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Element Enrichment and Gas Accumulation in Black Rock Series
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Element Enrichment and Gas Accumulation in Black Rock Series

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Geochemistry and Geochronology".

Deadline for manuscript submissions: 30 June 2025 | Viewed by 3973

Special Issue Editors

Prof. Dr. Tingshan Zhang

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Guest Editor
School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, China
Interests: sedimentology; paleoecology; unconventional oil and gas geology
Prof. Dr. Lei Chen

E-Mail Website
Guest Editor
School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, China
Interests: sedimentology; paleoecology; unconventional oil; gas geology
Dr. Chang'an Shan

E-Mail Website
Guest Editor
School of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, China
Interests: shale sediments and reservoirs
Dr. Xi Zhang

E-Mail Website
Guest Editor
School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, China
Interests: sedimentology; paleoecology; unconventional oil and gas geology

Special Issue Information

Dear Colleagues,

The enrichment of elements in black shale and the accumulation of natural gas exhibit a complex relationship, encompassing various fields such as geology, geochemistry, and organic geoscience. This enrichment is manifested during the organic matter preservation stage of sedimentation, the diagenetic evolution stage of shale reservoirs, and the stages involving organic matter pyrolysis and natural gas generation. However, this intricate process is influenced by multiple factors. The development of high-spatial- and -mass-resolution microprobes (e.g., LA-ICP-MS, SHRIMP, SIMS) allows in situ measurements of major and trace elements in microdomains smaller than 30–50 microns. We can explore and characterize this complex system change process in more detail.

We seek original research that explores element enrichment and gas accumulation in black rock series, including the relationship between element enrichment and organic carbon burial in sedimentary environments, the response characteristics of element enrichment during reservoir pore evolution, and the response characteristics of element enrichment during the production stage of organic gas pyrolysis.

Prof. Dr. Tingshan Zhang
Prof. Dr. Lei Chen
Dr. Chang'an Shan
Dr. Xi Zhang
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • shale gas occurrence mechanism
  • electrical properties of rock
  • paleoclimate, paleotemperature, paleostructure
  • upwelling and hydrothermal solution
  • element enrichment
  • enrichment of shale gas

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Published Papers (9 papers)

