Program > By author > Dojen Claudia

This contribution is the result of a joint venture by the Research Center Julich and the Bundesanstalt f. Geowissenschaften u. Rohstoffe (BGR) established 2005 and extended with colleagues from Italy and Austria in 2022. Previous results were published by Kranendonck (2004), Luppold (2008), Dojen (2009) and Lupplod et al. (2012).

The Hazro area in SE Anatolia, Turkey, is part of the Arabian Plate which adjoined the Tauride Block at the northern border. Both tectonic units strike the Assyrian/Zagros suture. The investigated succession is situated within the Border Fold zone and is part of the Hazro anticline, where Palaeozoic non-metamorphic sequences with a low thermal stage are exposed. The total thickness of the sequence is 700 m thick and includes Palaeozoic to Tertiary sediments.

The investigated Silurian carbonate sequence was deposited in an eroded anticline, which was deposited in a near shore environment at the northern margin of Gondwana. New biostratigraphic investigation enabled a new subdivision of formerly lithostratigrphic units. The lower part of the sequence is characterized by the Silurian Middle Dadas Formation (64 m) with black marl- and siltstones (Kranendonck 2004). The upper part of these sequence shows a biocalcarenitic limestone which grades to dolomitic limestone/claystone succession (12 m). The upper part belongs to the Devonian Upper Dadas Formation (54 m) represented by marl-, silt- and claystones and the Hazro Formation on top.

Beside the key section (Fetlika I) another section has been investigated only few meters away from the first one (Fetlika II). In contrast to Fetlika I, in Fetlika II there are some additional fossilferous limestones above the biocalcareneitic limestone unit with frequent brachiopod shells which were preliminary determined as Pridoli/Lochkovian in age. The facies reconstruction comprises proximal to distal sequences of a middle to outer shelf (Kranendonck 2004).

The first report on conodonts in this area were made by Fontaine et al. (1980). Beside conodonts, our samples (3 to 11 kg) contains a rich well preserved ostracod-fauna of fine-grained pyrit. The preservation corresponds to the Colour Alteration Index (CAI) of less than 2, indicating a low-grade temperature. Most of the specimens show the white matter.

Twelve conodont species, belonging to 7 genera (Coryssognathus, Oulodus, Ozarkodina, “Ozarkodina”, Panderodus, Wurmiella and Zieglerodina) were collected. The association can be referred to the lower-middle Pridoli “Oz.” eosteinhornensis s.l. interval Zone and Lower Oul. el. detortus Zone.

Representatives of family Spatognathodontidae dominates the fauna, whereas conoform elements are very rare. The basal phosphatic quarz layers are of special interest, because the conodont faunas contain more frequent specimens, most of gerontic age as in other layers, so it seemed to be a horizon of assorting mechanism. Other comparable rich conodont faunas appear at the upper part of the section, in limestone layers of a distal environment. In these limestones ramiform elements are very common and of good preservation, because a quiet water environment is assumed.

References

Dojen C. (2009): Late Silurian and Early Devonian Beyrichioidea from Gondwana and Perigondwanan terranes and their palaeobiogeographical implacations. Bull.Soc.Geol.Fr., 180: 215-221.

Fontaine J.M., Brunton C.H., Lys M., Rauscher R. & Balkas O. (1980): Données nouvelles sur la stratigraphie des formations palaéozoiques de la plat-forme arabe dans la région d'Hazro (Turquie). C.R.Acad.Sc.Paris, 291: 917-920.

Kranendonck O. (2004): Geo- and Biodynamic Evolution during Late Silurian/Early Devonian Time (Hazro Area, SE Turkey). Schriften des Forschungszentrums Jülich, Reihe Umwelt/Environment, 49, 268 pp.

Luppold, F. W. (2008): Conodont biostratigraphy around the Silurian/Devonian Boundary in SE Anatolia, Turkey. In: Königshof, P. & Linnemann, U. (Eds.) From Gondwana and Laurussia to Pangea: Dynamics of Oceans and Supercontinents. 20th International Senckenberg Conference Abstracts and Programs, 86-87.

Luppold, F.W., Brocke, R., Dojen. C., Mann, U. (2012): Silurian-Devonian Boundary in SE Anatolia: Present stage for the biostratigraphic positioning of the Boundary based on brachiopods, conodonts, ostracods and palynomorphs at the Hazro area. Turkish Association of Petroleum Geologists, Spec. Publ., 6: 111-113.