Pub Date : 2025-01-01DOI: 10.1016/j.jop.2024.12.003
Oladapo O. Akinlotan , Sunday E. Okunuwadje , Stuart J. Hatter
Modelling the diagenetic history of a tectonically active basin is crucial for understanding the depositional and post-depositional processes including the evolution and development of porosity and permeability. This study describes the diagenetic imprints of the inverted Lower Cretaceous Weald Basin and examines the depositional and tectonic controls on the diagenetic, porosity and permeability evolution of its sandstones. Seventy-two representative sandstone samples from the Weald Basin were subjected to detailed microscopic (optical and scanning electron) analyses. The dominant early diagenetic fabrics include grain-coating detrital clays, degraded and dissolved detrital grains, and vermiform kaolinite pore-filling cement while uplift-related or telogenetic characteristics are mainly post-compactional pore-filling goethite and hematite cement. This work is significant because it presents the first diagenetic model of the Lower Cretaceous Wealden sandstones which can be very useful for understanding basins with similar depositional and tectonic settings.
{"title":"Basin inversion controls on diagenetic evolution of Lower Cretaceous non-marine succession: the English Wealden sandstones","authors":"Oladapo O. Akinlotan , Sunday E. Okunuwadje , Stuart J. Hatter","doi":"10.1016/j.jop.2024.12.003","DOIUrl":"10.1016/j.jop.2024.12.003","url":null,"abstract":"<div><div>Modelling the diagenetic history of a tectonically active basin is crucial for understanding the depositional and post-depositional processes including the evolution and development of porosity and permeability. This study describes the diagenetic imprints of the inverted Lower Cretaceous Weald Basin and examines the depositional and tectonic controls on the diagenetic, porosity and permeability evolution of its sandstones. Seventy-two representative sandstone samples from the Weald Basin were subjected to detailed microscopic (optical and scanning electron) analyses. The dominant early diagenetic fabrics include grain-coating detrital clays, degraded and dissolved detrital grains, and vermiform kaolinite pore-filling cement while uplift-related or telogenetic characteristics are mainly post-compactional pore-filling goethite and hematite cement. This work is significant because it presents the first diagenetic model of the Lower Cretaceous Wealden sandstones which can be very useful for understanding basins with similar depositional and tectonic settings.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 15-39"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.jop.2024.10.002
Pradip Samanta , Soumik Mukhopadhyay , Arunava Sen , Madhurya Roy
The distinctive sedimentation patterns of the late Neoproterozoic Girbhakar Sandstone were investigated within the context of a Precambrian sedimentation system devoid of vegetation. This comprehensive study utilized an integrated approach, incorporating facies analysis, fluvial architectural elements analysis, and palaeocurrent analysis, to offer detailed insights into the controlling factors of sedimentology and depositional settings within the studied interval. Process-based facies analysis revealed thirteen distinct facies types organized into five associations, uncovering a diverse range of depositional palaeoenvironments — from alluvial fan and braided fluvial to transitional marine settings. An alluvial fan, dominated by debris flow and multiple ephemeral channels at the basin margin, emerged initially. The stratigraphic architecture of this alluvial fan and the associated ephemeral fluvial system was primarily influenced by water table fluctuations in arid to semiarid climatic conditions. A transition to a semi-perennial to perennial braided fluvial system occurred as the depositional slope decreased. However, the stratigraphic architecture of these fluvial systems exhibited distinctive variations in response to fluctuating base level rise. Notably, the basal segment, characterized by an unconformity below and a granular lag succeeded by wave-agitated sandstone above, represented the lowstand systems tract (LST). During the early LST, channel belts prograded at the northern distal end of upstream aggradational semi-perennial braided systems in response to the transgression of Girbhakar Sea from the north, aligning with the late Neoproterozoic Indian plate configuration. The coarsening upward deposits suggest a potential classification as a braid-delta, formed by a gradual rise in base level, low epeiric gradient, and episodic flashy discharges, which facilitate the downstream development of this deposit. During the late LST, the evolution of perennial fluvial systems resulted in braid-plain deposits throughout the study area, with a transitional marine unit at the downstream site. An accelerated rate of base level rise facilitated marine reworking, leading to the deposition of transitional marine sediments. The final phase of base level rise marked the cessation of terrestrial deposition, culminating in the submergence of the site underneath the sea. The study highlights the unique responses of alluvial sediments to diverse controlling factors along the deposition downslope. This enhances insights into Neoproterozoic alluvial sedimentation dynamics and the resulting stratigraphic architecture in time and space from a broad perspective.
