Pub Date : 2025-05-27DOI: 10.1016/j.coal.2025.104813
Majid Safaei-Farouji , David Misch , Reinhard F. Sachsenhofer , Johannes Weitz , Ivan Kojic , Ksenija Stojanović , Serik Tursyngaliyev , Medet Junussov , Milovan Fustic
The Bogatyr Komin open-pit mine in the Ekibastuz Basin, located in north-east Kazakhstan, is one of the largest coal mines in the world. It is based on three Lower Carboniferous seams (from bottom to top: seams 3, 2, and 1), which together form a 150 m thick, uniform seam complex. At the study site on the western basin edge, the seams dip steeply. Organic petrological and geochemical investigations have been performed to determine the maturity and depositional environment of these exceptionally thick seams.
Vitrinite reflectance (0.8–1.1 %Rr) classifies the coal as high-volatile bituminous A coal, which is also supported by Tmax values and maturity-related biomarker ratios. Vitrinite reflectance patterns prove pre-deformational coalification and a relatively high paleo-heat flow, likely caused by magmatic activity.
High ash yields and relatively low sulfur contents indicate that the coal accumulated in low-lying mires without marine influence. The input of detrital minerals decreased during peat accumulation. Relatively high concentrations of sulfur-bearing aromatic compounds, particularly in the lower part of seam 3, may reflect volcanic activity, which is also evidenced by the presence of distinct ash layers (“kaolinitic beds”) and kaolinite in coal samples.
Thick wood-forming plants were rare in the peat-forming vegetation. However, samples from seams 1 and 3 contain higher concentrations of aromatic compounds derived from lignin-bearing arborescent cordiaite-conifer-pteridosperm vegetation. Enhanced bacterial activity during deposition of the upper part of seam 2 and seam 1 is indicated by elevated hopane concentrations.
The exceptional thickness of the coal complex indicates a geodynamic setting with high subsidence rates.
{"title":"Organic petrography and geochemistry of the Lower-Carboniferous coals from the Ekibastuz Basin, Kazakhstan","authors":"Majid Safaei-Farouji , David Misch , Reinhard F. Sachsenhofer , Johannes Weitz , Ivan Kojic , Ksenija Stojanović , Serik Tursyngaliyev , Medet Junussov , Milovan Fustic","doi":"10.1016/j.coal.2025.104813","DOIUrl":"10.1016/j.coal.2025.104813","url":null,"abstract":"<div><div>The Bogatyr Komin open-pit mine in the Ekibastuz Basin, located in north-east Kazakhstan, is one of the largest coal mines in the world. It is based on three Lower Carboniferous seams (from bottom to top: seams 3, 2, and 1), which together form a 150 m thick, uniform seam complex. At the study site on the western basin edge, the seams dip steeply. Organic petrological and geochemical investigations have been performed to determine the maturity and depositional environment of these exceptionally thick seams.</div><div>Vitrinite reflectance (0.8–1.1 %Rr) classifies the coal as high-volatile bituminous A coal, which is also supported by Tmax values and maturity-related biomarker ratios. Vitrinite reflectance patterns prove pre-deformational coalification and a relatively high paleo-heat flow, likely caused by magmatic activity.</div><div>High ash yields and relatively low sulfur contents indicate that the coal accumulated in low-lying mires without marine influence. The input of detrital minerals decreased during peat accumulation. Relatively high concentrations of sulfur-bearing aromatic compounds, particularly in the lower part of seam 3, may reflect volcanic activity, which is also evidenced by the presence of distinct ash layers (“kaolinitic beds”) and kaolinite in coal samples.</div><div>Thick wood-forming plants were rare in the peat-forming vegetation. However, samples from seams 1 and 3 contain higher concentrations of aromatic compounds derived from lignin-bearing arborescent cordiaite-conifer-pteridosperm vegetation. Enhanced bacterial activity during deposition of the upper part of seam 2 and seam 1 is indicated by elevated hopane concentrations.</div><div>The exceptional thickness of the coal complex indicates a geodynamic setting with high subsidence rates.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104813"},"PeriodicalIF":5.6,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170243","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}
Pub Date : 2025-05-23DOI: 10.1016/j.coal.2025.104812
Ji Chen , Jingwen Zheng , Daxiang He , Peng Cheng , Qin Zhou , Tengfei Li , Haifeng Gai
Solid bitumen constitutes a predominant organic component in thermally mature source rocks, yet its role in shale reservoirs remains poorly constrained. This study integrated hydrocarbon expulsion simulation via sequential solvent extraction with isothermal pyrolysis experiments conducted on an early mature bituminite-rich shale sample from the Mesoproterozoic Xiamaling Formation in North China. Organic petrography and gas adsorption were applied to characterize the solid bitumen and pore structure in pyrolysis residues, respectively. The primary objective was to advance the understanding of the solid bitumen formation and its influence on the porosity development of shales within the dry gas window. Quantitative petrographic evidence confirms that the composition of retained extractable organic matter exerts fundamental control over the yield and properties of solid bitumen. Notably, the polar fraction (e.g., asphaltene component) exhibits superior solid bitumen-generating capacity, indicating that expulsion-driven compositional fractionation of residual hydrocarbons serves as the primary determinant of intraformational solid bitumen heterogeneity. Furthermore, empirical data demonstrate an inverse relationship between solid bitumen content and porosity development of shales across the investigated maturity spectrum (vitrinite reflectance 1.02 %–3.62 %), manifested through depressed specific surface area and diminished pore volume metrics. Our findings suggest that provenance-controlled variations in solid bitumen occurrence and subsequent pore architecture may induce complex reservoir quality modifications, potentially accounting for divergent porosity trends observed in natural shale systems. While this investigation provides fundamental insights into organo-petrophysical relationships, the general applicability of these conclusions warrants further validation through subsequent research.