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Research

26 pages, 14460 KiB  
Article
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
by Dahai Wang, Lichi Ma, Qian Yu, Tao Zhang, Jian Bai, Chuan An, Chuntang Li and Jun Peng
Minerals 2025, 15(5), 505; https://doi.org/10.3390/min15050505 - 9 May 2025
Viewed by 257
Abstract
This study identifies the following three key factors controlling shale gas reservoirs in the lower Cambrian Niutitang Formation, northern Guizhou, China: sedimentary features, diagenetic modification, and stable tectonic conditions. This research addresses gaps in previous studies by investigating how tectonic and diagenetic conditions [...] Read more.
This study identifies the following three key factors controlling shale gas reservoirs in the lower Cambrian Niutitang Formation, northern Guizhou, China: sedimentary features, diagenetic modification, and stable tectonic conditions. This research addresses gaps in previous studies by investigating how tectonic and diagenetic conditions contribute to the unique characteristics of shale gas enrichment in tectonically complex areas with high thermal maturity (Ro > 2.5%). Sedimentary conditions revealed a positive correlation between total organic carbon (TOC) content and gas adsorption capacity, with higher TOC enhancing adsorption. Experimental data indicate that the TOC content (2.33%–9.07%) significantly correlates with methane adsorption capacity (Langmuir volume VL = 1.87–8.78 cm3/g at 30 °C and 10 MPa), as evidenced by the linear relationship between TOC and VL in shale samples. Clay mineral content exhibited a dual role as moderate levels (15%–25%) improved adsorption, while excessive amounts (>30%) reduced efficiency due to pore occlusion. Diagenesis, including compaction, cementation, and thermal evolution of organic matter, significantly reshaped reservoir porosity. Quantitative analysis of core samples demonstrates that compaction caused a porosity reduction of 18%–25% in samples with burial depths exceeding 1500 m, thereby influencing gas retention capacity. The reservoir has entered the anchizone (average vitrinite reflectance Ro = 2.54%), characterized by advanced organic matter maturation and widespread organic porosity development. Tectonic activity was critical for gas retention; intense tectonic activity led to shallower burial depths and gas loss, whereas structurally stable areas favored preservation. This study emphasizes the significance of tectonic conditions and their role in maintaining gas reservoirs in the anchizone, reconciling discrepancies in gas storage mechanisms observed in basins with similar TOC and thermal maturity. In summary, deep marine shale gas enrichment relies on the synergistic effects of high-quality sedimentary foundations (TOC > 4%, quartz > 30%), diagenetic evolution optimizing pore structures, and stable tectonic conditions ensuring gas retention. These findings provide new insights into the exploration of shale gas in complex tectonic regions and offer a framework for improving prediction models in shale gas enrichment by integrating micro-scale organic–inorganic interactions with macro-scale tectonic controls. Full article
(This article belongs to the Special Issue Element Enrichment and Gas Accumulation in Black Rock Series)
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20 pages, 16179 KiB  
Article
Source-Reservoir Characteristics and Pore Evolution Model of the Lower Paleozoic Shales in the Neijiang–Rongchang Area, Sichuan Basin
by Shizhen Chen, Zhidian Xi, Fei Huo and Bingcheng Jiang
Minerals 2025, 15(5), 499; https://doi.org/10.3390/min15050499 - 8 May 2025
Viewed by 227
Abstract
The Wufeng–Longmaxi formations in the Sichuan Basin have emerged as China’s principal shale gas exploration target, with drilling results confirming substantial resource potential. Although the Neijiang–Rongchang Block demonstrates promising production, significant performance variations among lithofacies and reservoir types highlight the need for enhanced [...] Read more.
The Wufeng–Longmaxi formations in the Sichuan Basin have emerged as China’s principal shale gas exploration target, with drilling results confirming substantial resource potential. Although the Neijiang–Rongchang Block demonstrates promising production, significant performance variations among lithofacies and reservoir types highlight the need for enhanced understanding of reservoir evolution. This study integrates petrological analyses, SEM imaging, XRD characterization, seismic interpretation, and production data from multiple wells targeting the Wufeng–Long 1-1 Sub-member. Key insights reveal the following: (1) reservoir lithology consists predominantly of siliceous shale (68% occurrence), characterized by high quartz content (48% avg), low carbonates (<15%), and low clay (<30%); (2) organic-rich intervals contain Type I kerogen derived from planktonic algae, with thermal maturity indicating post-mature evolution; (3) premium reservoirs develop multi-scale pore networks combining organic-hosted pores, interparticle pores, and micro-fractures. Despite high brittle mineral content, mechanical competence decreases stratigraphically from the Wufeng Formation (78%) to Long 1-17 (63%); (4) depositional redox conditions facilitated exceptional organic preservation. Core analyses reveal low porosity (5.5% avg) and ultra-low permeability (0.27 × 10⁻3 μm2 avg), classifying reservoirs as multiple tight unconventional systems in the study area. The proposed lithofacies-controlled pore evolution model elucidates reservoir heterogeneity mechanisms, providing critical geological criteria for optimized shale gas development. Full article