{"title":"Responses of non-marine deposits to fluctuating base level and their implications in the Precambrian sequence building: Late Neoproterozoic Girbhakar Sandstone, Rajasthan, India","authors":"Pradip Samanta , Soumik Mukhopadhyay , Arunava Sen , Madhurya Roy","doi":"10.1016/j.jop.2024.10.002","DOIUrl":"10.1016/j.jop.2024.10.002","url":null,"abstract":"<div><div>The distinctive sedimentation patterns of the late Neoproterozoic Girbhakar Sandstone were investigated within the context of a Precambrian sedimentation system devoid of vegetation. This comprehensive study utilized an integrated approach, incorporating facies analysis, fluvial architectural elements analysis, and palaeocurrent analysis, to offer detailed insights into the controlling factors of sedimentology and depositional settings within the studied interval. Process-based facies analysis revealed thirteen distinct facies types organized into five associations, uncovering a diverse range of depositional palaeoenvironments — from alluvial fan and braided fluvial to transitional marine settings. An alluvial fan, dominated by debris flow and multiple ephemeral channels at the basin margin, emerged initially. The stratigraphic architecture of this alluvial fan and the associated ephemeral fluvial system was primarily influenced by water table fluctuations in arid to semiarid climatic conditions. A transition to a semi-perennial to perennial braided fluvial system occurred as the depositional slope decreased. However, the stratigraphic architecture of these fluvial systems exhibited distinctive variations in response to fluctuating base level rise. Notably, the basal segment, characterized by an unconformity below and a granular lag succeeded by wave-agitated sandstone above, represented the lowstand systems tract (LST). During the early LST, channel belts prograded at the northern distal end of upstream aggradational semi-perennial braided systems in response to the transgression of Girbhakar Sea from the north, aligning with the late Neoproterozoic Indian plate configuration. The coarsening upward deposits suggest a potential classification as a braid-delta, formed by a gradual rise in base level, low epeiric gradient, and episodic flashy discharges, which facilitate the downstream development of this deposit. During the late LST, the evolution of perennial fluvial systems resulted in braid-plain deposits throughout the study area, with a transitional marine unit at the downstream site. An accelerated rate of base level rise facilitated marine reworking, leading to the deposition of transitional marine sediments. The final phase of base level rise marked the cessation of terrestrial deposition, culminating in the submergence of the site underneath the sea. The study highlights the unique responses of alluvial sediments to diverse controlling factors along the deposition downslope. This enhances insights into Neoproterozoic alluvial sedimentation dynamics and the resulting stratigraphic architecture in time and space from a broad perspective.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 66-90"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.jop.2024.12.004
Zhen-Hua Xu , Sheng-He Wu , Piret Plink-Björklund , Tao Zhang , Da-Li Yue , Qi-Hao Qian , Qing Li , Wen-Jie Feng
River-dominated lacustrine deltas typically consist of multiple lobes due to autogenic lobe switching that occurs over short time scales. However, the switching patterns of multiple lobes in these deltas remain poorly understood, and the architectural features attributed to lobe switching are also lacking. By integrating Delft3D simulations, flume experiments, and modern deposit analysis, we proposed that autogenic lobe switching follows a cyclic pattern. Autocyclicity begins with the formation of an offshore lobe and concludes after a series of longshore lobe growth events, marked by longshore avulsions occurring along the sides of offshore distributary channels. Longshore avulsions follow a sequence that usually occurs earlier distally than proximally and subsequently occurs on one longshore side and then on the other side. Each lobe begins with rapid growth, which gradually slows and then stops once a channel avulsion is influenced by the backwater effect that triggers lobe switching. Three signals indicate lobe switching: a decrease in progradation rate, foreset slope steepening coupled with topset slope gentling, and the deposition of mud-dominated sediments. The number of autocyclic events never exceeds seven. The first two autocyclicities contribute to more than 55% of delta length and 70% of delta area. The lobes are separated by 1–6 stages of mud-dominated accretion beds that exhibit a downstream-inclined shape and convex-up or lateral overlapping pattern. This study conducts a coupled growth-geometric assessment to establish an architectural pattern for river-dominated lacustrine deltas. This architectural pattern offers valuable insights into predicting sandy lobe distribution in river-dominated lacustrine delta reservoirs, and the architecture of muddy accretion beds aids in predicting the rule of oil–water movement and distribution of remaining oil.
{"title":"Autocyclic switching processes and architecture of lobes in river-dominated lacustrine deltas","authors":"Zhen-Hua Xu , Sheng-He Wu , Piret Plink-Björklund , Tao Zhang , Da-Li Yue , Qi-Hao Qian , Qing Li , Wen-Jie Feng","doi":"10.1016/j.jop.2024.12.004","DOIUrl":"10.1016/j.jop.2024.12.004","url":null,"abstract":"<div><div>River-dominated lacustrine deltas typically consist of multiple lobes due to autogenic lobe switching that occurs over short time scales. However, the switching patterns of multiple lobes in these deltas remain poorly understood, and the architectural features attributed to lobe switching are also lacking. By integrating Delft3D simulations, flume experiments, and modern deposit analysis, we proposed that autogenic lobe switching follows a cyclic pattern. Autocyclicity begins with the formation of an offshore lobe and concludes after a series of longshore lobe growth events, marked by longshore avulsions occurring along the sides of offshore distributary channels. Longshore avulsions follow a sequence that usually occurs earlier distally than proximally and subsequently occurs on one longshore side and then on the other side. Each lobe begins with rapid growth, which gradually slows and then stops once a channel avulsion is influenced by the backwater effect that triggers lobe switching. Three signals indicate lobe switching: a decrease in progradation rate, foreset slope steepening coupled with topset slope gentling, and the deposition of mud-dominated sediments. The number of autocyclic events never exceeds seven. The first two autocyclicities contribute to more than 55% of delta length and 70% of delta area. The lobes are separated by 1–6 stages of mud-dominated accretion beds that exhibit a downstream-inclined shape and convex-up or lateral overlapping pattern. This study conducts a coupled growth-geometric assessment to establish an architectural pattern for river-dominated lacustrine deltas. This architectural pattern offers valuable insights into predicting sandy lobe distribution in river-dominated lacustrine delta reservoirs, and the architecture of muddy accretion beds aids in predicting the rule of oil–water movement and distribution of remaining oil.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 126-140"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.jop.2024.11.003
