A global view on the Ordovician stratigraphy of south-eastern Europe

The Ordovician documented in south-eastern Europe reflects different sedimentary environments, from shallow water to basin, belonging to diverse palaeogeographical domains. Some of these geological sectors and their palaeontological content have been well described for a long time, like the Carnic Alps, that represent one of the most continuous Palaeozoic sequence in the world. For some other areas, the quality of the data is variable and the knowledge is less detailed, sometimes with lithostratigraphic units still to be formalized, also reflecting the fragmentary nature of the outcrops. The Ordovician stratigraphy of diverse successions of south-eastern Europe has been herein revised and integrated with new data in the attempt of detecting a global scenario for this critical time interval in the evolution of life.This research was undertaken within the framework and with the financial support of the Spanish Ministry of Science and Innovation, project PID2021-125585NB-100 (to JCG-M and JC).Peer reviewe

The palaeopsychrosphere in the Devonian

International audienc

Late Telychian (early Silurian) graptolitic shales and the maximum Silurian highstand in the NW Anatolian Palaeozoic terranes

The late Llandovery included a period of global sea-level rise with a maximum in the spiralis graptolite Biozone, recorded by black graptolitic shales or red beds. Recent work in the less- known Silurian successions in the Zonguldak Terrane, NW Anatolia, has revealed the presence of Llandovery graptolitic black shales in the lower part of the Findikli Formation in the Camdag, Catak and Karadere areas. In the Camdag area, the "black shale member" yielded numerous well preserved graptolite rhabdosomes, including Oktavites spiralis, Barrandeograptus pulchellus and Retiolites geinitzianus. It is suggested that the graptolitic shales in this area were deposited during the spiralis-lower lapworthi zones. In the Catak and Ovacik areas, black shales intercalated with yellow shales yielded O. spiralis and R. geinitzianus. The deposition of black shales is related to the time of maximum Silurian sea level

Wenlock (Silurian) graptolitic shales from the Kocaeli Peninsula (Derince-Izmit), NW Turkey

Alternating dark grey to black thin-bedded limestones and yellowish-grey calcareous shales in a recently discovered section in Izmit (Derince), eastern Kocaeli Peninsula, yielded graptolites of the middle part of the Wenlock-Cyrtograptus lundgreni Zone and possibly Upper Cy. rigidus-Cy. perneri Zone. This is the first record of graptolitic shale facies rocks in the Kocaeli Peninsula. The succession described is more akin to the Silurian of the Zonguldak Terrane than the shallow-marine carbonate facies of the Istanbul Terrane. It is therefore suggested that the contact between the Istanbul and Zonguldak terranes should be located to the west of Izmit (Derince)

Thuringian affinity of the Silurian-Lower Devonian succession from the Eastern Taurus, Turkey

The Silurian-Lower Devonian succession in the Degirmentas-Halevikdere section (E Taurides) shows considerable lithostratigraphic similarities to the three-partite subdivision, initially documented in the same stratigraphic interval in Saxo-Thuringia and later in other peri-Gondwanan terrains. The Llandovery-Wenlockian part of the studied section (ca. 40 m) is characterized by black graptolitic shales. The Llandoverian part is dominated by radiolarian ribbon cherts (ca. 20 m). The Rhuddanian Akidograptus ascensus, Parakidograptus acuminatus, and Cystograptus vesiculosus biozones have been recognized in its lower part, while in the upper part of the succession, the lowermost Telychian Rastrites linnaei Biozone has been documented. The Telychian Spirograptus turriculatus and Streptograptus crispus biozones, as well as the Sheinwoodian Cyrtograptus rigidus/Monograptus belophorus Biozone, have been identified within this succession. Graptolites of the Homerian (Colonograptus deubeli + Col. praedeubeli and Col. ludensis biozones) are only found in the Pekmezkoy and Gurlesen areas, in the black shales, immediately before the first ocher-colored limestone, which is characteristic for the Ockerkalk Formation in the Thuringian facies. The dominantly ocher-colored shale-limestone alternation in the Degirmentas-Halevikdere section is ca. 50 m in thickness. The lower Ludlowian part is enriched by nautiloids, while in the Pridolian part crinoids are abundant. It is covered by 60-m-thick black shales and siltstones, corresponding to the Upper Graptolite Shale Formation in the Thuringian. The Silurian-Devonian boundary is located in the lower part of this unit on the basis of lobolith findings. The depositional model proposed here accounts for the migration of the considered peri-Gondwana terrains from high to low paleogeographic latitudes that has triggered changes not only in the ocean water thermohaline circulation but also in the wind-driven downwelling or upwelling systems. These changes are responsible for the progressive transition from an oxic regime to an anoxic one in the deep oceanic depositional environments (outer continental shelf, slope, and ocean basin settings) and the deposition of light and dark sediments there

