International Journal of Coal Geology最新文献

{"title":"Noble gases in Paleozoic shale fluids document tectonic events and fluid migration in the Upper Yangtze Block","authors":"Rui Liu ,&nbsp;Tao Wen ,&nbsp;Daniele L. Pinti ,&nbsp;Rui Xu ,&nbsp;Fang Hao ,&nbsp;Shang Xu ,&nbsp;Zhiguo Shu","doi":"10.1016/j.coal.2024.104671","DOIUrl":"10.1016/j.coal.2024.104671","url":null,"abstract":"<div><div>Major and noble gases of natural gas extracted from the low-permeability Paleozoic Wufeng-Longmaxi shale were measured to reconstruct the multi-stage, spatially varying tectonic evolution of the Upper Yangtze Block, China, one of the oldest parts of the Earth continents. The high gas dryness ratio [C₁/(C₂ + C₃)] and high carbon isotopic ratios (δ¹³C-C₁, δ¹³C-C₂, δ¹³C-CO₂) suggest a late mature thermogenic origin of shale gas. The highly fractionated atmospheric ²⁰Ne/³⁶Ar and ⁸⁴Kr/³⁶Ar ratios in our gas samples suggest they result from solubility-based partitioning of noble gases between oil and water followed by gas-water partitioning. Calculated volume ratios of oil, water, and gas phases vary spatially and temporally. In particular, the western Yangtze Block shows a lower reconstructed oil/water ratio, suggesting oil leakage promoted by the Triassic exhumation of Paleozoic shale, while a low gas/water ratio in the central-eastern Yangtze Block suggests gas leakage promoted by basin-wide Jurassic fold-thrust faulting. The lowest C₁/³⁶Ar volume ratio around faults at the basin edges indicates extensive gas expulsion. Delineated radiogenic ⁴He in gas samples are several orders lower than calculated in-situ produced radiogenic ⁴He, likely suggesting widespread ⁴He loss. Spatially-varying ⁴He/nucleogenic ²¹Ne ratios in the shale indicated that ⁴He loss in the western Yangtze Block predated that in the central-eastern portion. Such He loss was also coupled with the Triassic exhumation and the Jurassic fold-thrust faulting episodes. In summary, noble gas in pore fluids extracted from low-permeability shale can preserve reliable records of tectonic events produced during upper crust evolution.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"297 ","pages":"Article 104671"},"PeriodicalIF":5.6,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142874791","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":"Elemental geochemical insights into sediment sources, influx variations and depositional environment changes in the Eocene–Miocene Lark Formation, Danish North Sea","authors":"Zhiheng Zhou ,&nbsp;Qingyong Luo ,&nbsp;Niels Hemmingsen Schovsbo ,&nbsp;Henrik Ingermann Petersen ,&nbsp;Arka Rudra ,&nbsp;Hamed Sanei","doi":"10.1016/j.coal.2024.104673","DOIUrl":"10.1016/j.coal.2024.104673","url":null,"abstract":"<div><div>The Lark Formation in the Danish North Sea holds great paleoenvironmental interest for understanding climatic and tectonic impacts on sediment supply and depositional environment during the latest Eocene to the Middle Miocene. This study investigates sediment provenance, variations in sediment flux, chemical weathering intensity, and redox conditions in relation to these climatic and tectonic events. A dataset of 86 cuttings and one core from six wells in the Danish North Sea was analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The recently published maceral composition of these samples was also included in this research.</div><div>Provenance investigation indicates that the sediment originated from felsic sources within a continental arc tectonic setting. Such a source area is currently located in southern Norway and Sweden on the southwest margin of the Baltic Shield. During the Eocene–Miocene progressive filling of the eastern North Sea Basin, climatic conditions primarily controlled chemical weathering intensity and sediment influx. This is evidenced by higher Chemical Index of Alteration (CIA) and Zr concentrations in the Lower Miocene compared to other series deposited under cooler and less humid climates. Additionally, elemental proxies (Ce_anom, V/(V + Ni), Th/U), along with organic petrological and geochemical evidence, indicate that the Lark Formation was deposited in dysoxic-anoxic environments. Variations of these proxies further reveal that sea-level changes primarily controlled fluctuations in redox condition, resulting in more oxic environments. Moreover, the impact of marine productivity on U and Mo is revealed by the positive correlations between the enrichment factors of U (U_EF) and Mo (Mo_EF) and the abundances of liptinite and Cd. Increased productivity, combined with bottom water anoxia, led to the enrichment of U and Mo in the sediment, with upwelling further enhancing this process.