Holger Petermann , Annaka M. Clement , Patrick M. Sullivan , Hannah M. Bonner , James W. Hagadorn
The story of the Earth's changing landscapes is often told through paleogeographic maps. These images are some of the most accessible and widely used illustrations in the Earth sciences. However, no formal procedure for the creation of photorealistic paleomaps (i.e., paleosatellite images) exists. Using an example from the Late Jurassic of the Rocky Mountain region, we present a method for making paleoenvironmental and paleosatellite maps that is scalable, reproducible, testable, and incorporates peer review. The process includes a literature review followed by data-visualization, paleoenvironmental interpretation, peer-review, iterative revisions, and the creation of a false contour map and color gradient used to render a paleosatellite image. Paleosatellite images are photorealistic versions of paleoenvironmental maps that incorporate global climatic and tectonic information as well as principles of actualism; they can be made through comparison to analogous modern landscapes. An important component of this process is that the data maps that ground this paleomapping process allow evaluation of where paleoenvironmental interpretations are well-supported by outcrop and subsurface data, and where such visualization is highly interpretive – often because of lack of available rocks or studies in a given area. As such, our paleoenvironmental maps and paleosatellite images are testable pictorial hypotheses. By outlining a procedure that produces referenced, data-rich, and visually realistic maps, we hope to demystify the paleoenvironmental map-making process and improve accessibility of paleomaps for the broader geoscience community. Where resources and complementary data are available, such maps also have potential for georeferencing and integration with larger continent-scale paleogeographic maps.
{"title":"Paleomapping: Creating testable visual hypotheses of ancient worlds","authors":"Holger Petermann , Annaka M. Clement , Patrick M. Sullivan , Hannah M. Bonner , James W. Hagadorn","doi":"10.1016/j.jop.2024.11.003","DOIUrl":"10.1016/j.jop.2024.11.003","url":null,"abstract":"<div><div>The story of the Earth's changing landscapes is often told through paleogeographic maps. These images are some of the most accessible and widely used illustrations in the Earth sciences. However, no formal procedure for the creation of photorealistic paleomaps (i.e., paleosatellite images) exists. Using an example from the Late Jurassic of the Rocky Mountain region, we present a method for making paleoenvironmental and paleosatellite maps that is scalable, reproducible, testable, and incorporates peer review. The process includes a literature review followed by data-visualization, paleoenvironmental interpretation, peer-review, iterative revisions, and the creation of a false contour map and color gradient used to render a paleosatellite image. Paleosatellite images are photorealistic versions of paleoenvironmental maps that incorporate global climatic and tectonic information as well as principles of actualism; they can be made through comparison to analogous modern landscapes. An important component of this process is that the data maps that ground this paleomapping process allow evaluation of where paleoenvironmental interpretations are well-supported by outcrop and subsurface data, and where such visualization is highly interpretive – often because of lack of available rocks or studies in a given area. As such, our paleoenvironmental maps and paleosatellite images are testable pictorial hypotheses. By outlining a procedure that produces referenced, data-rich, and visually realistic maps, we hope to demystify the paleoenvironmental map-making process and improve accessibility of paleomaps for the broader geoscience community. Where resources and complementary data are available, such maps also have potential for georeferencing and integration with larger continent-scale paleogeographic maps.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 91-104"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.jop.2024.09.003
Zhen-Sheng Shi , Tian-Qi Zhou , Hui-Bo Song , Yong-Bin Niu , Sha-Sha Sun
The hydrodynamics and their evolution on the Upper Yangtze Block during the Ordovician–Silurian transition period remain unclear. The present study is an assessment of how regional and global events may have influenced the hydrodynamic evolution based on a planar lamination investigation of the shales from the Upper Yangtze Block. Analyses of large thin sections and argon-ion polished thin sections using field emission-scanning electron microscopy (FE-SEM) showed that there are four types of planar lamination, namely, silty graded planar lamination (SGPL), silt–clay graded planar lamination (SCGPL), silt–clay interlaminated planar lamination (SCIPL), and paper-like planar lamination (PPL). SGPL is formed by turbidity current with a flow speed less than 15 cm/s. SCGPL is formed by turbidity currents with a flow speed less than 15 cm/s for normal grading type and 15–25 cm/s for alternating grading type. SCIPL has a continuum of sparsely spaced type, closely spaced type, and alternating type, which is formed by bottom current with an increasing flow speed from 15 to 25 cm/s to above 25 cm/s. PPL can be divided into normal grading and composite grading types. The former is formed by vertical settling, while the latter is formed by bottom current with a flow speed of 5–15 cm/s. Vertically, types of planar lamination varied from SGPL to PPL and then SCIPL manifesting the waxing and waning of flow speed with a positive excursion at graptolite biozone Metabolograptus extraordinarius (WF4) and a negative excursion at graptolite biozone Persculptograptuspersculptus (LM1). The sudden decrease in flow speed across Linxiang and graptolite biozone Paraorthograptuspacificus (WF3) and the subsequent progressive increase from graptolite biozone Akidograptus ascensus (LM2) to graptolite biozone Demirastrites triangulatus (LM6) and to graptolite biozone Stimulograptus sedgwickii (LM8) during deposition of the Ordovician–Silurian transition succession on the Upper Yangtze Block were linked to the bulge uplift, the rapid subsidence, and the relaxation controlled by the Kwangsian orogeny. In contrast, the positive excursion at WF4 and the negative excursion at LM1 were strongly controlled by the Hirnantian Glaciation and global warming, respectively.
