The enrichment of elements in black shale and the accumulation of natural gas exhibit a complex, coupled relationship that spans multiple critical geological stages, from sedimentary organic matter preservation and diagenetic evolution to organic matter pyrolysis and gas generation. This intricate process, governed by a multitude of interacting factors, lies at the heart of geology, geochemistry, and organic geoscience. In recent years, the development of high-spatial and high-mass resolution microprobe techniques (e.g., LA-ICP-MS, SHRIMP, SIMS) has enabled precise in situ measurements of major and trace elements within microdomains smaller than 30–50 microns. This technological advancement provides unprecedented opportunities to explore and characterize the evolutionary dynamics of this complex system at an exceptionally fine scale. Against the backdrop of intensifying challenges related to resource security, environmental pressures, and the energy transition, the in-depth characterization of such critical geological materials is not only fundamental to deciphering Earth’s systems but also essential for supporting shale gas exploration and evaluation, the recovery of critical metals, and environmentally sustainable management. The development of innovative analytical methodologies, coupled with multidisciplinary research frameworks, is therefore pivotal to addressing these complex scientific and societal challenges. This Special Issue aims to bring together cutting-edge research to advance our integrated understanding of black shale systems, from deposition to accumulation.
The papers in this edition are organized around several core themes. Several contributions delve into the mechanisms of organic matter (OM) enrichment in various shale formations, a process fundamental to the formation of high-quality source rocks. Huang et al. (Contribution 1) investigated the Lianggaoshan Formation lacustrine shale in the Sichuan Basin, revealing that lake-level variations exert a primary control on OM accumulation by modulating paleo-productivity and bottom-water redox conditions. Zhang et al. (Contribution 2) studied the Wufeng Formation shale in the Fenggang area, demonstrating that organic-rich shale formation was primarily influenced by a combination of favorable preservation conditions in a reducing environment and high primary productivity, within a complex tectonic and sedimentary setting. Wang et al. (Contribution 3) conducted a detailed comparative geochemical study of lacustrine shale and mudstone from the Triassic Yanchang Formation in the Ordos Basin, establishing that OM enrichment is primarily controlled by paleo-productivity and redox conditions. Liao et al. (Contribution 4) systematically analyzed the sedimentary environment and reservoir characteristics of the Wufeng–Longmaxi formations in the Changning area, identifying a multi-stage coupling process that controls reservoir development. Huang et al. (Contribution 5) investigated the Xujiahe Formation on the southeastern margin of the Sichuan Basin, proposing two distinct composite models for OM enrichment dominated by climate and sedimentation rate. Wang et al. (Contribution 6) examined the controlling factors of shale gas reservoirs in the Lower Cambrian Niutitang Formation, northern Guizhou, emphasizing the significance of sedimentary features, diagenesis, and structural preservation. Wang et al. (Contribution 7) investigated the depositional environment and OM enrichment in the Lower Silurian Gaojiabian Formation, Lower Yangtze region, revealing that the perennial oxygen minimum zone (P-OMZ) and euxinic environments were key factors.
The influence of depositional processes and paleogeomorphology on shale reservoirs is further explored. Yuan et al. (Contribution 8) investigated the impact of lacustrine gravity-flow deposits on pore structure in the Dongyuemiao Member, demonstrating that different microfacies, particularly lobe deposits, create distinct lithofacies with superior reservoir properties. Zhang et al. (Contribution 9) examined thin shale reservoirs in the denudation area of the Sichuan Basin, finding that the enrichment mechanism is controlled by the positive effects of silt laminae on pore preservation and the role of carbonate minerals as the main carrier of inorganic pores.
The role of mineralogy and diagenesis in reservoir quality is a recurring theme. Lin et al. (Contribution 10) explored the formation of medium- to high-porosity and ultralow-permeability tuff reservoirs in the Songliao Basin, elucidating the dual roles of diagenetic fluids in governing porosity–permeability evolution. Shen et al. (Contribution 11) studied Permian black shales in the Lower Yangtze area, revealing that the heterogeneous accumulation of OM is jointly controlled by the redox state and primary production. Min et al. (Contribution 12) provided critical new evidence on the destruction of OM pores in post-mature shales of the Qiongzhusi Formation, challenging the view that graphitization is the primary cause and proposing instead that compaction plays the dominant role, introducing a “depth window” concept for high-quality reservoir development.
