Pub Date : 2025-07-05DOI: 10.1016/j.marpetgeo.2025.107536
Kanchana Kularatne , Nicolas E. Beaudoin , Pascale Sénéchal , Peter Moonen , Souhail Youssef , Fadi H. Nader
In this study, we present, for the first time, the spectral computed tomography (sp-CT) signatures of key carbonate rock-forming minerals namely, calcite, magnesian calcite, dolomite, and magnesite. Although the raw spectra of these phases may not be readily distinguishable, we demonstrate that they appear in clusters on a multi-energy histogram derived from laboratory sp-CT. These clusters show a strong correlation with the MgCO3 mol.% of the carbonate phases. In addition to discriminating among these carbonate phases, we demonstrate the capability of time-resolved sp-CT to monitor mineral replacement reactions in carbonates. As an example, we analyze a series of time-lapse sp-CT images of a carbonate sample undergoing hydrothermal dolomitization in the laboratory. The results reveal a progressive transformation of pure calcite into an Mg-rich carbonate, with the sp-CT data indicating a final composition of approximately 32 mol.% MgCO3. This estimate, while lower than the 46–50 mol.% MgCO3 determined through complementary chemical analysis, provides a valuable first-order approximation. This contribution introduces a novel methodology for visualizing, monitoring, and quantifying such chemical reactions in multi-phase carbonate systems, in 2D, 3D and even 4D, offering advantages over destructive techniques such as 3D FIB-tomography. Our findings pave the way to further exploration of carbonate diagenesis and open up new perspectives for the application of spectral tomography in Earth sciences.
{"title":"Pioneering data on detection, identification and quantification of key carbonate minerals using spectral tomography","authors":"Kanchana Kularatne , Nicolas E. Beaudoin , Pascale Sénéchal , Peter Moonen , Souhail Youssef , Fadi H. Nader","doi":"10.1016/j.marpetgeo.2025.107536","DOIUrl":"10.1016/j.marpetgeo.2025.107536","url":null,"abstract":"<div><div>In this study, we present, for the first time, the spectral computed tomography (sp-CT) signatures of key carbonate rock-forming minerals namely, calcite, magnesian calcite, dolomite, and magnesite. Although the raw spectra of these phases may not be readily distinguishable, we demonstrate that they appear in clusters on a multi-energy histogram derived from laboratory sp-CT. These clusters show a strong correlation with the MgCO<sub>3</sub> mol.% of the carbonate phases. In addition to discriminating among these carbonate phases, we demonstrate the capability of time-resolved sp-CT to monitor mineral replacement reactions in carbonates. As an example, we analyze a series of time-lapse sp-CT images of a carbonate sample undergoing hydrothermal dolomitization in the laboratory. The results reveal a progressive transformation of pure calcite into an Mg-rich carbonate, with the sp-CT data indicating a final composition of approximately 32 mol.% MgCO<sub>3</sub>. This estimate, while lower than the 46–50 mol.% MgCO<sub>3</sub> determined through complementary chemical analysis, provides a valuable first-order approximation. This contribution introduces a novel methodology for visualizing, monitoring, and quantifying such chemical reactions in multi-phase carbonate systems, in 2D, 3D and even 4D, offering advantages over destructive techniques such as 3D FIB-tomography. Our findings pave the way to further exploration of carbonate diagenesis and open up new perspectives for the application of spectral tomography in Earth sciences.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107536"},"PeriodicalIF":3.7,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144654698","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}
Pub Date : 2025-07-05DOI: 10.1016/j.marpetgeo.2025.107535
Alina Karamova, Tagir Karamov, Mikhail Spasennykh
Pyrite is a common authigenic mineral in organic-rich source rocks, which is diverse in morphology and carries valuable genetic information about geological processes. This study proposes comprehensive genetic morphological classification of pyrite aggregates in organic-rich shales of the Bazhenov Formation – one of the world largest source rock located in the Western Siberia. Scanning electron microscopy was used to analyze over 530 samples from 17 wells, identifying various types of pyrite such as framboids (with corresponding subtypes based on orderliness of the internal structure, crystallographic shape of microcrystals, infilling of internal structure, and integrity), euhedral crystals, and pyrite pseudomorphosis. The obtained sulfur isotopic composition for framboidal pyrite, which turned out to be the lightest (δ34S vary in the range from −55.38 ‰ to −26.02 ‰), is indicative of anoxic conditions on seafloor. Euhedral pyrite develops in diagenesis under limited sulfate supply, reflecting slow growth in pore-water depleted in 32S (δ34S values range from +15.05 ‰ to +26.49 ‰). Described morphological types cover the diversity of pyrite forms in other similar geological objects around the world, which allows pyrite to be used as a geochemical proxy for paleoenvironmental reconstructions and hydrocarbon exploration, enhancing understanding of sulfur cycle and basin evolution.