{"title":"Vertical variations in planar lamination of marine shale: Elucidating hydrodynamic changes during the Ordovician–Silurian transition on the Upper Yangtze Block","authors":"Zhen-Sheng Shi , Tian-Qi Zhou , Hui-Bo Song , Yong-Bin Niu , Sha-Sha Sun","doi":"10.1016/j.jop.2024.09.003","DOIUrl":"10.1016/j.jop.2024.09.003","url":null,"abstract":"<div><div>The hydrodynamics and their evolution on the Upper Yangtze Block during the Ordovician–Silurian transition period remain unclear. The present study is an assessment of how regional and global events may have influenced the hydrodynamic evolution based on a planar lamination investigation of the shales from the Upper Yangtze Block. Analyses of large thin sections and argon-ion polished thin sections using field emission-scanning electron microscopy (FE-SEM) showed that there are four types of planar lamination, namely, silty graded planar lamination (SGPL), silt–clay graded planar lamination (SCGPL), silt–clay interlaminated planar lamination (SCIPL), and paper-like planar lamination (PPL). SGPL is formed by turbidity current with a flow speed less than 15 cm/s. SCGPL is formed by turbidity currents with a flow speed less than 15 cm/s for normal grading type and 15–25 cm/s for alternating grading type. SCIPL has a continuum of sparsely spaced type, closely spaced type, and alternating type, which is formed by bottom current with an increasing flow speed from 15 to 25 cm/s to above 25 cm/s. PPL can be divided into normal grading and composite grading types. The former is formed by vertical settling, while the latter is formed by bottom current with a flow speed of 5–15 cm/s. Vertically, types of planar lamination varied from SGPL to PPL and then SCIPL manifesting the waxing and waning of flow speed with a positive excursion at graptolite biozone <em>Metabolograptus extraordinarius</em> (WF4) and a negative excursion at graptolite biozone <em>Persculptograptus</em> <em>persculptus (</em>LM1). The sudden decrease in flow speed across Linxiang and graptolite biozone <em>Paraorthograptus</em> <em>pacificus</em> (WF3) and the subsequent progressive increase from graptolite biozone <em>Akidograptus ascensus</em> (LM2) to graptolite biozone <em>Demirastrites triangulatus</em> (LM6) and to graptolite biozone <em>Stimulograptus sedgwickii</em> (LM8) during deposition of the Ordovician–Silurian transition succession on the Upper Yangtze Block were linked to the bulge uplift, the rapid subsidence, and the relaxation controlled by the Kwangsian orogeny. In contrast, the positive excursion at WF4 and the negative excursion at LM1 were strongly controlled by the Hirnantian Glaciation and global warming, respectively.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 221-244"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.jop.2024.12.002
Oumar Ibrahima Kane , Ming-Yi Hu , Quan-Sheng Cai , Qing-Jie Deng , Ze-Bin Tong
Various data were utilized to analyze the sedimentary facies, completely reconstruct the palaeogeographic maps, and evaluate the reservoir quality of the Middle-Upper Cambrian Xixiangchi Formation in the Sichuan Basin, including evidence from field outcrops, drilling cores, microscopic thin sections, scanning electron microscopy (SEM), combined with experimental analysis data, such as petrophysical data (porosity (%) and permeability (mD)), and radioactive elements (uranium (238U), thorium (232Th), and potassium (40K)), and isotopic data (δ13C)). In the Sichuan Basin, the Middle-Upper Cambrian Xixiangchi Formation was principally deposited in a restricted platform with a lithology predominantly composed of dolomite, with local occurrences of limestone and other rock types in small thicknesses. Graded beddings, cross beddings, horizontal beddings, storm depositions, and mud cracks locally developed in some samples. Four 3rd-order sequences (SQ1-SQ4) were identified within the Xixiangchi Formation in this study. Each sequence is subdivided into a highstand systems tract (HST) and a transgressive systems tract (TST). Reservoirs are principally developed in high-energy grain shoal deposits located in SQ2 and SQ3, with a minor occurrence in SQ1 and SQ4. The lithology of these shoal deposits is essentially composed of sandy dolomite and crystalline dolomite characterized by relatively low average porosity (2.61 %) and permeability (1.0073 mD) values. The increase of these values in several studied samples might be related to seepage and connecting dissolution pores and vugs through fractures which have a constructive effect on porosity and permeability. The occurrence of karst caves through superimposed supergene karstification and bedding karstification highly improved the reservoir's physical properties in some areas. The reservoir space is dominated by intergranular dissolution pores, karst caves, and fractures, and their formation was controlled by sedimentation, diagenesis, penecontemporaneous dissolution, and tectonic fractures, which can also be influenced by palaeogeomorphology and sea level fluctuation. Favorable hydrocarbon exploration areas with relatively good source conditions, high positions in the paleostructure, which are conducive to the migration and accumulations of hydrocarbon were identified in three areas of the basin: (1) on the slope around the Central Sichuan Uplift; (2) in the northeastern part, dolomite reservoirs developed with good physical properties and large cumulative thicknesses; and (3) in the southeastern part, shoal facies reservoirs were developed in high and steep structural settings with anticlinal traps. The insights gained in this study fill a significant gap in geological complexities related to sedimentology, palaeogeography, and hydrocarbon reservoir prediction.