(This article belongs to the Special Issue Element Enrichment and Gas Accumulation in Black Rock Series)
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22 pages, 112804 KiB  
Article
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
by Qingwu Yuan, Yuqiang Jiang, Zhujiang Liu, Xiangfeng Wei and Yifan Gu
Minerals 2025, 15(5), 473; https://doi.org/10.3390/min15050473 - 30 Apr 2025
Viewed by 186
Abstract
In recent years, the successful application of gravity-flow deposit theory in major petroliferous basins in China had attracted extensive attention in the field of sedimentology and had become a key research frontier. This study utilized core, drilling, logging, and microphotograph data, along with [...] Read more.
In recent years, the successful application of gravity-flow deposit theory in major petroliferous basins in China had attracted extensive attention in the field of sedimentology and had become a key research frontier. This study utilized core, drilling, logging, and microphotograph data, along with low-temperature nitrogen adsorption and high-pressure mercury injection experiments. It discussed the characteristics of gravity-flow deposits, sedimentary microfacies, sedimentary models, and the significance of gravity-flow deposits to pore heterogeneity in shale reservoirs, focusing on the first submember of the Dongyuemiao Member (referred to as the Dong 1 Member) in the Fuling area of the Sichuan Basin. The results indicated the development of four types of mudrock in the Dong 1 Member: massive to planar laminated shell mudrock (F1), planar laminated bioclastic mudrock (F2), planar laminated silty mudrock (F3), and massive mudrock (F4). These corresponded to debris flow deposits (F1, F2), turbidite deposits (F3), and suspension deposits (F4). According to the characteristics of lithofacies combinations and sedimentary features, four sedimentary microfacies were identified: gravity-flow channel, tongue-shaped, lobate, and semi-deep lake mud. The Shell Banks were disturbed by earthquakes, tides, storms, and other activities. Silt, clay, fossil fragments, plant debris, and other materials were deposited under the influence of gravity, mixing with surrounding water to form an unbalanced and unstable fluid. When pore pressure exceeded viscous resistance, the mixed fluid became unbalanced, and gravity flow began to migrate from the slope to the center of the lake basin. A sedimentary unit of gravity-flow channel-tongue-shaped-lobate was developed in the Fuling area. The Fuling area’s gravity-flow depositional system resulted in distinct microfacies within the Dongyuemiao Member, each exhibiting characteristic lithofacies associations. Notably, lobate deposits preferentially developed lithofacies F3, which is distinguished by significantly higher clay mineral content (60.8–69.1 wt%) and elevated TOC levels (1.53–2.45 wt%). These reservoir properties demonstrate statistically significant positive correlations, with clay mineral content strongly influencing total pore volume and TOC content specifically enhancing mesopore development (2–50 nm pores). Consequently, the F3 lithofacies within lobe deposits emerges as the most prospective shale gas reservoir unit in the study area, combining optimal geochemical characteristics with favorable pore-structure attributes. Full article
(This article belongs to the Special Issue Element Enrichment and Gas Accumulation in Black Rock Series)
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23 pages, 6741 KiB  
Article
The Formation of Organic Matter Pores in Shales: Implications from Combined Thermal Heating and Scanning Electron Microscopy Imaging
by Hui Han, Chunchen He, Suqi Xiao, Jintao Chen, Anton Kalmykov, Wenjie Wu, Yixing Wang and Jiang Wang
Minerals 2025, 15(4), 336; https://doi.org/10.3390/min15040336 - 23 Mar 2025
Viewed by 318
Abstract
To reveal the forming process of organic matter pores in shales, an experiment combining thermal heating and scanning electron microscopy (SEM) was conducted on an oil shale sample with a vitrinite reflectance value of 0.46% from the Huadian Formation in the Huadian Basin, [...] Read more.
