In the digital-intelligent era,disruptive technologies such as artificial intelligence and big data are driving sedimentology into its fourth research paradigm shift. This transformation profoundly reshapes its research philosophy and methodological system,which is critical not only for the disciplinary innovation of sedimentology itself but also for national strategic demands including energy security and ecological governance. To clarify the disciplinary evolution,core challenges,and proactive response strategies,this paper systematically reviews the intelligent development,problem typology,technological innovation,and application expansion of sedimentology. Results show that the intelligent evolution of sedimentology can be divided into four stages,with a fundamental shift from experience driven to data and knowledge dual driven mode. Based on the four major question types in natural science,sedimentology is confronted with a series of core propositions including the Soul Question,Mystery Question,Century Question,and Epochal Question,among which the mass slope coupling and heterogeneity of terrestrial reservoirs represent key breakthroughs. Currently,the application of AI in sedimentology is constrained by methodological conflicts,data fragmentation,and lagging theoretical development. To meet these challenges,sedimentology must break traditional mindsets,reject imitative research and empty conceptual innovation,and establish a new logic integrating theory,technology,and data. The deployment and optimization of AI models constitute the cornerstone of intelligent transformation,emphasizing fullcycle implementation: application deployment,realtime monitoring,and continuous iteration. Only by rooting in the disciplinary essence of sedimentology,deeply integrating AI with sedimentary dynamics,forming a closed loop of “data-simulation-verification”,strengthening interdisciplinary integration,and expanding frontier fields such as deep Earth,deep sea,and carbon neutrality,can sedimentology accomplish the leap from interpretive science to predictive and generative science and provide solid scientific support for national energy security and ecological civilization.

Four representative coal-bearing basins,including the Late Paleozoic North China epicontinental sea basin and the marginal sea basins of the South China Sea,were selected for a comparative analysis of the formation and evolutionary characteristics of autochthonous and allochthonous peat mires. The identification features for coal seams formed by autochthonous and allochthonous peat mires are proposed,and the differences between the two types of peat mires are summarized in terms of peat material accumulation,coal seam architecture,coal-interbed interfaces,and paleosol development. In addition,the characteristic attributes of allochthonous peat mires are elucidated. Research indicates that peat mires serve as the primary carriers of coal formation,represent a key type of sedimentary environment,and constitute a distinctive and significant feature of basin palaeogeography. Its significance and value lie in the following aspects: the attributes of sedimentary basins vary,and the palaeogeographic characteristics of autochthonous and allochthonous peat mires differ accordingly. The development and evolution of two mire types constitute important events in the evolution of coal-forming environments within basins;during the Late Paleozoic,frequent marine transgressions in the North China Basin not only suppressed peat mire development but also preserved peat material,producing a distinctive stratigraphic association in which marine transgressive layers are in direct contact with coal seams. The palaeogeography of transgression events represents a typical landscape of autochthonous peat mires;analysis of peat mire formation and evolution in the Huangxian terrestrial lacustrine faulted basin and the northern depression of the Pearl River Mouth Basin reveals that tectonic activity exerted a primary control on basin infill as well as on the development and evolution of peat mires. On steep slopes,unstable autochthonous mires were established,whereas stable autochthonous mires formed on gentle slopes. During critical stages of basin evolution,stable allochthonous mires developed in lacustrine or shallow-water settings,giving rise to the distinctive coal-oil shale assemblages.