{"title":"Sedimentary facies analysis, palaeogeography, and reservoir quality of the Middle-Upper Cambrian Xixiangchi Formation in southeast Sichuan Basin, southwest China","authors":"Oumar Ibrahima Kane , Ming-Yi Hu , Quan-Sheng Cai , Qing-Jie Deng , Ze-Bin Tong","doi":"10.1016/j.jop.2024.12.002","DOIUrl":"10.1016/j.jop.2024.12.002","url":null,"abstract":"<div><div>Various data were utilized to analyze the sedimentary facies, completely reconstruct the palaeogeographic maps, and evaluate the reservoir quality of the Middle-Upper Cambrian Xixiangchi Formation in the Sichuan Basin, including evidence from field outcrops, drilling cores, microscopic thin sections, scanning electron microscopy (SEM), combined with experimental analysis data, such as petrophysical data (porosity (%) and permeability (mD)), and radioactive elements (uranium (<sup>238</sup>U), thorium (<sup>232</sup>Th), and potassium (<sup>40</sup>K)), and isotopic data (δ<sup>13</sup>C)). In the Sichuan Basin, the Middle-Upper Cambrian Xixiangchi Formation was principally deposited in a restricted platform with a lithology predominantly composed of dolomite, with local occurrences of limestone and other rock types in small thicknesses. Graded beddings, cross beddings, horizontal beddings, storm depositions, and mud cracks locally developed in some samples. Four 3rd-order sequences (SQ1-SQ4) were identified within the Xixiangchi Formation in this study. Each sequence is subdivided into a highstand systems tract (HST) and a transgressive systems tract (TST). Reservoirs are principally developed in high-energy grain shoal deposits located in SQ2 and SQ3, with a minor occurrence in SQ1 and SQ4. The lithology of these shoal deposits is essentially composed of sandy dolomite and crystalline dolomite characterized by relatively low average porosity (2.61 %) and permeability (1.0073 mD) values. The increase of these values in several studied samples might be related to seepage and connecting dissolution pores and vugs through fractures which have a constructive effect on porosity and permeability. The occurrence of karst caves through superimposed supergene karstification and bedding karstification highly improved the reservoir's physical properties in some areas. The reservoir space is dominated by intergranular dissolution pores, karst caves, and fractures, and their formation was controlled by sedimentation, diagenesis, penecontemporaneous dissolution, and tectonic fractures, which can also be influenced by palaeogeomorphology and sea level fluctuation. Favorable hydrocarbon exploration areas with relatively good source conditions, high positions in the paleostructure, which are conducive to the migration and accumulations of hydrocarbon were identified in three areas of the basin: (1) on the slope around the Central Sichuan Uplift; (2) in the northeastern part, dolomite reservoirs developed with good physical properties and large cumulative thicknesses; and (3) in the southeastern part, shoal facies reservoirs were developed in high and steep structural settings with anticlinal traps. The insights gained in this study fill a significant gap in geological complexities related to sedimentology, palaeogeography, and hydrocarbon reservoir prediction.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 245-276"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.08.006
Wei Yu , Feng Wang , Jing-Chun Tian , Jiao Wang , Benjamin Kneller , Tian Yang , Wei-Zhen Chen
Shales in deep lake basins have become the main focus of continental shale oil and gas exploration. In order to highlight the sedimentary dynamics of mud deposition in deep lake basins, a combination of core observation, thin section examination, X-ray diffraction, and QEMSCAN (quantitative evaluation of minerals by scanning electron microscopy) was used to analyze the depositional characteristics of mudrocks in the Chang-7 Member from the Yanchang Formation (Upper Triassic) in Ordos Basin, and to establish a depositional model for mud accumulation in deep lake basins. This study recognizes four mudrock lithofacies in the Chang-7 Member: (1) the laminated silt-bearing mudstone, which generally develops a binary composition of “silt–clay” or a ternary composition of “silt–clay–organic matter”; (2) the graded mudstone, mainly composed of dark gray and gray-black mudstone sandwiched by silt-bearing mudstone; (3) the massive mudstone, internally showing a uniform distribution of quartz, clay, and carbonate minerals, with also a small amount of organic detritus; and (4) the laminated shale, which is generally composed of clay laminae, and organic laminae of the former two. Sediment supply, topographic slope, and flood intensity combine to control the evolution of gravity flows and the transport and deposition of the mudrock in the Chang-7 Member. The influence of orogeny provides terrain gradient, water depth, abundant sediments at source areas, and triggering mechanism for the formation of gravity flows. Floods triggered by wetting events provide the impetus for sediment transport. Mud deposition in the Chang-7 Member was mainly related to the transport and sedimentation of mud by hyperpycnal flows and rapid sedimentation by buoyant plume flocculation. A comprehensive evolutionary model for shale accumulation in the deep lake basin is established by integrating various triggering mechanisms and mud transport sedimentary processes.