{"title":"Pyrite morphologies in Bazhenov Formation source rocks: diversity, systematic classification, sulfur isotopic composition and insights into sedimentation and diagenesis processes","authors":"Alina Karamova, Tagir Karamov, Mikhail Spasennykh","doi":"10.1016/j.marpetgeo.2025.107535","DOIUrl":"10.1016/j.marpetgeo.2025.107535","url":null,"abstract":"<div><div>Pyrite is a common authigenic mineral in organic-rich source rocks, which is diverse in morphology and carries valuable genetic information about geological processes. This study proposes comprehensive genetic morphological classification of pyrite aggregates in organic-rich shales of the Bazhenov Formation – one of the world largest source rock located in the Western Siberia. Scanning electron microscopy was used to analyze over 530 samples from 17 wells, identifying various types of pyrite such as framboids (with corresponding subtypes based on orderliness of the internal structure, crystallographic shape of microcrystals, infilling of internal structure, and integrity), euhedral crystals, and pyrite pseudomorphosis. The obtained sulfur isotopic composition for framboidal pyrite, which turned out to be the lightest (δ<sup>34</sup>S vary in the range from −55.38 ‰ to −26.02 ‰), is indicative of anoxic conditions on seafloor. Euhedral pyrite develops in diagenesis under limited sulfate supply, reflecting slow growth in pore-water depleted in <sup>32</sup>S (δ<sup>34</sup>S values range from +15.05 ‰ to +26.49 ‰). Described morphological types cover the diversity of pyrite forms in other similar geological objects around the world, which allows pyrite to be used as a geochemical proxy for paleoenvironmental reconstructions and hydrocarbon exploration, enhancing understanding of sulfur cycle and basin evolution.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107535"},"PeriodicalIF":3.7,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588495","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}
Pub Date : 2025-07-04DOI: 10.1016/j.marpetgeo.2025.107534
Yuedong Sun , Shanggui Gong , Jörn Peckmann , Fang Chen , Yao Guan , Dong Feng
Oil seeps are important hydrocarbon sources to the ocean and sustain diverse chemosynthesis-based ecosystems. Distinguishing oil- from methane-dominated seeps in the geological record is crucial for reconstructing the evolution of chemosynthetic communities, yet remains challenging. Authigenic carbonates precipitating at seeps offer a valuable archive of the composition of seep fluid. While previous work has focused on fibrous aragonite cement, the geochemical potential of volumetrically dominant microcrystalline analog remains underexplored. Here, we present a comprehensive study of the petrography and stable isotope as well as element composition of oil-derived seep carbonates from the northern Gulf of Mexico (sites GC232, GC185), compared to methane-derived seep carbonates from the northern Gulf of Mexico (site AT340) and the South China Sea (site GMGS2-08). All studied samples are dominated by microcrystalline aragonite. Carbon isotope data (average δ13C = −20.9 ± 4.5 ‰; VPDB) and the presence of oil residues agree with crude oil degradation as the main carbon source of the oil-seep carbonate. Compared to methane-seep carbonates, oil-seep carbonates exhibit higher rare earth elements (REE) contents, slight light-REE enrichment, and elevated contents of uranium (U), molybdenum (Mo), zinc (Zn), and cobalt (Co), signatures linked to microbial oil oxidation. These element patterns preserved in microcrystalline aragonite offer a novel proxy for identifying oil seepage in the rock record, particularly in cases where fibrous cement is absent.
{"title":"Trace and rare earth element signatures in microcrystalline aragonite as indicators of oil vs. methane seepage","authors":"Yuedong Sun , Shanggui Gong , Jörn Peckmann , Fang Chen , Yao Guan , Dong Feng","doi":"10.1016/j.marpetgeo.2025.107534","DOIUrl":"10.1016/j.marpetgeo.2025.107534","url":null,"abstract":"<div><div>Oil seeps are important hydrocarbon sources to the ocean and sustain diverse chemosynthesis-based ecosystems. Distinguishing oil- from methane-dominated seeps in the geological record is crucial for reconstructing the evolution of chemosynthetic communities, yet remains challenging. Authigenic carbonates precipitating at seeps offer a valuable archive of the composition of seep fluid. While previous work has focused on fibrous aragonite cement, the geochemical potential of volumetrically dominant microcrystalline analog remains underexplored. Here, we present a comprehensive study of the petrography and stable isotope as well as element composition of oil-derived seep carbonates from the northern Gulf of Mexico (sites GC232, GC185), compared to methane-derived seep carbonates from the northern Gulf of Mexico (site AT340) and the South China Sea (site GMGS2-08). All studied samples are dominated by microcrystalline aragonite. Carbon isotope data (average δ<sup>13</sup>C = −20.9 ± 4.5 ‰; VPDB) and the presence of oil residues agree with crude oil degradation as the main carbon source of the oil-seep carbonate. Compared to methane-seep carbonates, oil-seep carbonates exhibit higher rare earth elements (REE) contents, slight light-REE enrichment, and elevated contents of uranium (U), molybdenum (Mo), zinc (Zn), and cobalt (Co), signatures linked to microbial oil oxidation. These element patterns preserved in microcrystalline aragonite offer a novel proxy for identifying oil seepage in the rock record, particularly in cases where fibrous cement is absent.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107534"},"PeriodicalIF":3.7,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144579701","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}
Pub Date : 2025-07-03DOI: 10.1016/j.marpetgeo.2025.107533
Enze Wang , Maowen Li , Xiaoxiao Ma , Menhui Qian , Tingting Cao , Zhiming Li , Zhijun Jin
Traditionally, shale petroleum systems are considered to possess self-generating and self-storing characteristics. However, with the advancement in understanding of these systems, researchers have discovered that hydrocarbon migration is a common phenomenon within them. Given that the scale of hydrocarbon migration in shale petroleum systems is significantly smaller compared to conventional systems, identifying such migration within shales remains a challenging endeavor. Moreover, few studies have systematically discussed the impact of hydrocarbon migration on petroleum accumulation in shale systems. This study focuses on the Lucaogou Formation in the Jimusar Sag of the Junggar Basin. Building upon geochemical data reported by previous research, we have reinterpreted and further explored geochemical data, presenting a novel approach for quantitatively identifying various types of hydrocarbon migration within shale using pyrolysis and molecular geochemical parameters, which are commonly generated in the petroleum industry. Additionally, it