International Journal of Coal Geology最新文献

{"title":"In loving memory of Deolinda Flores (1958–2025)","authors":"Manuela Marques , Isabel Suárez-Ruiz , Lopo Vasconcelos , Henrique Pinheiro , João Graciano Mendonça Filho","doi":"10.1016/j.coal.2025.104923","DOIUrl":"10.1016/j.coal.2025.104923","url":null,"abstract":"","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"313 ","pages":"Article 104923"},"PeriodicalIF":5.7,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145732135","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":"A deep learning system for sporomorph identification and Spore Coloration Index (SCI) calculation for evaluating source rocks' thermal maturity","authors":"Richard Bryan Magalhaes Santos ,&nbsp;Karen Soares Augusto ,&nbsp;Sidnei Paciornik ,&nbsp;Marcos Henrique de Pinho Maurício ,&nbsp;Tiago de Souza Mota ,&nbsp;Bruno Conceição do Nascimento ,&nbsp;Italo de Oliveira Matias ,&nbsp;Lauro Tiago Souza Santos ,&nbsp;Leandra Costa Lages ,&nbsp;Gil Marcio Avelino Silva ,&nbsp;André Luiz Durante Spigolon","doi":"10.1016/j.coal.2025.104921","DOIUrl":"10.1016/j.coal.2025.104921","url":null,"abstract":"<div><div>Determining the degree of maturation and thermal evolution in kerogen is vital to the hydrocarbons industry. This study evaluates the thermal maturation of source rock sections in sedimentary basins. Its determination makes it possible to estimate whether a sample from a given depth in an oil well falls within the window of oil or natural gas generation or remains immature. The Spore Coloration Index (SCI) can indicate the maturation of oil- and gas-prone material. The objective of this study is to automate this analysis, thereby achieving significant improvements in time efficiency and reliability. Traditionally, an operator visually identifies the presence of sporomorphs in slides using an optical microscope. When they encounter a sporomorph, the operator visually compares it with standard reference slides. The standard consists of 19 slides of spores of different degrees of maturity, ranging from the lightest to the darkest, from 1.0 to 10.0, in increments of 0.5. Comparison with the standard allows the operator to estimate the Spore Coloration Index (SCI) of a sporomorph. Various tests corroborated the literature's indication that the red channel best correlates with the thermal maturation index. A linear relationship was obtained between the average intensity of the red channel and the SCI (correlation coefficient R² = 0.97). Images of samples from various wells at different depths were acquired under conditions similar to those standardized for organopalynological slides. Deep Learning-based systems were trained to identify sporomorphs in the images. With the help of an expert operator, the objects were manually outlined in the images to create a reference database. This database was separated into a training set and a validation set, allowing the network to learn and then have its performance evaluated (accuracy ≈ 86 %). The captured images feed the system, which identifies the presence of sporomorphs, measures the SCI value of each one, and generates a histogram of SCI distribution for each case, allowing, for the first time, the direct calculation of the SCI without the need for visual analysis.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"313 ","pages":"Article 104921"},"PeriodicalIF":5.7,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689426","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":"Isotope and chemical alteration of coalbed gases during migration from underground coal mine into the atmosphere","authors":"Yaroslav Bezyk ,&nbsp;Dawid Szurgacz ,&nbsp;Maciej Górka ,&nbsp;Dariusz Strąpoć ,&nbsp;Łukasz Kruszewski ,&nbsp;Przemysław Wachniew ,&nbsp;Jarosław Nęcki ,&nbsp;Miroslaw Zimnoch ,&nbsp;Izabela Sówka ,&nbsp;Magdalena Modelska ,&nbsp;Wojciech Wołkowicz ,&nbsp;Carina van der Veen ,&nbsp;Thomas Röckmann","doi":"10.1016/j.coal.2025.104922","DOIUrl":"10.1016/j.coal.2025.104922","url":null,"abstract":"<div><div>Methane release into mine workings and the atmosphere poses a serious environmental and safety risks. This study examines the composition and stable isotope geochemistry of coalbed methane in a hard coal mine of the Upper Silesian Coal Basin (Poland), with emphasis on gas migration pathways from the coal seam through mine workings and ventilation shaft to the atmosphere. Methane concentrations decrease progressively with distance from the active excavation zone toward the exhaust shaft. In addition to CH₄ and CO₂, the coalbed gas contained notable amounts of nitrogen heterocyclic compounds, sulfur-bearing species, and chlorinated gases, depending on the sampling location and temporal window.