As one of the core dynamic mechanisms for the transport of fine-grained sediments in the deep-water environment of continental lacustrine basins,the meticulous characterization and genetic analysis of the sedimentary sequences of fine-grained turbidite deposits constitute a key entry point for revealing the shale oil accumulation mechanism and improving the classification system of shale oil types. Taking the Member 1 of the Upper Cretaceous Qingshankou Formation in the Changling sag of the Songliao Basin as the research object,a total of nine sedimentary units have been identified based on the data from three full-core drilling wells,and the Markov chain method was adopted to analyze the turbidite sedimentary sequences,which reveals the transition laws of turbidite events from initiation,high-energy transportation to terminal attenuation in the prodelta-semi-deep lake-deep lake sedimentary environments. Based on the actual geological data of the study area,the sedimentary characteristics of fine-grained turbidite currents in continental lacustrine basins were characterized,and a sedimentary sequence model for fine-grained turbidite deposits in continental lacustrine basins is established,among which the fine-grained turbidite deposits are composed of Units T₁ to T₇ that clearly reflect the high-energy to low-energy sedimentary evolution laws of turbidites. Synthesizing such parameters as lithologic assemblages,sedimentary structures and sand-to-shale ratio,a classification scheme for shale oil types in the study area is proposed. The characteristics of different shale oil types are significantly controlled by the fine-grained turbidite deposits: the interbedded type is governed by proximal turbidite deposits,with sandstone and siltstone interbeds providing high-quality reservoir spaces for shale oil;the laminated type is associated with distal turbidite deposits,dominated by high-frequency thin-bedded silty mudstones and shales and possessing favorable reservoir physical properties and brittleness;the massive type is related to the combined effects of terminal turbidite deposits and lacustrine still-water deposits in the lacustrine basin,with relatively poor reservoir physical properties and brittleness.

As a super basin,the Ordos Basin currently lacks a unified understanding of its Paleozoic-early Mesozoic tectono-sedimentary evolutionary stages and key basin prototypes. This study systematically examines the tectono-sedimentary evolution of the Hinggan-Mongolian and Qin-Qi orogenic belts,regional unconformities and distribution of Paleozoic formations within the basin,stratigraphic genesis and distribution of volcanic tuff events,and sedimentary filling characteristics from the Paleozoic to Middle Triassic. The tectono-sedimentary evolution of the Ordos Basin is divided into eight stages in this periods. During the Cambrian and Early-Middle Ordovician periods,three types of basin prototypes coexisted: passive continental margin subsidence along the southwestern margin,northwest margin graben,and intra-cratonic subsidence in the central-eastern region. The Late Ordovician had coexistence of two basin prototypes: post-arc rift along the southwestern margin and northwest margin graben. The Late Carboniferous-Early Permian witnessed coexistence of two basin prototypes: intra-cratonic subsidence and post-arc rift along the northwest margin. Following mid-Permian land-building movements, intra-cratonic subsidence and Baotou foreland basin developed during the Late Permian-Middle Triassic. Based on the development and distribution of basin prototypes from the Cambrian to Middle Triassic,their superimposed relationships,and the oil and gas geological conditions they control,combined with recent exploration progress,this study proposes that the Lower Paleozoic formations along the southern margin,sub-salt formations in the central-eastern region,Upper Ordovician shale oil and gas along the western margin,and multi-type natural gas in the Upper Paleozoic constitute the oil and gas succession zones of the Ordos super basin.

Marine red beds(MRBs)have attracted considerable attention due to their distinctive coloration,complex formation mechanisms,diverse sedimentary types,and valuable information regarding palaeo-oceanography,palaeoclimate,and even biological evolution. However,there are obvious bias in geological time and regional research and knowledge on MRBs,with particular focus concentrated on Precambrian,Early Paleozoic,Early Triassic,and Jurassic-Cretaceous MRBs. The late Silurian to Early Devonian represents a critical interval of global palaeogeographical reorganization,atmospheric compositional changes,and ecosystem transformation,yet MRBs from this period have received limited attention. Northern Xinjiang is one of the regions with relatively continuous late Silurian to Early Devonian strata in China. Based on previous research data,combined with our extensive regional investigations in recent years,newly acquired fossils dominated by conodonts,and sedimentary facies markers,this paper preliminary identifies the spatiotemporal distribution,lithological and biological assemblage characteristics of MRBs in the study area,and then makes comparisons with other contemporaneous MRBs in China. On this basis,the prospects for the study of MRBs in the late Silurian-Early Devonian are proposed. On the premise of establishing a high-precision biochronostratigraphical framework,a global database of MRBs at the late Silurian-Early Devonian is established to identify the distribution and characteristics of MRBs at this interval,and to carry out comprehensive comparison,then to explore the relationships between MRBs and important bio-environmental events in the period. It will contribute to a more comprehensive,systematic and in-depth understanding of the characteristics of the Earth’s multi-geosphere transformation and their coupling relationships during the late Silurian-Early Devonian.

