mudfl ows, where the sand temperature is approximately pyroclastics, etc. 100oC, conditions that favor a great deal a kind of Near Xylokeratia, we arrive at two very large quarries “geothermal cooking”. of puzzolan, a fresh pyroclastic formation, mainly composed of pumice breccias, volcanic ash, and DAY 5 (rarely) lithics from older volcanites. There are two cement companies operating here, Stop 1: having an intensive activity and appropriate facilities Coutsounorachi. to put the product directly into cargo containers, and The Mesozoic limestone basement, that follows an carry it away by boat. E-W direction, emerges from the volcanic formations, The group could visit both or one of these quarries above them the Neogene limestones. The outcrops of (depending mainly on the time left). the schists are limited. The fi eld trip ends at about midday, the participants will go back to Adamas, to prepare their departure Stop 2: from Milos by high-speed boat or airplane. Vrissidia. Acknowledgments

In Vrissidia, the older rhyodacitic lavas of the great P14 to P36 n° 4 - from Volume extrusive complex of domes and lava fl ows of Halepa, The elaboration of this guide was supported by the are found. There is more than one lava fl ow, and these Ministry of Environment and Water of the Republic fl ows follow various directions. In this particular of Bulgaria and by the French-Bulgarian project location, they have moved towards the NE, while at RILA-4, involving the cooperation between EGIDE the back of the big main dome, they moved towards the (France), and the Ministry of Education and Sciences south. The age of this complex has been determined, of Republic of Bulgaria. by K/At method, to 1.13+0.10 m.y., by using the relatively great amount of biotite phenocrystals. The

37 - P36

P36_R_OK 37 3-06-2004, 10:18:03 P36_R_OK 38

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas infl generating processesintheMilosBentonitesandtheir Christidis, G.andMarkopoulos, Th. (1992).Kaolinite Balcanica from EasternRhodopes,Bulgaria. (1988). Electronparamagneticresonanceofperlites Calas, G., Angelov, S., Yanev, Y. andKostov, R.I. 46, H2,309-385. Haskovo (Bulgarien). Bontscheff, St.(1897).Das Tertiärbecken von 290. analysis. Kinetics ofperliteglassesdegassing: TG andDSC Bagdassarov, N.,Ritter, F. and Yanev, Y. (1999). Volcanology andGeothermalRes Thermal propertiesofvesicular rhyolite. Bagdassarov, N.S.andDingwill,D.B.(1994). Meeting, of MilosIsland(Greece). Argyropoulos, G.andFytikas,M.,(1991).Perlites Soc. Geol.France dans l’arcégeén interne:I’lle deMilos(Gréce). Neotectonique cassanteetvolcanisme plioquaternaire Angelier, J.,Cantagrel,J.M.,D. Vilminot, J.C.(1977). Sciences nordest. Aleksiev, B.(1968).ClinoptilolitedesRhodopesdu References cited Journal of Volcanology andGeothermalResearch ignimbrite brecciafacies onSantorini,Greece. DruittT. H.andSparks,R.T.J. (1982). A proximal Interaction mineral glasses:EastRhodopesperlites. Y. andRenaudin,P. (1989).Mössbauer studyof Dormann, J.-L.,Djega-Mariadassou, C., Yanev, Univiversity,Greece. Thessaloniki, (S. Konstantinos Ed.).2,pp.279-489. Aristotl Rhodopica, 2ndHellenic-BulgarianSymposium”, to theeastoftown ofKurdjali. In:“ related tothesecondacidicPaleogene volcanism Djourova, E.G.and Aleksiev, B.(1990).Zeoliticrocks Sofi perlites. M. (1984).IR-spectroscopy ofEasternRhodopes Dimitrov,V., Yanev,Dimitrova-Pankova, Y.and 3-15. magmatism inBulgaria. Yanev, Y. (1991). Geodynamicmodelofthealpine Mavroudchiev, B.,Stanisheva-Vassileva, G.and Dabovski, H.,Harkovska, A., Kamenov, B., Congress oftheGeol.Soc.Greece uence on thephysicalpropertiesofbentonit. a 19,86-96(inRussianwithanEnglishabstract). Comptes rendus del’Académiebulgare des 21, 1093-1095. Geochemistry, Mineralogy andPetrol 4-6 May1991,HotelHilton, Athens. Glass Sciencesand Technol 18(5),53-60. s, J.C.Baltzer A. G.,Basel6,651-658. , 19,119-121. Jahrb. Geol.Reichsanstalt Geologica Balcanica In: Proceedings ofPerlite earch 60,179-191. , p.13. ogy 72,277- Journal of Geologica Geologica Hyperfi ne 21(4), , Bd. Bull. ogy, 6 th