{"title":"Solid bitumen formation and resulting differential porosity development in the Mesoproterozoic Xiamaling shale during artificial thermal maturation","authors":"Ji Chen , Jingwen Zheng , Daxiang He , Peng Cheng , Qin Zhou , Tengfei Li , Haifeng Gai","doi":"10.1016/j.coal.2025.104812","DOIUrl":"10.1016/j.coal.2025.104812","url":null,"abstract":"<div><div>Solid bitumen constitutes a predominant organic component in thermally mature source rocks, yet its role in shale reservoirs remains poorly constrained. This study integrated hydrocarbon expulsion simulation via sequential solvent extraction with isothermal pyrolysis experiments conducted on an early mature bituminite-rich shale sample from the Mesoproterozoic Xiamaling Formation in North China. Organic petrography and gas adsorption were applied to characterize the solid bitumen and pore structure in pyrolysis residues, respectively. The primary objective was to advance the understanding of the solid bitumen formation and its influence on the porosity development of shales within the dry gas window. Quantitative petrographic evidence confirms that the composition of retained extractable organic matter exerts fundamental control over the yield and properties of solid bitumen. Notably, the polar fraction (e.g., asphaltene component) exhibits superior solid bitumen-generating capacity, indicating that expulsion-driven compositional fractionation of residual hydrocarbons serves as the primary determinant of intraformational solid bitumen heterogeneity. Furthermore, empirical data demonstrate an inverse relationship between solid bitumen content and porosity development of shales across the investigated maturity spectrum (vitrinite reflectance 1.02 %–3.62 %), manifested through depressed specific surface area and diminished pore volume metrics. Our findings suggest that provenance-controlled variations in solid bitumen occurrence and subsequent pore architecture may induce complex reservoir quality modifications, potentially accounting for divergent porosity trends observed in natural shale systems. While this investigation provides fundamental insights into organo-petrophysical relationships, the general applicability of these conclusions warrants further validation through subsequent research.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104812"},"PeriodicalIF":5.6,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170242","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}
Pub Date : 2025-05-15DOI: 10.1016/j.coal.2025.104810
M.M. Bicca , W. Kalkreuth , T.F. Silva , M. Guerra-Sommer , I. Degani-Schmidt , C.M. Felix , D.R. Boardman , P.A. Souza
Coals from southern Brazil are preserved in the Lower Permian postglacial Rio Bonito Formation of the Paraná Basin. Previous studies on the Candiota Coalfield have shown intervals with significant accumulations of inertinite macerals in the Banco Louco and S9 coal seams. Aiming to understand the causes of these anomalous inertinite accumulations, this study analyzed coal samples from the anomalous inertinite-rich interval and underlying carbonaceous siltites from the top of the Candiota Coal Superior (CCS), Banco Louco (BL), S9, and overlying S8 seams (post-anomalous) obtained from two borehole cores. The samples were analyzed using organic petrology, SEM, palynology, and biomarker (PAH) techniques. The results indicate that inertinite macerals accumulated in the paleoswamp in alternating small cycles, with general inertinite enrichment (fusinite, semifusinite, and inertodetrinite) towards the top of each coal seam analyzed. Macrocharcoal was present in all coal seams as charred wood, leaf fragments, and one reproductive structure. The peak of the inertinite-rich interval occurs at the S9 seam with the dominance of microcharcoal dispersed in fine-grained sediments and completely black palynomorphs, suggesting a significant wildfire event affecting the interval. Inertinite reflectance measurements indicated the predominance of ground and surface fire events with the rare occurrence of crown fires. Combustion of organic matter is also marked by the dominant presence of 3–5 ring PAHs and local occurrence of 6-ring PAHs (including coronene). The peatland flora was mainly composed of hygrophilous lycopsids and filicopsids, with subordinate elements represented by sphenopsids, mesophilous glossopterids, and meso-xerophilous conifers. The frequent oscillations in the vegetation composition were potentially related to climate changes and related environmental conditions, varying from hygrophilous to meso-hygrophilous and mesophilous, indicating that the vegetation composition adapted to environmental/climate changes as recognized by the alteration in the pollen-spore-producing flora towards the top of BL seam and their expansion in the overlying seams at the top of the anomalous interval. In the middle of the S9 seam, the completely dark palynomorphs and phytoclasts, plus a high abundance of pyrogenic biomarkers including 6-ring PAHs, point to significant fire events linked to the peak of the inertinite-rich interval during drier, warming intervals, which contributed to modifying the paleoecological patterns of the peatland. The paleo-wildfires of the Asselian age (ca. 298 Ma) Candiota Coalfield are the oldest record of wildfires in peat-forming environments of southern Brazil, being coeval with a warming period at the end of the Late Paleozoic Ice Age in Western Gondwana.
