Ruiwen Yan , Jun Zhu , Qingyi Cao , Gang Lin , Xiang Li , Furui Xi
{"title":"Geochemical mapping and distribution patterns of critical elements resources in Chinese coal-bearing strata","authors":"Ruiwen Yan , Jun Zhu , Qingyi Cao , Gang Lin , Xiang Li , Furui Xi","doi":"10.1016/j.coal.2025.104848","DOIUrl":"10.1016/j.coal.2025.104848","url":null,"abstract":"<div><div>Critical elements in coal have attracted global attention in recent years due to a substantial increase in demand driven by economic development and defense security needs. Understanding their geochemical distribution patterns is crucial for the future strategic management and effective utilization of these metals. As the world's largest coal-producing country which has a complex condition of coal formation, China provides an ideal natural laboratory for studying the geochemical characteristics of critical elements in coal. This work collected a large dataset on critical elements, including U (<em>n</em> = 1461), Ga (<em>n</em> = 1556), Ge (<em>n</em> = 1210), V (n = 1461), Zr (<em>n</em> = 1199), and Li (<em>n</em> = 1122) from Chinese coal using multi-analysis methods to understand their spatial distribution patterns. With these data, we have: (1) updated the average contents of critical elements (U, Ga, Ge, V, Zr, and Li) in Chinese coals, which showed a more enriched Ga, V, Zr, and Li level compared with the global average; (2) generated a set of geochemical distribution maps for these elements in Chinese coals and coal ashes, targeting key potential areas for their exploration within China's coal-bearing regions based on development and utilization grades. With these important geochemical data, this work provides critical information for studying geochemical characteristics of the trace elements in coal, offering a valuable reference for prospecting and utilizing critical elements in coal.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"309 ","pages":"Article 104848"},"PeriodicalIF":5.7,"publicationDate":"2025-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fernando Michels , Joana Ribeiro , Maria Helena Henriques , Ádám Nádudvari , Magdalena Misz-Kennan , Monika J. Fabiańska
{"title":"Industrial and mining impacts on the organic matter of soils in a protected area of the Central Portuguese Coast: A petrographic and geochemical approach","authors":"Fernando Michels , Joana Ribeiro , Maria Helena Henriques , Ádám Nádudvari , Magdalena Misz-Kennan , Monika J. Fabiańska","doi":"10.1016/j.coal.2025.104847","DOIUrl":"10.1016/j.coal.2025.104847","url":null,"abstract":"<div><div>Long-term industrial operations fueled by coal and oil have the potential to significantly impact surrounding ecosystems, particularly in the past when environmental regulations were less stringent. In this study, organic contamination was investigated in soils surrounding a former industrial complex and coal mining area on the Portuguese Atlantic coastline, active from the 19th century through the early 21st century. This area is currently included in the Natural Monument of Cabo Mondego, which highlights concerns regarding its environmental quality. Surface soil samples were investigated through a multi-technique approach using organic petrography, an uncommon yet powerful tool that provides unequivocal evidence of contaminants, and geochemical methods to identify sources of fossil fuel-derived contaminants. Results indicate that most of the samples exceed national reference levels for priority polycyclic aromatic hydrocarbons (PAH), with the highest concentrations found in the samples located up to 500 m from the former industrial facilities. These findings suggest that emissions from the industrial complex are the primary source of organic contamination in the area. Elevated levels of PAH (recognized environmental pollutants and human carcinogens) associated with contaminant combustion-derived organic particles (coke and char) raise environmental concerns. The presence of both local and imported coal particles in soil, along with the disposal of coal residues in the area, highlights contamination linked to historical coal handling and transport. The detection of charcoal particles in soil reflects the influence of regional wildfires that occurred in recent decades. These findings contribute to understanding the environmental vulnerabilities of the Cabo Mondego Natural Monument.