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"297 ","pages":"Article 104673"},"PeriodicalIF":5.6,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142901786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The geochemical and organic petrological characteristics of kolm (upper Cambrian, Sweden): Implications for genesis","authors":"Anji Liu ,&nbsp;Niels Hemmingsen Schovsbo ,&nbsp;Arne Thorshøj Nielsen ,&nbsp;Qingyong Luo ,&nbsp;Ningning Zhong ,&nbsp;Leibo Bian ,&nbsp;Xiaowei Zheng ,&nbsp;Rasmus Andreasen ,&nbsp;Hamed Sanei","doi":"10.1016/j.coal.2025.104687","DOIUrl":"10.1016/j.coal.2025.104687","url":null,"abstract":"<div><div>Kolm refers to uraniferous (1280–7100 ppm) and organic-rich (25–71 wt%) lenses occurring exclusively within the Furongian part of the Alum Shale Formation in south-central Sweden. It typically less than 7 cm thick and forms thin discontinuous layers. This study investigates the geochemical and organic petrological characteristics of kolm, and it is shown that the organic matter likely represents secondarily formed solid bitumen rather than a primary organic-rich component. The high uranium content is concentrated in specific uranium‑yttrium‑zinc-rich (U-Y-Zn-rich) particles. A model for kolm formation is presented, suggesting that during sedimentation, initial uranium-enriched particles were formed and then became concentrated, probably by winnowing at the sea floor under euxinic conditions. This lag deposit rich in uranium particle subsequently formed the radioactive nuclei (U-Y-Zn-rich particles) for the kolm nodules that grew during the early diagenesis. Initial kolm was apparently formed by in-situ accumulation of diagenetically formed solid bitumen (R_o &lt; 0.5 %) onto these strongly radioactive U-Y-Zn-rich particles. The more abundant development of kolm in the Billingen area of Västergötland, compared to other regions in south-central Sweden where kolm occurs, is likely due to increased generation of solid bitumen associated with localized heating from Permo-Carboniferous intrusions.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"299 ","pages":"Article 104687"},"PeriodicalIF":5.6,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wood-degrading fungal origin of perylene in peatlands of southern Poland: A molecular and statistical approach","authors":"J. Smolarek-Lach,&nbsp;E. Szram,&nbsp;K.J. Wójcicki,&nbsp;L. Marynowski","doi":"10.1016/j.coal.2025.104685","DOIUrl":"10.1016/j.coal.2025.104685","url":null,"abstract":"<div><div>Perylene is a polycyclic aromatic hydrocarbon (PAH) whose origin remains enigmatic. It has been thought to be derived from hydrocarbons, however much uncertainty remains over whether it is natural or anthropogenic. In this study, a comprehensive study of peat was conducted in the Osobłoga and Kłodnica River Valleys of southern Poland. Here, we show a significant advance in our understanding of the source of perylene using a detailed analysis of macro and minor elements along with its correlation with other PAHs and biogenic compounds. Based on principal component analysis (PCA), a negative correlation between perylene and combustion-derived PAHs was demonstrated, suggesting different origins for these compounds. Diagnostic ratios, such as %Pe/∑PAH and %Pe/∑PAI above 10 %, and a Py/Pe ratio below 9, indicate that the perylene present in these peat samples is of natural origin, formed from terrestrial organic matter. Furthermore, perylene is associated with a dominance of long-chain <em>n</em>-alkanes, which exhibit a strong odd-over-even preference, further supporting its biogenic source. The analysis revealed a weak correlation between total organic carbon (TOC) and perylene content, indicating that perylene concentration does not directly depend on the overall organic carbon content in peat. In contrast, a strong correlation was observed between perylene and wood-type biogenic compounds, specifically periderm (correlation coefficient of 0.2) and wood (correlation