Goranov, A., Vutkov, V. andPetrov, P. (1960). pp. 65-75.NaukaEd.House,Moscow (inRussian). Tzeoliti” (Natural Zeolites) example ofthe Transcaucasus). In:“ stratiﬁ Gogishvili, V.G. (1980).Epigeneticcharacterof 49-54. rendus del’Académiebulgare desSciences Momchilgrad volcanotectonic depression. (2003). K-Ardatingofthemagmaticactivity inthe Georgiev, V., Milovanov, P. andMonchev, P. 25.000. IGME (1977).GeologicalMapofMilosIsland,1: 18, pp.485-496. geothermal researchonMilosisland, Fytikas, M.(1989).Updatingofthegeologicaland Geotherm. Res. the islandofMilosandneighboringislets. Volcanology andpetrologyofvolcanic productsfrom Mazzuoli, R.,Poli,G.,Rita,F. and Villari, L.(1986). Fytikas, M.,Innocenti,F., Kolios, N.,ManettiP., publication A.H.F.), Geological SocietyofLondon,Special Mediterranean (EditedbyDixon,J.E. andRobertson, region. Quaternary evolution ofvolcanism inthe Aegean R., Peccerilo, A. and Villari, L.(1984). Tertiary to Fytikas, M.,Innocenti,F., ManettiP., Mazzuoli, Proc. Geotherm.Energy geothermics oftheislandMilos(Greece).IGME, Fytikas, M.andMarinelli,G.(1976).Geology of MilosIsland. Fytikas, M.(1977).Geologicalandgeothermalstudy 73, 201-215. modeling andthermometry. Fuhrman, M.andLindsley, P. (1988). Ternary feldspar Alaska. eruption of1912atNovarupta, KatmaiNationalPark, Fierstein, J.andHildreth, W. (1992). The Plinian Thermal Waters, Athens, October1976 Milos. productive geothermalwellsdrilledattheislandof (1976). Preliminarygeologicaldatafromtheﬁ Fytikas, M.,Kouris, D.,Marinelli,G.andSurgin, J. Report onwellMILOS-3.GR/MI-14 ENEL andPPC(1982).MilosGeothermalProject. Report onwellMILOS-2.GR/MI-11 ENEL andPPC(1981b).MilosGeothermalProject. Report onwellMILOS-1.GR/MI-9 ENEL andPPC(1981a).MilosGeothermalProject, 13, 147-171 ed depositsofhighly-siliceouszeolites(on Proceedings oftheInternationalCongress of Bulletin of Volcanology The Geological EvolutionoftheEastern No.17,pp.687-699,Blackwell,Oxford. 28,pp.297-317. IGMR , Vol. XVII,No1. 1: 516-524. (Kossovskaya, A.G., Ed), American Mineral 54,646-684. , May1981. , January1982. , July1981. , pp.511-515. Geothermics J. Volcanol. Prirodnie Comptes 3-06-2004, 10:18:05 56 (8), rst two o gist

PALEOGENE AND RECENT VOLCANISM IN THE EASTERN RHODOPES (BULGARIA), AND ON MILOS ISLAND (GREECE), AND RELATED INDUSTRIAL MINERALS P36