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"309 ","pages":"Article 104847"},"PeriodicalIF":5.6,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144714490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Enrichment of Ni-Zn-Cd-Mo-V in the Şırnak asphaltites, Türkiye: The effects of organic matter, sedimentary processes, and hydrothermal fluids on element concentrations and occurrences","authors":"Emine Cicioglu Sutcu","doi":"10.1016/j.coal.2025.104846","DOIUrl":"10.1016/j.coal.2025.104846","url":null,"abstract":"<div><div>There are numerous asphaltite veins in southeastern Anatolia, Turkey. The Avgamasya, Anılmış, Harbul, Silip, and Üçkardeşler veins, which are the focus of this study, are enriched in elements such as As, Cd, Mo, Ni, Sb (except in Harbul), U, V, Zn, and Hg. Commonly detected minerals across all samples include dolomite, calcite, apatite, pyrite, sphalerite, alkali feldspar, quartz, illite, and iron oxides. Additionally, smectite, barite, celestine, ilmenite, galena, hematite, rutile, and strontianite were also observed. The mineral matter present can be both syngenetic and epigenetic. The microcrystalline minerals present within solid bitumen may have precipitated from supersaturated fluids during the maturation of hydrocarbons. In contrast, epigenetic minerals may have originated from hydrothermal fluids after the solid bitumen was formed or may have been incorporated from the surrounding host rocks during the hydrocarbon migration process. Organisms in the shelf environment likely played a crucial role in the enrichment of these elements. Sedimentary and diagenetic processes, sediment pore waters, and hydrothermal fluids may have significantly contributed to the formation of minerals that host these enriched elements. Solid bitumen, iron oxides, pyrite, and sphalerite can serve as major carriers of these enriched elements. Meanwhile, lithophile elements such as Sr, Ba, and Na are typically found in minerals like barite, strontianite, celestine, calcite, apatite, and fossil shells.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"308 ","pages":"Article 104846"},"PeriodicalIF":5.6,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexander Zdravkov , Achim Bechtel , Ksenija Stojanović , Doris Groβ , Johannes Weitz , Ivan Kojić , Reinhard F. Sachsenhofer , David Misch , Dragana Životić
{"title":"Petrological and organic geochemical insights into the peat-forming environmental settings during the deposition of the early Oligocene Pirin coal deposit, SW Bulgaria","authors":"Alexander Zdravkov , Achim Bechtel , Ksenija Stojanović , Doris Groβ , Johannes Weitz , Ivan Kojić , Reinhard F. Sachsenhofer , David Misch , Dragana Životić","doi":"10.1016/j.coal.2025.104843","DOIUrl":"10.1016/j.coal.2025.104843","url":null,"abstract":"<div><div>The up to 30-m-thick Brezhani coal seam in the Pirin deposit (SW Bulgaria) is the only coal of early Oligocene age on the territory of Bulgaria, providing important insights into peat-forming environments during that period. The coal seam was investigated using organic petrography, bulk organic geochemistry and biomarker analysis.</div><div>Coal is predominantly composed of detrovitrinite with subordinate collotelinite and abundant corpogelinite. Liptinite macerals are mostly represented by alginite and suberinite, and locally resinite. The coal commonly contains semi-inertinized (oxidized) root tissues without apparent thermal influence. The low- to moderate tissue preservation indicates predominant contribution from plants with low preservation potential. Rare resin-impregnated woody tissues argue for peat accumulation within a sparsely forested shrub-dominated mire. Biomarker proxies indicate a contribution from mixed vegetational communities, composed of flowering plants and bald cypresses. A contribution of aquatic macrophytes is also evident.</div><div>Variable ash yields and sulfur contents indicate changeable water supply and pH conditions. However, high sulfur contents and ash yields in a large number of the samples denote organic matter accumulation within a topogenous mesotrophic marginal limno-telmatic mire. Plant material accumulated at or very close to the water surface in a predominantly water-logged environment, indicated by strong gelification. The initial oxidizing conditions were quickly shifted to reductive settings due to flooding of the peat surface with possible seasonal dynamics.</div><div>Low maturity of the organic matter and limited hydrocarbon generation potential are evident from the low vitrinite reflectance (avg. Ro = 0.52 %), biomarker parameters and Rock-Eval data.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"308 ","pages":"Article 104843"},"PeriodicalIF":5.6,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144621965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hongbiao Wang , Daming Niu , Zhisheng Luan , Hongliang Dang , Xinyu Pan , Pingchang Sun
