Marine and Petroleum Geology最新文献

{"title":"Geological characteristics and in-situ retention mechanisms of clay-rich lacustrine shale oil in the Songliao Basin","authors":"Min Wang ,&nbsp;Yan Wu ,&nbsp;Xuefeng Bai ,&nbsp;Ming Li ,&nbsp;Junhui Li ,&nbsp;Xin Wang ,&nbsp;Jinyou Zhang ,&nbsp;Jinbu Li ,&nbsp;Changqi Yu ,&nbsp;Roufeida Bennani","doi":"10.1016/j.marpetgeo.2025.107593","DOIUrl":"10.1016/j.marpetgeo.2025.107593","url":null,"abstract":"<div><div>The Cretaceous Qingshankou Formation in the Gulong Sag of the Songliao Basin, located in the eastern of the Eurasian Plate, exhibits unique shale oil properties, including high clay mineral content (&gt;40 %), high organic matter maturity (&gt;1.0 %), and low shale oil density (∼0.78 cm³/g). This represents the first globally documented shale oil produced from clay-rich shales. This study systematically investigates the characteristics and controlling factors of reservoir space, oil-bearing properties and the formation and enrichment processes of shale oil. Findings reveal that the Qing-1 Member predominantly comprises laminated argillaceous shale, bedded mixed shale, and massive calcareous shale. The kerogen is mainly Type I, characterized by well-developed lamalginite and high organic matter (OM) abundance, with an average Total Organic Carbon (TOC) of 2.27 %. Thermal maturity (R_o) in oil-producing intervals typically exceeds 1.0 %. The main pore types are intergranular pores, intragranular pores, OM-hosted pores, exposed pores after OM degradation, and microfractures, with pore development influenced by TOC, clay mineral content, and R_o. The Gulong shale is notably oil-rich, with oil films present observed in different types and sizes of pores, and oil content significantly affected by TOC and R_o. The coupling of hydrocarbon evolution, fault activity periods, and regional stress changes governs the in-situ retention of light oil within the sag and dictates the reservoir formation sequence and spatial distribution of tight and conventional oil outside the source rock. This study offers critical insights for the exploration and development of continental clay-rich shale oil reservoirs.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107593"},"PeriodicalIF":3.6,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144921642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanisms for initiation and termination of extraordinarily high total organic carbon in the Longmaxi Formation, Yangtze Platform, South China","authors":"Zongyuan Sun ,&nbsp;Hao Chen ,&nbsp;Xianguo Lang ,&nbsp;Bolin Zhang ,&nbsp;Qing Chen ,&nbsp;Kun Zhao ,&nbsp;Shengxian Zhu ,&nbsp;Fangqi Zhao ,&nbsp;Feng Liang ,&nbsp;Chuyuan Liu ,&nbsp;Junxuan Fan","doi":"10.1016/j.marpetgeo.2025.107588","DOIUrl":"10.1016/j.marpetgeo.2025.107588","url":null,"abstract":"<div><div>The Early Silurian Longmaxi Formation in the Yangtze Platform of South China hosts exceptional shale gas reservoirs, particularly in intervals where total organic carbon (TOC) exceeds 3 wt%. However, the initial TOC values and termination timing of these “extraordinarily high TOC” intervals differ markedly among localities, especially between inner- and outer-shelf settings. In this study, we integrate graptolite biostratigraphy, carbon isotope chemostratigraphy, and multiple geochemical proxies (e.g., major–trace elements and sulfur isotopes) from drill cores in Yichang, Hubei Province, South China (outer shelf). We establish a refined chronostratigraphic framework, identifying an extraordinarily high TOC interval (&gt;3 wt%) and a subsequent high TOC interval (2–3 wt%), and then compare these intervals with representative inner-shelf sections. Our results show that at the base of the Longmaxi Formation in Yichang, TOC values are notably lower than those in the inner-shelf Changning area, Sichuan Province, South China, whereas the extraordinarily high TOC interval extends to a higher stratigraphic level in Yichang. Paleoenvironmental proxies indicate that extraordinarily high TOC intervals formed in a euxinic setting with higher primary productivity, and moderate restriction, whereas the high TOC interval reflects an anoxic setting, lower productivity, and stronger restriction. By determining sedimentation rates, sulfur isotope values, paleogeographic setting, and