coefficient of 0.3). This finding suggests that perylene formation is closely linked to woody biomass. The Conifer Wood Degradation Index (CWDI) was calculated for samples containing conifer wood phytoclasts, providing insights into the degradation processes affecting these components and their relation to perylene formation. Further molecular and statistical studies on Vistulian and Holocene peats in our study also confirm the hypothesis of a natural, specifically fungal, origin of perylene. A comprehensive analysis of peat deposits, combined with advances in molecular and statistical techniques, continues to elucidate on the complex biogeochemical processes that contribute to the presence of perylene in natural environments.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"299 ","pages":"Article 104685"},"PeriodicalIF":5.6,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143050021","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":"Horgen-Käpfnach, the largest Swiss coal deposit: Geology, petrology and geochemistry","authors":"R.F. Sachsenhofer ,&nbsp;V. Aghayeva ,&nbsp;S. Ajuaba ,&nbsp;I. Kojić ,&nbsp;D. Misch ,&nbsp;K. Stojanović","doi":"10.1016/j.coal.2025.104684","DOIUrl":"10.1016/j.coal.2025.104684","url":null,"abstract":"<div><div>The Miocene Käpfnach seam is only about 0.5 m thick but offers interesting insights into the depositional environments during the early stages (∼16 Ma) of the deposition of the Upper Freshwater Molasse in the Swiss part of the North Alpine Foreland Basin. It is also the most important coal deposit in Switzerland. The study focused on the coal seam, which includes a marly parting (“Stinkstein”), but the underlying and overlying sediments were also investigated.</div><div>The coal seam, which is separated by the “Stinkstein” parting into a lower and an upper part, was investigated using bulk geochemical data, biomarker composition, isotope data and organic petrography. The coal accumulated in a freshwater environment. High sulphur contents and the presence of carbonate shells in the upper part of the seam reflect a high pH value related to a carbonate-rich environment. A significant part of sulphur in the upper part of the seam is organically bound. Petrographical investigations show that herbaceous plants rather than big trees contributed to the organic matter. Biomarker data show the presence of ferns, angiosperms and gymnosperms, albeit in highly variable proportions across the seam. Representatives of the Cupressaceae, Taxaceae and Sciadopityaceae families contributed to the peat-forming vegetation during the early stages of peat accumulation. Open water areas, colonized by freshwater gastropods, existed during deposition of the upper part of the seam. High contents of inertinite macerals in this part of the seam reflect frequent wildfires in the paleomire surroundings.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"299 ","pages":"Article 104684"},"PeriodicalIF":5.6,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Organic petrology and geochemistry of the late Neogene Shizigou Formation in the Qaidam Basin, China: Characteristics of a prospective microbial gas source rock","authors":"Jinqi Qiao ,&nbsp;Qingyong Luo ,&nbsp;Shouxin Guo ,&nbsp;Xianglu Tang ,&nbsp;Ludmila Kopaevich ,&nbsp;Ralf Littke","doi":"10.1016/j.coal.2024.104658","DOIUrl":"10.1016/j.coal.2024.104658","url":null,"abstract":"<div><div>The discovery of natural gas trapped in the late Neogene Shizigou Formation in the Yikeyawuru anticline indicates the potential for additional microbial gas reservoirs outside of the primary exploration targets for microbial gas in the younger, i.e., the Pleistocene sediments of the Qaidam Basin. In this study, a detailed investigation is presented on the bulk geochemistry and organic petrography of the potential microbial source rocks as well as on molecular organic geochemistry of the solvent extracts obtained from the late Neogene Shizigou Formation of the Yiliping Depression. The objectives are to elucidate i) the depositional environment, ii) biological sources of organic matter (OM), and iii) biodegradation levels in these microbial gas source rocks.