r internationaies Büro " elogical investi,,v_ t n eelo Oslan MO d Dionissios Matarangas Bergheim/Eisdorf Jülich-Mersch \t -=_ 55 Jülich-Kostar Jülich\ Berichte des Forschungszentrums :oich •; 2684 ISSN 0366-0885 Internationales Büro Jü1-2684 D 188 (Diss. Freie Universität Berlin) Zu beziehen durch : Forschungszentrum Jülich GmbN Zentralbibliothek Postfach 1913 . D-5170 Jülich - Bundesrepublik Deutschland Telefon : 02461/61-61 02 • Telefax : 02461/61-6103 - Telex : 833556-70 kfa d ® Geol ~ i n no ..m Sporad -~~ ~ ez ®IOilIS510S Matarangas Zusammenfassung Die Nordsporaden Insel Skopelos besteht aus folgenden tektoni- schen Einheiten: I . Von der Pelagonischen Einheit im Zentrum sind nur der oberste Teil der metaklastischen Skiathos - Serie (Ladin Karn) sowie frühdiagenetisch gebildete Dolomite des Nor - Rhat aufgeschlos- sen . DarUber liegt typisches Mesoautochthon : Fe/Ni Laterite und Bauxite der Unterkreide sowie Transgressionskonglomerate des Alb (Vracon) füllen ein Erosionsrelief, gefolgt von Rudistenkalken der Oberkreide und alttertidrem Flysch . Das Mesoautochthon weist eine sehr schwachgradige Metamorphose auf. 2. Die Glossa - Einheit im Nordwestteil der Insel ist von NE auf das Pelagonikum überschoben . Sie besteht aus Phylliten, Kalk- schiefern, Marmoren und Grunsshiefern, die aus Tholeiiten mit MORE Charakter hervorgegangen sind . Nach ihrem Gesteinsbestand und ihrer tektonischen Position wird die Glossa -Einheit als Teil der Eohellenischen Decke gedeutet, Ihre Metamorphose ist alter als die unterkretazische Laterit Bildung. 3. In der Palouki Einheit im Ostteil von Skopelos bilden Ero- sionsreste der Eohellenischen Decke die Unterlage einer schwach- gradig metamorphen Schichtfolge aus einer hemipelagischen Kalk- serie mit klastischen Zwischenlagen (Unterkreide), die nach oben in Rudistenkalke und alttertidren Flysch, also in Schichten mesoautochthonen Charakters ubergeht . Die Palouki - Einheit wurde wahrend der mesohellenischen Orogenese im Eozdn auf die Pelago- nische Einheit Uberschoben . Metamorphose und interne Deformation der Palouki Einheit weisen daraufhin, dagdiese im Eozdn von einem Deckenstapel überlagert wurde. Alle Einheiten weisen Falten mit Achsenrichtungen NNE/SSW, WNW/ ESE und ENE/WSW auf, die erst im Eozan geprdgt wurden . Auch die Richtungen der Klüfte, Bruchstörungen und Photolineationen stim- men in allen Einheiten überein . Ihre Maxima NNW/SSE, NE/SW und NW/SE können mit Vorbehalt auf den Faltenbau bezogen werden. Deutlich jünger sind ENE/WSW verlaufende Elemente, die auf die Nordagaische Störungszone unmittelbar nördlich von Skopelos hin- deuten. Paldogeographisch betrachtet war das Pelagonikum wahrend der Trias Tell einer Karbonat = Plattform am Südwestrand des Tethys - Ozeans, aus dem die Eohellenische Decke abgeleitet wird . Die Pa- louki - Einheit war vermutlich am Ostrand der Pelagonischen Plattform beheimatet. Abstract The island of Skopelos is composed of the following tectonic units: I . The Pelagonian unit in the central part comprises the upper part of the metaclastic Skiathos series (Ladinian - Carnian) and early diagenetic dolomites (Norian Rhaetian), which are over- lain by a typical mesoautochthonous sequence : Fe/Ni laterites and bauxites of Early Cretaceous age and transgressive conglomerates filling in a deep relief . They are covered by Upper Cretaceous nudist limestones and Palaeogene flysch . The Pelagonian rocks had suffered a low grade metamorphism . whereas the Mesoautochthonous II was metamorphosed merely under very low grade conditions. 