Abstract The Dardanelles region has formed a key gateway connecting the Eastern Paratethys and the Aegean/Mediterranean since the late Miocene. Its sedimentary sequences contain crucial information about connectivity and tectonics but so far lack unambiguous age constraints. Only a few Miocene marine episodes have been documented and fossil assemblages are predominantly composed of Paratethyan fauna (mollusks and ostracods). Here, we apply an integrated stratigraphic approach and use the recently established chronostratigraphy for the Eastern Paratethys to re-evaluate the faunal assemblages and palaeoenvironments of the Seddulbahir and Intepe sections that allegedly played a crucial role in the geodynamic evolution of the Dardanelles during the Messinian-Zanclean. The Paratethyan ostracods and mollusks, however, clearly indicate that these sections correspond to the middle Tortonian (~9 Ma; Bessarabian–Khersonian in Eastern Paratethys terminology). Nannofossil assemblages are dominated by a mixing of reworked taxa from the late Eocene and Oligocene and no age-diagnostic taxa have been observed. Dinoflagellate analyses are also hampered by reworking and mainly reveal non-marine (fresh to oligohaline) aquatic conditions. Fossil mammal remains in the Seddulbahir section and other localities in the region confirm the late Miocene age. Strontium (87Sr/86Sr) isotope ratios of the anomalohaline (brackish) ostracods are significantly below open ocean values and similar to values obtained from Khersonian ostracods of Bulgaria. Fresh water assemblages reveal much higher 87Sr/86Sr values, which are interpreted to reflect the composition of local rivers. We conclude that in late Miocene times the Dardanelles region was a fresh to anomalohaline embayment, ephemerally connected to the Eastern Paratethys. We found no evidence for a major Messinian erosional surface nor for marine Mediterranean fossils indicative of the early Zanclean. Our results furthermore indicate that the proposed Messinian age for the propagation of the North Anatolian Fault into the Dardanelles region must be revised.

中文翻译：

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墨西拿达达尼尔海峡的神话：古爱琴海-黑海门户的晚中新世地层学和古地理

摘要 中新世晚期以来，达达尼尔海峡地区已成为连接东帕特提斯海和爱琴海/地中海的重要门户。它的沉积层序包含有关连通性和构造的重要信息，但迄今为止缺乏明确的年龄限制。只有少数中新世海洋事件被记录在案，化石组合主要由Paratethyan动物群（软体动物和介形动物）组成。在这里，我们应用综合地层学方法并使用最近建立的东帕特提斯年代地层学来重新评估 Seddulbahir 和 Intepe 部分的动物群组合和古环境，据称这些部分在墨西拿-赞克利。然而，Paratethyan 介形动物和软体动物，清楚地表明这些部分对应于托托尼阶中期（~9 Ma；东帕特提斯术语中的比萨拉比亚-赫尔松阶）。纳米化石组合主要由始新世晚期和渐新世重新加工的分类群的混合组成，并且没有观察到具有年龄诊断的分类群。甲藻分析也受到返工的阻碍，主要揭示非海洋（新鲜到低盐）水生条件。化石哺乳动物仍然在 Seddulbahir 部分，该地区的其他地方证实了晚中新世时代。异常盐碱（微咸）介形虫的锶 (87Sr/86Sr) 同位素比率明显低于公海值，与从保加利亚的赫尔松介形虫获得的值相似。淡水组合显示出更高的 87Sr/86Sr 值，这被解释为反映了当地河流的组成。我们得出的结论是，在中新世晚期，达达尼尔海峡地区是一个新鲜到异常盐碱的海湾，短暂地与东帕特提斯相连。我们没有发现主要的墨西拿侵蚀表面的证据，也没有发现表明早期赞克林的地中海海洋化石的证据。我们的研究结果进一步表明，必须修改提议的将北安纳托利亚断层传播到达达尼尔海峡地区的墨西拿时代。