For the problem of unclear evolutionary process of deep-water gravity flow deposition in the first member of Ordovician Lashizhong Formation in northwestern margin of Ordos Basin,the characteristics and evolution are studied on the basis of outcrop data,microscopic observation and grain size analysis,and finally the sedimentary modles are established. The results show that: (1)five lithofacies are developed in the study area,corresponding to horizontal bedding shale facies(F1),massive bedding calcirudite facies(F2),graded bedding fine sandstone facies(F3),parallel bedding fine sandstone to siltstone facies(F4)and small-scale cross-bedding siltstone facies(F5);(2)four deep-water depositional types are identified according to the shapes and stacking styles of sandstones: complex channels deposition,migrating channels depositon,proximal lobes deposition and distal lobes deposition;(3)complex channels,lobes,migrating channels and lobes are developed vertically in sequence;and(4)gravity flow deposition can be divided into two stages. In the first stage,the energy of gravity flow is high,forming the complex channel;With energy attenuation,small-scale lobes are developed. When in the second stage,the gravity flow erupts,which the energy is lower than the gravity flow in the first stage,and migrating channel is developed. As the energy of gravity flow continues to wane,deposition becomes dominant,resulting in a vertical transition form channels to lobes,with proximal lobes and distal lobes sequentially are developing in the depositional system. This study can improve the understanding of the sedimentary evolution law of gravity flow and is helpful to deep-water oil and gas exploration.

The frequently dynamic changes in the mixed fine-grained sedimentary environment of shale oil in saline lacustrine basins exert a decisive controlling influence on organic matter enrichment,source rock development,and the distribution of sweet spots. This study focuses on the Lucaogou Formation in the Jimusar sag,Junggar Basin and the Member 2 of Funing Formation in the Gaoyou sag,Subei Basin,both typical saline lacustrine basins. Through systematic integrated methods of petrology and organic-inorganic geochemistry,a comparative investigation was conducted from the perspective of lithofacies sedimentary genesis. The results indicate that there are significant differences in the lithofacies types and their sedimentary genesis between the Lucaogou Formation and the Member 2 of Funing Formation. The four main lithofacies types in the Lucaogou Formation developed in a relatively cold,arid,and saline water-mass environment. They are controlled by a composite model of “saline deep-water for preservation and less saline shallow-water with high productivity”. The mudstones exhibit high productivity and the best hydrocarbon generation potential,while carbonate rocks and siltstones represent high-quality sweet spots. The palaeoenvironment undergoes abrupt changes,resulting in the formation of the shale interbedded/intercalated with sand. In contrast,the Member 2 of the Funing Formation formed in a warm and humid climate,developed six main lithofacies types under a composite model of “saline shallow-water for preservation and less saline deep-water with high productivity”. The felsic-clay mixed shale and clay-bearing felsic shale,which exhibit the highest TOC content,developed in less saline deep-water environments. The combination of favorable preservation conditions and high productivity jointly enhances their superior hydrocarbon generation potential. Unlike the source-reservoir separated sweet spots in the Lucaogou Formation,the sedimentary facies in the Member 2 of Funing Formation exhibit gradual transitions,with various lithofacies possessing both hydrocarbon generation and reservoir capacities,forming a integrated source rock-reservoir,namely mixed shale type of sweet spots. This study emphasizes the differential palaeoenvironments of various lithofacies formed under the dynamic saline lacustrine basins,which is expected to provide scientific references for predicting and evaluating the distribution of sweet spots in shale oil exploration and development.