2. The Glossa unit in the northwestern part of the island was overthrust from the NE onto the Pelagonian . It consists of phyl- lit.es, cipolines, marbles and greenschists, which had originated from tholeiites with MORE affinities . According to its rock asso- ciation and its tectonic position, the Glossa series is inter- preted to belong to the Eohellenic nappe . Its low grade metamor- phism is older than the Lower Cretaceous laterite formation. 3. Within the Palouki unit of Eastern Skopelos . Eohellenic nappe relics form the base of a low grade metamorphic sequence : Hemipe- lagic limestones with clastic intercalations and Lower Cretaceous fossils grade to Upper Cretaceous rudist limestones and Palaeo- gene flysch, i .e . to typical Mesoautochthonous beds. During the Mesohellenic orogenesis (Eocene), the Palouki unit was thrust upon the Pelagonian unit . Metamorphism and internal defor- mation of the Palouki unit indicate that it was overthrust itself by a nappe pile during the Eocene. Within all units folds occur with axes in NNE/SSW, WNW/ESE, and ENE/WSW directions, The directions of faults, joints, and photo- lineations are identical all over the island . The systems with NNW/SSE,NE/SW, and NW/SE may be related to the fold systems men- tioned above, whereas fractures in ENE/WSW direction are obviou- sly younger and originated probably in connection with the adja- cent North Aegean fracture zone In a palaeogeographical view, the Pelagonian rocks of Skopelos had been part of the Pelagonian platform at the southwestern mar- gin of the Triassic Tethys ocean . The Eohellenic nappe is derived from that ocean itself, whereas the Palouki unit originated prob- ably upon the eastern margin of the Pelagonian pl at f orm . III Zusammenfassung l Abstract 1 Contents 111 1. Introduction 1 1 .1 . Aims of the research 1 1 .2 . Bibliographic review on Skopelos 3 1 .3 . General outlines of the Hellenides 6 2. Geological units of Skopelos and their stratigraphy 11 2 .1 . Pelagonian unit 15 21 .1 . Skiathos series 15 2 .1 .1 .1 . Previous work 15 2 .1 .1 .2 . Description of the Skiathos Series 16 2 .1 .1 .2 .1 . Outcrops of Ag . loannis 1 2 .1 .1 .2 .2 . Outcrops of Ag . Paraskevi 22 2 .1 .1 .2 .3 . Skiathos series of nearby areas°comparis ons 25 2 .1 .2 . Pelagonian dolomites 27 2 .1 .2 .1 . Previous work 27 2 .1 .2 .2 . Description of Pelagonian dolomites 23 2 .1 .2 .2 .1 . Stratigraphy 30 2 .1 .2 .2 .2 . Microfacies analysis 32 2 .1 .2 .2 .3 . Interpretation of the depositional environment 36 2 .1 .2 .2 .4 . Ooloffiitization 37 2 .1 .2 .2 .5 . Karstification 40 2 .1 .2 .2 .6 . Pelagonian dolomites . Comparison with occurrences in adjacent areas 41 2 .2 . Glossa unit (Eohellenic nappe) 49 2 .2 .1 . Previous work 49 2 .2 .2 . Petrography and metamorphism 52 2 .2 .3 . Geochemistry 55 2 .2 .4 . Correlation of the Glossa Series with those of adjacent areas 59 2 .2 .5 . Conclusions 61 2 .3 . Mesoautochthonous 62 2 .3 .1 . Cretaceous formation 62 2 .3 .1 .1 . Previous work 63 2 .3 .1 .2 . Description of the Cretaceous formations 64 2 .3 .1 .2 .1 . Fe, Ni ° laterites and bauxites 64 2 .3 .1 .2 .2 . Breccio-conglomerates 75 2 .3 .1 .2 .3 . Quartz schists 79 2 .3 .1 .2 .4 . Upper Cretaceous