{"title":"Kinetic characteristics of secondary hydrocarbon generation from oil shale and coal at different maturation stages: Insights from open-system pyrolysis","authors":"Hongbiao Wang , Daming Niu , Zhisheng Luan , Hongliang Dang , Xinyu Pan , Pingchang Sun","doi":"10.1016/j.coal.2025.104845","DOIUrl":"10.1016/j.coal.2025.104845","url":null,"abstract":"<div><div>Understanding secondary hydrocarbon generation from organic matter is critical for assessing source rock potential in thermally complex basins. This study investigates the hydrocarbon generation kinetics of immature to low-maturity kerogen types (Type I, II, III) using open-system pyrolysis experiments on oil shale and coal samples from the Minhe and Meihe Basins, China. Results show that Type I kerogen exhibits a narrow hydrocarbon generation window and rapid depletion of generative potential, whereas Types II and III display broader, more gradual trends. Activation energy increases with thermal maturity, and interruptions during active generation raise the energy threshold for reactivation. A parallel first-order reaction model accurately simulates generation rates (R<sup>2</sup> > 0.9998). By integrating kinetic parameters with burial and thermal histories, we reconstructed hydrocarbon evolution pathways in the Minhe Basin. Simulations indicate that <em>in-situ</em> conversion of shallow oil shale at a heating rate of 0.35 °C/day over 881 days yields maximum hydrocarbon output with minimal energy consumption. These insights provide a theoretical foundation for both conventional reservoir prediction and unconventional resource development.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"308 ","pages":"Article 104845"},"PeriodicalIF":5.6,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144596540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Juan Sebastian Gomez-Neita , Ana Maria Pimentel Mizusaki , Taís Freitas da Silva , Sandra Rocio Manosalva-Sanchez , Jorge Eliecer Mariño-Martínez , David Enrique Vega Porras , Simone Patricia Aranha da Paz
{"title":"FTIR spectral signatures of Cretaceous-Paleogene sub-bituminous and bituminous coal: Insights into molecular structure evolution during coalification in the Eastern Cordillera Basin, Colombian Andes","authors":"Juan Sebastian Gomez-Neita , Ana Maria Pimentel Mizusaki , Taís Freitas da Silva , Sandra Rocio Manosalva-Sanchez , Jorge Eliecer Mariño-Martínez , David Enrique Vega Porras , Simone Patricia Aranha da Paz","doi":"10.1016/j.coal.2025.104844","DOIUrl":"10.1016/j.coal.2025.104844","url":null,"abstract":"<div><div>The coalification process and maceral composition influence the molecular structure of the organic matter, yet their precise effects remain a significant challenge in coal geology studies. This investigation focused on sub-bituminous and bituminous coal from the Cretaceous-Paleogene Guaduas Formation in the Colombian Andes, concurrently creating an extensive database of FTIR spectral signatures with 118 samples. Analytical techniques employed in this study included Fourier Transform Infrared spectroscopy in the mid-Infrared Region (FTIR-MIR) using the KBr pellet method, micro-FTIR spectroscopy, and X-ray diffraction (XRD). Molecular structural parameters, such as Aromaticity (AR1 and AR2), Degree of Condensation (DOC1 and DOC2), methylene-to-methyl ratio (CH<sub>2</sub>/CH<sub>3</sub>), and Factor A, were determined. The random vitrinite reflectance (VRr%) of the studied samples ranged from 0.46 % to 1.65 %, indicating the occurrence of sub-bituminous and bituminous coals. The results revealed AR1 ranging from 0.026 to 0.182, AR2 from 0.208 to 1.282, DOC1 from 0.048 to 0.244, DOC2 from 0.373 to 1.797, CH<sub>2</sub>/CH<sub>3</sub> from 2.444 to 6.430, and Factor A from 0.559 to 0.701. The prominent inorganic peaks in the FTIR spectra corroborated with the coal mineralogy, kaolinite and quartz, which are dominant, with minor occurrences of siderite, pyrite, and iron oxides. Micro-FTIR data indicated higher aromaticity and condensation in macerals of the inertinite group compared to vitrinite and liptinite groups. The correlation of structural parameters showed an increase in condensation and aromaticity with higher VRr% (or increased coal rank). The aromaticity and condensation increased with depth, suggesting that burial affected