explores the influence of hydrocarbon migration on oil enrichment. The findings reveal that various forms of hydrocarbon migration have contributed to the paradoxes in the pyrolysis (the mismatch between TOC and S1 contents) and molecular geochemical features (anomalies of the C29 αββ/(αββ+ααα) and C29 ααα 20S/(20S + 20R) ratios) of the Lucaogou Formation. Based on the hydrocarbon migration status, four distinct types of reservoirs are identified within the Lucaogou Formation shale: lateral migration, carrier bed, inter-layer migration, and in situ retention. According to exploration practices, the Lucaogou shale can be divided into different sections (upper section sweet spot, middle section mudstone, and lower section sweet spot), each exhibiting distinct differences in hydrocarbon migration types. Lateral migration is commonly observed in the upper section sweet spot, whereas in the middle-section mudstone and the lower section sweet spot, the occurrence of lateral migration is limited, with inter-layer migration and in situ retention being more prevalent. In shale systems, extensive lateral hydrocarbon migration facilitates the formation of localized, high-quality exploration sweet spots, although these sweet spots bear more resemblance to conventional structural-lithologic reservoirs. Future exploration and development strategies for shale petroleum systems should consider the patterns of hydrocarbon migration when formulating plans. This study offers a framework for the detailed characterization of hydrocarbon migration types within shale petroleum systems and highlights the impact of hydrocarbon migration on shale oil enrichment.
{"title":"Inter-strata oil migration and its implications of hydrocarbon accumulation in the lacustrine shale system of the Lucaogou Formation, Jimusaer Sag, Junggar Basin","authors":"Enze Wang , Maowen Li , Xiaoxiao Ma , Menhui Qian , Tingting Cao , Zhiming Li , Zhijun Jin","doi":"10.1016/j.marpetgeo.2025.107533","DOIUrl":"10.1016/j.marpetgeo.2025.107533","url":null,"abstract":"<div><div>Traditionally, shale petroleum systems are considered to possess self-generating and self-storing characteristics. However, with the advancement in understanding of these systems, researchers have discovered that hydrocarbon migration is a common phenomenon within them. Given that the scale of hydrocarbon migration in shale petroleum systems is significantly smaller compared to conventional systems, identifying such migration within shales remains a challenging endeavor. Moreover, few studies have systematically discussed the impact of hydrocarbon migration on petroleum accumulation in shale systems. This study focuses on the Lucaogou Formation in the Jimusar Sag of the Junggar Basin. Building upon geochemical data reported by previous research, we have reinterpreted and further explored geochemical data, presenting a novel approach for quantitatively identifying various types of hydrocarbon migration within shale using pyrolysis and molecular geochemical parameters, which are commonly generated in the petroleum industry. Additionally, it explores the influence of hydrocarbon migration on oil enrichment. The findings reveal that various forms of hydrocarbon migration have contributed to the paradoxes in the pyrolysis (the mismatch between TOC and S<sub>1</sub> contents) and molecular geochemical features (anomalies of the C<sub>29</sub> αββ/(αββ+ααα) and C<sub>29</sub> ααα 20S/(20S + 20R) ratios) of the Lucaogou Formation. Based on the hydrocarbon migration status, four distinct types of reservoirs are identified within the Lucaogou Formation shale: lateral migration, carrier bed, inter-layer migration, and in situ retention. According to exploration practices, the Lucaogou shale can be divided into different sections (upper section sweet spot, middle section mudstone, and lower section sweet spot), each exhibiting distinct differences in hydrocarbon migration types. Lateral migration is commonly observed in the upper section sweet spot, whereas in the middle-section mudstone and the lower section sweet spot, the occurrence of lateral migration is limited, with inter-layer migration and in situ retention being more prevalent. In shale systems, extensive lateral hydrocarbon migration facilitates the formation of localized, high-quality exploration sweet spots, although these sweet spots bear more resemblance to conventional structural-lithologic reservoirs. Future exploration and development strategies for shale petroleum systems should consider the patterns of hydrocarbon migration when formulating plans. This study offers a framework for the detailed characterization of hydrocarbon migration types within shale petroleum systems and highlights the impact of hydrocarbon migration on shale oil enrichment.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107533"},"PeriodicalIF":3.7,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144556798","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}
Pub Date : 2025-07-02DOI: 10.1016/j.marpetgeo.2025.107532
A. Permanyer , M.A. Kruge , L. Gibert
The Messinian Salinity Crisis (MSC) generated extensive anoxic sediments under the evaporitic deposits in marginal Mediterranean basins. In an interdisciplinary approach combining field work with multiple laboratory techniques, the oil source rock potential and biomarkers of pre-evaporitic Messinian sediments from the Caltanissetta Basin (Sicily) were evaluated using Rock-Eval pyrolysis, gas chromatography-mass spectrometry, isotopic analysis and optical and electron microscopy. Organic-rich samples from the 45 m Serra Pirciata section consist of cycles of diatomaceous and carbonate layers alternating with organic shales of variable TOC. The organic matter is mostly optically amorphous, increasing in content upwards in the section. Of the 43 samples analyzed within the section, an especially organic- and sulfur-rich interval shows TOC values up to 10 %, and oil generation potential (Rock-Eval S2) up to 75 mg HC/g rock. Samples show Rock-Eval Hydrogen Indices (HI) up to ca. 800 mg HC/g TOC, but most fall in the range of 300–600 mg HC/g TOC, indicating type II kerogen. Within this section, a specific interval is especially remarkable for its unusual biomarker assemblage, having abundant sulfur compounds including isoprenoid, steroid, and hopanoid thiophenes and thiolanes, as well as microscopic sponge fossils. We propose that this organic-rich interval with its distinctive biomarkers represents an initial episode of basin restriction and, based on cyclostratigraphic interpretations, constitutes a non-evaporitic record of the onset of the MSC in the deeper part of the Caltanissetta Basin, where gypsum deposits were initially absent. If the depocenter of the Caltanissetta Basin is an analog for the deep Mediterranean basin, these results suggest that a large volume of organic matter of bacterial origin accumulated in the deep Mediterranean prior to evaporitic deposition.
