Turkish Journal of Earth Sciences (Turkish J. Earth Sci.),V. Vol. SACHANSKI 21, 2012, pp. ET 867–903. AL. Copyright ©TÜBİTAK doi:10.3906/yer-1004-4 First published online 12 October 2011 Silurian Graptolite, Conodont and Cryptospore Biostratigraphy of the Gülüç Section in Ereğli, Zonguldak Terrane, NW Anatolia, Turkey VALERI SACHANSKI1, MEHMET CEMAL GÖNCÜOĞLU2, ISKRA LAKOVA1, ILIANA BONCHEVA1 & GÜLNUR SAYDAM DEMİRAY3 1 Geological Institute, Bulgarian Academy of Sciences, 1113 Sofi a, Bulgaria 2 Middle East Technical University, Department of Geological Engineering, Üniversiteler Mahallesi, Dumlupınar Bulvarı No. 1, TR–06800 Ankara, Turkey (E-mail: [email protected]) 3 Department of Geological Research, General Directorate of Mineral Research and Exploration (MTA), TR−06520 Ankara, Turkey Received 10 April 2010; revised typescripts receipt 04 August 2010 & 28 September 2010; accepted 12 October 2010 Abstract: Th e studied Gülüç section of the Silurian Fındıklı Formation is situated on the western bank of Gülüç Creek in Ereğli, NW Anatolia, Turkey, in the eastern part of the Zonguldak Terrane. Th e Gülüç section consists of 3 sedimentary packages: greenish grey limy siltstones, 5–7 m thick (1), overlain by an irregular alternation of black shales and clayey limestones, about 15 m thick (2), and a 6–7 m thick succession of mainly siltstones and sandy limestones (3). A combined biostratigraphy based upon graptolites, cryptospores and conodonts indicates that Package 1 is of Llandovery (Rhuddanian, Aeronian and/or early Telychian) age, Package 2 and Package 3 are of late Wenlock–early Ludlow (Homerian and Ludfordian) age. Graptolites in packages 2 and 3 indicate the presence of the Cyrtograptus lundgreni, Neodiversograptus nilssoni and Lobograptus scanicus graptolite biozones. Th e Ozarkodina crassa Biozone occurs in the lower Gorstian (Ludlow). Th e specifi c features of the Gülüç section (lithological changes, condensation, stratigraphic gap, change in graptolite diversity) are related to the global model of Silurian T–R cycles. Th e Silurian Fındıklı Formation in the Gülüç section, about 20 m thick, represents a condensed lithological succession which diff ers signifi cantly from the coeval thick, stratigraphically widespread black shales and siltstones of the same formation in the Zonguldak and İstanbul terranes. Sixteen cryptospore species are described and their stratigraphic and geographic distributions are summarised. Key Words: Ereğli, Zonguldak Terrane, Graptolites, Conodonts, Cryptospores, biostratigraphy Siluriyen Graptolit, Konodont ve Kriptospor Biyostratigrafi si, Gülüç Kesiti-Ereğli, Zonguldak Tektonik Birliği, KB Anadolu Özet: İncelenen Siluriyen yaşlı Fındıklı Formasyonu’na ait Gülüç kesiti Zonguldak tektonik birliğinin doğu kesiminde yer almakta olup Ereğli yakınındaki Gülüç Çayı’nın batı yamacında bulunur. Kesitte alttan üste; 5–7 m kalınlıkta yeşilimsi gri karbonatlı şeyller (1), 15 m kadar kalınlıkta düzensiz ardalanmalı siyah şeyl ve killi kireçtaşları (2) ve 6–7 m kalınlıkta silttaşı ve kumlu kireçtaşından (3) oluşma üç çökel paket gözlenir. Graptolit, kriptospor ve konodontların birlikte kullanılarak kurulan biyostratigrafi ye göre Paket 1 Landoveryen (Ruddaniyen, Aeroniyen ve/veya erken Telişiyen) Paket 2 ve 3 ise geç Venlokiyen–erken Ludloviyen (Homeriyen ve Ludfordian) yaşındadır. İkinci ve Üçüncü paketlerde yer alan graptolitler Cyrtograptus lundgreni, Neodiversograptus nilssoni ve Lobograptus scanicus graptolit biyozonlarına işaret eder. Ozarkodina crassa Biozonu alt Gorstiyen’de (Ludloviyen) yer alır. Gülüç kesitinin özellikleri (litolojik değişimler, kondenzasyon, stratigrafi k boşluk, graptolit çeşitliliğinde değişiklikler) Siluriyen T-R döngelerinin global modeli ile uyum içindedir. Gülüç kesitinde yaklaşık 20 m kalınlık sunan Fındıklı Formasyonu kondanse bir istifi temsil etmekte olup aynı formasyonun İstanbul ve Zonguldak tektonik birliklerinde yaygın olarak yüzeylenen siyah şeyl ve silttaşı istifl erinden belirgin olarak farklıdır. Çalışmada onaltı kriptospor türü tanımlanmış, bunların stratigrafi k ve coğrafi dağılımları özetlenmiştir. Anahtar Sözcükler: Ereğli, Zonguldak Tektonik Birliği, Graptolit, Konodont, Kriptospor, biyostratigrafi 867 SILURIAN BIOSTRATIGRAPHY NEAR EREĞLİ, NW ANATOLIA Introduction 1968; Önalan 1981). Th e lower Silurian (Llandovery) Th e Silurian in NW Anatolia is part of the Alpine in this area is repesented mainly by a thick package of İstanbul–Zonguldak Terrane, separated by the Intra- siliciclastics, overlain by shallow-marine limestones Pontide Suture from the Alpine Sakarya Composite that continue up to the upper Ludlow. Th e succession Terrane to the South (Göncüoğlu et al. 1997). To is about 800 m thick and consists of shallow ramp the North, it is