the rank of the Guaduas Formation coal. Coal with a higher inertinite content showed higher aromaticity/condensation and shorter aliphatic chain length (CH<sub>2</sub>/CH<sub>3</sub>). The FTIR spectra of the analyzed dataset reveal that coalification was the dominant factor that affected the organic molecular structure of coal in the Eastern Cordillera Basin. It was found that maceral composition is also crucial in explaining the variations in molecular structural parameters observed in isorank coals. In this sense, liptinite-rich coal was enriched in aliphatic components, whereas vitrinite and inertinite-rich coals were enriched in aromatic compounds, exhibiting gas-prone characteristics.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"308 ","pages":"Article 104844"},"PeriodicalIF":5.6,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144621964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Editorial of the special issue: 75th ICCP meeting: Organic petrology research and applications for the 21st Century","authors":"Angeles G. Borrego","doi":"10.1016/j.coal.2025.104842","DOIUrl":"10.1016/j.coal.2025.104842","url":null,"abstract":"","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"308 ","pages":"Article 104842"},"PeriodicalIF":5.7,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144621942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Geochemical perspectives of the rare earth elements and yttrium in some Permian and Paleogene coals of India: A review","authors":"Monica Sahoo , James C. Hower , Ganesh Chalavadi","doi":"10.1016/j.coal.2025.104831","DOIUrl":"10.1016/j.coal.2025.104831","url":null,"abstract":"<div><div>The increasing demand and utilization of rare earth elements (REE or REY, if yttrium is included) in numerous sectors have led to the consideration of secondary resources for their recovery. The worldwide research has been focused on coal beds that may have potential recovery of REE or REY. Despite India's extensive coal reserves, the complex geochemistry of REE in its coalfields remains underexplored, with only a few basins being investigated. This paper reviews existing literature on the enrichment types, modes of occurrence, and anomalies of REE in Indian coal measures. Key findings indicate the presence of REY-bearing minerals such as xenotime, rhabdophane, mixed layer smectite/illite, etc., in Gondwana and Paleogene coals along with a high fractionation of LREE (light REE). Coals from Satupalli, Hura, Meghalaya, and Jharia show strong potential for the REY extraction. The Upper Continental Crust (UCC)-normalized REE patterns of the coal deposits illustrate variations in their distribution types. Satupalli coals exhibit an heavy-type distribution, Hura coals display light- and medium-type distribution patterns, Sohagpur coals show light-type pattern, while Assam coals have an heavy-type distribution pattern. The modes of occurrence of the REE in Indian coals are primarily influenced by the input of detrital minerals in erosional areas. The Paleogene coals have experienced marine-influenced environments; however, few of them exhibit distinctive depositional settings as well. Limited coal samples from Meghalaya and Raniganj show substantial REE enrichment. This study highlights the dissimilar characteristics in REE distribution patterns across India's coalfields, each with disparate geological settings, which need supplementary research work to establish their precise modes of occurrence and incorporation mechanisms into the peat depositional environment.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"308 ","pages":"Article 104831"},"PeriodicalIF":5.6,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144596541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhenyu Xu , Xiaomei Wang , Fan Deng , Xingxing Guo , Yuxuan Han , Ke Sheng , Yuanhe Mu , Qin Yang
{"title":"Modes of occurrence of rare earth elements and yttrium in bituminous coals with different ranks from the Hedong Coalfield, northern China","authors":"Zhenyu Xu , Xiaomei Wang , Fan Deng , Xingxing Guo , Yuxuan Han , Ke Sheng , Yuanhe Mu , Qin Yang","doi":"10.1016/j.coal.2025.104833","DOIUrl":"10.1016/j.coal.2025.104833","url":null,"abstract":"<div><div>As the promising critical metal elements in coal, rare earth elements and yttrium (REY) can occur in minerals or complex with organic matter. Some differences have been observed in the modes of occurrence of REY in coals with different ranks, which raises interesting questions on their variation characteristic and mechanism