To reveal the forming process of organic matter pores in shales, an experiment combining thermal heating and scanning electron microscopy (SEM) was conducted on an oil shale sample with a vitrinite reflectance value of 0.46% from the Huadian Formation in the Huadian Basin, northeastern China. The heating temperatures were from 417.8 °C to 700.8 °C, and the corresponding Easy%Ro values were between 1.00% and 3.70%. Four pieces of macerals in the SEM images, including vitrinite (one piece), funginite (one piece), and solid bitumen (two pieces), were observed during the whole heating process. The results showed that organic pores started to appear and increased in all the studied macerals. Each piece of maceral had two rapid growth points of organic matter pores. During heating, organic pores were initially isolated and then became connected. Among the three types of macerals, solid bitumen was more porous, which may be related to the fact that solid bitumen was more easily thermally degraded. Funginite had more pores than vitrinite at all the heating temperatures. Cracks were observed in vitrinite and funginite during heating, and the vitrinite had more cracks, which may be attributed to its stiffness and brittleness. Almost all the organic matter pores were irregular in this study, but bubble-like or sponge-like organic pores have been reported in natural shales. The difference in shapes of organic matter pores may be derived from our experimental system as it cannot consider pressure. These results provide some implications for the mechanism of formation of organic matter pores. Full article
(This article belongs to the Special Issue Element Enrichment and Gas Accumulation in Black Rock Series)
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26 pages, 28443 KiB  
Article
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
by Siya Lin, Xiaobo Guo, Lili Li, Jin Gao, Song Xue, Yizhuo Yang and Chenjia Tang
Minerals 2025, 15(3), 319; https://doi.org/10.3390/min15030319 - 19 Mar 2025
Viewed by 363
Abstract
The fluid action mechanism and diagenetic evolution of tuff reservoirs in the Cretaceous Huoshiling Formation of the Dehui fault depression are discussed herein. The fluid properties of the diagenetic flow are defined, and the pore formation mechanism of the reservoir space is explained [...] Read more.
The fluid action mechanism and diagenetic evolution of tuff reservoirs in the Cretaceous Huoshiling Formation of the Dehui fault depression are discussed herein. The fluid properties of the diagenetic flow are defined, and the pore formation mechanism of the reservoir space is explained by means of thin sections, X-ray diffraction, electron probes, scanning electron microscopy (SEM), cathodoluminescence, and stable carbon and oxygen isotopic composition and fluid inclusion tests. The results reveal that the tuff reservoir of the Huoshiling Formation is moderately acidic, and the physical properties of the reservoir are characterized by middle to high porosity and ultralow permeability. The pore types are complex, comprising both primary porosity and secondary porosity, with dissolution pores and devitrification pores being the most dominant. Mechanical compaction and cementation are identified as key factors reducing reservoir porosity and permeability, while dissolution and devitrification processes improve pore structure and enhance pore connectivity. Diagenetic fluids encompass alkaline fluids, acidic fluids, deep-seated CO+-rich hydrothermal fluids, and hydrocarbon-associated fluids. These fluids exhibit dual roles in reservoir evolution: acidic fluids enhance the dissolution of feldspar, tuffaceous materials, and carbonate minerals to generate secondary pores and improve reservoir quality, whereas alkaline fluids induce carbonate cementation, and clay mineral growth (e.g., illite) coupled with late-stage mineral precipitation obstructs pore throats, reducing permeability. The interplay among multiple fluid types and their varying dominance at different burial depths collectively governs reservoir evolution. This study underscores the critical role of fluid–rock interactions in controlling porosity–permeability evolution within tuff reservoirs. Full article
(This article belongs to the Special Issue Element Enrichment and Gas Accumulation in Black Rock Series)
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20 pages, 6150 KiB  
Article
Evolution of Permian Sedimentary Environment in South China: Constraints on Heterogeneous Accumulation of Organic Matter in Black Shales
by Weibing Shen, Weibin Shen, Xiao Xiao and Shihao Shen
Minerals 2025, 15(3), 296; https://doi.org/10.3390/min15030296 - 14 Mar 2025
Viewed by 453
Abstract
Permian black shale, as a potential target for marine shale gas exploration in South China, is characterized by its great thickness and organic matter (OM) content. To understand the constraints on the heterogeneous accumulation of OM in Permian black shale, high-resolution geochemical data [...] Read more.