来自巴西南部的煤被保存在帕拉南盆地的下二叠世冰期后里约热内卢Bonito组中。以往对坎迪奥塔煤田的研究表明，Banco Louco和S9煤层具有明显的惰性矿物聚集。为了了解这些异常惰质岩聚集的原因，本研究分析了来自candota coal Superior （CCS）、Banco Louco （BL）、S9和上覆S8煤层（异常后）顶部的异常富惰质层和下伏碳质粉砂岩的煤样。利用有机岩石学、扫描电镜、孢粉学和生物标志物（PAH）技术对样品进行了分析。结果表明，古沼泽中惰质组以交替小旋回的方式富集，各煤层顶部均有普遍富集的惰质组（云母组、半云母组和惰质组）。大炭在所有煤层中以烧焦的木材、叶片碎片和一个生殖结构的形式存在。富贫质层段的峰值出现在S9煤层，微炭主要分布在细粒沉积物中，呈全黑色，表明该层段受野火事件影响较大。惯性反射率测量表明，地面和地面火灾事件占主导地位，很少发生树冠火灾。有机质的燃烧也以3-5环多环芳烃为主，局部出现6环多环芳烃（包括冠烯）。泥炭地植物区系主要由喜湿石松类和丝松类组成，次要成分以喜湿石松类、中湿石松类和中湿针叶树类为代表。植被组成的频繁振荡可能与气候变化和相关环境条件有关，从亲湿型到中亲湿型再到中亲湿型，表明植被组成适应环境/气候变化，这主要表现在产花粉菌群向BL层顶部的变化及其在异常区间顶部的上覆层中的扩张。在S9煤层中部，全暗的孢岩和植物碎屑，加上6环多环芳烃等高丰度的热生生物标志物，表明在干燥、变暖时期，泥炭地富惰质层的峰值与显著的火灾事件有关，这有助于改变泥炭地的古生态模式。阿塞利亚时代（约298 Ma）坎迪奥塔煤田的古野火是巴西南部泥炭形成环境中最古老的野火记录，与冈瓦纳西部晚古生代冰期结束时的一个变暖期同期。
{"title":"Multiproxy-based evidence of wildfire occurrence in the Lower Permian coal-bearing Rio Bonito Formation, Paraná Basin, Brazil","authors":"M.M. Bicca , W. Kalkreuth , T.F. Silva , M. Guerra-Sommer , I. Degani-Schmidt , C.M. Felix , D.R. Boardman , P.A. Souza","doi":"10.1016/j.coal.2025.104810","DOIUrl":"10.1016/j.coal.2025.104810","url":null,"abstract":"<div><div>Coals from southern Brazil are preserved in the Lower Permian postglacial Rio Bonito Formation of the Paraná Basin. Previous studies on the Candiota Coalfield have shown intervals with significant accumulations of inertinite macerals in the Banco Louco and S9 coal seams. Aiming to understand the causes of these anomalous inertinite accumulations, this study analyzed coal samples from the anomalous inertinite-rich interval and underlying carbonaceous siltites from the top of the Candiota Coal Superior (CCS), Banco Louco (BL), S9, and overlying S8 seams (post-anomalous) obtained from two borehole cores. The samples were analyzed using organic petrology, SEM, palynology, and biomarker (PAH) techniques. The results indicate that inertinite macerals accumulated in the paleoswamp in alternating small cycles, with general inertinite enrichment (fusinite, semifusinite, and inertodetrinite) towards the top of each coal seam analyzed. Macrocharcoal was present in all coal seams as charred wood, leaf fragments, and one reproductive structure. The peak of the inertinite-rich interval occurs at the S9 seam with the dominance of microcharcoal dispersed in fine-grained sediments and completely black palynomorphs, suggesting a significant wildfire event affecting the interval. Inertinite reflectance measurements indicated the predominance of ground and surface fire events with the rare occurrence of crown fires. Combustion of organic matter is also marked by the dominant presence of 3–5 ring PAHs and local occurrence of 6-ring PAHs (including coronene). The peatland flora was mainly composed of hygrophilous lycopsids and filicopsids, with subordinate elements represented by sphenopsids, mesophilous glossopterids, and meso-xerophilous conifers. The frequent oscillations in the vegetation composition were potentially related to climate changes and related environmental conditions, varying from hygrophilous to meso-hygrophilous and mesophilous, indicating that the vegetation composition adapted to environmental/climate changes as recognized by the alteration in the pollen-spore-producing flora towards the top of BL seam and their expansion in the overlying seams at the top of the anomalous interval. In the middle of the S9 seam, the completely dark palynomorphs and phytoclasts, plus a high abundance of pyrogenic biomarkers including 6-ring PAHs, point to significant fire events linked to the peak of the inertinite-rich interval during drier, warming intervals, which contributed to modifying the paleoecological patterns of the peatland. The paleo-wildfires of the Asselian age (ca. 298 Ma) Candiota Coalfield are the oldest record of wildfires in peat-forming environments of southern Brazil, being coeval with a warming period at the end of the Late Paleozoic Ice Age in Western Gondwana.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104810"},"PeriodicalIF":5.6,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144069774","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}
Pub Date : 2025-05-11DOI: 10.1016/j.coal.2025.104805
Aleš Šoster , Viktor Bertrandsson Erlandsson , Stephen Ajuaba , Nastja Rogan Šmuc
The coal-bearing basal section of the Late Eocene Socka Beds in northeastern Slovenia exhibits iron sulfide mineralization associated with coal. Detailed petrographic analyses have identified five distinct textural and geochemical varieties of pyrite and marcasite. Geochemical analyses reveal that pyrite is notably enriched in Cu, Zn, and Mo, while marcasite shows enrichment in Co, Ni, As, Se, and Sb. Geochemical proxies suggest that marcasite formed under relatively higher temperatures, significantly more reducing conditions, and lower pH compared to pyrite, a distinction that is reflected in their contrasting geochemical signatures. Pyrite incorporates trace elements linked to seawater incursions, while marcasite contains trace elements associated with the progressive degradation of organic matter and the release of organically-bound trace elements. This study demonstrates that iron sulfide speciation is not confined to a single precipitation phase but involves multiple generations of minerals that reflect shifts in physicochemical conditions over time. Additionally, it demonstrates that the incorporation of trace elements is primarily governed by the availability of metals and fluid chemistry, rather than by mineral-specific selective sequestration. These findings offer new insights into the physicochemical pathways that govern sulfide formation in coal-forming environments.