The perlites in the Eastern Rhodopes. Izvestia na Seria Geologicheskaia 1, 3-18 (in Russian). Geologicheskia Institut, Bulgarian Academy of McKenzie, D.P. (1978). Active teconics of the Alpine- Sciences 7, 323-345 (in Bulgarian with an English Himalayan belt: the Aegean Sea and surrounding abstract). regions. Geophys. J. R. Astron Soc. pp. 217-254 Hanski, E. J. (1993). Globular ferropicritic rocks McPhie, J. and Stewart A. (2003). Shallow submarine at Pechenga, Kola Peninsula (Russia): Liquid felsic volcanism, Milos, Greece. Presented in the immiscibility versus alteration. Lithos 29, 197-216. Intern. Conf. on The South Aegean Active Volcanic Harkovska, A., Yanev, Y. and Marchev, P. (1989). Arc: Present knowledge and future perspectives General features of the Paleogene orogenic (SAAVA 2003), Milos island 17-20 Sept. 2003. magmatism in Bulgaria. Geologica Balcanica 19 (1), Mercier, J.L. (1981). Extensional-compressional 37-72. tectonics associated with the Aegean Arc: comparison Hervig, R.L., Dunbar, N., Westrich, H.R. and with the Andean Cordillera of South Peru-North Kyle, P.R. (1989). Preeruptive water contents of Bolivia. Philos. Trans. R. Soc. London. Ser. A. 300, rhyolitic magmas by ion microprobe analysis of melt pp. 337-355. inclusions in phenocrysts. Journal of Volcanology and Mercier, J. L., Sorel, D., Vergely, P., Simeakis, K. Geothermal Research 36, 293-302. (1989). Extensional tectonic regimes in the Aegean Innocenti, F., Manetti, P., Peccerilo, A. and Poli, G. basins during Cenozoic. Basin Res. 2. pp. 49-71 (1981). South Aegean Volcanic Arc: Geochemical Moore, D.M. and Reynolds, R.C. (1997). X-ray variations and geotectonic implications. Bull. Volcan. Diffraction and the Identifi cation and Analysis of Vol. 44 No 3, pp. 371-391. Clay Minerals. Oxford Univ. Press, 378 p. Innocenti, F., Manetti, P., Peccerilo, A. and Poli, G. Papazachos, B.C., Papazachou, C.B. (1997). The (1979). Inner Arc volcanism in NW Aegean Arc: Earthquakes of Greece. Ziti Publ., Thessaloniki, geochemical and geochronological data. Neues Greece, pp. 304. Jahrbuch Fur Mineralogie Mnashefte H4. pp. 145- Noble, D.C. (1967). Sodium, potassium and ferrous 158 iron contents in some secondarily hydrated natural Ivanov, R. (1960). Magmatism of the Eastern silicic glasses. American Mineralogist 52, 280-286. Rhodope depression. Part I-Geology. Trudove varhu Peccerillo, A. and Taylor, R.S. (1976). Geochemistry Geologiata na Bulgaria, Seria Geohimia y Polezni of Eocene calc-alkaline volcanic rocks from the Izkopaemi 1, 311-387 (in Bulgarian with a German Kastamonu area, N. Turkey. Contr. Miner. Petrol. 58. abstract). pp. 63-81. Kocik, J., Nebrensky, J. and Fanderlik, I. (1983). Pe Piper, G., Piper, D.J.W., Reynolds, P.H. (1983). Colour of the glasses. Stroyisdat, Moskow, 212 p. Regional implications of geochemistry and style of (in Russian). emplacement of Miocene I-type diorite and granite, Koukouzas, N. and Dunham, A., (1994). Genesis of Delos, Cyclades, Greece. Lithos 60. pp. 47-66. a Volcanic Industrial Rock, Trachilas Perlite Deposit, Plimer, I. And Nethery J., (2001). Epithermal Gold Milos Island, Greece. Bull. of the Geological Society Deposits, Milos, Greece. In: Proceedings of 4th of Greece, Vol. XXX/3, pp. 333-340. International Symposioum on Eastern Mediterranean Lilov, P., Yanev, Y. and Marchev, P. (1987). K- Geology, 21-25 May 2001, Isparta, Turkey. Ar dating of the Eastern Rhodopes Paleogene Simeakis, C. (1985). Neotectonic evolution of the magmatism. Geologica Balcanica 17 (4), 49-58. Milos island complex. IGME Report (in Greek), p. Makropoulos, Th. and Katerinopoulos, A. (1986). 50. Die Alunit-Vorkommen von Milos (Griecheland): Popov, S., Janeva, J., Russev, K. and Bocev, P. (1989). Mineralbestand und Genese. Chem. Erde 45, pp. Evaluation des perlites du Rhodope oriental comme 105-112. matière première dans la production d’agrégats pour P14 to P36 n° 4 - from Volume Makropoulos, Th. and Katerinopoulos, A. (1988). les bétons légers. Ore-forming Processes and Mineral Mineralogical and petrographic study of samples Deposits, Sofi a 30, 46-64 (in Bulgarian with a French from wells in the geothermal fi eld of Milos island. abstract). Submitted report to the Public Power Corporation Raynov, N., Popov, N., Yanev, Y., Petrova, P., Popova, Greece. T., Hristova, V., Atanasova, R. and Zankarska, R. Marakushev, A.A. and Yakovleva, E.B. (1980). On the (1997). Geological, mineralogical and technological origin of perlites. Vestnik Moskovskogo Universiteta, characteristics of zeolitized (clinoptilolitized) tuffs