the influence of the Kwangsian Orogeny, we propose two sedimentary models to explain TOC variability in the Longmaxi Formation. The Sedimentation Rate–H₂S Concentration Model highlights how rapid sedimentation and abundant availability of ³⁴S-enriched H₂S promote extraordinarily TOC enrichment in inner-shelf settings, while slower burial and limited H₂S availability inhibit TOC accumulation in outer-shelf locations. The Kwangsian Orogeny–Hydrographic Restriction Model associates tectonic uplift with enhanced hydrographic restriction, reducing sulfate supply and driving the diachronous termination of high TOC intervals across the platform. These insights refine our understanding of early Silurian black-shale deposition and offer practical guidance for future shale-gas exploration in South China.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107588"},"PeriodicalIF":3.6,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144988702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical insights into authigenic pyrite formation in central Yellow Sea sediments: influence of sedimentary environment and microbial sulfate reduction","authors":"Yu Gu ,&nbsp;Xin Chang ,&nbsp;Xiting Liu ,&nbsp;Mingyu Zhang ,&nbsp;Yanfei An ,&nbsp;Guangchao Zhuang ,&nbsp;Houjie Wang","doi":"10.1016/j.marpetgeo.2025.107587","DOIUrl":"10.1016/j.marpetgeo.2025.107587","url":null,"abstract":"<div><div>Authigenic pyrite is a key archive of paleo-redox conditions and sulfur cycling in marine sediments, yet its formation mechanisms under variable marginal sea environments remain incompletely understood. This study investigates the formation of authigenic pyrite in Holocene sediments from the central Yellow Sea, focusing on its morphology, sulfur isotopes, and environmental controls. Pyrite formation is primarily constrained by the availability of reactive organic carbon, as revealed by total organic carbon–total sulfur relationships (C/S ratios) and reactive iron content. High C/S ratios suggest that the supply of organic matter, rather than the availability of sulfate or iron, plays the dominant role. Framboidal pyrite is the most common morphology. These framboids consist of tightly packed microcrystals, primarily octahedral and truncated octahedral in shape, indicating rapid precipitation under early diagenetic, low-oxygen, and low-energy conditions. The sulfur isotopes of pyrite (δ³⁴S_pyr, Vienna Canyon Diablo Troilite; V-CDT) range from −47.4 ‰ to −7.8 ‰, reflecting large fractionations associated with microbial sulfate reduction (MSR). The vertical δ³⁴S_pyr profile shows transitions from open- to closed-system MSR regimes, modulated by changes in sedimentation rate, freshwater input, and stratification linked to the Yellow Sea Cold Water Mass. These findings reveal the interplay between sedimentary environment, pyrite morphology, and sulfur isotope composition, offering insights into sulfur cycling in modern marginal marine settings and ancient analogues.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107587"},"PeriodicalIF":3.6,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144931635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diagenesis and burial history controls on Oligocene Huagang sandstones, southern Xihu Sag (East China Sea Basin): Implications for the formation of effective reservoirs","authors":"Hong-Liang Huo ,&nbsp;Cheng-Lin Liu ,&nbsp;Dao-Wu Huang ,&nbsp;An-Qi Tian ,&nbsp;Rizwan Sarwar Awan ,&nbsp;Hong-Yan Gao ,&nbsp;Chuang-Xin Liu ,&nbsp;Xue-Yong Chen ,&nbsp;Zi-Ye Tian ,&nbsp;Tao-Zheng Yang ,&nbsp;Bin-Bin Liu ,&nbsp;Chao-Jun Liang","doi":"10.1016/j.marpetgeo.2025.107592","DOIUrl":"10.1016/j.marpetgeo.2025.107592","url":null,"abstract":"<div><div>This study aims to reveal the diagenetic evolution sequence and controlling factors of Oligocene Huagang Formation (E₃h) sandstone reservoirs in the HY area, and predict high-quality reservoir distribution to guide hydrocarbon exploration. A comprehensive approach integrating core observation, thin-section petrography, geochemical analysis, and seismic-log interpretation was employed. By combining burial history simulation and diagenetic analysis, we systematically analyzed reservoir quality and diagenetic evolution and established evolution models for effective reservoir pore spaces. Results indicate