{"title":"Selective trace element uptake in iron sulfides during burial metamorphism of coal: Insights from the coal-bearing Socka Beds, Northeastern Slovenia","authors":"Aleš Šoster , Viktor Bertrandsson Erlandsson , Stephen Ajuaba , Nastja Rogan Šmuc","doi":"10.1016/j.coal.2025.104805","DOIUrl":"10.1016/j.coal.2025.104805","url":null,"abstract":"<div><div>The coal-bearing basal section of the Late Eocene Socka Beds in northeastern Slovenia exhibits iron sulfide mineralization associated with coal. Detailed petrographic analyses have identified five distinct textural and geochemical varieties of pyrite and marcasite. Geochemical analyses reveal that pyrite is notably enriched in Cu, Zn, and Mo, while marcasite shows enrichment in Co, Ni, As, Se, and Sb. Geochemical proxies suggest that marcasite formed under relatively higher temperatures, significantly more reducing conditions, and lower pH compared to pyrite, a distinction that is reflected in their contrasting geochemical signatures. Pyrite incorporates trace elements linked to seawater incursions, while marcasite contains trace elements associated with the progressive degradation of organic matter and the release of organically-bound trace elements. This study demonstrates that iron sulfide speciation is not confined to a single precipitation phase but involves multiple generations of minerals that reflect shifts in physicochemical conditions over time. Additionally, it demonstrates that the incorporation of trace elements is primarily governed by the availability of metals and fluid chemistry, rather than by mineral-specific selective sequestration. These findings offer new insights into the physicochemical pathways that govern sulfide formation in coal-forming environments.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104805"},"PeriodicalIF":5.6,"publicationDate":"2025-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143942438","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}
Pub Date : 2025-05-10DOI: 10.1016/j.coal.2025.104806
S. Omodeo-Salé , T. Cassola , A. Moscariello
Geothermal exploration can be complicated by the presence of hydrocarbons in the subsurface. This is a well-known issue in Switzerland, where geothermal projects were affected by the consequences of an unexpected finding of hydrocarbons during drilling operations. This was the case of the Schlattingen-1 well in 2011 and the St. Gallen-GT-1 well in 2013, both located in the north-eastern part of the Swiss Plateau. To confidently predict the potential of hydrocarbon occurrence in the subsurface, a 2D basin and petroleum system modelling (BPSM) was performed along a regional geological section of the eastern sector of the Swiss Plateau, including the Schlattingen-1, Herdern-1 and St. Gallen-GT-1 wells.
The BPSM reconstructs the temperature history of the basin by considering the geodynamic, structural and stratigraphic evolution of the basin. The modelling results were calibrated with present-day borehole temperature, porosity and vitrinite reflectance data. To calculate the hydrocarbon generation and accumulation potential in the studied area, the source rocks were geochemically and petrographically characterized. In the southern part of the section, gas accumulations are predicted by the model at the top of the Permo-Carboniferous graben, just beneath the St. Gallen GT-1 well. In the northern part, around the Schlattingen-1 and Herdern-1 well sites, the model indicates the migration and accumulation of hydrocarbons within the Mesozoic units. Migration to the uppermost Molasse units also occurs along faults, thrust planes and permeable units, when present.
The main uncertainties of the modelling results include: i) distribution and characteristics of faults; ii) thickness and hydrocarbon potential of the source rocks; iii) lithological and petrophysical properties of potential reservoir and seal units; iv) calibration data with big ranges and not uniformly measured. To refine the assumptions and enhance the understanding of the basin's evolution, further data should be collected and existing data reanalysed. Building risk analysis and probabilistic models would also help to plan drilling mitigation measures aimed at reducing these uncertainties. The workflow presented in this study can be highly valuable to geothermal projects. It allows more effective planning of the drilling procedure, thus reducing the operational risks and contributing to the overall project success.
{"title":"Mitigation of geothermal energy drilling risks in the presence of hydrocarbons: A basin scale approach applied to the eastern Swiss Plateau area (Schlattingen-1, Herdern-1 and St. Gallen-GT-1 geothermal transect)","authors":"S. Omodeo-Salé , T. Cassola , A. Moscariello","doi":"10.1016/j.coal.2025.104806","DOIUrl":"10.1016/j.coal.2025.104806","url":null,"abstract":"<div><div>Geothermal exploration can be complicated by the presence of hydrocarbons in the subsurface. This is a well-known issue in Switzerland, where geothermal projects were affected by the consequences of an unexpected finding of hydrocarbons during drilling operations. This was the case of the Schlattingen-1 well in 2011 and the St. Gallen-GT-1 well in 2013, both located in the north-eastern part of the Swiss Plateau. To confidently predict the potential of hydrocarbon occurrence in the subsurface, a 2D basin and petroleum system modelling (BPSM) was performed along a regional geological section of the eastern sector of the Swiss Plateau, including the Schlattingen-1, Herdern-1 and St. Gallen-GT-1 wells.</div><div>The BPSM reconstructs the temperature history of the basin by considering the geodynamic, structural and stratigraphic evolution of the basin. The modelling results were calibrated with present-day borehole temperature, porosity and vitrinite reflectance data. To calculate the hydrocarbon generation and accumulation potential in the studied area, the source rocks were geochemically and petrographically characterized. In the southern part of the section, gas accumulations are predicted by the model at the top of the Permo-Carboniferous graben, just beneath the St. Gallen GT-1 well. In the northern part, around the Schlattingen-1 and Herdern-1 well sites, the model indicates the migration and accumulation of hydrocarbons within the Mesozoic units. Migration to the uppermost Molasse units also occurs along faults, thrust planes and permeable units, when present.</div><div>The main uncertainties of the modelling results include: i) distribution and characteristics of faults; ii) thickness and hydrocarbon potential of the source rocks; iii) lithological and petrophysical properties of potential reservoir and seal units; iv) calibration data with big ranges and not uniformly measured. To refine the assumptions and enhance the understanding of the basin's evolution, further data should be collected and existing data reanalysed. Building risk analysis and probabilistic models would also help to plan drilling mitigation measures aimed at reducing these uncertainties. The workflow presented in this study can be highly valuable to geothermal projects. It allows more effective planning of the drilling procedure, thus reducing the operational risks and contributing to the overall project success.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104806"},"PeriodicalIF":5.6,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947696","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}
