Abstract Cyclostratigraphy plays a pivotal role in detecting and reporting Milankovitch cycles in sedimentary successions which allows for creating an independent astronomical time scale and estimates of sediment accumulation rates. In this study, cyclostratigraphic analysis of petrophysical logs from Lower Triassic Kangan Formation was performed in two wells of the Salman gas field, eastern part of the Persian Gulf, Iran. The results of power spectral analysis in the two studied wells reveal the main spectral peaks at wavelengths of long-eccentricity, short-eccentricity, obliquity, and precession cycles. Based on the orbital tuning using the long-eccentricity cycles, a floating astronomical time scale was established, according to which the depositional duration of Kangan Formation was estimated to be 1.6 ± 0.1 Myr. As well as, the duration of the Induan Stage of the Early Triassic Epoch in this study is estimated to be at least 1.6 Myr. Also, by integrating cyclostratigraphic analysis, results of the statistical methods of sedimentation rate evaluation, i.e., evolutionary correlation coefficient (COCO), it was estimated that the sedimentation rates of Kangan Formation in the two studied wells of Salman gas field increased from ~8 cm/kyr in the bottom to about 12–18 cm/kyr in the upper part, which were linked with the delayed life recovery in Early Triassic. We also observed an enhanced sedimentary noise (ESN) interval in eCOCO maps of the K1 member (upper part of Kangan Formation) at two studied wells, which were linked with the global sea-level fall in the late Griesbachian substage of the Early Triassic. The results of this study show that cyclostratigraphy has made an effective contribution towards analyzing sea-level change and estimating sediment accumulation rates and depositional duration of the Kangan Formation.

中文翻译：

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伊朗波斯湾东部Salman气田下三叠统Kangan组旋回地层学

摘要 旋回地层学在检测和报告沉积层序中的米兰科维奇旋回方面发挥着关键作用，它允许创建独立的天文时间尺度和沉积物堆积速率的估计。在这项研究中，在伊朗波斯湾东部的 Salman 气田的两口井中对下三叠统康安组的岩石物理测井进行了旋回地层分析。两口井的功率谱分析结果揭示了长偏心、短偏心、倾角和进动周期波长处的主要光谱峰。基于长偏心率周期的轨道调谐，建立了一个浮动天文时间尺度，据此估计康安组的沉积持续时间为1.6±0.1 Myr。也，在这项研究中，早三叠世的 Induan 阶段的持续时间估计至少为 1.6 Myr。同时，综合旋回地层分析、沉积速率评价统计方法的结果，即演化相关系数(COCO)，估计Salman气田2口研究井康安组沉积速率从~8 cm提高底部的 /kyr 到上部的约 12-18 cm/kyr，这与早三叠世的生命恢复延迟有关。我们还在两口研究井的 K1 段（康安组上部）的 eCOCO 图中观察到沉积噪声 (ESN) 间隔增强，这与早三叠世晚期 Griesbachian 亚阶段的全球海平面下降有关。