Abstract Calcareous nannofossils are a valuable proxy commonly used in biostratigraphic and paleoenvironmental studies. A high-resolution biostratigraphic analysis of the Pabdeh Formation and transitional interval was undertaken in one of the oilfields, located in the Strait of Hormuz in Iran. The stratigraphic interval studied includes marl, argillaceous limestones and interlayers of limestone and shale. In this study, for the first time, Paleogene calcareous nannofossil assemblages comprising 67 species belonging to 28 genera were identified. The calcareous nannofossils data led to the identification of several bio-zones NP5-NP20 (CNP7-CNE20) in the Pabdeh Formation and transitional interval, these nannofossil zones allow dating the section to the Late Paleocene (Selandian) - Late Eocene (Priabonian). The biostratigraphy model, highlights the existence of relatively good continuity across the Selandian/Thanetian (S/T), Thanetian/Ypresian, Ypresian/Lutetian and Bartonian/Priabonian stage boundaries. Also, the presence of index calcareous nannofossils (e.g., Discoaster, Sphenolithus, Reticulofenestra, Dictyococcites and Helicosphaera) from the Tethyan realm and low latitude in the studied section indicates that sea level temperature has been frequently warm between the Selandian and Priabonian intervals. In addition, the calcareous nannofossils analysis indicated that their diversity and abundance changed with climate fluctuations from the Paleocene to Eocene.

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特提斯王国扎格罗斯盆地（伊朗）晚古新世-晚始新世钙质纳米化石生物地层学

摘要 钙质纳米化石是生物地层学和古环境研究中常用的一种有价值的替代物。在位于伊朗霍尔木兹海峡的一个油田中对 Pabdeh 组和过渡层段进行了高分辨率生物地层分析。研究的地层层段包括泥灰岩、泥质石灰岩以及石灰岩和页岩夹层。本研究首次鉴定出古近系钙质纳米化石组合，包括28属67种。钙质纳米化石数据导致在 Pabdeh 组和过渡层段中确定了几个生物带 NP5-NP20 (CNP7-CNE20)，这些纳米化石带允许将该剖面定年为晚古新世 (Selandian) - 晚始新世 (Priabonian)。生物地层模型，突出了跨越 Selandian/Thanetian (S/T)、Thanetian/Ypresian、Ypresian/Lutetian 和 Bartonian/Priabonian 阶段边界的相对良好的连续性。此外，来自特提斯王国和低纬度研究部分的指数钙质纳米化石（例如，Discoaster、Sphenolithus、Reticulofenestra、Dictyococcites 和 Helicosphaera）的存在表明，Selandian 和 Priabonian 间隔之间的海平面温度经常温暖。此外，钙质纳米化石分析表明，从古新世到始新世，它们的多样性和丰度随着气候波动而变化。来自特提斯王国和低纬度的 Discoaster、Sphenolithus、Reticulofenestra、Dictyococcites 和 Helicosphaera）表明，海平面温度在 Selandian 和 Priabonian 区间之间经常温暖。此外，钙质纳米化石分析表明，从古新世到始新世，它们的多样性和丰度随着气候波动而变化。来自特提斯王国和低纬度的 Discoaster、Sphenolithus、Reticulofenestra、Dictyococcites 和 Helicosphaera）表明，海平面温度在 Selandian 和 Priabonian 区间之间经常温暖。此外，钙质纳米化石分析表明，从古新世到始新世，它们的多样性和丰度随着气候波动而变化。