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The Silurian-Lower Devonian succession in the Değirmentaş-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 Gurleşen 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 Değirmentaş-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. [ABSTRACT FROM AUTHOR]

Abstract: 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. The graptolitic shales in the Zonguldak Terrane are time-equivalents of the (late Llandovery) violet shales with green layers from a less deep basin in E Istanbul Terrane. In the W Istanbul Terrane, reddish sandstones with Fe-oolitic minerals and brachiopod-bearing carbonates were deposited during the late Llandovery maximum transgression. The early Silurian deposits in the Zonguldak Terrane are more akin to those of E Avalonian successions, whereas those of the Istanbul terrane resemble those of the Gondwanan periphery. Moreover, the studied sections enable the recognition of the regressive trend (or part of it) in this high level stand, as indicated by the deposition of pale and grey-greenish mudstone layers, carbonates and shell beds. [Copyright &y& Elsevier]