Pub Date : 2025-05-10DOI: 10.1016/j.coal.2025.104807
J.E. Ogala , K. Perleros , E. Kyriazaki , M. Angelopoulos , O.I. Ejeh , M. Wojtaszek-Kalaitzidi , S. Kalaitzidis , K. Christanis
<div><div>Twenty eight (7 coal, 12 organic-rich and 9 inorganic) cutting samples obtained from six boreholes drilled over a <em>c</em>. 60-km<sup>2</sup>-large area in the alluvial plain of Niger River between Obomkpa and Issele-Azagba, southern Nigeria, were examined and evaluated by means of coal-petrography, mineralogical (XRD) and geochemical (CHNS, Rock Eval, XRF) analyses. This study aimed to provide an initial assessment of the palaeoenvironmental conditions during the Oligocene-Miocene peat accumulation.</div><div>As the samples were received a long time after sampling, moisture could not be determined. The ash and the volatile matter yields of the samples vary from 19.9 to 88.5 wt% (db) and 63.5–67.9 wt% (daf), respectively. Huminite is the dominant maceral group ranging from 60.6 to 90.6 vol% (on mineral matter-free basis), with detrohuminite being the major sub-group. The inertinite content is very low (<1.5 %), whereas liptinite macerals are frequent to quite enriched (8.8–37.9 %) with alginite and liptodetrinite being the most common. The mean random huminite reflectance of all the coal samples varies between 0.32 % and 0.39 %.</div><div>As mainly sandstones, intercalated with siltstones and claystones are the main sedimentary rocks deposited in the Niger-River alluvial plain, the inorganic part of all the studied coaly and carbonaceous samples consists primarily of quartz and kaolinite, whereas goethite, mixed clay layers (illite-montmorillonite), anatase and gypsum occur in minor amounts. Accordingly, SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> display values ranging from 9 to 58 % and up to 23 wt%, respectively, while Fe<sub>2</sub>O<sub>3</sub> up to 12 wt% and TiO<sub>2</sub> up to 2 wt%.</div><div>Palaeoenvironmental geochemical proxies indicate a mixed source area for the siliciclastic facies, with significant recycling and weathering, deposited under a pure freshwater regime. The carbonaceous layers seem to have been deposited in a relative semi-arid climate, while the palaeomires were established under a more humid regime, promoting anaerobic conditions, which is in agreement with the observed very low inertinite content. Facies diagrammes based on the maceral contents were applied to reconstruct the environmental conditions in the palaeomires. According to the TPI <em>vs.</em> GI diagramme, the peat-forming vegetation was mostly herbaceous yielding low TPI and medium GI values, and the conditions were fluvial-limnotelmatic. The GWI <em>vs.</em> VI diagramme points to herbaceous vegetation on the palaeomire surface and mesotrophic water conditions with intense mineral matter influx from palaeo-Niger River. The area received frequent rainfall along with river flooding; thus, peat remained water-logged. Within the several hundred metres thick alluvial sediments, only short periods of limnotelmatic conditions prevailed in the area, yielding coal beds less than 17 m thick. The small number of the available cores distribut
{"title":"Palaeoenvironmental reconstruction of the coal-forming conditions during Oligocene in Niger Delta, Southern Nigeria: Implications for organic matter preservation and hydrocarbons potential","authors":"J.E. Ogala , K. Perleros , E. Kyriazaki , M. Angelopoulos , O.I. Ejeh , M. Wojtaszek-Kalaitzidi , S. Kalaitzidis , K. Christanis","doi":"10.1016/j.coal.2025.104807","DOIUrl":"10.1016/j.coal.2025.104807","url":null,"abstract":"<div><div>Twenty eight (7 coal, 12 organic-rich and 9 inorganic) cutting samples obtained from six boreholes drilled over a <em>c</em>. 60-km<sup>2</sup>-large area in the alluvial plain of Niger River between Obomkpa and Issele-Azagba, southern Nigeria, were examined and evaluated by means of coal-petrography, mineralogical (XRD) and geochemical (CHNS, Rock Eval, XRF) analyses. This study aimed to provide an initial assessment of the palaeoenvironmental conditions during the Oligocene-Miocene peat accumulation.</div><div>As the samples were received a long time after sampling, moisture could not be determined. The ash and the volatile matter yields of the samples vary from 19.9 to 88.5 wt% (db) and 63.5–67.9 wt% (daf), respectively. Huminite is the dominant maceral group ranging from 60.6 to 90.6 vol% (on mineral matter-free basis), with detrohuminite being the major sub-group. The inertinite content is very low (<1.5 %), whereas liptinite macerals are frequent to quite enriched (8.8–37.9 %) with alginite and liptodetrinite being the most common. The mean random huminite reflectance of all the coal samples varies between 0.32 % and 0.39 %.</div><div>As mainly sandstones, intercalated with siltstones and claystones are the main sedimentary rocks deposited in the Niger-River alluvial plain, the inorganic part of all the studied coaly and carbonaceous samples consists primarily of quartz and kaolinite, whereas goethite, mixed clay layers (illite-montmorillonite), anatase and gypsum occur in minor amounts. Accordingly, SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> display values ranging from 9 to 58 % and up to 23 wt%, respectively, while Fe<sub>2</sub>O<sub>3</sub> up to 12 wt% and TiO<sub>2</sub> up to 2 wt%.</div><div>Palaeoenvironmental geochemical proxies indicate a mixed source area for the siliciclastic facies, with significant recycling and weathering, deposited under a pure freshwater regime. The carbonaceous layers seem to have been deposited in a relative semi-arid climate, while the palaeomires were established under a more humid regime, promoting anaerobic conditions, which is in agreement with the observed very low inertinite content. Facies diagrammes based on the maceral contents were applied to reconstruct the environmental conditions in the palaeomires. According to the TPI <em>vs.</em> GI diagramme, the peat-forming vegetation was mostly herbaceous yielding low TPI and medium GI values, and the conditions were fluvial-limnotelmatic. The GWI <em>vs.</em> VI diagramme points to herbaceous vegetation on the palaeomire surface and mesotrophic water conditions with intense mineral matter influx from palaeo-Niger River. The area received frequent rainfall along with river flooding; thus, peat remained water-logged. Within the several hundred metres thick alluvial sediments, only short periods of limnotelmatic conditions prevailed in the area, yielding coal beds less than 17 m thick. The small number of the available cores distribut","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104807"},"PeriodicalIF":5.6,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143942439","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}
Pub Date : 2025-05-10DOI: 10.1016/j.coal.2025.104809
Maria Mastalerz , Agnieszka Drobniak , Bei Liu , Peter E. Sauer
Biochar, a carbon-rich product of biomass pyrolysis, holds considerable potential for carbon sequestration, soil amendment, and environmental remediation. Its effective application, however, hinges on understanding biochar permanence and on employing robust methodologies to reliably assess its stability and reactivity.