39 - P36

P36_R_OK 39 3-06-2004, 10:18:07 P36_R_OK 40

Volume n° 4 - from P14 to P36 P36 - P36 Leader: M.Fytikas NaAlSi of mineralglasses–I. The feldsparglasses Taylor, M.andBrown, G.E.Jr. (1979).Structure Princeton. Yoder, Ed.),pp.339-350.PrincetonUniv. Press, Igneous Rocks. 50th Anniversary Perspectives potassic glassyrocks.In“ Steward, D.B.(1979). The formationofsiliceous Soc. Geochem. of America, D.L. andMing,D.W. Eds),pp.261-275.Miner. Soc. l’ iledeMilos(Greece). evidence d’ uneeruptionphreatiquehistoriquesur Traineau, H.andDalabakis,P. (1989).Miseen Cosmochimica Acta Reviews ofMineralogy andGeochemistry Zeolites: Occurrence, Properties, Applications”. zeolites inopenhydrologicsystems. Sheppard, R.A.andHay, R.L.(2001).Formation of Glassern II. Scholze, H.(1959).DerEinbaudes Wassers in 15-57. PrincetonUniv. Press,Princeton. Perspectives”50th Anniversary magmas. In“ Roedder, E.(1979).Silicateliquidimmiscibilityin Moscow. and O.Petrov Eds.),pp.263-275.Pensoft,Soﬁ “ deposits intheEasternRhodopes,Bulgaria.In glasses fromtheEasternRhodopes,Bulgaria. In“ Yanev, Y. (1987). Characterizationofvolcanic 219 (inBulgarianwithaFrenchabstract). Geochemistry, Mineralogy andPetrography de l’Est. de StudenKladénetzl’OligocènedansleRhodope Yanev, Y. (1970).Sphéruloidsderhyolitesduvolcan future prospects. geothermal resourcesinGreece:Presentstatuesand Vrouzi, F. (1985).Researchanddevelopment of America, Geochem.Soc. Ming, D.W., Eds),pp.277-304.Mineral.Soc.of Mineralogy andGeochemistry Occurrence, Properties, Applications”. Reviews of low-grade metamorphicrocks.In: Utada, M.(2001)Zeolitesinburial diagenesisand 1-308 Natural Zeolites,Soﬁ a’95 3 O Bulletin oftheGeological Institute, Series 8 , KAlSi Glastechn. Ber The EvolutionoftheIgneousRocks. Geothermics 3 O 43, 61-75. 8 , CaAl C-R Acad. Sci. ParisSci. C-R Acad. . 32,142-152. ” (G.Kirov, L.Filizova 2 Si 14,pp.213-227. The Evolutionofthe (H.S. Yoder, Ed.),pp. 2 O 45 8 “Natural Zeolites: . (Bish,D.L.and Geochimica and In: “Natural

45 19,201- ” (H.S. (Bish, . pp. II a- nd

and ChemistryofMinerals glasses fromtheEasternRhodopes,Bulgaria. radial distribution functionanalysisofacidvolcanic Zotov, N.,Dimitrov, V. and Yanev, Y. (1989).X-ray 97-110 (inBulgarianwithanEnglishabstract). Geochemistry, Mineralogy andPetrol and Stalevo, EasternRhodopesvolcanic area. magmatism intheregion ofthevillages Yabalkovo Petrology andK-ArdatingofthePaleogene Yanev, Y., Stoykov, S.andPecskay, Z. (1998b). 279-291 geodynamic signifi Western Thrace (Greece):Petrogeneticaffi related volcanism inEasternRhodopes(Bulgaria)- G. (1998a).UpperEocene-Oligocenecollision- Yanev, Y., Innocenti, F., Manetti,P. andSerri, English abstract). Geolgica Balcan rocks inpartofEastRhodopesPaleogene depression. Distribution ofalkalisandgenesistheacidvolcanic Yanev, Y., Karadjova, B.and Andreev, A. (1983). Moscow 5(2),1-9. water involcanic glasses. Yanev, Y. andZotov, N(1996).Infraredspectraof Mineralogy andPetrol volcano Briastovo (EasternRhodopes). on thepetrologyandK-ArdatingofOligocene Yanev, Y. andPecskay, Z.(1997).Preliminarydata “ Yanev, Y. (2000).Immiscibilityintheacidlavas. In: Vulcanologica Rhodopes Paleogene acidvolcanics, Bulgaria. Yanev, Y. (1998).PetrologyoftheEastern Petrology Borovitza calderaintheEasternRhodopes,Bulgaria. Yanev, Y. (1994).Cesium-bearingperlitesfromthe 129-138. Univ. Karlova Ed.,Prague. International Conference onNatural Glasses” l’Académie desSciencesdeParis Rhodopes orientaux(Bulgarie). éruptifs duvolcanisme paléogène decollisiondes Yanev, Y. andBardintzeff, J.-M.(1996). Dynamismes 31st IGC. Abstract 2(1),82-97. 10(2),265-278. ica 13(3),15-44(inRussianwithan cance. ”, Section6-7. ogy, Sofi Experiment inGeoSciences Acta Volcanologica 16,774-782. a 32,59-66. Comptes-Rendus de 322,IIa,437-444. ogy, Sofi Geochemistry, nt and nity 3-06-2004, 10:18:08 Physics 10(2), a 34, a , pp. Acta , Back Cover: fi eld trip itinerary

P36_copertina_R_OK E 3-06-2004, 10:07:07 FIELD TRIP MAP INTERNATIONAL GEOLOGICAL CONGRESS nd 32

Edited by APAT

P36_copertina_R_OK B 3-06-2004, 10:07:56