</div><div>Geochemical results reveal a strong link between gas migration and isotopic variability in the underground environment. Zones of methane accumulation, commonly associated with bends in return airways, showed enrichment in ¹³C, consistent with diffusive fractionation. Variations in CH₄ and corresponding isotope effects during coal transport indicate multiple gas origins within the coal seam. Isotope signatures point to predominantly thermogenic CH₄ at the active mining level, whereas ¹³C-depleted methane at the exploited and flooded levels suggests secondary microbial generation. The microbial contribution is likely promoted by infiltrating meteoric waters supplying nutrients for methanogenic archaea, as supported by δ²H, δ¹⁸O signatures of mine water, and measurable tritium activity. The absence of enriched δ¹³C values in CO₂ and dissolved inorganic carbon (DIC) further implies mixed thermogenic-microbial gas origin in abandoned mine workings.</div><div>These findings highlight the combined influence of mining operations, diffusion-desorption processes, microbial activity, and gas mixing on the molecular and isotope composition of coalbed gases transported toward the exhaust shaft. Moreover, isotopic data from downwind emission plumes demonstrate the value of integrating underground measurements with atmospheric observations to trace and quantify methane emissions from coal mining operations.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"313 ","pages":"Article 104922"},"PeriodicalIF":5.7,"publicationDate":"2025-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689431","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":"Origin and diagenetic evolution of claystones in the CP2 coal seam, Adaohai Mine, Daqingshan Coalfield: Evidence from mineralogy and geochemistry","authors":"Ni He ,&nbsp;Shangying Li ,&nbsp;Hongfei Cheng ,&nbsp;Zhenxiao Wu ,&nbsp;Yichen Wang ,&nbsp;Shaoxian Liang","doi":"10.1016/j.coal.2025.104913","DOIUrl":"10.1016/j.coal.2025.104913","url":null,"abstract":"<div><div>The Daqingshan Coalfield in Inner Mongolia takes the CP₂ coal section (Shuanmazhuang Formation) as its primary mineable layer, with the CP₄ coal section (Zahuaigou Formation) as a local mineable layer. These coal sections contain abundant claystone resources. This study presents a systematic analysis of claystone samples from the CP₂ seam in the Adaohai Mine, integrating mineralogical and geochemical data to elucidate sediment provenance and diagenetic evolution. The dominant clay minerals include kaolinite, illite (with K⁺ primarily occupying the interlayer sites), and NH₄⁺-bearing illite (with NH₄⁺ primarily occupying the interlayer sites), with minor non-clay phases such as quartz, pyrite, diaspore, anatase, and calcite. The provenance of the claystones in the study area mainly derives from the intermediate-felsic volcanic ash associated with the Late Paleozoic continental arc volcanic activities in the Inner Mongolia Uplift, which is located on the northern margin of the North China Block. During the Late Paleozoic, the Paleo-Asian Ocean Plate subducted beneath the North China Block triggered extensive volcanic activity in the Inner Mongolia Uplift along the northern margin of the North China Block. The erupted volcanic ash was deposited in the coeval peat swamp basins of the North China region. Kaolinite primarily formed through the alteration of volcanic ash in basins, with minor kaolinite originating from the recrystallization of aluminosilicate colloidal solutions. Numerous fine-grained illite and NH₄⁺-bearing illite exhibit textural characteristics of replacing kaolinite grains, indicating that illite and NH₄⁺-bearing illite were formed by the transformation of the precursor mineral kaolinite under hydrothermal fluids associated with thermal anomaly activity in the Late Jurassic-Early Cretaceous of North China. These fluids, enriched in Ca, Mg, Al, Si, and N, can form fracture fillings predominantly composed of silexite, dickite, calcite, diaspore, and NH₄⁺-bearing illite with fractures. Beyond providing thermal impetus for mineral alteration, the hydrothermal fluids also have provided the necessary elements supply for the compositional changes of the claystone, promoting mineral transformation. This work highlights the complex interplay between volcaniclastic provenance and post-depositional hydrothermal processes in shaping clay mineral assemblages in coal-bearing sequences.