that E₃h sandstones underwent intense diagenetic processes including compaction, cementation, and dissolution. Diagenesis plays a critical role in controlling reservoir quality: compaction is the primary factor that governs vertical variations in petrophysical properties, where shallower intervals typically exhibit better quality than deeper ones. In contrast, cementation and dissolution serve as secondary controls, explaining property differences between Blocks A and B, with Block A reservoirs being superior. A three-stage relationship has been identified between burial history and diagenesis: (1) early gradual subsidence stage (GSS) with weak feldspar dissolution, early carbonate cementation, chlorite coating, and mechanical compaction; (2) intermediate tectonic activity stage (TAS) with massive feldspar dissolution, quartz overgrowth precipitation, and ferruginous cement formation; (3) late stable burial stage (SBS) featuring intensified compaction and clay mineral transformations. The spatial configuration of fault systems and sandstones, combined with compositional attributes, strongly controls diagenetic evolution. Favorable zones for dissolution development occur at intersections of fault zones and acidic fluid migration pathways, while quartz-feldspar-rich zones mitigate porosity loss via compaction resistance. Three effective reservoir development models were proposed: high dissolution-low cementation-low compaction, moderate dissolution-low cementation-low compaction, and low compaction-low cementation-low dissolution. This research provides a critical basis for predicting E₃h high-quality reservoirs in the study area. Furthermore, the comprehensive burial history-diagenesis analysis method presented here offers a valuable reference for studies on sandstone diagenetic evolution and hydrocarbon exploration in similar geological settings.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107592"},"PeriodicalIF":3.6,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145044394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Depositional conditions affecting proximal to distal variation in the crystallo-chemical properties of Paleogene glauconites: Example from the Mesopotamian basin, Iraq","authors":"Tarang Sarin ,&nbsp;Santanu Banerjee ,&nbsp;Ibrahim Q. Mohammed ,&nbsp;Nibras Zaki ,&nbsp;Sherif Farouk ,&nbsp;Howri Mansurbeg ,&nbsp;Pragya Singh","doi":"10.1016/j.marpetgeo.2025.107591","DOIUrl":"10.1016/j.marpetgeo.2025.107591","url":null,"abstract":"<div><div>The proximal to distal variation in glauconite composition across a basin, although rarely attempted, may provide crucial insights into the depositional conditions. The Paleogene glauconites from the transgressive and condensed deposits are tracked from the proximal to the distal parts of the Mesopotamian basin in Iraq, to delineate their compositional variation. They prevail within the Paleocene Upper Aaliji Formation and the Eocene basal Jaddala Formation. The Fe₂O₃(total) (av. 16.78 wt%) and K₂O (av. 7.04 wt%) contents, and the ordering of the crystal structure and maturity (decreasing d-spacing and FWHM of 001 basal reflection) of glauconites increase, while the Al₂O₃ (av. 9.82 wt%) and MgO (av. 5.24 wt%) contents decrease from the proximal to distal settings. Therefore, the Al-rich and less mature glauconite is attributed to the proximal setting, whereas Fe-rich and more mature glauconites are attributed to the central and distal settings. The proximal setting is enriched with detrital Al-rich clay minerals forming less mature, Al-rich glauconites in kaolinite and illite-smectite precursors within the prevailing gently suboxic conditions. Whereas the central and distal settings sustain a lower sedimentation rate and enhanced mobility of ferrous ions, forming more mature, Fe-rich glauconites within the prevailing oxygen-depleted conditions. Glauconites form within two warming intervals from Late Danian to Late Ypresian and Late Lutetian to Late Bartonian. Warm climatic conditions amplify elemental supply, promote transgressive conditions, intensify reaction kinetics, and produce redox conditions encouraging abundant growth of glauconite. The composition and abundance of glauconites corroborate their formation within warm climatic conditions.