{"title":"Onset of the Messinian Salinity Crisis: Insights from molecular organic geochemistry","authors":"A. Permanyer , M.A. Kruge , L. Gibert","doi":"10.1016/j.marpetgeo.2025.107532","DOIUrl":"10.1016/j.marpetgeo.2025.107532","url":null,"abstract":"<div><div>The Messinian Salinity Crisis (MSC) generated extensive anoxic sediments under the evaporitic deposits in marginal Mediterranean basins. In an interdisciplinary approach combining field work with multiple laboratory techniques, the oil source rock potential and biomarkers of pre-evaporitic Messinian sediments from the Caltanissetta Basin (Sicily) were evaluated using Rock-Eval pyrolysis, gas chromatography-mass spectrometry, isotopic analysis and optical and electron microscopy. Organic-rich samples from the 45 m Serra Pirciata section consist of cycles of diatomaceous and carbonate layers alternating with organic shales of variable TOC. The organic matter is mostly optically amorphous, increasing in content upwards in the section. Of the 43 samples analyzed within the section, an especially organic- and sulfur-rich interval shows TOC values up to 10 %, and oil generation potential (Rock-Eval S2) up to 75 mg HC/g rock. Samples show Rock-Eval Hydrogen Indices (HI) up to ca. 800 mg HC/g TOC, but most fall in the range of 300–600 mg HC/g TOC, indicating type II kerogen. Within this section, a specific interval is especially remarkable for its unusual biomarker assemblage, having abundant sulfur compounds including isoprenoid, steroid, and hopanoid thiophenes and thiolanes, as well as microscopic sponge fossils. We propose that this organic-rich interval with its distinctive biomarkers represents an initial episode of basin restriction and, based on cyclostratigraphic interpretations, constitutes a non-evaporitic record of the onset of the MSC in the deeper part of the Caltanissetta Basin, where gypsum deposits were initially absent. If the depocenter of the Caltanissetta Basin is an analog for the deep Mediterranean basin, these results suggest that a large volume of organic matter of bacterial origin accumulated in the deep Mediterranean prior to evaporitic deposition.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107532"},"PeriodicalIF":3.7,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144556799","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}
Pub Date : 2025-06-28DOI: 10.1016/j.marpetgeo.2025.107526
Mengfei Zhang , Mingjie Liu , Bo Cao , Peng Huang , Zilong Wang
<div><div>The tight sandstone reservoirs of the Xu3 Member in the Depression Zone of the Western Sichuan Foreland Basin (WSFB-DZ) are characterized by the widespread development of kaolinite cement, with notable cementation variations observed between the northern and southern regions of the depression zone. Utilizing an integrated methodology that encompasses cast thin section petrography, SEM, XRD, CL, fluid inclusion homogenization temperatures, in-situ micro-area carbon and oxygen isotopes, and trace element analysis, this study compared the differential cementation traits and genetic mechanisms of authigenic kaolinite within the Xu3 Member tight sandstone reservoirs, distinguishing between the northern and southern regions of WSFB-DZ. The study indicates that the northern Xu3 Member tight sandstone reservoirs are predominantly litharenite. The authigenic kaolinite crystals exhibit well-defined structures, predominantly, manifesting as pseudo-hexagonal platy single crystals and vermicular-to-booklet-like aggregates. These crystals fill predominantly intragranular dissolution pores and intergranular pores, and coexist mainly with quartz cement and carbonate cement. In contrast, the southern region is primarily litharenite and sublitharenite. The crystal morphology of authigenic kaolinite in this area is less well-developed compared to that in the northern region, with rare vermicular aggregates. Additionally, kaolinite cement in this region underwent substantial transformation into illite and chlorite through late diagenetic alteration. The Xu3 Member tight sandstone reservoirs in the WSFB-DZ exhibit two stages of kaolinite cementation, early and late. These cements originated from the dissolution of easily soluble grains such as feldspar and rock fragments by humic acids derived from early coal-bearing strata and organic acids generated during organic matter maturation and decarboxylation in the late stage. The southern Xu3 Member sandstone reservoirs exhibit a relatively high content of K-feldspar grains, and the dissolution of K-feldspar by organic acids released a significant amount of K<sup>+</sup> ions. Additionally, the late-stage carbonate cementation consumed only a small amount of Fe<sup>2+</sup> and Mg<sup>2+</sup> ions, resulting in late diagenetic fluids that were rich in K<sup>+</sup>, Fe<sup>2+</sup>, and Mg<sup>2+</sup> ions. These geochemical conditions favor the widespread transformation of authigenic kaolinite into illite and chlorite in the southern Xu3 Member sandstone reservoirs. Consequently, the southern sandstones are characterized by a low content of kaolinite cement and a relatively high content of illite and chlorite cement. In contrast, the northern Xu3 Member sandstone reservoirs have a lower content of K-feldspar grains, resulting in reduced K<sup>+</sup> ions release from organic acid dissolution. Simultaneously, the late-stage carbonate cementation sequestered substantial Fe<sup>2+</sup> and Mg<sup>2+</sup> ion
