Stable carbon isotope chemostratigraphy and the associated reference curves have proved to be valuable tools for stratigraphic calibration and long-distance correlations. Nonetheless, the reference curves covering the Cretaceous have mostly been produced from localities located within the W Neo-Tethys. In order to establish a reference curve for the SE Neo-Tethys margin, an Aptian–Albian hemipelagic carbonate-rich succession deposited along the Zagros Basin (SW Iran) was examined for planktic foraminifera biostratigraphy, carbon isotope stratigraphy, and sedimentological characteristics. Eight biozones including Globigerinelloides ferreolensis, Globigerinelloides algerianus, Hedbergella trocoidea, Paraticinella bejaouaensis, Muricohedbergella planispira, Ticinella (T.) primula, Biticinella breggiensis, and Pseudothalmanninella (P.)ticinensis as well as two subzones enclosing T. praeticinensis and P. subticinensis assign the strata to the early late Aptian–late Albian age. A carbon isotope record constrained by the planktic foraminifera zonation scheme shows good concordance with existing composite reference curves from the W Neo-Tethys region. Several carbon isotope excursions (CIEs) characterizing global marine events including Oceanic Anoxic Event (OAE) 1a, OAE1b, OAE1c and associated sub-events can be identified in the studied section. Deoxygenated bottom waters associated with the formation of OAE1a and OAE1b are indicated by distinct lithological signatures including enrichment in pyrite and glauconite, nodular and stratiform chert beds, as well as enhanced organic matter contents. We integrate the here-studied interval with a previously published upper Albian−Turonian succession from the same outcrop section, forming a composite, stratigraphically well-constrained section. This results in a high-resolution carbon isotope record for the SE Neo-Tethys margin, considered to represent an expedient reference Aptian–Turonian curve for this region. Correlation of this new curve with previously published records from the Middle East has helped to address ambiguities regarding the stratigraphic positions of the early/late Aptian and Aptian/Albian boundaries identified by previous studies.

中文翻译：

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东南新特提斯地区（伊朗西部扎格罗斯）的白垩纪中期碳同位素参考曲线


稳定碳同位素化学地层学和相关的参考曲线已被证明是地层校准和长距离相关性的宝贵工具。尽管如此，覆盖白垩纪的参考曲线大多来自位于 W Neo-Tethys 内的地方。为了建立 SE Neo-Tethys 边缘的参考曲线，研究了沿 Zagros 盆地（伊朗西南部）沉积的 Aptian-Albian 半弹性富含碳酸盐的演替，以评估浮游有孔虫生物地层学、碳同位素地层学和沉积学特征。八个生物区，包括 Globigerinelloides ferreolensis、Globigerinelloides algerianus、Hedbergella trocoidea、Paraticinella bejaouaensis、Muricohedbergella planispira、Ticinella （T.） primula、Biticinella breggiensis 和 Pseudothalmanninella （P.）ticinensis，以及包围 T. praeticinensis 和 P. subticinensis 的两个亚区，将地层归类为阿普蒂安晚期至晚期阿尔比亚时代早期。受浮游有孔虫分区方案约束的碳同位素记录与 W Neo-Tethys 区域的现有复合参考曲线具有良好的一致性。在研究部分可以确定表征全球海洋事件的几种碳同位素偏移 （CIE），包括海洋缺氧事件 （OAE） 1a、OAE1b、OAE1c 和相关子事件。与 OAE1a 和 OAE1b 形成相关的脱氧底水由不同的岩性特征表明，包括黄铁矿和海绿石中的富集、结节状和层状燧石床，以及有机质含量的增加。 我们将本文研究的层段与先前发表的来自同一露头部分的上阿尔比亚-图罗尼亚演替相结合，形成了一个复合的、地层学上约束良好的部分。这导致了 SE Neo-Tethys 边缘的高分辨率碳同位素记录，被认为代表了该区域的权宜之计参考 Aptian-Turonian 曲线。这条新曲线与先前发表的中东记录的相关性有助于解决先前研究确定的 Aptian 和 Aptian/Albian 边界的早期/晚期地层位置的歧义。