This study investigates the relationship between reflectance and the chemical composition (elemental ratios and organic functional groups) of biochar produced from sycamore wood, wheat straw, and peanut shells across well-controlled pyrolysis temperatures ranging from 300 °C to 700 °C, aiming to assess the potential of biochar reflectance as an indicator of biochar permanence.
The results demonstrate strong correlations between biochar reflectance and H/C and O/C molar ratios and show that the reflectance increases systematically with pyrolysis temperature. A strong correlation between the elemental O/C ratio and the FTIR-derived ratio of oxygenated groups to aromatic carbon across different pyrolysis temperatures provides additional valuable insights for predicting biochar stability.
The findings point to pyrolysis temperature as the dominant factor influencing biochar longevity and reinforce the suggestion that biochars with reflectance values above 2.0 % are non-reactive and are expected to be stable in the environment for a very long time. The results highlight biochar reflectance as a rapid and effective proxy for predicting biochar permanence, supporting its utility in carbon sequestration and environmental management.
{"title":"Reflectance as an indicator of biochar permanence","authors":"Maria Mastalerz , Agnieszka Drobniak , Bei Liu , Peter E. Sauer","doi":"10.1016/j.coal.2025.104809","DOIUrl":"10.1016/j.coal.2025.104809","url":null,"abstract":"<div><div>Biochar, a carbon-rich product of biomass pyrolysis, holds considerable potential for carbon sequestration, soil amendment, and environmental remediation. Its effective application, however, hinges on understanding biochar permanence and on employing robust methodologies to reliably assess its stability and reactivity.</div><div>This study investigates the relationship between reflectance and the chemical composition (elemental ratios and organic functional groups) of biochar produced from sycamore wood, wheat straw, and peanut shells across well-controlled pyrolysis temperatures ranging from 300 °C to 700 °C, aiming to assess the potential of biochar reflectance as an indicator of biochar permanence.</div><div>The results demonstrate strong correlations between biochar reflectance and H/C and O/C molar ratios and show that the reflectance increases systematically with pyrolysis temperature. A strong correlation between the elemental O/C ratio and the FTIR-derived ratio of oxygenated groups to aromatic carbon across different pyrolysis temperatures provides additional valuable insights for predicting biochar stability.</div><div>The findings point to pyrolysis temperature as the dominant factor influencing biochar longevity and reinforce the suggestion that biochars with reflectance values above 2.0 % are non-reactive and are expected to be stable in the environment for a very long time. The results highlight biochar reflectance as a rapid and effective proxy for predicting biochar permanence, supporting its utility in carbon sequestration and environmental management.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104809"},"PeriodicalIF":5.6,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144070582","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}
Pub Date : 2025-05-09DOI: 10.1016/j.coal.2025.104808
Georgeta Predeanu , Bruno Valentim , Luminita Georgeta Popescu , Alexandru Traian Abagiu , Lucica Anghelescu , Mihaela Niculina Bălănescu , Barbara Białecka , Elza Bontempi , Magdalena Cempa , Marius Florin Drăgoescu , Alexandra Guedes , Özben Kutlu , Mattia Massa , Elsayed Mousa , Adrian Ionut Nicoară , Hayati Olgun , Valerica Slăvescu , Bogdan Stefan Vasile , Guozhu Ye
This paper presents the prospect of phosphorus (P) - rich poultry litter manure ash (PLA) used to recover P through microwave heating methods, aiming for residual slag recycling in constructions.
The results show the complex composition of the ashes characterized by X-ray fluorescence (XRF), reflected light optical microscopy, X-ray microanalysis (SEM/EDS) and X-ray diffraction (XRD), which explains the differences between the ash types and the operation temperature in the combustion chamber. At the same time, the results present a novel approach of using microwave heating by reducing energy consumption to extract/enrich P from PLA and forming a by-product/residual slag used as a supplementary cementing material.
Samples of fly ash (FA) and bottom ash (BA) were collected from two fluidized bed incinerators (Güres and Beypi in Türkiye) operating at 750 °C and 850 °C within the PHIGO project funded by the 3rd ERA-MIN Program of the European Union Commission.