{"title":"Genesis of differential cementation by authigenic kaolinite in deep-buried tight sandstone reservoirs for the upper Triassic Xujiahe Formation, western Sichuan foreland basin, China","authors":"Mengfei Zhang , Mingjie Liu , Bo Cao , Peng Huang , Zilong Wang","doi":"10.1016/j.marpetgeo.2025.107526","DOIUrl":"10.1016/j.marpetgeo.2025.107526","url":null,"abstract":"<div><div>The tight sandstone reservoirs of the Xu3 Member in the Depression Zone of the Western Sichuan Foreland Basin (WSFB-DZ) are characterized by the widespread development of kaolinite cement, with notable cementation variations observed between the northern and southern regions of the depression zone. Utilizing an integrated methodology that encompasses cast thin section petrography, SEM, XRD, CL, fluid inclusion homogenization temperatures, in-situ micro-area carbon and oxygen isotopes, and trace element analysis, this study compared the differential cementation traits and genetic mechanisms of authigenic kaolinite within the Xu3 Member tight sandstone reservoirs, distinguishing between the northern and southern regions of WSFB-DZ. The study indicates that the northern Xu3 Member tight sandstone reservoirs are predominantly litharenite. The authigenic kaolinite crystals exhibit well-defined structures, predominantly, manifesting as pseudo-hexagonal platy single crystals and vermicular-to-booklet-like aggregates. These crystals fill predominantly intragranular dissolution pores and intergranular pores, and coexist mainly with quartz cement and carbonate cement. In contrast, the southern region is primarily litharenite and sublitharenite. The crystal morphology of authigenic kaolinite in this area is less well-developed compared to that in the northern region, with rare vermicular aggregates. Additionally, kaolinite cement in this region underwent substantial transformation into illite and chlorite through late diagenetic alteration. The Xu3 Member tight sandstone reservoirs in the WSFB-DZ exhibit two stages of kaolinite cementation, early and late. These cements originated from the dissolution of easily soluble grains such as feldspar and rock fragments by humic acids derived from early coal-bearing strata and organic acids generated during organic matter maturation and decarboxylation in the late stage. The southern Xu3 Member sandstone reservoirs exhibit a relatively high content of K-feldspar grains, and the dissolution of K-feldspar by organic acids released a significant amount of K<sup>+</sup> ions. Additionally, the late-stage carbonate cementation consumed only a small amount of Fe<sup>2+</sup> and Mg<sup>2+</sup> ions, resulting in late diagenetic fluids that were rich in K<sup>+</sup>, Fe<sup>2+</sup>, and Mg<sup>2+</sup> ions. These geochemical conditions favor the widespread transformation of authigenic kaolinite into illite and chlorite in the southern Xu3 Member sandstone reservoirs. Consequently, the southern sandstones are characterized by a low content of kaolinite cement and a relatively high content of illite and chlorite cement. In contrast, the northern Xu3 Member sandstone reservoirs have a lower content of K-feldspar grains, resulting in reduced K<sup>+</sup> ions release from organic acid dissolution. Simultaneously, the late-stage carbonate cementation sequestered substantial Fe<sup>2+</sup> and Mg<sup>2+</sup> ion","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107526"},"PeriodicalIF":3.7,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144523363","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}
Pub Date : 2025-06-27DOI: 10.1016/j.marpetgeo.2025.107522
Xiujuan Wang , Wenlu Wang , Jiapeng Jin , Guangxu Zhang , Zhendong Luan , Chaolun Li , Minxiao Wang , Zhengyi Zhang , Bo Liu , Wei Li , Sanzhong Li
Cold seeps in the Qiongdongnan Basin have been identified from three-dimensional (3D) seismic data, geophysical attributes, and in situ observations. Amplitude, dip, coherence and acoustic impedance attributes are employed to delineate the spatial variations of cold seeps across different layers by identifying faults, fractures and reservoir properties. These variations arise from the differences inside and outside of cold seeps due to the occurrence of gas hydrate, where mass transport deposits (MTDs) are widely distributed. The primary objective is to characterize the diverse features of cold seep systems, including seafloor features, plumbing systems, and their potential relationships with gas hydrates and shallow gas. Moreover, new remotely operated vehicle (ROV) dives have been utilized to distinguish two distinct chemosynthetic biological communities associated with methane bubble plumes. One community represents an active cold seep, characterized by abundant mussels and clams on or around carbonates, while the other is a paleo-cold seep that has been reactivated by gas hydrate drilling due to the leakage of trapped gas near the base of gas hydrate stability zone. All identified cold seeps exhibit weak amplitude anomalies, pull-up reflections, and chimney-like structures, which are located within high amplitude zones above local uplift in different sags of the Qiongdongnan Basin. Logging-while-drilling and coring data within these chimney-like structures have confirmed moderate to high gas hydrate saturations with diverse morphologies, as well as methane-related carbonates, indicating the presence of buried or active cold seeps. These findings suggest that cold seep activity is influenced by MTDs and that the upward fluid migration is closely linked to deep gas or shallow gas below the BGHSZ, which penetrate through MTDs along fault and fracture systems, suggesting pressure-controlled gas seepage.
