P36 Copertina R OK C August 20-28,2004 Florence -Italy Field Trip Guide Book - P36 Associate Leader:Y
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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 Leader: M. Fytikas Associate Leader: Y. Yanev Field Trip Guide Book - P36 Field Trip Florence - Italy August 20-28, 2004 Post-Congress P36 P36_copertina_R_OK C 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 Leader: M. Fytikas P36 Volume n° 4 - from P14 to P36 n° 4 - from Volume P36 - P36_R_OK 4 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