</div><div>The samples from the well situated at the center of the Yiliping Depression (the H 1 well) exhibit minor variations in total organic carbon (TOC) and total sulfur contents, whereas the samples from the well located at the margin of the depression (the Y 3 well) show large variations in these values. All these samples are presently thermally immature. The kerogen of the TOC-rich Y 3 well samples is mainly composed of mixed types II–III kerogen and characterized by a complex maceral composition (i.e., a mixture of large fragments of huminite, semifusinite, fusinite, resinite/fluorinite, lamalginite, and liptodetrinite). In contrast, samples from the H 1 well contain typically type III kerogen with a less complex maceral composition consisting of huminite, lamalginite, and liptodetrinite. The molecular data illustrates that the OM is predominantly derived from bacterial and algal biomass as well as aquatic higher plants (primarily in the Y 3 well samples), while angiosperms are the primary source of the subordinate terrestrial OM in the samples. The marginal area is characterized by salinity levels akin to normal marine conditions with bottom-water paleoredox conditions ranging from dyoxic (samples with high TOC content) to oxic, whereas the central area developed a mesosaline environment with oxic bottom-water conditions prevailing. In contrast to the primary microbial gas producing layer, the Pleistocene Qigequan Formation, the late Neogene Shizigou Formation exhibits a higher contribution of emergent macrophytes but a reduced abundance of lower aquatic organisms in the OM as well as a higher salinity level in the water column. Despite the late Neogene Shizigou Formation demonstrating a lower potential for hydrocarbon generation and a lower degree of biodegradation of OM than the Qigequan Formation, it still shows generally favorable geological and geochemical conditions that are conducive to the development of microbial gas reservoirs, which is underscored by the biodegradation levels between 3 and 4 for the studied samples.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"296 ","pages":"Article 104658"},"PeriodicalIF":5.6,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142747671","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":"Anomalies in Vicker's microhardness of subbituminous and high volatile bituminous coals","authors":"Saeed Chehreh Chelgani ,&nbsp;James C. Hower ,&nbsp;Maria Mastalerz ,&nbsp;Susan M. Rimmer","doi":"10.1016/j.coal.2024.104659","DOIUrl":"10.1016/j.coal.2024.104659","url":null,"abstract":"<div><div>Vickers microhardness (MH) of coal is known to be strongly correlated with coal rank. To examine coal rank and other coal quality parameters, such as organic sulfur, that might influence MH, a suite of more than 300 samples from the Penn State Coal Quality database with vitrinite R_max &lt; 1.1 % were examined. The data set was narrowed down to 296 coals with moisture (as-received basis) &lt; 20 %. As MH is a parameter measured on vitrinite, vitrinite R_max was used as the rank parameter. The Eocene Big Dirty coal (Washington state) stood out as a high MH/high-moisture coal while Hanna and Green River basin coals (Wyoming) had low atomic H/C values and K Unita Basin (Utah) coals had high H/C. Organic S did not show a correlation with MH within discrete rank ranges. With respect to vitrinite R_max vs. MH, the Big Dirty coal and some Illinois and Iowa coals lie on the high-MH/low-R_max side and the Pennsylvanian Tioga (West Virginia) and the Indiana Brazil Formation coals, all dominated by dull lithotypes, lie on the low-MH/high-R_max side of the main data trend. Overall, the quadratic regression of vitrinite R_max vs. MH yields an R² of 0.55, indicating a significant correlation at the 95 % level.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"296 ","pages":"Article 104659"},"PeriodicalIF":5.6,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142696909","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":"Corrigendum to “Characteristics of the low-pressure spatial and temporal distributions of oil- and gas-bearing layers in the Ordos Basin, China” [Int. J. Coal Geol. 2024 (285) 104476].","authors":"Yang Qin ,&nbsp;Chiyang Liu ,&nbsp;Lei Huang ,&nbsp;Jianqiang Wang ,&nbsp;Junfeng Zhao ,&nbsp;Deyong Shao ,&nbsp;Lihua Yang ,&nbsp;Xiaochen Zhao ,&nbsp;Ehsan Khalaf ,&nbsp;Shaohua Zhang ,&nbsp;Nan Du","doi":"10.1016/j.coal.2024.104622","DOIUrl":"10.1016/j.coal.2024.104622","url":null,"abstract":"","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"295 ","pages":"Article 104622"},"PeriodicalIF":5.