{"title":"Multiple observations to delineate the characteristics of cold seep system in the Qiongdongnan Basin","authors":"Xiujuan Wang , Wenlu Wang , Jiapeng Jin , Guangxu Zhang , Zhendong Luan , Chaolun Li , Minxiao Wang , Zhengyi Zhang , Bo Liu , Wei Li , Sanzhong Li","doi":"10.1016/j.marpetgeo.2025.107522","DOIUrl":"10.1016/j.marpetgeo.2025.107522","url":null,"abstract":"<div><div>Cold seeps in the Qiongdongnan Basin have been identified from three-dimensional (3D) seismic data, geophysical attributes, and in situ observations. Amplitude, dip, coherence and acoustic impedance attributes are employed to delineate the spatial variations of cold seeps across different layers by identifying faults, fractures and reservoir properties. These variations arise from the differences inside and outside of cold seeps due to the occurrence of gas hydrate, where mass transport deposits (MTDs) are widely distributed. The primary objective is to characterize the diverse features of cold seep systems, including seafloor features, plumbing systems, and their potential relationships with gas hydrates and shallow gas. Moreover, new remotely operated vehicle (ROV) dives have been utilized to distinguish two distinct chemosynthetic biological communities associated with methane bubble plumes. One community represents an active cold seep, characterized by abundant mussels and clams on or around carbonates, while the other is a paleo-cold seep that has been reactivated by gas hydrate drilling due to the leakage of trapped gas near the base of gas hydrate stability zone. All identified cold seeps exhibit weak amplitude anomalies, pull-up reflections, and chimney-like structures, which are located within high amplitude zones above local uplift in different sags of the Qiongdongnan Basin. Logging-while-drilling and coring data within these chimney-like structures have confirmed moderate to high gas hydrate saturations with diverse morphologies, as well as methane-related carbonates, indicating the presence of buried or active cold seeps. These findings suggest that cold seep activity is influenced by MTDs and that the upward fluid migration is closely linked to deep gas or shallow gas below the BGHSZ, which penetrate through MTDs along fault and fracture systems, suggesting pressure-controlled gas seepage.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107522"},"PeriodicalIF":3.7,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144523394","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}
Pub Date : 2025-06-27DOI: 10.1016/j.marpetgeo.2025.107527
M.S. Bauck , J.I. Faleide , H. Fossen , R.L. Gawthorpe
Mapping the diachronous Top Basement in the North Sea reveals a complex amalgamation of paleolandscapes and provides valuable insights into the Late Paleozoic and Mesozoic geologic history. To illuminate the temporal geologic and geomorphic evolution, we document and analyze geomorphic characteristics and relate these to the regional tectonostratigraphic events. The paleolandscapes represented by the Top Basement surface generally fall into the following categories: rough, irregular terrains; rough, confined drainage networks; and smooth, planar landscapes. Notably, the irregular landscape found at the base of the deep basins is covered by Upper Paleozoic sediments and represents a potential late stage of the Devonian denudation of the Caledonian mountain chain. A distinct drainage network on the Top Basement of the Patch Bank Ridge represents two exposure phases: one related to extension during Devonian exhumation and the other associated with Carboniferous exhumation. Two regional tectonic events are candidates for such Carboniferous exhumation, one is Variscan contraction, the other is the Pennsylvanian event dated onshore Greenland and Fenoscandia. Preserved drainage networks observed on various basement highs correspond to local Late Permian to Early Triassic fault block uplift. In tilted fault blocks, these features are significant, while in horst block structures, smooth, planar landscape expression occurs. This is linked to repeated uplift of horst block structures, while tilted fault blocks get buried sooner. A distinct terrain observed in a confined area on the western Måløy Slope exhibits geomorphic characteristics comparable to those found on the tilted Vette and Tusse fault blocks overlain by sediment of Triassic or older origin. Thus, we suggest that this is a strong indication that Late Permian to Early Triassic rifting impacted the Måløy Slope. Tectonic and climatic processes controlled the relief and spatial extent of these landscapes. Our findings correlate with onshore exhumation and landscape development documented from other studies onshore East Greenland and Fennoscandia. These insights highlight the potential for identifying further paleolandscape features across the wider North Sea region and beyond.