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"313 ","pages":"Article 104913"},"PeriodicalIF":5.7,"publicationDate":"2025-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145619780","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":"Hydrothermal enrichment of rare earth elements in Carboniferous–Permian coal-measure kaolins in the Datong Coalfield, North China, linked to Paleo-Asian Ocean evolution","authors":"Shuai Zhang,&nbsp;Yong Ding,&nbsp;Xiliang Zhang,&nbsp;Zhengguo Hu,&nbsp;Qinfu Liu","doi":"10.1016/j.coal.2025.104912","DOIUrl":"10.1016/j.coal.2025.104912","url":null,"abstract":"<div><div>Carboniferous–Permian coals in North China are widely recognized for their enrichment in critical metals, yet the enrichment within their adjacent rocks has received comparatively less attention. Recent investigations have identified rare earth elements and yttrium (REY)-enriched coal-measure kaolins, occurring as partings and floor of coal seams in the southeastern Datong Coalfield. These REY anomalies are of economic interest for potential recovery during kaolin utilization. This study integrates petrological, mineralogical, geochemical, and isotopic geochronological analyses with sequential chemical extraction to determine the origin of the kaolins, the modes of REY occurrence, and their enrichment mechanisms. Zircon U-Pb dating reveals a dominant age peak at ∼300 Ma, consistent with the depositional age of the coal seams. This, together with the presence of volcanic quartz and well-developed columnar/tabular and vermicular kaolinite, indicates a genesis from altered volcanic ash. Zircon geochemistry further suggests that the volcanic ash was derived from continental arc volcanism linked to the southward subduction of the Paleo-Asian Ocean (PAO) beneath the North China Craton (NCC) during the Late Paleozoic. The REY are predominantly hosted in epigenetic siderite and ankerite of hydrothermal origin and in hydrothermally altered kaolinite. Carbon and oxygen isotopic compositions, together with the trace element assemblages enriched in the carbonates, indicate that the hydrothermal fluids were derived from carbonatitic magmas. These magmas formed by partial melting of an enriched mantle that had been metasomatized by carbonate-rich fluids released during dehydration of the subducted PAO slab and its associated sediments. Following PAO closure, the northern NCC transitioned into an extensional tectonic regime during the Middle to Late Triassic. Asthenospheric upwelling triggered partial melting of the metasomatized mantle, generating carbonatitic magmas that intruded along lithosphere-scale faults at the eastern margin of the Datong Coalfield. The evolved hydrothermal fluids infiltrated the coarse-grained coal-measure kaolins and reacted with kaolinite to form carbonate minerals via replacement. The REY and other elements transported by these fluids were incorporated into the crystallizing carbonates and captured by hydrothermally altered kaolinite.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"312 ","pages":"Article 104912"},"PeriodicalIF":5.7,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145593672","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 characteristics, volatilization properties, speciation transformation, and environmental implications of trace elements during coal combustion from Huaibei Coalfield, Anhui, China","authors":"Mengfei Lu,&nbsp;Ruijia Liu,&nbsp;Minglian Shen,&nbsp;Guijian Liu,&nbsp;Hao Hu,&nbsp;Zongfan Xie,&nbsp;Zhen Yue","doi":"10.1016/j.coal.2025.104911","DOIUrl":"10.1016/j.coal.2025.104911","url":null,"abstract":"<div><div>The behavior of trace elements (TEs) during coal combustion is highly temperature-dependent, presenting a dual challenge of environmental risk and resource potential. However, the strategic utilization and effective pollution control of coal ash are hindered by insufficient understanding of how combustion temperature differentially governs the fate of critical and harmful elements. Combining combustion experiments with thermodynamic simulations, this study systematically investigated the impact of temperature (400–1100 °C) on the enrichment, volatilization, and speciation transformation of selected critical (Li, V, Ga, Ge, Zr, and Mo) and harmful elements (Cr, Ni, Cu, Zn, Cd, and Pb) in Huaibei coal, and evaluated their distinct environmental implications. The results show that the elements Li, Ga, Zr and Pb are all slightly enriched or enriched in five coal samples, and their contents in coal ashes are on average more than twice those in raw coals, and up to more than four times. The decomposition of organic matter is completed at 500/600 °C, and kaolinite-quartz-muscovite in the raw coal transform into mullite-quartz in coal ash. Trace elements are mainly stabilized as sulfate (Li, V, Cr, Ni, Cu, Zn, Cd, and Pb) at low temperatures, and partially volatilized as gaseous hydroxides (Li, Ga, Mo, Cr, Ni, Cu, Zn, and Cd) with increasing temperatures, or exist as metal oxides in coal ash (Li, V, Ga, Ge, Zr, Cr, Cu, Zn, and Pb). Principal component analysis (PCA) reveals differential responses of TEs to progressive temperature increases. The generally lower volatility of critical elements compared to harmful elements in coal ash leads to their higher retention, highlighting their potential for resource recovery and the consequent positive environmental benefits. However, the presence of harmful elements in ash also causes tangible negative environmental effects, primarily manifested as increased potential ecological risks with increasing temperatures. Cadmium is identified as the dominant risk contributor capable of reaching high risk levels at elevated temperatures. This study provides scientific basis for the harmless utilization of coal ash resources through temperature regulation.