The formation of organic matter reflects the integrated physical,chemical,and biological responses to key global and regional geological events occurring across the lithosphere,hydrosphere,atmosphere,and biosphere. Organic-rich shales of Paleogene-Eocene age in terrestrial lake basins of eastern China are characterized by extensive lateral distribution,high total organic carbon(TOC)content,and considerable stratigraphic thickness—making them ideal archives for investigating the controls on organic-rich shale deposition under multi-sphere interactions. This study focuses on the Middle Eocene Shahejie Formation in the Jiyang Depression(Bohai Bay Basin)and integrates geochemical proxies—including TOC and total sulfur(TS)concentrations,organic carbon isotopic composition( {\delta }^{13} C_{org}),iron speciation,and pyrite sulfur isotopes( {\delta }^{34} S_{pyr})—with regional stratigraphic data from eastern China basins. Our findings indicate that TOC values in the Shahejie Formation range from 1 wt% to 10 wt%,with most samples exhibiting a TOC/TS ratio>2,a highly reactive iron to total iron ratio>0.38,and a pyrite iron(Fe_Py)to Fe_HR ratio<0.6. These geochemical signatures suggest that organic shale accumulation was primarily driven by elevated primary productivity under warm-humid paleoclimatic conditions,further modulated by co-occurring tectono-volcanic processes—including volcanic input,hydrothermal fluid influx,and episodic marine incursions. Comparative analysis across eastern China basins reveals that widespread Middle Eocene organic carbon burial was ultimately governed by deep-Earth-driven geological events that facilitated cross-sphere exchange of mass and energy. Although volcanic,hydrothermal,and marine inputs may have introduced additional sulfate,bacterial sulfate reduction efficiently depleted the sulfate reservoir,establishing ferruginous(anoxic,non-sulfidic)bottom-water conditions conducive to the preservation of organic matter.

To investigate the pore structure characteristics of the shale oil reservoir in the Jurassic Da’anzhai Member in Longgang area,northern Sichuan Basin,a systematic analysis of pore features and their controlling factors in the Da’anzhai shale was conducted using organic carbon analysis,field emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),nitrogen adsorption,and nuclear magnetic resonance(NMR)experiments. The results indicate that: (1)The pore types in the Da’anzhai shale oil reservoir are dominated by clay mineral intercrystalline pores,followed by calcite intercrystalline pores,quartz intercrystalline pores,with minor organic matter pores and pyrite intercrystalline pores. (2)Clay content controls the pore volume and specific surface area of the shale,while organic matter content has minimal influence on porosity. (3)Calcite intercrystalline pores primarily contribute to larger pores but are limited in number and volume. Microscopically,these pores are mainly found within biogenic shells,with the shell edges being dense and non-porous. The low degree of asphalt filling and poor connectivity are notable. The development of calcite intercrystalline pores is controlled by shell recrystallization,with larger shells being more prone to recrystallization and forming intercrystalline porosity. (4)Authigenic quartz intercrystalline pores are distributed along shell edges,exhibiting better connectivity than calcite intercrystalline pores. These pores formed earlier than the hydrocarbon generation stage of organic matter and are often filled with hydrocarbons,contributing significantly to effective storage space. Their development is controlled by the degree of silicification of shells,with larger shells more susceptible to replacement,forming quartz intercrystalline pores. (5)The mixing of clay and shells results in a distinct “binary” structure in the reservoir space: clay-rich areas are characterized by pores with high specific surface area,small pore size,and good adsorption capacity,while shell-rich areas are dominated by pores with low specific surface area,large pore size,but limited connectivity.