Detailed characterization of key formations and elements forms a significant part of this collection. Liu et al. (Contribution 13) discussed the brittle-plastic transition of deep shales, constructing a new brittleness evaluation index based on energy evolution from complete stress–strain curves. Wang et al. (Contribution 14) conducted a lithofacies identification study of shallow shale gas in the Zhaotong area, concluding that biogenic siliceous shale represents the optimal lithofacies. Chen et al. (Contribution 15) evaluated the source–reservoir characteristics and proposed a pore evolution model for Lower Paleozoic shales in the Neijiang–Rongchang area. Chen et al. (Contribution 16) provided a comprehensive characterization of laminae in the Qiongzhusi Formation shale, establishing a three-level classification system and demonstrating the significant control of lamina development on reservoir properties.
The broader geological context, including tectonic setting, provenance, and hydrothermal activity, is also addressed. Luo et al. (Contribution 17) investigated the origin of Ordovician siliceous rocks and their implications for hydrothermal reservoirs in the northwestern Tarim Basin. Pu et al. (Contribution 18) applied molecular simulation technology to reveal the methane’s microscopic occurrence mechanism, particularly the main controlling factor of adsorbed methane in deep marine shale. Han et al. (Contribution 19) conducted a pioneering experimental study combining thermal heating and SEM imaging to investigate the formation of organic matter pores in shales, providing direct observations of pore evolution across a thermal maturity gradient. Zhang et al. (Contribution 20) employed molecular simulation to investigate the occurrence state and controlling factors of methane in deep marine shale under in situ conditions, revealing the controlling effects of temperature, pressure, pore size, and mineral composition on methane adsorption capacity.
The papers published in this second edition of the Special Issue on black rock series demonstrate the vitality, diversity, and interdisciplinary nature of current research in this field. They advance knowledge on critical topics, from the fundamental controls on OM enrichment and pore evolution to the practical implications for shale gas exploration and the recovery of critical metals. The collection highlights the importance of integrating innovative analytical techniques with a deep understanding of geological processes to support sustainable resource development and environmental stewardship.
As Guest Editors, we extend our sincere gratitude to all the authors for their excellent contributions, to the reviewers for their rigorous evaluations and constructive comments, and to the editorial team of Minerals for their unwavering support throughout the publication process. We hope that this Special Issue will serve as a valuable reference for researchers, practitioners, and policymakers working in the fields of sedimentology, geochemistry, mineralogy, and energy resources, stimulating further research and fostering new advances in the sustainable utilization of these critical geological materials.
Conflicts of Interest
The authors declare no conflicts of interest.
List of Contributions
- Huang, D.; Qi, M.; Deng, X.; Huang, Y.; Wang, H.; Li, X. Organic matter accumulation model of Jurassic Lianggaoshan shale under lake-level variations in Sichuan Basin: Insights from environmental conditions. Minerals 2025, 15, 159. https://doi.org/10.3390/min15020159.
- Zhang, Q.; Zhang, H.; Men, Y.; Yu, Q.; Cao, J.; Zhou, Y.; Feng, X.; Zhao, A.; Zhou, D. Influence of tectonic setting and sedimentary environment on organic-rich shale in the Wufeng Formation, Fenggang area. Minerals 2025, 15, 191. https://doi.org/10.3390/min15020191.
- Wang, Z.; Cheng, H.; Wang, Y. Differential geochemical features of lacustrine shale and mudstone from Triassic Yanchang Formation, Ordos Basin, China: Insights into their sedimentary environments and organic matter enrichment. Minerals 2025, 15, 656. https://doi.org/10.3390/min15060656.
- Liao, C.; Chen, L.; Lu, C.; Chen, K.; Zheng, J.; Chen, X.; Wang, G.; Cao, J. Depositional and paleoenvironmental controls on shale reservoir heterogeneity in the Wufeng–Longmaxi Formations: A case study from the Changning area, Sichuan Basin, China. Minerals 2025, 15, 677. https://doi.org/10.3390/min15070677.
- Huang, H.; Zhang, T.; Zhang, X.; Chen, Z.; Zhang, J. Sedimentary environment and organic matter enrichment mechanisms of the Upper Triassic Xujiahe Formation fine-grained sedimentary rocks, southeastern Sichuan Basin. Minerals 2025, 15, 1071. https://doi.org/10.3390/min15101071.
- Wang, D.; Ma, L.; Yu, Q.; Zhang, T.; Bai, J.; An, C.; Li, C.; Peng, J. Identifying the key control factors of deep marine shale gas reservoirs: A case study on Lower Cambrian fine-grained sedimentary rocks in Cen Gong, Guizhou, China. Minerals 2025, 15, 505. https://doi.org/10.3390/min15050505.