本文介绍了利用富磷禽畜粪便灰（PLA）利用微波加热法回收磷的前景，旨在实现建筑残渣的资源化利用。结果表明，通过x射线荧光（XRF）、反射光光学显微镜、x射线显微分析（SEM/EDS）和x射线衍射（XRD）对炉灰的复杂组成进行了表征，从而解释了炉灰类型和燃烧室操作温度的差异。同时，研究结果提出了一种利用微波加热降低能耗从PLA中提取/富集P，并形成副产品/残渣作为补充胶凝材料的新方法。在欧盟委员会第三ERA-MIN计划资助的PHIGO项目中，从两个流化床焚烧炉（g res和Beypi in t rkiye）在750°C和850°C下运行，收集了粉煤灰（FA）和底灰（BA）样本。
{"title":"Characterization of the ash samples before and after thermal processing aiming phosphorus extraction and residues valorization","authors":"Georgeta Predeanu , Bruno Valentim , Luminita Georgeta Popescu , Alexandru Traian Abagiu , Lucica Anghelescu , Mihaela Niculina Bălănescu , Barbara Białecka , Elza Bontempi , Magdalena Cempa , Marius Florin Drăgoescu , Alexandra Guedes , Özben Kutlu , Mattia Massa , Elsayed Mousa , Adrian Ionut Nicoară , Hayati Olgun , Valerica Slăvescu , Bogdan Stefan Vasile , Guozhu Ye","doi":"10.1016/j.coal.2025.104808","DOIUrl":"10.1016/j.coal.2025.104808","url":null,"abstract":"<div><div>This paper presents the prospect of phosphorus (P) - rich poultry litter manure ash (PLA) used to recover P through microwave heating methods, aiming for residual slag recycling in constructions.</div><div>The results show the complex composition of the ashes characterized by X-ray fluorescence (XRF), reflected light optical microscopy, X-ray microanalysis (SEM/EDS) and X-ray diffraction (XRD), which explains the differences between the ash types and the operation temperature in the combustion chamber. At the same time, the results present a novel approach of using microwave heating by reducing energy consumption to extract/enrich P from PLA and forming a by-product/residual slag used as a supplementary cementing material.</div><div>Samples of fly ash (FA) and bottom ash (BA) were collected from two fluidized bed incinerators (Güres and Beypi in Türkiye) operating at 750 °C and 850 °C within the PHIGO project funded by the 3rd ERA-MIN Program of the European Union Commission.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"307 ","pages":"Article 104808"},"PeriodicalIF":5.6,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144221756","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}
Pub Date : 2025-05-08DOI: 10.1016/j.coal.2025.104803
Rongjie Wang , Shifeng Dai , David French , Ian T. Graham , Victor P. Nechaev , Robert B. Finkelman
Surficial low-temperature sedimentary clay-type Li deposit is one of three major types of Li deposits in the world; however, its formation and corresponding Li isotope fractionation mechanisms are still unclear. In this study, we demonstrate an unusually high Li concentration (89.1 ppm to 520 ppm) within a Late Triassic coal-hosted clay Li deposit from the Sichuan Basin, China. In-situ mapping of the Li distribution combined with isotopic analysis of Li occurring as clay-hosted ion-exchangeable and structurally bound Li was carried out to investigate low temperature Li migration and enrichment processes near the Earth's surface. The in-situ mapping shows that the dominant host of Li is fracture-fill and vermicular chlorite, while massive illite aggregate and fracture-fill paragonite contains lesser amounts of Li. Kaolinite and chlorite also absorbed a part of Li on surface/interlayer sites. The Li enrichment processes involve a contribution from detrital clastics (aggregate illite and kaolinite), especially felsic pyroclastics (vermicular-kaolinite) from collisional- and subduction setting, as well as the water-rock interactions during peat accumulation/burial stage between the acidic groundwater and primary Li-bearing clays. The primary kaolinite and illite was replaced with chlorite and paragonite accompanied with Li isotopic fractionation (Δ7Li: +2.67 ‰ to +15.4 ‰).
{"title":"Near surface lithium isotopic fractionation and lithium enrichment in coal-hosted Li-rich clays from the South China Block","authors":"Rongjie Wang , Shifeng Dai , David French , Ian T. Graham , Victor P. Nechaev , Robert B. Finkelman","doi":"10.1016/j.coal.2025.104803","DOIUrl":"10.1016/j.coal.2025.104803","url":null,"abstract":"<div><div>Surficial low-temperature sedimentary clay-type Li deposit is one of three major types of Li deposits in the world; however, its formation and corresponding Li isotope fractionation mechanisms are still unclear. In this study, we demonstrate an unusually high Li concentration (89.1 ppm to 520 ppm) within a Late Triassic coal-hosted clay Li deposit from the Sichuan Basin, China. In-situ mapping of the Li distribution combined with isotopic analysis of Li occurring as clay-hosted ion-exchangeable and structurally bound Li was carried out to investigate low temperature Li migration and enrichment processes near the Earth's surface. The in-situ mapping shows that the dominant host of Li is fracture-fill and vermicular chlorite, while massive illite aggregate and fracture-fill paragonite contains lesser amounts of Li. Kaolinite and chlorite also absorbed a part of Li on surface/interlayer sites. The Li enrichment processes involve a contribution from detrital clastics (aggregate illite and kaolinite), especially felsic pyroclastics (vermicular-kaolinite) from collisional- and subduction setting, as well as the water-rock interactions during peat accumulation/burial stage between the acidic groundwater and primary Li-bearing clays. The primary kaolinite and illite was replaced with chlorite and paragonite accompanied with Li isotopic fractionation (Δ<sup>7</sup>Li: +2.67 ‰ to +15.4 ‰).</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104803"},"PeriodicalIF":5.6,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143942437","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}
Pub Date : 2025-05-08DOI: 10.1016/j.coal.2025.104804
José A. D'Angelo , James C. Hower , Gerardo Camí , Maiten A. Lafuente Diaz
As part of the ongoing research project “Chemistry, Biomechanics, and Physiology of Carboniferous plants”, this study investigates two of the largest Canadian specimens of Odontopteris cantabricaWagner, 1969 (22-cm long) and Odontopteris schlotheimiiBrongniart, 1828-1831 (7-cm long) from the Pennsylvanian Sydney Coalfield. Specimens of both species co-occur in the roof shale of the Lloyd Cove coal seam (Asturian-Cantabrian boundary; vitrinite reflectance Ro% = 0.65) at Brogan's pit locality, Cape Breton Island, Nova Scotia, Canada. Well-preserved compressions of pinnules (rachises were not preserved) are analyzed by Fourier transform infrared (FTIR) spectroscopy. These data are examined with the purpose of (i) calculating pinnular density (δ) and associated biomechanical and physiological properties, i.e., tensile strength (TS = resistance to fracture), tensile modulus of elasticity (TME = stiffness), and leaf mass per area (LMA = biomass investment and construction cost); (ii) comparing the data for δ, TS, TME, and LMA of O. cantabrica and O. schlotheimii at two levels: interspecific differences and intraspecific variations between pinnules representing different (proximal and distal) parts of each frond; (iii) comparing data for δ, TS, TME, and LMA of O. cantabrica and O. schlotheimii with those of previously studied medullosalean frond taxa, namely Alethopteris ambigua and Neuropteris ovata var. simonii; and (iv) obtaining new insights into the possible growth habit of both fronds. Results indicate that pinnular density, resistance to fracture, stiffness, and leaf mass per area vary continuously throughout the fronds and indicate biomechanical resistance and physiological efficiency. ANOVA tests show that the pinnules of O. cantabrica and O. schlotheimii are not significantly different in terms of density and biomechanical/physiological characteristics overall. However, within each species, proximal pinnules exhibit statistically higher density, stiffness, resistance to fracture, and metabolic construction cost compared to distal pinnules. The δ, TS, TME, and LMA data for O. cantabrica and O. schlotheimii are notably lower than those of N. ovata var. simonii and A. ambigua. The order of values for δ, TS, TME, and LMA follows: N. ovata var. simonii > A. ambigua > O. cantabrica = O. schlotheimii. Considering the values for δ, TS, TME, LMA, and general morphology, it is possible that O. cantabrica and O. schlotheimii had a semi-self-supporting to self-supporting (arborescent) growth form.