during complex coalification. In this study, the modes of occurrence of REY and organic structure characteristics in bituminous coals with different ranks from the Hedong Coalfield are investigated. The sequential chemical extraction procedure shows that REY mainly remain in the residue in the low-rank bituminous coals and display an increasing total leaching rate as vitrinite reflectance increases. While in the high-rank bituminous coals, REY are dominated by HCl-leachable and residual phases. These results demonstrate that organic matter is the dominant carrier of REY in the low-rank bituminous coals. While in the high-rank bituminous coals, REY predominantly associate with phosphates and organic matter, indicating a gradual transformation from organic to mineral forms during coalification. Fourier Transform infrared (FTIR) spectroscopy experiments have found that the peak areas of most oxygenated functional groups are negatively correlated with vitrinite reflectance. In comparison to other functional groups, the content of phenolic group (Ar-OH) displays a strong positive correlation with the proportion of residual REY in the sequential chemical extraction experiment. This indicates that Ar-OH probably serves as the dominant organic binding site of REY during coalification. The loss of organic binding sites during coalification may result in the gradual decline of the proportion of organic-bound REY. Meanwhile, some REY released from these binding sites probably form authigenic minerals, leading to the higher proportion of mineral-associated forms of REY in the high-rank bituminous coals.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"308 ","pages":"Article 104833"},"PeriodicalIF":5.6,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144515584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Relationship between vitrinite reflectance, fluoresence red/green quotients, apatite fission tracks and temperature by joint inversion of three wells","authors":"Søren B. Nielsen, Oskar Hagelskjær, Hamed Sanei","doi":"10.1016/j.coal.2025.104832","DOIUrl":"10.1016/j.coal.2025.104832","url":null,"abstract":"<div><div>Thermal maturity assessment in sedimentary basins often relies on thermal indicators of varying quality and sensitivity, frequently available in an uneven distribution across wells. To improve interpretative reliability and reduce the influence of local statistical variability, we apply a joint inversion approach to thermal maturity data from three wells situated in contrasting geological settings. One well, Aars-1, located in the Danish Basin of the eastern North Sea, is constrained by high-quality data including present-day temperature, vitrinite reflectance (VRo), red-to-green (R/G) fluorescence quotients, and apatite fission track (AFT) ages. The other two wells, from the northwestern Black Sea Basin, contain VRo and R/G data but lack temperature and AFT records.</div><div>All wells contribute to constraining a kinetic model for the R/G quotient and the thermal evolutiuon of the Black Sea wells. The resulting models yield predicted present-day bottom hole temperatures of approximately 100 °C at 4000 m depth, consistent with values from independent studies in the region. The thermal immaturity of the Black Sea wells is attributed to low background heat flow and high sedimentation rates. In the immature to early mature maturity window, a linear relationship is established between VRo and R/G, described by the equation: VRo = 1.3239 × R/G – 0.2352, valid within the calibration range of 0.43 < R/G < 0.73 and 0.33 < VRo < 0.73. Based on this relationship, the previously reported VRo discontinuities at the base of the Black Sea wells are likely artefactual.</div><div>This study demonstrates the value of combining independent thermal indicators across multiple wells and depositional settings. The approach enhances the robustness of thermal history reconstructions and offers a practical framework for evaluating relative heat flow and maturity in basins with incomplete or uneven datasets. Particularly, the R/G quotient, derived from autochthonous alginite deposited within the basin, is less affected by transport-related degradation than VRo and may offer a more representative measure of in-place thermal maturity, particularly in high-sedimentation environments.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"308 ","pages":"Article 104832"},"PeriodicalIF":5.6,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144515591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}