Permian black shale, as a potential target for marine shale gas exploration in South China, is characterized by its great thickness and organic matter (OM) content. To understand the constraints on the heterogeneous accumulation of OM in Permian black shale, high-resolution geochemical data related to paleoenvironment variations are collected on the Gufeng and Dalong Formations of the Putaoling area, the Anhui province, and the Lower Yangtze area. The OM was heterogeneously enriched in the Permian shales, as shown by the highly organic-matter-rich Gufeng Formation and the moderately organic-matter-rich Dalong Formation. The distribution patterns of rare earth elements (REEs) indicate a stably high sedimentary rate throughout the shale deposition. Redox indexes, including MoEF, UEF, V/Sc, and U/Th, indicate anoxic conditions for the deposition of the Gufeng and Dalong Formations, and that seawater oxygenation has occurred. The stratigraphic decreases in the (Fe+Mn)/Ti ratios, the index of chemical alteration (CIA), and the content of nutrient elements demonstrate the upward weakening patterns of hydrothermal activity and chemical weathering, which result in a reduction in the primary production. The redox state combined with the primary production jointly control the heterogeneous accumulation of OM in the Permian shales. Our paleoenvironmental evolution model for OM accumulation in the black shales indicates that the Gufeng Formation might be the priority object for the exploration of shale gases in the Permian strata within the Lower Yangtze area. Full article
(This article belongs to the Special Issue Element Enrichment and Gas Accumulation in Black Rock Series)
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23 pages, 9334 KiB  
Article
Sedimentary Environment and Organic Matter Enrichment Mechanism of the Silurian Gaojiabian Black Shales in the Lower Yangtze Region, South China
by Wenjuan Wang, Jianwen Chen, Xiuli Feng, Xiangying Ge, Yinguo Zhang, Jie Liang and Lei Xu
Minerals 2025, 15(3), 204; https://doi.org/10.3390/min15030204 - 21 Feb 2025
Viewed by 423
Abstract
A set of organic-rich black shales has developed in the lower Gaojiabian Formation (Lower Silurian) in the Lower Yangtze region, South China. However, limited research on its paleoenvironment and the mechanisms of organic matter enrichment has hindered further analysis of shale gas exploration [...] Read more.
A set of organic-rich black shales has developed in the lower Gaojiabian Formation (Lower Silurian) in the Lower Yangtze region, South China. However, limited research on its paleoenvironment and the mechanisms of organic matter enrichment has hindered further analysis of shale gas exploration prospects in this area. Utilizing samples from the Akidograptus ascensus to Cystograptus vesiculosus graptolite biozones in the Gaojiabian Formation obtained from well SY-1, we analyzed geochemical elements and pyrite framboids to reconstruct paleoenvironmental characteristics and paleoproductivity, revealing factors influencing organic matter enrichment. The results indicate that the total organic carbon (TOC) content and paleoproductivity levels of the shale are both high, with a significant enrichment of redox-sensitive elements. Additionally, the pyrite framboids are well developed, characterized by small particle sizes and a narrow range of variation. This study reveals that during this period, the region generally developed a perennial oxygen minimum zone (P-OMZ) environment, accompanied by transient euxinic conditions during the Akidograptus ascensus and the early stages of Parakidograptus acuminatus and Cystograptus vesiculosus. This situation represents the extension of the Rhuddanian Oceanic Anoxic Event (R-OAE) into the Lower Yangtze region, where the water body exhibited moderate restrictions. Compared to paleoproductivity indicators, there is a stronger positive correlation between TOC and the redox-sensitive elements vanadium (V), molybdenum (Mo), and uranium (U) in the samples. This finding indicates that the P-OMZ and euxinic environments of the Lower Yangtze Sea were the key factors influencing organic matter enrichment in the Akidograptus ascensus to Cystograptus vesiculosus biozones. Consequently, the overall pattern of organic matter enrichment was predominantly determined by preservation conditions. Full article
(This article belongs to the Special Issue Element Enrichment and Gas Accumulation in Black Rock Series)
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18 pages, 11606 KiB  
Article
Influence of Tectonic Setting and Sedimentary Environment on Organic-Rich Shale in the Wufeng Formation, Fenggang Area
by Qian Zhang, Haiquan Zhang, Yupeng Men, Qian Yu, Junfeng Cao, Yexin Zhou, Xintao Feng, Ankun Zhao and Daorong Zhou
Minerals 2025, 15(2), 191; https://doi.org/10.3390/min15020191 - 19 Feb 2025
Viewed by 378
Abstract
Drawing on extensive geological surveys, as well as systematic mineralogical, petrological, and geochemical analyses, the study evaluates the provenance, tectonic setting, paleo-redox conditions, and paleoclimate characteristics of the Wufeng Formation black shale in the Fenggang area. The analysis of mineral components reveals that [...] Read more.