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107591"},"PeriodicalIF":3.6,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144921643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Origin and controls on shale oil enrichment of bedding-parallel fractures in the Chang 73 lacustrine shales, Yanchang Formation, Ordos Basin","authors":"Zilong Li ,&nbsp;Kelai Xi ,&nbsp;Yingchang Cao ,&nbsp;Yifan Zhang ,&nbsp;Xiaobing Niu ,&nbsp;Xiujuan Wang ,&nbsp;Wenzhong Ma ,&nbsp;Yuan You ,&nbsp;Yuxuan Wang ,&nbsp;Guanghui Yuan","doi":"10.1016/j.marpetgeo.2025.107590","DOIUrl":"10.1016/j.marpetgeo.2025.107590","url":null,"abstract":"<div><div>As the main fracture type of lacustrine shales, bedding-parallel fractures (BPFs) play a key controlling role in diagenetic mass transfer as well as hydrocarbon migration and accumulation. To reveal the origin of BPFs and their controls on shale oil enrichment, this study integrates core, thin section, scanning electron microscopy (SEM) observations, and fluid inclusion analysis, focusing on the BPFs of the lacustrine shales of the Chang 7₃ sub-member, Yanchang Formation, Ordos Basin. The results show that the variations in mineral composition, arrangement, and size on both sides of the laminae interface induce significant mechanical anisotropy, which become the essential geological prerequisite for the generation and extension of BPFs along the laminae interface. Furthermore, influenced by the mineral planar fabrics, BPFs can also develop within the laminae. Compared with laminated shale, massive mudstone does not show significant BPFs development characteristics due to the lack of lamina fabric. As a consequence of disequilibrium compaction, the vertical seepage force gradient caused by hydrocarbon generation overpressure periodically breaks through the pressure threshold of the closed shale system, resulting in the episodic opening of weak interfaces, thereby constituting the major formation mechanism of BPFs. In addition, the tectonic compression effect near the basin margin can also promote the development of BPFs to a certain extent. In different lithofacies of shales, the differences in the development characteristics and degree of BPFs are mainly caused by the variations in laminae attributes including laminae combination, linear density, and average thickness. High total organic carbon (TOC) content is conducive to increasing hydrocarbon generation overpressure. However, excessive TOC content reduces the compressive strength of rocks and has an adverse effect on the development of BPFs. The analysis of shale oil production indicates that, compared with non-bedding-parallel fractures (NBPFs), BPFs play a dominant role in the enrichment of shale oil and can significantly increase the daily oil production of individual wells. These findings provide a theoretical basis for revealing the origin, development pattern of BPFs and their influence on fluid activity in lacustrine shales.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107590"},"PeriodicalIF":3.6,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145010435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New data on the identification of magnesium-rich carbonate phases using Fourier Transform Infrared Spectroscopy","authors":"Katarzyna Stanienda-Pilecki ,&nbsp;Dariusz Łukowiec","doi":"10.1016/j.marpetgeo.2025.107585","DOIUrl":"10.1016/j.marpetgeo.2025.107585","url":null,"abstract":"<div><div>This paper presents the theory behind the importance and applicability of Fourier infrared spectroscopy in identifying carbonate phases with varying magnesium content. It presents the results of studies of Triassic limestone and dolomite samples taken from the Polish part of the Germanic Basin, which were analysed using this method. The scientific significance of the FTIR method lies in its ability to identify carbonate phases with varying magnesium content, even at low levels. FTIR is one of the few methods that offer such possibilities.