Geochemical characteristic of different-lithofacies source rocks and its implications for ultradeep hydrocarbon exploration in the lower cambrian Yuertus formation, Tarim basin

作者：Qianghao Zeng, Taohua He, Ya Zhao, Ke Zhang, Zhigang Wen, Yaohui Xu, Jiayi He, Weichao Tian, Shuangfang Lu, Wangming Cheng, Zhou Xie, Kaiwen Xue, Changjun Ji · 发表于：Scientific Reports · 年份：2025 · DOI：10.1038/s41598-025-09636-1 · 被引用次数：5 · 研究领域：Hydrocarbon exploration and reservoir analysis、Geological Studies and Exploration、Geochemistry and Geologic Mapping

The Tarim Basin harbors abundant deep to ultra-deep hydrocarbon resources, yet detailed oil-source correlation remains to be further investigated. As a potential key source rock, the organic geochemical characteristics of the Yuertus Formation (Є 1 y) warrant additional research. This study integrates biomarker, carbon, and sulfur isotope data from Є 1 y source rocks in existing wells and outcrops across the eastern, northern, and northwestern Tarim Basin to better constrain the distribution, hydrocarbon generation potential, biomarker features, and oil-source relations of Є 1 y. Results reveal that Є 1 y exhibits diverse lithofacies, including calcareous mudstones, siliceous shales, and shales as potential source rocks. The calcareous mudstone shows the highest total organic carbon (TOC) content (up to 29.8%), characterized by Type II kerogens and mature to over-mature thermal maturity. Stable biomarkers including triaromatic steroids (TAS), triaromatic dinoflagellate steroids (TDSI), and aryl isoprenoids (1-alkyl-2,3,6-trimethylbenzenes, ATMBs) reveal significant differences among the three lithological types of source rocks: Calcareous mudstones exhibit biomarker distribution patterns similar to those of classical Ordovician source rocks (C 26 R + C 27 S TAS < C 28 S TAS, TDSI < 0.6), while simultaneously containing high abundances of ATMBs characteristic of the Є 1 y. Siliceous rocks display typical Cambrian characteristics with low C 28 TAS, high TDSI, but absence of ATM...