bounded by the Black Sea Basin, the deposits (Önalan 1981). In the easternmost outcrops remnant of the Para-Tethys ocean (e.g., Stampfl i of the Zonguldak terrane in the East, in the Karadere 2000). It is considered to be a Gondwana-derived area (Figure 1), the early Silurian rocks were studied fragment that amalgamated with southern Europe or in detail by Dean et al. (2000). Laurussia during the Variscan Orogeny (Göncüoğlu In contrast to these recent studies in the west and 1997, 2001; Yanev et al. 2006). Some authors (e.g., east, in the Gülüç area located south of Ereğli (Figure Görür et al. 1997; Stampfl i 2000; Raumer et al. 2002), 1), the Silurian succession, known since the late 1940s however, suggested a southern Baltican origin. In (Egemen 1947), has not been studied. previous studies it was considered as a single entity, In this study the authors describe for the fi rst with Palaeozoic successions overlying a Cadomian time the litho- and bio-stratigraphy of a condensed basement (Şengör et al. 1984). A recent review sequence of strata of Llandovery to Ludlow age and of the Palaeozoic stratigraphy (e.g., Göncüoğlu correlate the succession with coeval ones in the 1997) has shown that the succession of events and İstanbul and Zonguldak terranes in NW Anatolia. the lithostratigraphic successions in the east and It is the fi rst biostratigraphic study of the Silurian of west areas diff er in a way that can not be explained Turkey that combines data obtained from graptolites, simply by changes in the depositional environment. conodonts and cryptospores contributing to our Th erefore, Göncüoğlu & Kozur (1998, 1999) and understanding of chronostratigraphy and basin Kozur & Göncüoğlu (2000) have suggested that the development. Palaeozoic successions in the west and east should represent two distinct terranes, the İstanbul and Zonguldak terranes, respectively (Figure 1). Geological Framework and Previous Findings In the İstanbul Terrane around İstanbul (Figure Th e studied Silurian rocks in the Gülüç section occur 1), the Silurian stratigraphy is well studied (e.g., Haas in a tectonic inlier south of Ereğli, NW Anatolia. In N 42° E 30° E 35° E 40° ’36’’ Ereğ li ZONGULDAK Black Sea İSTANBUL N 41°16’30’’ E 31°24 E 31°25’48’’ E 31°28’12’’ N 40° E 31°27’ ANKARA N 38° N 41°15’54’’ N 36° N 41°15’18’’ Mediterranean Sea 200 km E 29° E 30° E 31° E 32° E 33° Glüüç İSTANBUL TERRANE N 41°14’42’’ ZONGULDAK TERRANE Amasra Egemen (1947) ’ Dağlar ZONGULDAK Topçı al N 41°14’06’’ B l a c k S e a Ereğli N 41°30 Safranbolu Studied section Karasu Akç akoca Karadere ’ İSTANBUL Kabalakdere r N 41°13’30’’ Gö ktepe Çğamda N 41°00 Hamzafak ııl İİZM T Hendek Gebze BOLU 50 km 1 km Figure 1. Geographic position of the Gülüç section and Palaeozic outcrops in the İstanbul and Zonguldak terranes and Çamdağ area. 868 V. SACHANSKI ET AL. the recently published 1/100,000 scale geological above them and is characterized by three concordant maps (Altun & Aksay 2002) the Silurian outcrops packages. Th e succession is 28 m thick and is are not shown, although they had already been unconformably overlain by the Upper Cretaceous dated by Egemen (1947). Later, Dean in Dean et al. Yemişliçay Formation, comprising conglomerates, (2000) reported on Wenlock graptolites from grey volcaniclastic sandstones and andesites (Altun & mudstones of the Fındıklı Formation near Ereğli. Aksay 2002). Th e section is located on the road to the Gülüç Dam From the Gülüç section, Egemen (1947) fi rst (Figure 1) and includes a NE-dipping homoclinal fi gured and described Monograptus cf. armoricanus succession. Th e lowest part observed comprises Philippot, Monograptus cf. miloni Philippot brownish weathering mudstones and shales of and Monograptus cf. dubius Suess. We have no unknown age. Th e measured section (Figure 2) starts information whether this collection is stored. Th e G RAPTOLITES samples G-147 m CONODONTS 04-147 20 3 04-146 obograptus 15 L scanicus G-146 Gorstian 04-145 G-145 L U D L O W 04-144 03-8=04-143 Ozarkodina crassa Ozarkodina excavata excavata ex. gr. chimaera G-03-8 nilssoni sp. 04-142 10 eodiversograptus N G03-7 istiograptus b Kockelella Pr0-34 du ius sp. obograptus 04-141 L scanicus Saetograptus chimaera 04-140 5 O C K ? sp. onograptus 04-139 olonograptus obograptus Pristiograptus dubius pseudodubius M flemingii Cyrtograptus G03-2 C colonus L progenitor Homerian 04-138 ohemograptus B bohemicus W E N L ograptus Saetograptus chimaera semispinosus estograptus lundgreni G03-1 Gothograptus T testis Eisenackograptus eisenacki Cyrt 2 04-137 0 C RYPTOS SPORE Y Laevolancisdivellomedium , L. chibrikovae, L . sp. 1 , Dyadospora murusattenuata, Rugosphaera cerebra, nian- Pseudodyadospora petasus, Ps. laevigata, Gul1 Abditusdyadus laevigatus, Rimosotetras problematica,