- Wang, W.; Chen, J.; Feng, X.; Ge, X.; Zhang, Y.; Liang, J.; Xu, L. Sedimentary environment and organic matter enrichment mechanism of the Silurian Gaojiabian black shales in the Lower Yangtze Region, South China. Minerals 2025, 15, 204. https://doi.org/10.3390/min15030204.
- Yuan, Q.; Jiang, Y.; Liu, Z.; Wei, X.; Gu, Y. Lacustrine gravity-flow deposits and their impact on shale pore structure in freshwater lake basins: A case study of Jurassic Dongyuemiao Member, Sichuan Basin, SW China. Minerals 2025, 15, 473. https://doi.org/10.3390/min15050473.
- Zhang, H.; Shi, Z.; Jiang, L.; Chen, W.; Luo, T.; Qi, L. Enrichment mechanism and development technology of deep marine shale gas near denudation area, SW China: Insights from petrology, mineralogy and seismic interpretation. Minerals 2025, 15, 619. https://doi.org/10.3390/min15060619.
- Lin, S.; Guo, X.; Li, L.; Gao, J.; Xue, S.; Yang, Y.; Tang, C. Diagenetic evolution and formation mechanism of middle to high-porosity and ultralow-permeability tuff reservoirs in the Huoshiling Formation of the Dehui Fault Depression, Songliao Basin. Minerals 2025, 15, 319. https://doi.org/10.3390/min15030319.
- Shen, W.; Shen, W.; Xiao, X.; Shen, S. Evolution of Permian sedimentary environment in South China: Constraints on heterogeneous accumulation of organic matter in black shales. Minerals 2025, 15, 296. https://doi.org/10.3390/min15030296.
- Min, H.; Xu, J.; Liang, S.; Liu, C.; Zhao, L. The origin of organic matter pore destruction in post-mature shales of the Qiongzhusi Formation, southwestern Upper Yangtze, China: Evidence from scanning electron microscopy. Minerals 2026, 16, 529. https://doi.org/10.3390/min16050529.
- Liu, W.; Pan, B.; Li, C.; Song, Y.; Huang, Y.; Yang, X. Brittle–plastic transition law of deep shale based on energy evolution and its control mechanism for reservoir fracability. Minerals 2026, 16, 291. https://doi.org/10.3390/min16030291.
- Wang, G.; Shu, H.; Jiang, L.; Zhao, X.; Gu, X.; Zhang, C.; Zou, C.; Mei, J.; Jiang, Z. Lithofacies identification and reservoir control of shallow shale gas in the Wufeng–Longmaxi Formations in the Taiyang area, Zhaotong. Minerals 2026, 16, 290. https://doi.org/10.3390/min16030290.
- Chen, S.; Xi, Z.; Huo, F.; Jiang, B. Source–reservoir characteristics and pore evolution model of the Lower Paleozoic shales in the Neijiang–Rongchang area, Sichuan Basin. Minerals 2025, 15, 499. https://doi.org/10.3390/min15050499.
- Chen, X.; Li, B.; Chen, L.; Zhang, C.; Xie, S.; Wang, G.; Luo, Y.; Yang, H.; Zhao, S.; Zhou, S. Laminae development characteristics and reservoir significance of the Cambrian Qiongzhusi Formation shale in the southern Sichuan Basin. Minerals 2026, 16, 552. https://doi.org/10.3390/min16050552.
- Luo, J.; Zhang, T.; Shi, P.; Xie, Z.; Zeng, J.; Gao, L.; Ma, Z.; Zhang, X. Genesis and reservoir implications of multi-stage siliceous rocks in the Middle–Lower Ordovician, northwestern Tarim Basin. Minerals 2026, 16, 107. https://doi.org/10.3390/min16010107.
- Pu, J.; Luo, T.; Li, Y.; Jiang, H.; Qi, L. Occurrence State and Controlling Factors of Methane in Deep Marine Shale: A Case Study from Silurian Longmaxi Formation in Sichuan Basin, SW China. Minerals 2025, 15, 820. https://doi.org/10.3390/min15080820.
- Han, H.; He, C.; Xiao, S.; Chen, J.; Kalmykov, A.; Wu, W.; Wang, Y.; Wang, J. The formation of organic matter pores in shales: Implications from combined thermal heating and scanning electron microscopy imaging. Minerals 2025, 15, 336. https://doi.org/10.3390/min15040336.
- Zhang, J.; Zhang, X.; Zhang, T.; Shi, P.; Xie, Z.; Zeng, J.; Gao, L.; Li, Q. A mechanistic framework linking climate forcing, microbial transformation, and sedimentary carbon sinks in deep-time oceans. Minerals 2026, 16, 221. https://doi.org/10.3390/min16020221.
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