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"312 ","pages":"Article 104911"},"PeriodicalIF":5.7,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145560220","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":"Sweet spot development in heterogeneous shales of lower Silurian","authors":"Yujie Yuan ,&nbsp;Songtao Wu ,&nbsp;Emad Al-Khdheeawi ,&nbsp;Zihao Lin ,&nbsp;Jun Wang ,&nbsp;Menglei Wang ,&nbsp;Yuhan Zhou ,&nbsp;Lai-Chang Zhang ,&nbsp;Zhuo Feng","doi":"10.1016/j.coal.2025.104902","DOIUrl":"10.1016/j.coal.2025.104902","url":null,"abstract":"<div><div>The identification of sweet spots in shale is crucial for ensuring energy security and the economic development of gas resources. However, the pronounced heterogeneity of laminae and lithofacies presents substantial challenges in the accurate identification of sweet spots, particularly in shale formations deposited across the Early Silurian, which was significantly affected by episodic volcanism. To achieve a high-resolution understanding of sweet spot development and accurately identify the economic intervals, this study conducted an integrated analysis of continuous borehole core samples mostly from the Longmaxi Formation. This involved high-resolution lithological, mineralogical, petrophysical, and geochemical characterizations, combined with in-situ gas content measurements. The results establish lamina-scale criteria for sweet spot identification, emphasizing the critical role of fine-scale heterogeneity. Our findings demonstrate that sweet spot development during the Early Silurian is strongly governed by the architecture of laminae and lithofacies, which significantly influence reservoir quality. Based on the proposed criteria, the optimal sweet spot interval (Class I) was identified in the lower Longmaxi Formation, specifically within the integrated sublayer of ‘upper Long-1₁² + Long-1₁³’. This interval is characterized by interbedded thick silty-thin muddy laminae and organic matter (OM)-rich mixed shale (ORMS). It exhibits the highest total organic carbon (TOC), excellent petrophysical and mechanical properties, well-developed nanopore systems, and the highest in-situ gas content. Additionally, Class II and III sweet spots were identified in the Long-1₁⁴ and the integrated ‘Long-1₁¹ + upper Long-1₁²’ sublayers, respectively. These intervals experienced a less intensive volcanism, exhibiting comparable laminae configurations and dominated by OM-moderate siliceous and mixed shale lithofacies, resulting in favorable reservoir quality and gas content, albeit relatively inferior compared to Class I. In contrast, no sweet spots are observed in the Long-1₂ and Long-2 intervals of the upper Longmaxi Formation, with trace volcanism evidence. These intervals are dominated by thick massive, muddy laminae and OM-poor argillaceous shale lithofacies and exhibit poor petrophysical and mechanical properties with low gas content. This study underscores the importance of laminae and lithofacies in heterogeneous shales and the controlling mechanisms of sweet spot development. The findings provide a scientific basis for more accurate resource evaluation and exploitation of shale gas resources.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"313 ","pages":"Article 104902"},"PeriodicalIF":5.7,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145553671","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":"Raman spectroscopy of electrostatically isolated organic matter for thermal maturity assessment: A case study on the Mowry Shale","authors":"Tarek Ismail,&nbsp;Soheil Saraji","doi":"10.1016/j.coal.2025.104910","DOIUrl":"10.1016/j.coal.2025.104910","url":null,"abstract":"<div><div>Organic Matter (OM) thermal maturity plays a critical role in hydrocarbon generation within unconventional systems, controlling the transformation of kerogen to oil, and from oil to gas/condensate, thereby defining the fluid type in place. Reliable maturity evaluation underpins resource assessment, sweet-spot mapping, landing-zone selection, and calibration across geochemical, petrographic, and spectroscopic proxies. This study evaluates the thermal maturity of the Mowry Shale in the Powder River Basin using pyrolysis, vitrinite reflectance, and Raman spectroscopy, with emphasis on the impact of sample preparation. Three sample preparation approaches (powdered rock, polished kerogen concentrates, and electrostatically isolated organic-matter) were tested and compared. The novel electrostatic isolation technique separates organic matter from the surrounding mineral matrix, effectively exposing and concentrating it for analysis and substantially improving Raman spectral quality by reducing background noise and mineral interference. Raman parameters derived from electrostatically isolated OM showed a strong correlation between Raman Band Separation (RBS) and VRo-equivalent (R² = 0.85). This approach facilitates rapid and reliable OM identification with reduced preparation compared to conventional methods; however, its broader applicability to other formations needs further investigation. Furthermore, organic petrography provided a formation-specific calibration between Vitrinite Reflectance (VRo) and thermal maturity (Tmax), which enabled extension of VRo equivalency across the full dataset (39 samples) despite direct VRo measurements being available for only 16 samples.