limestones 31 2 .3 .1 .2 .5 . Upper Cretaceous formations of nearby areas comparisons 07 2 .3 .2 . Flysch 39 2 .3 .2 .1 . Previous work 39 2 .3 .2 .2 . Description 90 IV 2 .4 . Palouki Unit 93 2 .4 .1 . Previous work 93 2 .4 .2 . Description of the Palouki Series 95 2 .4 .2 .1 . Basal magmatites 95 2 .4 .2 .2 . Lower series 93 2 .4 .2 .3 . Upper Cretaceous limestones 100 2 .4 .2 .4 . Flysch 100 2 .4 .3 . Summary 101 3. Structural Geology 103 3 .1 . Major tectonic structure of Skopelos island 103 3 .2 . Tectonic elements 106 3 .2 .1 . Folds 106 3 .2 .2, Fractural systems 111 3 .2 .2 .1 . Faults 111 3 .2 .2 .2 . Joints 114 3 .2 .2 .3 . Photolineations 119 3 .2 .2 .4 . Summary and interpretation 126 4. Palsogeography 123 4 .1 . Pelagonian unit 123 4 .2 . Glossa unit 130 4 .3 . Mesoautochthonous 131 4 .4 . Palouki unit 132 5. - Summary 134 Zusammenfasoung 140 6, References 143 Geological map of Skopelos island 1 . I ntr°oductio n . 1 .1 . Airs of the research In the frame of the project of the Institute of Geology and Mi- ning Exploration (I .G . .E .), Athens, for the Geological Map of Greece to the scale of 1 :50000, I was assigned to carry out the geological mapping of Skopelos island, which belongs to the North Sporades islands (Fig .1). During this work, along with the infor- mation drawn from the existing literature on the regional geology of the North Sporades archipelago and the Magnesian peninsula, the necessity of a new interpretation of the. geology of Skopelos island became apparent . Therefore detailed geological mapping to the scale of 1 :25000 was carried out . The necessity of structural investigations and detailed mapping of Skopelos island was also stressed by a publication & WALLBRECHER (1984), having in view the extremely complicated geological setting and structure of the island. Eased on the above and after many intensive discussions with Prof . Jacobshagen on the geological problems of the island, and mainly based on his encouragement, I decided to carry out a doc- toral thesis in the area . The interpretation of the geolo g ical structure of Skopelos island was strongly supported by the results of the geological mapping of Skyros island (1 :50000) coin- pleted by JACOBSHAGEN ~ MATARANGAS (1959)... I believe that the conclusions drawn . by this _work give a modern stratigraphic results from the metamorphic series, and on geoche- FORELAND fffg Preapulian Zone [fig Plattenkalk Series WEST HELLENIC NAPPES In Ionian Zone Gavrovo-Tripolitza Phyllite Series Tripoli Unit CENTRAL HELLENIC NAPPIES Pelagonian-Maliac-Lyeian Nappe r Parnass ` `1 Boeotian Serie Pindo s Zone IJ Basal units of Cyclades complex INTERNAL HELLENIC NAPPES rya Vardar Zone 11 Circum Rhodope belt HINTERLAND Serbo-Macedonian massif r+ ~ Tectonic boundaries (observed} Tectonic " (Supposed) 7 Zone boundaries 0 Border Fi .1 . Tectonic sketch-map of Gre44rr . (,klc(lbsha0eh , 1986 ) mical and petrographical studies . These results, moreover, will have a considerable influence on the geotectonic interpretation of the North Sporades archipelago and the Magnesian peninsula. 1 .2 . Bibliographic review on Skopelos VIRLET (1834) was the first researcher who gave geological infor- mation on Skopelos island . In his work "Expedition scientifique de Moree" he mentioned that he had recognized Hippurites in lime- stones which occur north of the town of Skopelos .