{"title":"Sedimentary dynamics and depositional model for mud accumulation in deep lake basins: A case study in the Upper Triassic Chang-7 Member, Ordos Basin, northern China","authors":"Wei Yu , Feng Wang , Jing-Chun Tian , Jiao Wang , Benjamin Kneller , Tian Yang , Wei-Zhen Chen","doi":"10.1016/j.jop.2024.08.006","DOIUrl":"10.1016/j.jop.2024.08.006","url":null,"abstract":"<div><div>Shales in deep lake basins have become the main focus of continental shale oil and gas exploration. In order to highlight the sedimentary dynamics of mud deposition in deep lake basins, a combination of core observation, thin section examination, X-ray diffraction, and QEMSCAN (quantitative evaluation of minerals by scanning electron microscopy) was used to analyze the depositional characteristics of mudrocks in the Chang-7 Member from the Yanchang Formation (Upper Triassic) in Ordos Basin, and to establish a depositional model for mud accumulation in deep lake basins. This study recognizes four mudrock lithofacies in the Chang-7 Member: (1) the laminated silt-bearing mudstone, which generally develops a binary composition of “silt–clay” or a ternary composition of “silt–clay–organic matter”; (2) the graded mudstone, mainly composed of dark gray and gray-black mudstone sandwiched by silt-bearing mudstone; (3) the massive mudstone, internally showing a uniform distribution of quartz, clay, and carbonate minerals, with also a small amount of organic detritus; and (4) the laminated shale, which is generally composed of clay laminae, and organic laminae of the former two. Sediment supply, topographic slope, and flood intensity combine to control the evolution of gravity flows and the transport and deposition of the mudrock in the Chang-7 Member. The influence of orogeny provides terrain gradient, water depth, abundant sediments at source areas, and triggering mechanism for the formation of gravity flows. Floods triggered by wetting events provide the impetus for sediment transport. Mud deposition in the Chang-7 Member was mainly related to the transport and sedimentation of mud by hyperpycnal flows and rapid sedimentation by buoyant plume flocculation. A comprehensive evolutionary model for shale accumulation in the deep lake basin is established by integrating various triggering mechanisms and mud transport sedimentary processes.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 775-792"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.07.004
Hua-Shan Zhang , Ming-Yue Dai , Yong-An Qi , Lan-Lan Han , Zhong-Lei Yin , Song-Hua Chen , Liang-Biao Lin
Girvanella is one of the common genera of cyanobacteria that plays a monumental role in the evolution of life on Earth and the formation of microbialites. Based on a detailed search in the literature of Girvanella fossils, we have compiled a global database of Girvanella fossils and revealed the evolution of Girvanella fossils throughout the Phanerozoic. Four species, Girvanella kasakiensis, Girvanella problematica, Girvanella wetheredii, and Girvanella staminea, are recognized and described. These data show that Girvanella fossils have well-defined temporal distribution during the Paleozoic Era, have a significant temporal gap in the Mesozoic Era, and have only been recorded sporadically in the Cenozoic Era. They were relatively abundant during the Cambrian Epoch 2–Early Ordovician, Late Ordovician, Late Devonian–Mississippian, and tended to lesser degrees during the Silurian–Early Devonian, Lopingian Epoch–Middle Jurassic, and Cretaceous–Present day. Furthermore, the evolution of the abundance and diversity of Girvanella fossils was fundamentally consistent and showed episodical declining during the Phanerozoic. To further explore these relationships, we thoroughly compared them with environmental factors such as seawater carbonate saturation state, Ca2+ concentration, pH values, and atmospheric partial pressure of carbon dioxide (pCO2). This study indicates that seawater carbonate saturation state and Ca2+ concentration are major controls on secular patterns of the abundance and diversity of Girvanella fossils, together with the secondary factors of pH values and pCO2. Considering the long history of Girvanella fossils, their abundance and diversity offer the potential to assist the interpretation of the long-term evolution of marine and atmosphere components during the Phanerozoic.
是蓝藻的常见属种之一，在地球生命进化和微生物岩的形成过程中发挥着不朽的作用。在对化石文献进行详细检索的基础上，我们编制了一个全球化石数据库，并揭示了化石在整个新生代的演化过程。确认并描述了、、和四个物种。这些数据表明，化石在古生代有明确的时间分布，在中生代有明显的时间空白，在新生代仅有零星记录。它们在寒武纪第二世-奥陶纪早期、奥陶纪晚期、泥盆纪晚期-密西西比期数量相对较多，在志留纪-泥盆纪早期、罗平纪-侏罗纪中期和白垩纪-现今数量较少。此外，化石的丰度和多样性的演变基本一致，在新生代期间呈偶发性下降。为了进一步探讨这些关系，我们将其与海水碳酸盐饱和状态、钙浓度、pH 值和大气二氧化碳分压等环境因素进行了深入比较。这项研究表明，海水碳酸盐饱和状态和钙的浓度是控制化石丰度和多样性的主要因素，pH 值和 CO 是次要因素。考虑到化石的悠久历史，它们的丰度和多样性有可能有助于解释新生代期间海洋和大气成分的长期演变。
{"title":"Girvanella fossils from the Phanerozoic: Distribution, evolution and controlling factors","authors":"Hua-Shan Zhang , Ming-Yue Dai , Yong-An Qi , Lan-Lan Han , Zhong-Lei Yin , Song-Hua Chen , Liang-Biao Lin","doi":"10.1016/j.jop.2024.07.004","DOIUrl":"10.1016/j.jop.2024.07.004","url":null,"abstract":"<div><div><em>Girvanella</em> is one of the common genera of cyanobacteria that plays a monumental role in the evolution of life on Earth and the formation of microbialites. Based on a detailed search in the literature of <em>Girvanella</em> fossils, we have compiled a global database of <em>Girvanella</em> fossils and revealed the evolution of <em>Girvanella</em> fossils throughout the Phanerozoic. Four species, <em>Girvanella kasakiensis</em>, <em>Girvanella problematica</em>, <em>Girvanella wetheredii</em>, and <em>Girvanella staminea</em>, are recognized and described. These data show that <em>Girvanella</em> fossils have well-defined temporal