绘制北海顶基底的历时图揭示了古地貌的复杂融合,为了解晚古生代和中生代的地质历史提供了有价值的见解。为了阐明时间地质和地貌演化,我们记录和分析了地貌特征,并将其与区域构造地层事件联系起来。以上基底面为代表的古地貌一般分为以下几类:粗糙、不规则的地形;粗糙的、密闭的排水网络;以及平滑、平面的景观。值得注意的是,在深盆底部发现的不规则景观被上古生界沉积物覆盖,代表了加里东山脉的泥盆世晚期剥蚀。Patch Bank Ridge顶部基底上有一个独特的排水网络,代表了两个暴露阶段:一个与泥盆纪挖掘时的伸展有关,另一个与石炭纪挖掘有关。两个区域构造事件是石炭纪发掘的候选事件,一个是Variscan收缩,另一个是宾夕法尼亚事件,可追溯到格陵兰岛和Fenoscandia岸上。在不同基底高地观测到的保留的水系网络对应于局部晚二叠世至早三叠世断块隆起。在倾斜断块中,这些特征非常明显,而在主体断块结构中,则表现为光滑的平面景观。这与主块体构造的反复隆升有关,而倾斜的断块被埋得更快。在马洛伊斜坡西部的一个封闭区域观察到的独特地形,其地貌特征与三叠纪或更早起源的沉积物覆盖的倾斜的Vette和Tusse断块相似。因此,我们认为这是一个强烈的迹象,表明晚二叠世至早三叠世的裂陷作用影响了马 løy斜坡。构造和气候过程控制着这些景观的地形和空间范围。我们的发现与东格陵兰岛和芬诺斯坎迪亚的其他陆上研究记录的陆上挖掘和景观发展有关。这些见解强调了在更广泛的北海地区及其他地区进一步识别古地貌特征的潜力。
{"title":"Paleolandscapes recorded by the Top Basement surface in the Norwegian North Sea","authors":"M.S. Bauck , J.I. Faleide , H. Fossen , R.L. Gawthorpe","doi":"10.1016/j.marpetgeo.2025.107527","DOIUrl":"10.1016/j.marpetgeo.2025.107527","url":null,"abstract":"<div><div>Mapping the diachronous Top Basement in the North Sea reveals a complex amalgamation of paleolandscapes and provides valuable insights into the Late Paleozoic and Mesozoic geologic history. To illuminate the temporal geologic and geomorphic evolution, we document and analyze geomorphic characteristics and relate these to the regional tectonostratigraphic events. The paleolandscapes represented by the Top Basement surface generally fall into the following categories: rough, irregular terrains; rough, confined drainage networks; and smooth, planar landscapes. Notably, the irregular landscape found at the base of the deep basins is covered by Upper Paleozoic sediments and represents a potential late stage of the Devonian denudation of the Caledonian mountain chain. A distinct drainage network on the Top Basement of the Patch Bank Ridge represents two exposure phases: one related to extension during Devonian exhumation and the other associated with Carboniferous exhumation. Two regional tectonic events are candidates for such Carboniferous exhumation, one is Variscan contraction, the other is the Pennsylvanian event dated onshore Greenland and Fenoscandia. Preserved drainage networks observed on various basement highs correspond to local Late Permian to Early Triassic fault block uplift. In tilted fault blocks, these features are significant, while in horst block structures, smooth, planar landscape expression occurs. This is linked to repeated uplift of horst block structures, while tilted fault blocks get buried sooner. A distinct terrain observed in a confined area on the western Måløy Slope exhibits geomorphic characteristics comparable to those found on the tilted Vette and Tusse fault blocks overlain by sediment of Triassic or older origin. Thus, we suggest that this is a strong indication that Late Permian to Early Triassic rifting impacted the Måløy Slope. Tectonic and climatic processes controlled the relief and spatial extent of these landscapes. Our findings correlate with onshore exhumation and landscape development documented from other studies onshore East Greenland and Fennoscandia. These insights highlight the potential for identifying further paleolandscape features across the wider North Sea region and beyond.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107527"},"PeriodicalIF":3.7,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548665","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}
Pub Date : 2025-06-27DOI: 10.1016/j.marpetgeo.2025.107525
Amir Kalifi , Jihede Haj Messaoud , Guillaume Baby , Khalil Ibrahim , John H. Powell , Frans van Buchem
The Late Cretaceous-Eocene geodynamic evolution of Jordan is presented, combining, for the first-time, outcrop and subsurface data in this poorly known, yet important part of the Arabian Plate. A new age model developed for outcrop sections, integrating biostratigraphy, C/O and Sr isotopes, together with seismic and well log data significantly improves the timing of the structural events in Jordan and shows their potential relationship to Arabian Plate scale deformation events.
The late Albian-early Turonian displays a gradual north-northwestward thickening trend across Jordan during a phase of tectonic quiescence, whereas in the overlying late Turonian-early Campanian there is ample evidence for extensional/transtensional tectonic activity, with an acme during the early Campanian, expressed in the development of the northwest-trending Azraq-Hamza Graben in central-east Jordan. This graben, with an offset of c. 1800 m, extends southeastwards to the Wadi Sirhan Graben in Saudi Arabia and northwestwards to the Levant Basin. The subsequent late Campanian-Eocene succession records reduced tectonic subsidence within the graben during a sag phase and marks a return to regional stability.
The Azraq-Hamza Graben is proven to be time-equivalent to the similarly oriented extensional events in Syria (Euphrates Graben) and Iraq (Sinjar Graben) and is coeval with the compressional structures of the foreland basins in Oman and Iran. This study contributes, to the large-scale tectonic evaluation of the African-Arabian plate deformation and evolution during the Late Cretaceous obduction and subduction phases, which played a critical role in the shaping of the petroleum systems and phosphorite sedimentation of the region.