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"312 ","pages":"Article 104910"},"PeriodicalIF":5.7,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531595","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":"Evaluation of lanthanides and yttrium in Chinese coal: Content, distribution, and recovery priority","authors":"Yunfei Li ,&nbsp;Chuncai Zhou ,&nbsp;Chen Li ,&nbsp;Feng Wang ,&nbsp;Shuheng Hu ,&nbsp;Wentao Wu ,&nbsp;Guijian Liu","doi":"10.1016/j.coal.2025.104901","DOIUrl":"10.1016/j.coal.2025.104901","url":null,"abstract":"<div><div>The rapid expansion of the new energy industry has resulted in a significant shift in the demand structure for specific lanthanides and yttrium (REY) and an overall increase in demand, thereby accelerating the depletion of conventional sources and driving the exploration of unconventional sources such as coal-based resources. This study established a comprehensive database of REY in Chinese coal, calculated the average REY content across the nation and various provinces using recoverable reserves, and classified recovery priorities accordingly. The results indicate that the average REY content in Chinese coal is 127.8 ppm, with significant regional variations: the highest contents are found in Shanxi, Qinghai, and the southwestern provinces. Coal-forming ages also influence REY resources potential, with late Carboniferous-early Permian (C₂-P₁) exhibiting the highest levels, followed by a gradual decline over ages until a minor rebound in the Paleogene to Neogene (E-N). Additionally, REY in coal exhibits both inorganic and organic affinities, with phosphorus-containing substances having the most substantial impact. Given the high potential for REY recovery and the considerable content of high supply risk rare earth elements (Pr, Nd, Gd, Tb, Dy, and Y in this work) in Guangxi and Chongqing, these regions are categorized as extremely high-priority areas.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"312 ","pages":"Article 104901"},"PeriodicalIF":5.7,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145491993","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":"Source of biodegraded oil seep and bitumen rock-impregnations from the Sicilian Orogen and Foreland (Italy): Rock-Eval 6/7S and GC-MS approach","authors":"Ádám Nádudvari ,&nbsp;Rosanna Maniscalco ,&nbsp;Martina Forzese ,&nbsp;Dorota Staneczek ,&nbsp;Dariusz Więcław ,&nbsp;Giovanni Silvio Cassarino ,&nbsp;Ewa Szram ,&nbsp;Leszek Marynowski","doi":"10.1016/j.coal.2025.104900","DOIUrl":"10.1016/j.coal.2025.104900","url":null,"abstract":"<div><div>Hydrocarbons have been known in Sicily for centuries from oil seeps and bitumen-impregnated limestones, which were exploited in the 19^th and early 20^th centuries. In the 1950s, several shallow wells were drilled in the Sicilian Foreland with the aim of hydrocarbon production. The study focuses on oil and bitumen seeps in Sicily, southern Italy. The oil seeps occur on the surface in Madonna dell’Olio (MA) in the Madonie Mountains in northern Sicily. They are also present as bitumen-impregnated porous carbonates in the Ragusa Formation on outcrops and in the subsurface in the Hyblean Foreland in southeastern Sicily (Streppenosa, Castelluccio, and Tabuna mines). Oil seeps introduce hydrocarbons into the natural environment, where biodegradation occurs. As biodegradation increases, the organic sulfur content increases, while the proportion of pyrolytic organic sulfur within total organic sulfur decreases. The Rock-Eval’s Multi-Heating Rates method shows that the Ragusa bitumen is dominated by the heavy fraction, in contrast to the diesel oil dominance of MA. Distinct oil families represent individual sources: carbonates in the Sicilian Fold-and-Thrust Belt, and shales and carbonates in the Ragusa Hyblean foreland. The distribution of biomarkers indicates an early oil window for both the MA and Ragusa fluids, with MA hydrocarbons slightly more mature than Ragusa ones.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"312 ","pages":"Article 104900"},"PeriodicalIF":5.7,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145478232","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}