The Miocene Climate Optimum (MCO) and the subsequent Miocene Climate Transition (MCT) are important biotic, environmental and geologic events. Here we address whether this holds true for the epicontinental Eastern Paratethys Sea (today's Black – Caspian Sea region). Two Tarkhanian – lower Chokrakian sequences of Middle Miocene age in the Kerch Peninsula were investigated using foraminifera, calcareous nannofossils, molluscs, fish otoliths, spores and pollen, oxygen and carbon stable isotopes and strontium isotope stratigraphy (SIS). Our results show that the marine environment during the Tarkhanian to early Chokrakian in the study area was characterized by open shelf conditions (near upper part of lower sublittoral zone), variable water column stratification and bottom water oxygen levels. Biostratigraphy and new SIS data suggest an age of >15.5 (∼16.0?) – 14.75 Ma for the Tarkhanian, which implies a considerably longer duration (> 0.75 Ma vs. 0.1 Ma) than was previously suggested. The maximum transgression seen in the middle Tarkhanian could be dated to ∼15.5–15.1 Ma and correlates with the highstand of sequence Bur 5/Lan 1 (15.2 Ma) and terminal phase of the MCO. The vegetation indicates a gradual change from subtropical humid (early Tarkhanian) to arid (early Chokrakian) conditions, which reflect the MCT. The climate change in the Eastern Paratethys occurred slightly earlier than in the Central Paratethys, possibly related to the existence of the large flat Eurasian continent.

中新世气候最适期 (MCO) 和随后的中新世气候转变 (MCT) 是重要的生物、环境和地质事件。在这里，我们讨论这是否适用于大陆表层东副提斯海（今天的黑-里海地区）。使用有孔虫、钙质超微化石、软体动物、鱼类耳石、孢子和花粉、氧和碳稳定同位素以及锶同位素地层学 (SIS) 研究了刻赤半岛中中新世的两个 Tarkhanian - 下 Chokrakian 序列。我们的研究结果表明，研究区塔尔干阶至早期乔克拉奇期的海洋环境具有开放陆架条件（靠近下滨海带上部）、可变水柱分层和底水含氧量的特征。生物地层学和新的 SIS 数据表明年龄 > 15.5 (∼16.0?) – 14.75 Ma 对于 Tarkhanian，这意味着持续时间比之前建议的要长得多（> 0.75 Ma 对 0.1 Ma）。在 Tarkhanian 中期看到的最大海侵可以追溯到 ~15.5-15.1 Ma，并且与序列 Bur 5/Lan 1（15.2 Ma）的高位和 MCO 的末期相关。植被表明从亚热带湿润（早期 Tarkhanian）到干旱（早期 Chokrakian）条件的逐渐变化，这反映了 MCT。东副陆的气候变化发生时间略早于中副陆，可能与大而平坦的欧亚大陆的存在有关。在 Tarkhanian 中期看到的最大海侵可以追溯到 ~15.5-15.1 Ma，并且与序列 Bur 5/Lan 1（15.2 Ma）的高位和 MCO 的末期相关。植被表明从亚热带湿润（早期 Tarkhanian）到干旱（早期 Chokrakian）条件的逐渐变化，这反映了 MCT。东副陆的气候变化发生时间略早于中副陆，可能与大而平坦的欧亚大陆的存在有关。在 Tarkhanian 中期看到的最大海侵可以追溯到 ~15.5-15.1 Ma，并且与序列 Bur 5/Lan 1（15.2 Ma）的高位和 MCO 的末期相关。植被表明从亚热带湿润（早期 Tarkhanian）到干旱（早期 Chokrakian）条件的逐渐变化，这反映了 MCT。东副陆的气候变化发生时间略早于中副陆，可能与大而平坦的欧亚大陆的存在有关。