Drawing on extensive geological surveys, as well as systematic mineralogical, petrological, and geochemical analyses, the study evaluates the provenance, tectonic setting, paleo-redox conditions, and paleoclimate characteristics of the Wufeng Formation black shale in the Fenggang area. The analysis of mineral components reveals that quartz content is notably the highest, suggesting that the shale is primarily siliceous. The TOC content was highest in the YI Outcrop, ranging from 2.19 to 5.56, with an average of 3.23, followed by the SX Outcrop. Redox-sensitive indices including MoEF, UEF, V/Cr, and U/Th exhibit considerable variability, indicating significant heterogeneity of the redox conditions, which is primarily characterized as a restricted marine shelf setting. The bottom water of YI Outcrop has the strongest reducing property, and mainly deposited in an anoxic environment. Organic-rich siliceous mudstone is widely distributed across the region. The provenance analysis indicates that the study area is predominantly sourced from felsic igneous rocks. Additionally, paleoclimate and paleo-weathering analyses suggest that the region underwent intense chemical weathering under warm climatic conditions. We found that the sedimentary environment exhibits pronounced spatial variability. In the northern part of the study area, water conditions were deeper, anoxic, and reducing. Toward the east, water depth gradually decreased, transitioning to weakly oxidizing and suboxic conditions. Furthermore, significant tectonic activity in the region led to the formation of multiple underwater highs, indicative of an active continental margin likely associated with the rapid uplift of paleo-uplifts. The formation of organic-rich shale was primarily influenced by two factors: favorable preservation conditions in reducing water bodies and high primary productivity driven by biological activity in weakly oxic environments. Full article
(This article belongs to the Special Issue Element Enrichment and Gas Accumulation in Black Rock Series)
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18 pages, 6792 KiB  
Article
Organic Matter Accumulation Model of Jurassic Lianggaoshan Shale Under Lake-Level Variations in Sichuan Basin: Insights from Environmental Conditions
by Dong Huang, Minghui Qi, Xiang Deng, Yi Huang, Haibo Wang and Xiawei Li
Minerals 2025, 15(2), 159; https://doi.org/10.3390/min15020159 - 9 Feb 2025
Viewed by 790
Abstract
Organic matter (OM) is the primary carrier for the generation and occurrence of shale oil and gas. The combination of sequence stratigraphy and elemental geochemistry plays a crucial role in the study of organic matter enrichment mechanisms in marine shale, but it is [...] Read more.
Organic matter (OM) is the primary carrier for the generation and occurrence of shale oil and gas. The combination of sequence stratigraphy and elemental geochemistry plays a crucial role in the study of organic matter enrichment mechanisms in marine shale, but it is rarely applied to terrestrial lacustrine basins. As a product of the last large-scale lake transgression in the Sichuan Basin, the Early Jurassic Lianggaoshan Formation (LGS Fm.) developed multiple organic-rich shale intervals, which is a good example for studying the OM enrichment in lacustrine basins. Based on a high-resolution sequence stratigraphic framework, the evolutionary process of terrestrial debris input, redox conditions, and paleo-productivity during the sedimentary period of the Lianggaoshan Formation lacustrine shale at different stages of lake-level variations has been revealed. The main controlling factors for OM enrichment and the establishment of their enrichment patterns have been determined. Sequence stratigraphy studies have shown that there are three third-order lake transgression-lake regression (T-R) cycles in the LGS Formation. The total organic carbon content (TOC) is higher in the TST cycle, especially in the T-R3 cycle, and lower in the RST cycle. There are differences in the redox conditions, paleo-productivity, terrestrial detrital transport, and OM accumulation under the influence of lacustrine shale deposition in different system tracts. The results indicate that changes in lake level have a significant impact on the reducibility of bottom water and paleo-productivity of surface seawater, but have a relatively small impact on the input of terrestrial debris. In the TST cycle, the reducibility of bottom water gradually increases, and the paleo-productivity gradually increases, while in the RST cycle, the opposite is true. Within the TST cycle, the OM accumulation is mainly influenced by paleo-productivity and redox condition of bottom water, with moderate input of terrestrial debris playing a positive role. In the RST cycle, the redox condition of bottom water is the main inducing factor for OM enrichment, followed by paleo-productivity, while terrestrial input flux plays a diluting role, which is generally not conducive to OM accumulation. Full article
(This article belongs to the Special Issue Element Enrichment and Gas Accumulation in Black Rock Series)
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