The Tethyan Seaway was the connection between the Eastern and Western Tethys which became restricted and finally closed during the Early and Middle Miocene. The growing Zagros Mountains split the seaway into two entities, the Iranian Gateway in the northeast and the Mesopotamian Gateway in the southwest. The reconstruction of the seaway is based on sedimentological and paleontological data of the Qom, Asmari and Gachsaran formations predominantly on biostratigraphy. This paper presents an evaluation and new data on the occurrence of the Qom Formation in the Zanjan area (Sheikh Jaber section) of Iran. The Qom Formation there is dominated by marls and sandstones and subordinated limestones. Unusual for the Qom Formation is the high share of volcanic rocks (basalts, tuffs, tuffitic marls, lapilli, coarse volcanoclastic components in all types of lithologies) which indicate that the Qom Formation in the Zanjan area belongs either to the Sanandaj-Sirjan Basin or the Urumieh-Dokhtar Basin. Planktonic foraminifers and mollusks, in particular, pteropods, indicate a late Burdigalian to Langhian age for the studied section. The mollusk fauna exhibits a pure Mediterranean character and no overlap with the Indo-Pacific fauna occurs. Both the fauna and the overlying continental deposits of the Upper Red Formation preclude a marine connection along the Iranian Gateway in the Langhian between the Proto-Mediterranean and Indian Ocean, the mollusk fauna also obviates a connection between the Proto-Mediterranean/Indian Ocean and the Eastern Paratethys. The sediments in the Mesopotamian Gateway are represented by the Asmari Formation, which is similar in facies and stratigraphy to the Qom Formation, and the Gachsaran Formation dominated by evaporites and shallow marine sediments. This gateway may have not been completely blocked in the Langhian, but the very shallow water connection was paleoceanographically ineffective and not passable for biota such as mollusks.

中文翻译：

---

中新世早期到中期的特提斯海道——新数据和回顾


特提斯海道是东特提斯海和西特提斯海的连接点，在早中新世期间受到限制并最终关闭。不断生长的扎格罗斯山脉将海道分成两个部分：东北部的伊朗门户和西南部的美索不达米亚门户。海道的重建基于库姆、阿斯马里和加赫萨兰地层的沉积学和古生物学数据，主要是生物地层学。本文介绍了伊朗赞詹地区（Sheikh Jaber 部分）库姆地层产状的评估和新数据。那里的库姆地层主要由泥灰岩和砂岩以及次要的石灰岩组成。库姆地层的不同寻常之处在于火山岩（玄武岩、凝灰岩、凝灰质泥灰岩、火山岩、所有类型岩性中的粗火山碎屑成分）所占比例很高，这表明赞詹地区的库姆地层要么属于萨南达季-锡尔詹盆地，要么属于萨南达季-锡尔詹盆地。乌鲁米耶-多赫塔尔盆地。浮游有孔虫和软体动物，特别是翼足类动物，表明所研究部分的年龄为布尔迪加晚期至朗吉期。软体动物群表现出纯地中海特征，与印度-太平洋动物群没有重叠。上红地层的动物群和上覆大陆沉积物都排除了原始地中海和印度洋之间的朗吉安伊朗门户沿线的海洋联系，软体动物群也排除了原始地中海/印度洋和印度洋之间的联系。东副特提斯。美索不达米亚门户地区的沉积物以阿斯马里组为代表，其相和地层与库姆组相似，而加赫萨兰组则以蒸发岩和浅海沉积物为主。 这个通道在朗吉亚可能没有被完全封锁，但从古海洋学角度来看，非常浅的水域连接是无效的，并且对于软体动物等生物群来说是无法通过的。