</div><div>The following phases were analysed: low-Mg calcite, high-Mg calcite, dolomite and huntite. These carbonate phases were identified based on wave numbers occurring in the infrared absorption spectra. Low-Mg calcite is the dominant phase in the limestones. Some samples also contain a small amount of high-Mg calcite. Dolomite and huntite were also identified. High-Mg calcite and dolomite are prevalent in dolomites and dolomitic limestones. The research results indicate that the rocks of the Gogolin Unit (Lower Muschelkalk) and Diplopor Unit (Middle Muschelkalk) exhibit the least differentiation in carbonate phase content with varying magnesium contents, whereas the rocks of the Tarnowice and Boruszowice Units (Upper Muschelkalk) exhibit the most. The results suggest that the rocks of the Lower Muschelkalk (Gogolin Unit) and Middle Muschelkalk (Diplopor Unit) are quartz- and kaolinite-rich limestones. In contrast, the rocks of the Upper Muschelkalk (Tarnowice and Boruszowice units) are dolomites and dolomitic limestones. The results of the study demonstrate that Fourier infrared spectroscopy is one of the most effective methods for identifying carbonate phases with varying magnesium content, including those with magnesium substitution, due to its ease of use and high level of accuracy.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107585"},"PeriodicalIF":3.6,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D reconstruction of pore throat connectivity in Shale: An SAXS-MICP integrated framework","authors":"Linhao Zhang ,&nbsp;Shu Jiang ,&nbsp;Jiale Fu ,&nbsp;Fei Xie ,&nbsp;Zhile Han ,&nbsp;Zihao Li ,&nbsp;Mengdi Sun","doi":"10.1016/j.marpetgeo.2025.107584","DOIUrl":"10.1016/j.marpetgeo.2025.107584","url":null,"abstract":"<div><div>Digital rock technology enables simulation of reservoir dynamic response under coupled multi-physical fields, providing scientific basis for optimization of development schemes through virtual experiments. However, traditional CT technology shows significant limitations in processing low-porosity samples (&lt;5 %), with insufficient ability to accurately identify nano-scale throats, resulting in unrealistic isolated pore networks in reconstruction. Meanwhile, challenges remain in balancing resolution and field of view, as well as experimental cost and efficiency. To address these issues, this study innovatively introduces Small-Angle X-ray Scattering technology, leveraging its advantages of wide testing range, excellent sample representativeness, and ability to characterize closed pores. The research employs fast Gaussian random field method for 3D reconstruction, combines Delaunay triangulation and minimum spanning tree algorithms for network structure optimization, and integrates throat parameters obtained from mercury intrusion capillary pressure data. Finally, a low-porosity porous media model with realistic connectivity characteristics was successfully constructed, laying a solid foundation for detailed reservoir characterization and fluid transport mechanism research.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107584"},"PeriodicalIF":3.6,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144892257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reservoir space types, controlling factors, and evolution models of interbedded shale in the Jurassic Lianggaoshan Formation, Sichuan Basin","authors":"Yan Wu ,&nbsp;Min Wang ,&nbsp;Xuefeng Bai ,&nbsp;Xin Wang ,&nbsp;Yu Sun ,&nbsp;Youzhi Wang ,&nbsp;Xinyi Yang ,&nbsp;Liang Xu ,&nbsp;Tianyi Li","doi":"10.1016/j.marpetgeo.2025.107583","DOIUrl":"10.1016/j.marpetgeo.2025.107583","url":null,"abstract":"<div><div>The type, structure, and origin of shale pores, which serve as both storage spaces for hydrocarbon accumulation and percolation pathways, fundamentally determine reservoir quality and further influence sweet spot identification and production performance in shale oil reservoirs. The heterogeneous interlayers such as siltstone and silty mudstone developed in continental shale have greatly altered the pore structure, fluid storage state and percolation capacity of the reservoir, resulting in significant differences in its reservoir properties compared with shale. This study investigates lacustrine interbedded shale reservoirs through a comprehensive approach incorporating X-ray diffraction (XRD), thin-section petrography, field emission scanning electron microscopy (FE-SEM), low temperature nitrogen adsorption, and nuclear magnetic resonance (NMR) techniques. The results demonstrate that the reservoir properties of different shale lithofacies are generally better than those of fine siltstone