Facies transition and biostratigraphic correlation of the Upper Silurian and Lower Devonian in West Bulgaria

Upper Silurian and Lower Devonian shelf deposits in West Bulgaria are exposed in three main Alpine tectonic units: the West Balkan Unit, the Lyubash Monocline and the Morava Unit. The West Balkan and Lyubash units consist of siliciclastic deposits: black graptolitic shales, banded pale shales and black siltstones. The Ludlow, Pridoli, Lochkovian, Pragian and Emsian were recognized on the basis of graptolite and tentaculite faunas. In the Morava Unit, the Ludlow black shales are progressively replaced by clayey limestones and nodular and micritic limestones in the Pridoli and Early Devonian. Newly obtained conodonts show the presence of the siluricus, eosteinhornensis, woschmidti, postwoschmidti, delta-pesavis, sulcatus, dehiscens and gronbergi zones. Petrographic study of the Morava Unit shows an increasing carbonate content and shallowing conditions upwards. The biostratigraphical correlation and facies interpretation reveal the coeval existence of two different depositional environments within the same shelf basin as well as a gradual shift in proximal direction

Nuevos hallazgos de graptolitos en el Ordovícico de Bulgaria

5 páginas.-- En Rábano, I. (Ed.), Actas de las XV Jornadas de Paleontología y Simposios de los Proyectos PICG 393, 410 y 421.Peer reviewe

Braquiópodos inarticulados del Ordovícico Inferior de la Unidad Ranovac-Vlasina ("Supragethicum") y paleobiogeografía de las unidades tectónicas balcánides de Serbia oriental (Yugoslavia)

9 páginas.-- En Rábano, I. (Ed.), Actas de las XV Jornadas de Paleontología y Simposios de los Proyectos PICG 393, 410 y 421.Peer reviewe

Ordovician graptolites from the basal part of the Palaeozoic transgressive sequence in the Karadere area, Zonguldak Terrane, NW Turkey

The Karadere area to the east of Safranbolu in NW Anatolia is one of the very few localities in Turkey where the contact between the Cadomian basement and the Lower Palaeozoic transgressive succession is well exposed. The Ordovician graptolite Rhabdinopora flabelliformis (Eichwald) ssp. was found in the basal part of the Bakacak Formation, indicating an Early to early Late Tremadocian age for the beginning of the Palaeozoic transgression in the Zonguldak terrane. A few metres above this occurrence, another horizon contains Paradelograptus cf. antiquus (T. S. Hall), which mainly ranges into the Late Tremadocian. Higher up in the Ordovician succession, a new graptolite bed confirms an early Darriwilian (Dw1) age for the middle part of the Karadere Formation with the occurrence of the biozonal index Levisograptus austrodentatus (Harris & Keble) and the first record of Tetragraptus cor (Strandmark) in the area. The palaeobiogeographic distribution of these Karadere fossils is in agreement with a peri-Gondwanan affinity of the Zonguldak Terrane of the Pontides, NW Anatolia, during the Early–Middle Ordovician

Silurian Graptolite, Conodont and Cryptospore Biostratigraphy of the Guluc Section in Eregli, Zonguldak Terrane, NW Anatolia, Turkey

The studied Guluc section of the Silurian Findikli Formation is situated on the western bank of Guluc Creek in Eregli, NW Anatolia, Turkey, in the eastern part of the Zonguldak Terrane. The Guluc 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. The Ozarkodina crassa Biozone occurs in the lower Gorstian (Ludlow). The specific features of the Guluc section (lithological changes, condensation, stratigraphic gap, change in graptolite diversity) are related to the global model of Silurian T-R cycles. The Silurian Findikli Formation in the Guluc section, about 20 m thick, represents a condensed lithological succession which differs significantly from the coeval thick, stratigraphically widespread black shales and siltstones of the same formation in the Zonguldak and Istanbul terranes. Sixteen cryptospore species are described and their stratigraphic and geographic distributions are summarised