distribution during the Paleozoic Era, have a significant temporal gap in the Mesozoic Era, and have only been recorded sporadically in the Cenozoic Era. They were relatively abundant during the Cambrian Epoch 2–Early Ordovician, Late Ordovician, Late Devonian–Mississippian, and tended to lesser degrees during the Silurian–Early Devonian, Lopingian Epoch–Middle Jurassic, and Cretaceous–Present day. Furthermore, the evolution of the abundance and diversity of <em>Girvanella</em> fossils was fundamentally consistent and showed episodical declining during the Phanerozoic. To further explore these relationships, we thoroughly compared them with environmental factors such as seawater carbonate saturation state, Ca<sup>2+</sup> concentration, pH values, and atmospheric partial pressure of carbon dioxide (<em>p</em>CO<sub>2</sub>). This study indicates that seawater carbonate saturation state and Ca<sup>2+</sup> concentration are major controls on secular patterns of the abundance and diversity of <em>Girvanella</em> fossils, together with the secondary factors of pH values and <em>p</em>CO<sub>2</sub>. Considering the long history of <em>Girvanella</em> fossils, their abundance and diversity offer the potential to assist the interpretation of the long-term evolution of marine and atmosphere components during the Phanerozoic.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 924-938"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.08.004
Carlos Zavala , Hua-Qing Liu , Xiang-Bo Li , Valentin Trobbiani , Yang Li , Mariano Arcuri , Agustin Zorzano
<div><div>Sequence stratigraphic concepts and methods provide novel tools for performing stratigraphic analysis, allowing us to improve our understanding of depositional models and basin evolution. Main controls and depositional elements (e.g., surfaces, systems tracts, parasequences, etc.) recognized in conventional sequence stratigraphy are designed for marine-related systems. In contrast, the sequence stratigraphy of lacustrine successions is much more complex and poorly understood, because it is not driven by sea-level changes, but by a complex interaction between tectonics and high-frequency climatic cycles. The comprehensive analysis of the water balance of lacustrine systems allows the recognition of three types of lake conditions: Underfilled, balanced-fill and overfilled lakes. Understanding the lake conditions in ancient successions is fundamental for unraveling lacustrine sequence stratigraphy, since these conditions effectively control water salinity, internal stacking pattern and the characteristics of systems tracts. Underfilled lakes are hydrologically closed lakes, and consequently, the lake-level can highly fluctuate, driven by high-frequency wet-dry climatic cycles. During wet periods, rivers supply water and sediments, resulting in fining-and thinning-upward elementary depositional sequences (EDS's) accumulated during the transgressive systems tract (TST). In contrast, dry periods are characterized by a relative lake-level fall with the subaerial exposure of lake margin areas during the regressive systems tract (RST). Lake water salinity can fluctuate from brackish to hypersaline. Balanced-fill lakes are partially closed lakes, and consequently, they have characteristics of both underfilled and overfilled lakes. During the TST, the lake is in underfilled condition, and consequently, the introduction of water and sediment will accumulate a fining-upward interval until reaching the spill point during the maximum flooding. The RST is accumulated under an overfilled lake condition, with coarsening-upward progradational littoral deltas and related subaqueous delta deposits. Lake water salinity fluctuates from brackish to freshwater. Overfilled lakes are hydrologically open lakes. Most deposits accumulate during the RST, forming coarsening-upward progradational littoral deposits, with associated subaqueous deltas. All overfilled lakes are freshwater lakes. Subsidence is crucial for allowing the long-term preservation of lacustrine deposits. Lakes can temporarily store water and sediments in areas that lack subsidence, but these deposits will not be preserved in the stratigraphic record. Consequently, two types of lakes are recognized: 1) subsiding lakes, which have permanent accommodation space and 2) hanging lakes, having temporary accommodation space. Although they cannot permanently store sediments, hanging lakes are fundamental for lacustrine sequence stratigraphy, since they can flood subsiding lakes with the near-instantaneous
{"title":"High-frequency lacustrine sequence stratigraphy of clastic lakes: lessons from ancient successions","authors":"Carlos Zavala , Hua-Qing Liu , Xiang-Bo Li , Valentin Trobbiani , Yang Li , Mariano Arcuri , Agustin Zorzano","doi":"10.1016/j.jop.2024.08.004","DOIUrl":"10.1016/j.jop.2024.08.004","url":null,"abstract":"<div><div>Sequence stratigraphic concepts and methods provide novel tools for performing stratigraphic analysis, allowing us to improve our understanding of depositional models and basin evolution. Main controls and depositional elements (e.g., surfaces, systems tracts, parasequences, etc.) recognized in conventional sequence stratigraphy are designed for marine-related systems. In contrast, the sequence stratigraphy of lacustrine successions is much more complex and poorly understood, because it is not driven by sea-level changes, but by a complex interaction between tectonics and high-frequency climatic cycles. The comprehensive analysis of the water balance of lacustrine systems allows the recognition of three types of lake conditions: Underfilled, balanced-fill and overfilled lakes. Understanding the lake conditions in ancient successions is fundamental for