Abstract

Diverse and well-preserved marine palynomorphs occur in the Padeha, Khoshyeilagh, and Mobarak formations in the Khoshyeilagh area, northeastern Alborz, northern Iran. The marine palynomorph assemblages consist of acritarchs, prasinophytes, and chitinozoans, comprising 27 genera and 46 species. In addition, the studied sediments contain 20 species of algae, foraminifera, and corals allocated to 11 genera. The vertical distribution of acritarchs and chitinozoans allows the erection within these sediments of three local assemblage zones. Biozone I occurs in the upper part of the Padeha Formation and the basal part of the Khoshyeilagh Formation, suggesting a Frasnian–early Famennian age; Biozone II is present in the Khoshyeilagh Formation and indicates a Famennian age. Biozone III, which occurs in the basal part of the Mobarak Formation, suggests a Tournaisian age for this interval. Many of the palynomorph species, such as Crassiangulina tessellita, Daillydium pentaster, Deltotosoma intonsum, Gorgonisphaeridium discissum, Helosphaeridium microclavatum, Horologinella horologia, Papulogabata annulata, Somphophragma miscellum, and Veryhachium downiei, are closely comparable with coeval assemblages recorded from Australia, Ireland, Portugal, Saudi Arabia, North Africa, South America, and North America. This indicates the close relationship of the Iranian Platform to other parts of the northern Gondwana and southern Laurentian domain during the Late Devonian–Early Carboniferous. Moreover, results of similarity indices of marine microphytoplankton indicate a relatively high degree of similarity between the assemblages of the Khoshyeilagh area and those elsewhere in the Alborz Mountains and the Kerman Basin. Palaeontological evidence indicates that the Khoshyeilagh Formation was deposited in a low-energy, somewhat offshore, normal marine environment within the Alborz Basin, along the Palaeo-Tethys Ocean during this time interval. Furthermore, based on palynological data gathered from Iran, it can be concluded that Iran was an island during this interval of time.

摘要

伊朗北部Alborz东北的Khoshyeilagh地区的Padeha，Khoshyeilagh和Mobarak地层中分布着多种多样且保存完好的海洋小孢粉。海洋古植物组合由顶头纲，古生物和奇偶虫组成，共27属46种。此外，研究的沉积物包含20种藻类，有孔虫和分布于11个属的珊瑚。头颅和甲壳动物的垂直分布允许在这些沉积物中勃起三个局部组合区。生物区I位于Padeha组的上部和Khoshyeilagh组的基部，暗示着一个弗拉斯尼期至早法门尼期。生物区II存在于Khoshyeilagh组中，表明法门尼时代。发生在莫巴拉克组基础部分的生物区III，建议在此间隔内使用图尔尼斯人的年龄。许多古植物种类，例如Crassiangulina tessellita，Daillydium pentaster，Dontosoma intonsum，Gorgonisphaeridium discissum，Helosphaeridium microclavatum，Horologinella horologia，Papulogabata annulata，Somphophragma miscellum和Veryhachium downiei与来自澳大利亚，爱尔兰，葡萄牙，沙特阿拉伯，北非，南美和北美洲的记录的中世纪组合非常相似。这表明在晚泥盆纪—石炭纪早期，伊朗平台与冈瓦纳北部和洛伦山脉南部的其他地区之间的紧密关系。此外，海洋微浮游植物相似性指数的结果表明，Khoshyeilagh地区的组合与Alborz山区和Kerman盆地其他地区的组合之间具有相对较高的相似性。古生物学证据表明，在此时间段内，Khoshyeilagh组沉积在Alborz盆地内沿古特提斯海洋的低能，近海，正常海洋环境中。此外，根据从伊朗收集的古生物学数据，