Geochemical characteristic of different-lithofacies source rocks and its implications for ultradeep hydrocarbon exploration in the lower cambrian Yuertus formation, Tarim basin
Abstract 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 (Є1y) warrant additional research. This study i...
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-07-01
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| Series: | Scientific Reports |
| Subjects: | |
| Online Access: | https://doi.org/10.1038/s41598-025-09636-1 |
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| Summary: | Abstract 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 (Є1y) warrant additional research. This study integrates biomarker, carbon, and sulfur isotope data from Є1y 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 Є1y. Results reveal that Є1y 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 (C26R + C27S TAS < C28S TAS, TDSI < 0.6), while simultaneously containing high abundances of ATMBs characteristic of the Є1y. Siliceous rocks display typical Cambrian characteristics with low C28 TAS, high TDSI, but absence of ATMBs. Shales present typical Cambrian features with low C28 TAS, high TDSI, and low ATMBs. Oil-source correlation based on n-alkane’ carbon and sulfur isotopes suggests that calcareous shales are likely one of the primary sources for currently explored oils. These findings enrich the fundamental understanding of deep and ultra-deep hydrocarbon exploration in the Tarim Basin and provide new insights into the reassessment of oil-source relations. |
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| ISSN: | 2045-2322 |