See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/250166975 Devonian in Turkey - A review Article in Geologica Carpathica · June 2010 DOI: 10.2478/v10096-010-0014-3 CITATIONS READS 27 1,025 2 authors: M. Namık Yalçın Isak yılmaz Istanbul University Istanbul University 89 PUBLICATIONS 1,087 CITATIONS 11 PUBLICATIONS 126 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: Silurian / Devonian Boundary View project Thermal Analysis of Source Rocks for characterization and decontamination View project All content following this page was uploaded by Isak yılmaz on 13 May 2015. The user has requested enhancement of the downloaded file. GEOLOGICA CARPATHICA, JUNE 2010, 61, 3, 235—253 doi: 10.2478/v10096-010-0014-3 Devonian in Turkey – a review M. NAMIK YALÇIN and ISAK YILMAZ Istanbul University, Faculty of Engineering, Department of Geological Engineering, TR-34850 Avcôlar-Istanbul, Turkey; [email protected]; [email protected] (Manuscript received August 13, 2009; accepted in revised form December 11, 2009) Abstract: The Devonian Period is represented in Turkey by almost complete non-metamorphic sections of more than 1000 meters, which exhibit varying lithofacial associations. They are parts of thick Paleozoic sedimentary successions in the Pontides, Taurides and Arabian Plate. The tectonic setting and the paleogeographical origin of these terranes is different. Therefore, the litho- and biostratigraphy and facies characteristics of these Devonian successions would enable a comparison and a paleogeographical assignment of these tectono-stratigraphic units. Devonian successions of the Arabian Plate and of the Taurides are represented by facies associations ranging from tidal flat to a deep shelf. Whereas, those of the Istanbul and Çamdag-Zonguldak˘ areas in the Pontides by a deepening upward sequence from a shallow shelf into a basin and a stable shelf, respectively. The Devonian of the Arabian Plate and the Taurides can surely be assigned to Gondwana. A Peri-Gondwanan (Avalonian) setting is suggested for the paleogeographic position of the Devonian of the Pontides. Key words: Devonian, Turkey, paleogeography, depositional environment, biostratigraphy, lithostratigraphy. Introduction ous authors from north to south as Pontides, Sakarya Conti- nent, Menderes and Kôrehir Blocks, Taurides and the Arabi- The geological and tectonic frame of Turkey, located in the an Plate (Fig. 1), generally represent continental terranes Alpine-Himalayan Orogenic Belt, is mainly formed by the separated by suture zones. The suture zones are in general Alpine orogeny. Accordingly, a number of E-W trending composed of ophiolitic and volcanic rocks of oceanic origin tectono-stratigraphic units are defined, which consist of ter- (Ketin 1966; engör & Yôlmaz 1981; Göncüoglu˘ 1997). Not ranes of different tectonic settings ranging from oceanic ba- only the tectonic setting of these terranes is different, but sins to active and passive continental margins. The also the geological age of the incorporated units reflects a tectono-stratigraphic units as distinguished by many previ- wide spectrum from Infra-Cambrian to Tertiary. Fig. 1. Tectonic map of Turkey showing the major blocks/terranes and the bounding suture zones. Distribution of Devonian succesions are also shown and those, which are discussed in detail, are indicated by numbers. 1 – Istanbul Zone, 2 – Çamda˘g area, 3 – Eastern Taurides, 4 – Cen- tral Taurides, 5 – Aladag˘ and Bolkardag˘ Units in Taurides, 6 – Western Taurides, 7 – Karaburun area, 8 – Hakkari area of Arabian Plate, 9 – Hazro area of Arabian Plate, 10 – Amanos area of Arabian Plate. (Modified from engör & Yôlmaz 1981 and Elmas & Yi˘gitba 2001.) www.geologicacarpathica.sk 236 YALÇIN and YILMAZ Devonian units of different litho-types and of different quently, the Silurian/Devonian (S/D) boundary has to be lo- paleogeographic origin are parts of thick Paleozoic sedimen- cated within the uppermost part of the Dada Formation. tary successions of the Pontides, Taurides and Arabian Plate. Some recent efforts to localize the S/D boundary in Hazro area Some minor occurrences of sedimentary Devonian are also along the measured stratigraphic section Fetlika and in the reported from the Karaburun area and Aegean Islands in well Fetlika-1 showed that the boundary cannot be localized westernmost Turkey relatively early by Ktenas (1925) only by palinomorphs (Mann et al. 2001; Kranendonck 2004; (Fig. 1). This region was studied then by many scientists be- Brocke et al. 2004). In the Amanos area and in the Hakkari cause of the complicated stratigraphy and tectonics (Höll area, respectively to the west and east of Southeastern Anato- 1966; Lehnert-Thiel 1969; Konuk 1979; Erdogan˘ et al. 1990; lia, Silurian is not represented (Yôlmaz & Duran 1997). Con- Kozur 1995; Kaya & Rezsu 2000; Rosselet & Stampfli sequently, Upper Devonian Yôg˘ ônlô and Köprülü Formations 2002; Eren et al. 2004; Çakmakoglu˘ & Bilgin 2006; Okay et lie with an angular unconformity on the Ordovician Bedinan al. 2006). A relatively thick succession bearing also Devo- Formation (Fig. 2). nian units is interpreted by Çakmakoglu˘ & Bilgin (2006) as autochthonous. The same succession was considered by Ko- Litho- and biostratigraphy of the Devonian in the Hazro zur (1995, 1997) and Rosselet et al. (2003) as an allochtho- area nous sedimentary melange. Most recent studies however showed that Devonian rocks in the Karaburun area are al- The Devonian succession in the Hazro area north of Di- lochthonous blocks and olistolith within the Carboniferous yarbakôr (Fig. 1) is named as the Diyarbakôr Group and is flysch (Robertson & Ustaömer 2009). composed of the Dada, Hazro and Kayayolu Formations Metamorphic Devonian units are reported from parts of the (Bozdogan˘ et al. 1987) (Fig. 2). The Kayayolu Formation is Central Anatolian Massif, Menderes Massif in western Turkey only encountered in wells, whereas outcrops of Dada and and in eastern Turkey from the Bitlis Massif (Göncüoglu˘ & Hazro Formations are represented in the so-called Hazro High. Turhan 1983). The total thickness of these units on the surface varies be- The aim of this paper is to give an overview of the Turkish tween 70 and 217 m (Sungurlu 1974; Bozdogan˘ et al. 1987). autochthonous and non-metamorphic Devonian. Hereby, In the subsurface they can be up to 500 m thick (Bozdogan˘ et based mainly on the data obtained from previous studies, the al. 1987). Within the Dada Formation, three subunits (mem- geographical distribution, general geological setting, litho- bers) are distinguished based on different lithological compo- and biostratigraphy and facies characteristics of these Devo- sition, which are reflected in log characteristics (Bozdogan˘ et nian successions will be addressed on the basis of the tectono- al. 1987). The Dada I Member consists of dark coloured, or- stratigraphic subdivision of Turkey. ganic rich shales with some limestone interbeds; the Dada II Member is composed of similar shales alternating with some sandstones and the Dada III Member consists of an alterna- Devonian of the Arabian Plate in Southeastern tion of sandstones, marls and calcareous siltstones. The Dada Anatolia Formation lies unconformably on the Middle—Upper Ordovi- cian Bedinan Formation and is overlain conformably by the The Devonian of the Arabian Plate is represented in South- Devonian Hazro Formation (Bozdogan˘ et al. 1987; Perinçek et eastern Anatolia by sedimentary sequences observed from al. 1991). The Dada Formation is rich in fossils of palinomor- west to east in the Amanos Mountains, Hazro High and phs, brachiopods, bryozoans, graptolites, conodonts, crinoids, Hakkari area. Furthermore, they are encountered in some corals and ostracods. Fossil assemblages reported by different wells around the Diyarbakôr area (Fig. 1). The Devonian of the authors (Çoruh et al. 1997 and references there in) from the northerly located Hazro area is represented by Lower to Upper middle and upper parts of the Dada Formation are listed in Devonian, while the Devonian of the other two regions con- the Appendix. According to these fossils and to detailed pali- sists of only Upper Devonian (Bozdogan˘ et al. 1987; Yôlmaz nological studies by Bozdogan˘ et al. (1987), Ertug˘ et al. & Duran 1997). But, in both geological settings the underlying (1998), Brocke et al. (2004), Bozdogan˘ et al. (2005) a Late units are similar. A thick Pre-Cambrian to Upper Ordovician Silurian—Early Devonian age is assigned to the Dada Forma- continuous sedimentary sequence forms the pre-Devonian tion. As mentioned before, the exact location of Silurian/De- basement in both settings (Fig. 2). The Silurian-Devonian vonian boundary is still not determined. The Dada Formation Dada Formation, outcrops only in Diyarbakôr in the Hazro was deposited on a restricted inner shelf, which was devel- High and is also encountered in some wells there. According oped on the irregular paleotopography of the eroded Bedinan to observations and records in Kayayolu-2 well this unit was Formation. The respective shelf became shallower and was deposited after a regional break in sedimentation (Bozdogan˘ et gradually converted to a tidal flat towards the top of the se- al. 1987; Yôlmaz & Duran 1997). Therefore it is inferred, that quence (Yôlmaz & Duran 1997). the Dada Formation lies with an angular unconformity on the The following Hazro Formation consists in general of an al-