{"title":"Tectono-stratigraphic evolution of the Late Cretaceous-Eocene of Jordan and implications for the Arabian Plate convergent margin phase","authors":"Amir Kalifi , Jihede Haj Messaoud , Guillaume Baby , Khalil Ibrahim , John H. Powell , Frans van Buchem","doi":"10.1016/j.marpetgeo.2025.107525","DOIUrl":"10.1016/j.marpetgeo.2025.107525","url":null,"abstract":"<div><div>The Late Cretaceous-Eocene geodynamic evolution of Jordan is presented, combining, for the first-time, outcrop and subsurface data in this poorly known, yet important part of the Arabian Plate. A new age model developed for outcrop sections, integrating biostratigraphy, C/O and Sr isotopes, together with seismic and well log data significantly improves the timing of the structural events in Jordan and shows their potential relationship to Arabian Plate scale deformation events.</div><div>The late Albian-early Turonian displays a gradual north-northwestward thickening trend across Jordan during a phase of tectonic quiescence, whereas in the overlying late Turonian-early Campanian there is ample evidence for extensional/transtensional tectonic activity, with an acme during the early Campanian, expressed in the development of the northwest-trending Azraq-Hamza Graben in central-east Jordan. This graben, with an offset of c. 1800 m, extends southeastwards to the Wadi Sirhan Graben in Saudi Arabia and northwestwards to the Levant Basin. The subsequent late Campanian-Eocene succession records reduced tectonic subsidence within the graben during a sag phase and marks a return to regional stability.</div><div>The Azraq-Hamza Graben is proven to be time-equivalent to the similarly oriented extensional events in Syria (Euphrates Graben) and Iraq (Sinjar Graben) and is coeval with the compressional structures of the foreland basins in Oman and Iran. This study contributes, to the large-scale tectonic evaluation of the African-Arabian plate deformation and evolution during the Late Cretaceous obduction and subduction phases, which played a critical role in the shaping of the petroleum systems and phosphorite sedimentation of the region.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107525"},"PeriodicalIF":3.7,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563090","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}
Pub Date : 2025-06-27DOI: 10.1016/j.marpetgeo.2025.107530
Andrea Argnani, Marzia Rovere
The narrow Calabrian Arc accretionary prism, in the Mediterranean Sea, is known to be populated by mud volcanoes, although only a few of them have been extensively documented. The Ionian Sea offshore the Crotone Promontory offers examples where the expressions of fluid expulsion and sediment mobilization are visible both in the subsurface and at the seafloor. The analysis of a proprietary 3D seismic data cube allows characterization of pockmark patterns and identification of a mud diapir, which appears at the seafloor as a large mud pool, ca. 1200 m in diameter. The high resolution 3D seismic profiles allow differences to be inferred about the mechanisms of fluid focusing at very shallow sub-seafloor depths. Fluid focusing and pockmark formation are aided by normal faults arising from both outer arc extension and dilation in shallow unconsolidated sediments influenced by sharp increases in slope gradient. In some instances, it can be shown that fluid venting also contributed to destabilizing the uppermost sedimentary strata, triggering small landslides along the slope. The mud diapir has apparently been mobilized along an extensional fault, which tapped into a mobile shale domain. A fossil mud pool has also been recognized in the study area. This fossil mud pool is sealed by undeformed sedimentary strata which constrains a minimum age for fluid and sediment mobilization in the accretionary prism. Seismic reflection amplitudes suggest that the fossil conduit still acts as a preferential fluid seepage pathway, contributing to destabilization of the overlying slope sediments.
{"title":"Submarine morphology offshore Crotone (Calabrian accretionary prism, Central Mediterranean): Pockmark fields and mud extrusion in a mobile shale domain","authors":"Andrea Argnani, Marzia Rovere","doi":"10.1016/j.marpetgeo.2025.107530","DOIUrl":"10.1016/j.marpetgeo.2025.107530","url":null,"abstract":"<div><div>The narrow Calabrian Arc accretionary prism, in the Mediterranean Sea, is known to be populated by mud volcanoes, although only a few of them have been extensively documented. The Ionian Sea offshore the Crotone Promontory offers examples where the expressions of fluid expulsion and sediment mobilization are visible both in the subsurface and at the seafloor. The analysis of a proprietary 3D seismic data cube allows characterization of pockmark patterns and identification of a mud diapir, which appears at the seafloor as a large mud pool, ca. 1200 m in diameter. The high resolution 3D seismic profiles allow differences to be inferred about the mechanisms of fluid focusing at very shallow sub-seafloor depths. Fluid focusing and pockmark formation are aided by normal faults arising from both outer arc extension and dilation in shallow unconsolidated sediments influenced by sharp increases in slope gradient. In some instances, it can be shown that fluid venting also contributed to destabilizing the uppermost sedimentary strata, triggering small landslides along the slope. The mud diapir has apparently been mobilized along an extensional fault, which tapped into a mobile shale domain. A fossil mud pool has also been recognized in the study area. This fossil mud pool is sealed by undeformed sedimentary strata which constrains a minimum age for fluid and sediment mobilization in the accretionary prism. Seismic reflection amplitudes suggest that the fossil conduit still acts as a preferential fluid seepage pathway, contributing to destabilization of the overlying slope sediments.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107530"},"PeriodicalIF":3.7,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518186","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}