unraveling lacustrine sequence stratigraphy, since these conditions effectively control water salinity, internal stacking pattern and the characteristics of systems tracts. Underfilled lakes are hydrologically closed lakes, and consequently, the lake-level can highly fluctuate, driven by high-frequency wet-dry climatic cycles. During wet periods, rivers supply water and sediments, resulting in fining-and thinning-upward elementary depositional sequences (EDS's) accumulated during the transgressive systems tract (TST). In contrast, dry periods are characterized by a relative lake-level fall with the subaerial exposure of lake margin areas during the regressive systems tract (RST). Lake water salinity can fluctuate from brackish to hypersaline. Balanced-fill lakes are partially closed lakes, and consequently, they have characteristics of both underfilled and overfilled lakes. During the TST, the lake is in underfilled condition, and consequently, the introduction of water and sediment will accumulate a fining-upward interval until reaching the spill point during the maximum flooding. The RST is accumulated under an overfilled lake condition, with coarsening-upward progradational littoral deltas and related subaqueous delta deposits. Lake water salinity fluctuates from brackish to freshwater. Overfilled lakes are hydrologically open lakes. Most deposits accumulate during the RST, forming coarsening-upward progradational littoral deposits, with associated subaqueous deltas. All overfilled lakes are freshwater lakes. Subsidence is crucial for allowing the long-term preservation of lacustrine deposits. Lakes can temporarily store water and sediments in areas that lack subsidence, but these deposits will not be preserved in the stratigraphic record. Consequently, two types of lakes are recognized: 1) subsiding lakes, which have permanent accommodation space and 2) hanging lakes, having temporary accommodation space. Although they cannot permanently store sediments, hanging lakes are fundamental for lacustrine sequence stratigraphy, since they can flood subsiding lakes with the near-instantaneous ","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 621-645"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.06.003
Anisotropy of Magnetic Susceptibility (AMS) data from a ∼27.8 m thick soft sedimentary mud sequence (∼10.5–3.25 k yrs) from the Spituk Palaeolake Sequence (SPSS) of Holocene age, located in the northern bank of the Indus River in the Leh-Ladakh Himalaya, show effects of tectonic versus climate dynamics responsible for the Himalayan sedimentation. The sedimentary sequence, consisting of alternating of aeolian sand and glacio-fluvial mud flow deposits, has been subdivided into an older Last Glacier Phase I (LGP 1) and a younger Last Glacier Phase II (LGP 2), where the termination of each phase is marked by the occurrence of gravel beds of thickness ≤1 m, which were deposited due to glacial melting. The present AMS data along with previously published information on sedimentology confirm that the mudflow deposits of the LGP 1 and LGP 2 phases were deposited in a lacustrine environment under glacio-fluvial conditions. However, a weak fluvial flow towards NW and NE could have existed for the LGP 1 and LGP 2, respectively. The glacial beds terminating LGP 1 and LGP 2 appear to have formed by climatic warming and tectonic activity, respectively. Hence, the Holocene Himalayan sedimentation was influenced by both climatic and tectonic activities. However, the thickness of the gravel bed (∼0.8 m) terminating LGP 2 occupies only ∼ 2.8 vol % of the total studied thickness ∼28 m, of the SPSS in the present study, which indicated a lesser control of tectonism in the growth of the Himalaya in and around the study area.
{"title":"A combined tectono-climatic control on Holocene sedimentation in Ladakh Himalaya, India: Clues from Anisotropy of Magnetic Susceptibility (AMS) of lake sediments","authors":"","doi":"10.1016/j.jop.2024.06.003","DOIUrl":"10.1016/j.jop.2024.06.003","url":null,"abstract":"<div><div>Anisotropy of Magnetic Susceptibility (AMS) data from a ∼27.8 m thick soft sedimentary mud sequence (∼10.5–3.25 k yrs) from the Spituk Palaeolake Sequence (SPSS) of Holocene age, located in the northern bank of the Indus River in the Leh-Ladakh Himalaya, show effects of tectonic versus climate dynamics responsible for the Himalayan sedimentation. The sedimentary sequence, consisting of alternating of aeolian sand and glacio-fluvial mud flow deposits, has been subdivided into an older Last Glacier Phase I (LGP 1) and a younger Last Glacier Phase II (LGP 2), where the termination of each phase is marked by the occurrence of gravel beds of thickness ≤1 m, which were deposited due to glacial melting. The present AMS data along with previously published information on sedimentology confirm that the mudflow deposits of the LGP 1 and LGP 2 phases were deposited in a lacustrine environment under glacio-fluvial conditions. However, a weak fluvial flow towards NW and NE could have existed for the LGP 1 and LGP 2, respectively. The glacial beds terminating LGP 1 and LGP 2 appear to have formed by climatic warming and tectonic activity, respectively. Hence, the Holocene Himalayan sedimentation was influenced by both climatic and tectonic activities. However, the thickness of the gravel bed (∼0.8 m) terminating LGP 2 occupies only ∼ 2.8 vol % of the total studied thickness ∼28 m, of the SPSS in the present study, which indicated a lesser control of tectonism in the growth of the Himalaya in and around the study area.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 738-753"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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