Authigenic kaolinite is developed in the tight sandstone reservoirs at the bottom of Xu 4 Member in the Qiongxi-Baimamiao area of southwestern Sichuan Basin. To investigate its formation and preservation mechanisms and their relationship with high-quality reservoir distribution,we conducted a comprehensive study integrating petrophysical analysis,rock thin sections,scanning electron microscopy(SEM),fluid inclusion analysis,cathodoluminescence(CL),and in-situ micro-scale carbon-oxygen isotope analysis. This research focuses on analyzing the microcharacteristics,formation stages,formation and preservation mechanisms of authigenic kaolinite,and its impact on reservoir quality of the Xu 4 Member tight sandstones. The study reveals that the tight sandstone reservoirs of Xu 4 Member are predominantly composed of lithic sandstones,and the reservoir space is dominated by intragranular dissolution pores,with lithic intragranular dissolution pores being the most prevalent type. Authigenic kaolinite in the reservoirs predominantly exhibits “worm”and “accordion”shapes,filling intergranular pores and intragranular dissolution pores. The reservoir contains two distinct stages of authigenic kaolinite formation,both derived from the dissolution of aluminosilicate lithics and feldspars within the reservoir. The early-stage dissolution was facilitated by humic acids sourced from adjacent coal-bearing strata,while the late-stage dissolution resulted from organic acids generated through decarboxylation of mature organic matter in mudstones. The potassium feldspar content in the sandstone reservoir of the Xu 4 Member is relatively low,providing only a minimal amount of K⁺. When late-stage organic acids are charged,the formation temperature is relatively low. As diagenesis progresses,the organic acids are gradually consumed. Meanwhile,a significant amount of Fe²⁺ and Mg²⁺ from mudstone participate in the precipitation of ankerite and are thus depleted. Consequently,the concentrations of K⁺,Fe²⁺,and Mg²⁺ in the diagenetic fluids are insufficient to facilitate large-scale illitization and chloritization of authigenic kaolinite. The formation temperature and the organic acid concentration can not simultaneously meet the conditions necessary for the transformation of authigenic kaolinite to dickite. As a result,authigenic kaolinite has not been able to convert in significant quantities into illite,chlorite,and dickite,and has been preserved to this day. Therefore,sandstones formed under high-energy hydrodynamic conditions with coarser grain sizes and better sorting exhibit stronger dissolution,resulting in developed authigenic kaolinite and superior reservoir properties. Research indicates that the unique preservation mechanism of authigenic kaolinite in Xu 4 Member has partly maintained reservoir porosity and permeability. Moreover,authigenic kaolinite content can reflect the intensity of dissolution,further indicating the quality of reservoir properties. Consequently,kaolinite content can be used as a reliable marker for identifying high-quality tight sandstone reservoirs in Xu 4 Member of the Qiongxi-Baimamiao area,southwestern Sichuan Basin.

Submarine fans commonly accumulate on a large scale within continental slope minibasins,where their architectural evolution is predominantly governed by paleotopographic configuration. In settings influenced by dip-oriented synsedimentary normal faults,such minibasins frequently host laterally elongated fault-controlled troughs,which are associated with longitudinally distributed,multi-tiered slope breaks. Although these multi-step slope breaks exert first-order control on the spatial distribution,internal architecture,and stacking patterns of submarine fan reservoirs,the underlying geomorphic and dynamic mechanisms remain inadequately constrained. This study focuses on the Upper Jurassic B4 reservoir in the X Oilfield(North Sea,UK),integrating high-resolution well-log data and 3D seismic interpretation to reconstruct paleobathymetry and decipher reservoir-scale architectural heterogeneity. Our analysis reveals that the submarine fan developed within a structurally confined slope fault trough,characterized by: (i)a western primary upper slope with an average gradient of~7.5°;(ii)three distinct,longitudinally aligned deepwater slope breaks;(iii)a pronounced gradient differential of 6.3° across the primary slope break,contrasting with sub-3° differentials across the secondary and tertiary breaks. Critically,the longitudinal multi-step slope breaks dictate both planform architectural organization and temporal migration-stacking behavior of fan elements. Elevated sediment supply coupled with steep upper-slope gradients promotes high-velocity,supercritical turbidity currents(Froude numbers>1),resulting in proximal bypass dominance—wherein sediment largely bypasses the primary lower slope. The large gradient differential at the primary break enhances flow confinement and sand-body thickness through hydraulic jump-induced deposition. In contrast,reduced gradient differentials across downstream(secondary-tertiary)slope segments decelerate flows,fostering the development of multibranched avulsion channels,levee-channel complexes,and distributary lobes on the lower slopes. As successive lower-slope tiers become progressively filled and aggraded,lobe deposition preferentially shifts toward lower-tier slopes possessing greater accommodation space,producing retrogradational stacking geometries. Furthermore,enhanced lateral confinement—imposed by adjacent fault-bounded margins—deflects lobe progradation trajectories and modifies lobe morphology from classic lobate to elongate,tongue-shaped forms.