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670370","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":"Deep syntectonic burial of the Anthracite belt, Eastern Pennsylvania","authors":"Mark A. Evans ,&nbsp;Aaron M. Jubb","doi":"10.1016/j.coal.2024.104646","DOIUrl":"10.1016/j.coal.2024.104646","url":null,"abstract":"<div><div>Fluid inclusion microthermometry and Raman spectroscopy of fluid inclusions in quartz veins from the Pennsylvanian rocks of the Anthracite belt, eastern Pennsylvania support a deep burial model of coalification in favor of focused orogenic hot fluid flow. High-temperature (250 to 255 °C) trapping of CH₄ ± CO₂ saturated aqueous fluids and CH₄ ± CO₂ inclusions indicate fluid trapping at depths of 11.5 to 13.4 km under a cover of Pennsylvanian to Permian(?) syntectonic load. In the folded rocks to the south of the Anthracite belt, CH₄ ± CO₂ fluid inclusions indicate a sediment load that was up to 16.3 km thick. <em>Re</em>-equilibrated aqueous fluid inclusions from veins in Silurian through Devonian rocks give the same range of trapping conditions but a wide range of fluid salinities suggesting that folding, fracturing, and meteoric recharge resulted in the intermixing of fluids from throughout the stratigraphic succession.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"295 ","pages":"Article 104646"},"PeriodicalIF":5.6,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661344","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":"Influence of tectonic evolution processes on burial, thermal maturation and gas generation histories of the Wufeng-Longmaxi shale in the Sichuan Basin and adjacent areas","authors":"Shuyong Shi ,&nbsp;Yunpeng Wang ,&nbsp;Chengsheng Chen ,&nbsp;Jinzhong Liu ,&nbsp;Ping'an Peng","doi":"10.1016/j.coal.2024.104642","DOIUrl":"10.1016/j.coal.2024.104642","url":null,"abstract":"<div><div>The Wufeng-Longmaxi (WL) shale is widely distributed in the Sichuan Basin and adjacent areas in southwest China. The basin experienced multiple-stage complex tectonic movements, whose influences on burial, thermal maturation and gas generation histories in different areas are poorly understood. Based on a detailed study of the denudation stages, strata thickness, and thermal history of the basin, burial and thermal maturation histories of seven wells in different areas were modelled using PetroMod software. Due to the high maturity of the WL shale, a low-maturity Silurian Polish Llandovery shale was used for gold tube closed-system pyrolysis experiments to obtain kinetic parameters for evaluating methane generation history. The Polish shale was selected due to its depositional age, sedimentary environment and organic type, which are similar to the WL shale. The burial history of the WL shale can be divided into five stages: I. Early to Middle Silurian rapid burial; II. Caledonian uplift and denudation; III. Permian to Triassic sustained burial and denudation; IV. sustained burial since the Late Triassic; and V. Late Cretaceous to present sustained uplift and denudation. The thermal maturity of the WL shale in all wells increased with burial depth during stage IV. In addition, high calculated reflectance increments in wells JY1 and N201 during stage III occurred due to the relatively high basal heat flow and deep burial depth, resulting in higher current thermal maturities than in the other wells. The late Permian–Early Triassic and the Middle Jurassic–Early (or Late) Cretaceous were the key methane generation periods for wells JY1 and N201. In contrast, the other five wells had a single methane generation stage, mainly determined by burial and thermal maturation processes. The time of uplift and the amount of denudation during stage V, the current burial depth, the development of faults and fractures, high proportion of retention and the seal capacity of the overlying caprock are key factors for shale gas preservation. Hence, this study will help guide future shale gas development in the Sichuan Basin.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"295 ","pages":"Article 104642"},"PeriodicalIF":5.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661343","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}