作为正在进行的研究项目“石炭纪植物的化学、生物力学和生理学”的一部分，本研究调查了两个最大的加拿大标本，1969年（22厘米长）的cantabrica Wagner和1828-1831年（7厘米长）的Odontopteris schlotheimii Brongniart，来自宾夕法尼亚悉尼煤田。在劳埃德湾煤层（阿斯图里—坎塔布连边界）顶板页岩中，这两种样品共存；加拿大新斯科舍省布雷顿角岛布罗根坑地区镜质组反射率Ro% = 0.65)。用傅立叶变换红外光谱分析了保存完好的小叶压缩（小叶未保存）。对这些数据进行检查的目的是：(1)计算叶尖密度（δ）和相关的生物力学和生理特性，即抗拉强度（TS =抗断裂）、抗拉弹性模量（TME =刚度）和每面积叶质量（LMA =生物量投资和建设成本）；（ii）在两个水平上比较了甘布兰和石竹的δ、TS、TME和LMA数据：代表每叶不同部分（近端和远端）的小叶之间的种间差异和种内差异；(3)与已有研究的延髓纲前叶类群Alethopteris ambigua和Neuropteris ovata var. simonii的δ、TS、TME和LMA数据进行比较；（iv）对两种叶子可能的生长习性有了新的认识。结果表明，叶尖密度、断裂阻力、刚度和单位面积叶质量在整个叶片中呈连续变化，表明了生物力学阻力和生理效率。方差分析结果表明，在密度和生物力学生理特征方面，两种植物的小叶总体上没有显著差异。然而，在每个物种中，与远端小叶相比，近端小叶在统计上表现出更高的密度、刚度、抗骨折性和代谢构建成本。坎塔布兰和施罗氏稻的δ、TS、TME和LMA数据均显著低于紫斑稻和双歧稻。δ、TS、TME和LMA的取值顺序为：N. ovata var. simonii >；A.歧义；O. cantabrica = O. schlotheimii。综合δ、TS、TME、LMA值和总体形态特征，推测其生长形态可能为半自立型到自立型（乔木型）。
{"title":"Biomechanics and physiology of Odontopteris cantabrica and Odontopteris schlotheimii (Medullosales, Pennsylvanian, Canada)","authors":"José A. D'Angelo , James C. Hower , Gerardo Camí , Maiten A. Lafuente Diaz","doi":"10.1016/j.coal.2025.104804","DOIUrl":"10.1016/j.coal.2025.104804","url":null,"abstract":"<div><div>As part of the ongoing research project “<em>Chemistry, Biomechanics, and Physiology of Carboniferous plants</em>”, this study investigates two of the largest Canadian specimens of <em>Odontopteris cantabrica</em> <span><span>Wagner, 1969</span></span> (22-cm long) and <em>Odontopteris schlotheimii</em> <span><span>Brongniart, 1828-1831</span></span> (7-cm long) from the Pennsylvanian Sydney Coalfield. Specimens of both species co-occur in the roof shale of the Lloyd Cove coal seam (Asturian-Cantabrian boundary; vitrinite reflectance Ro% = 0.65) at Brogan's pit locality, Cape Breton Island, Nova Scotia, Canada. Well-preserved compressions of pinnules (rachises were not preserved) are analyzed by Fourier transform infrared (FTIR) spectroscopy. These data are examined with the purpose of (i) calculating pinnular density (δ) and associated biomechanical and physiological properties, i.e., tensile strength (TS = resistance to fracture), tensile modulus of elasticity (TME = stiffness), and leaf mass per area (LMA = biomass investment and construction cost); (ii) comparing the data for δ, TS, TME, and LMA of <em>O. cantabrica</em> and <em>O. schlotheimii</em> at two levels: interspecific differences and intraspecific variations between pinnules representing different (proximal and distal) parts of each frond; (iii) comparing data for δ, TS, TME, and LMA of <em>O. cantabrica</em> and <em>O. schlotheimii</em> with those of previously studied medullosalean frond taxa, namely <em>Alethopteris ambigua</em> and <em>Neuropteris ovata</em> var. <em>simonii</em>; and (iv) obtaining new insights into the possible growth habit of both fronds. Results indicate that pinnular density, resistance to fracture, stiffness, and leaf mass per area vary continuously throughout the fronds and indicate biomechanical resistance and physiological efficiency. ANOVA tests show that the pinnules of <em>O. cantabrica</em> and <em>O. schlotheimii</em> are not significantly different in terms of density and biomechanical/physiological characteristics overall. However, within each species, proximal pinnules exhibit statistically higher density, stiffness, resistance to fracture, and metabolic construction cost compared to distal pinnules. The δ, TS, TME, and LMA data for <em>O. cantabrica</em> and <em>O. schlotheimii</em> are notably lower than those of <em>N. ovata</em> var. <em>simonii</em> and <em>A. ambigua</em>. The order of values for δ, TS, TME, and LMA follows: <em>N. ovata</em> var. <em>simonii</em> > <em>A. ambigua</em> > <em>O. cantabrica</em> = <em>O. schlotheimii</em>. Considering the values for δ, TS, TME, LMA, and general morphology, it is possible that <em>O. cantabrica</em> and <em>O. schlotheimii</em> had a semi-self-supporting to self-supporting (arborescent) growth form.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104804"},"PeriodicalIF":5.6,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947695","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}
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