lithofacies, especially the organic-rich laminated argillaceous shale (O-rLAS) lithofacies, which has the best reservoir properties. Organic matter (OM) - related pores (particularly organo-clay composite pores) and the interlayer fractures/intercrystalline pores of clay mineral constitute the primary contributors to the reservoir space. Thermal cracking of organic matter and clay mineral transformation enhance the storage capacity of shale lithofacies, whereas cementation is identified as the main factor responsible for the poor reservoir quality of fine siltstone lithofacies. The development of OM-related pores is jointly controlled by thermal maturity, total organic carbon (TOC), and OM type, as well as clay mineral content. The occurrence state of clay minerals with OM and clay mineral type predominantly influence the development of clay mineral interlayer pores. Dissolution pores are mainly affected by TOC and felsic mineral content, while felsic mineral content significantly impacts the development of intergranular pores and microfractures. This study enriches the theoretical understanding of diagenetic and reservoir-forming mechanisms in continental shale reservoirs. It provides critical geological basis and theoretical support for accurately identifying and evaluating the high-quality \"sweet spots\" of continental interbedded shale oil. These findings offer practical guidance for efficient exploration and development of such complex reservoirs.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107583"},"PeriodicalIF":3.6,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144863176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cenozoic sedimentary records from the eastern offshore of China reveal the Eocene birth of the Yangtze River","authors":"Qian Zhao ,&nbsp;Hongtao Zhu ,&nbsp;Tandis S. Bidgoli ,&nbsp;Yiming Jiang ,&nbsp;Yinshan Chang ,&nbsp;Qianghu Liu ,&nbsp;Wei Wang","doi":"10.1016/j.marpetgeo.2025.107558","DOIUrl":"10.1016/j.marpetgeo.2025.107558","url":null,"abstract":"<div><div>The Yangtze River, which links the Tibetan Plateau to the eastern offshore of China, is one of the most important sediment routing systems in East Asia. However, the timing of its establishment has remained controversial. This study examines new and published zircon U-Pb geochronology data from eastern offshore basins (the East China Sea Shelf Basin and South Yellow Sea Basin) and major rivers in East Asia, establishing new constraints on the timing of full integration of the Yangtze River. We report detrital zircon U-Pb ages (n = 664) from Paleogene strata in the East China Sea Shelf Basin, the primary sink for the river during the Cenozoic. Detrital zircons from the Eocene to early Oligocene Pinghu Formation range from 34.9 ± 0.7 to 2800 ± 42 Ma, with 100–250 Ma and 1700–2100 Ma age clusters, and small Paleozoic, Neoproterozoic, and Paleoproterozoic-Archean peaks. A similar age range (33 ± 0.4 to 2842 ± 43 Ma) and nearly identical peaks are documented for the Oligocene Huagang Formation. The maximum depositional age, based on the youngest single grains in our samples, is 34.9 ± 0.7 Ma for Pinghu Formation and 33 ± 0.4 Ma for Huagang Formation. Statistical comparison of the new U-Pb ages with published data from sands collected in major segments of the modern Yangtze River and its estuary demonstrate similar provenance, but with larger contributions of 700–1000 Ma and 1700–2100 Ma zircons, sourced from the Songpan-Garze terrane. Additionally, the new data suggest that both the East China Sea Shelf Basin and the South Yellow Sea Basin retain young (&lt;80 Ma) zircons, likely sourced from the Jinshajiang segment of the Yangtze River. The youngest of these zircons are ∼37-33 Ma and only occur in sands from the upper reaches of the modern river. The high degree of similarity between the eastern offshore samples and the modern Yangtze system suggests the river and source-to-sink system were established by the late Eocene, and may point to topographic adjustments in the Qiangtang portion of the Tibetan Plateau as a driver of drainage expansion and integration.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107558"},"PeriodicalIF":3.6,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144828920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}