Slope microbasin is an important sedimentary site of deep-sea fan,which has huge oil and gas resources and research value,but the research of deep-water sedimentary system in microbasin is relatively weak. Therefore,this paper takes a mud diapir micro-basin in the continental slope area of Niger Delta basin in West Africa as the research object. Based on shallow 3D seismic data and RGB frequency division attribute fusion technology,this paper analyzes the structural characteristics of the deep-water sedimentary system in the microbasin,and reveals the relevant evolutionary control factors and formation process. The results show that the deep-water sedimentary system in the microbasin develops in the sequence of Mass-transport deposition,submarine channel deposition and submarine lobe deposition,in which the submarine lobe occupies the dominant position in the microbasin deposition. By using seismic section and plane RGB frequency division attribute analysis,the lobes developed in the microbasin were divided into two hierarchical orders: composite lobe and single lobe. At different stages,single lobe exhibits has two stack patterns in radial direction,which are progradation and retrogradation,and lateral migration in transverse direction. The distribution and stack patterns of these sedimentary units reflect the influence of the initial topography of the micro basin and the fluctuation of the early sedimentary bodies on the late sedimentary logistics. In addition,the evolution of the depositional system in the micro basin has mainly gone through four stages: the filling of the original topography by the initial sediments,the regulation and restriction of the topography and geomorphology on the sedimentary flow,the compensation and superposition of secondary lobes in different stages,and the channel erosion after the filling of the micro basin. The single lobe superimposed stack pattern in different stages and sedimentary evolution stages have a great impact on the physical properties and connectivity of deep-water lobe reservoirs. This study has a certain reference value for the efficient development of lobe reservoirs in micro basins.

The shale oil in shale intercalated layer in the Yanchang Formation of Ordos Basin predominantly occurs in lacustrine gravity flow lobe “interlayers”,which serve as crucial reservoirs. However,the internal architecture patterns of single lobes remain unclear due to limited subsurface data resolution,constraining horizontal well drilling success rates and production efficiency. This study conducts refined architectural analysis of sublacustrine fan gravity flow lobes through integrated geological survey,UAV digital modeling,and sample analysis at the Maquan outcrop of the Triassic Chang 7 Member in Tongchuan City. Key findings include: (1)The Maquan outcrop primarily develops three sedimentary microfacies: lobes,deep-lake mudstone deposits,and slumps,containing seven lithofacies types: massive sandstone facies(Sm),normally graded siltstone facies(Sg),convolut-bedded siltstone facies(Ssd),massive muddy siltstone(Mp),massive mudstone facies(Mm),horizontal bedding shale facies(Sh),and tuff facies(Tb).(2)In direction of provenance,single lobes exhibit mound-shaped geometries composed of multi-stage stacked massive fine and very fine sandstones and black mudstone shale.(3)Single lobe stacking patterns are controlled by flood-induced sediment supply,showing progradational stacking. Erosional stacking occurs during high-magnitude floods,characterized by thick sandstone units with irregular erosional contacts and steep foreset angles. Draping stacking develops under low-magnitude floods,featuring thinner sandstone units separated by continuous mudstone layers with gentle foreset angles. These findings enhance the theoretical framework of sublacustrine fan lobe architecture and provide critical insights for optimizing horizontal well development in interlayered type shale oil.

The Permian Taiyuan Formation in Hengshan area of the central and eastern Ordos Basin is characterized by mixed sedimentation of coal-bearing continental clastic rocks and carbonates,with significant hydrocarbon generation and reservoir formation potential. However,there are still disputes regarding the sequence-sedimentary filling process,which hinders an accurate understanding of the development laws and configuration relationships of source and reservoir. Based on the latest drilling core and well-logging data,this study systematically sorts out the characteristics of sequence boundaries at different levels and reveals the sedimentary filling laws and source-reservoir development mechanisms of the Taiyuan Formation through detailed sequence division and correlation. The results show that: (1)The Taiyuan Formation developed one second-order sequence,five third-order sequences(SQ1-SQ5),and multiple fourth-order sequences,all exhibiting a binary system tract structure with no lowstand system tract developed. Among them,the lower part of the second-order sequence is dominated by clastic rocks,while the middle and upper parts are dominated by carbonates. Coal seams are generally developed at the top of the third-order sequences. SQ2-SQ4 are the main intervals for the development of Taiyuan Formation limestones and grain shoals,and SQ5 has a relatively high degree of missing. The fourth-order sequence has a small thickness of strata. The maximum flooding surface is located within the Xiedao Section. (2)The stratigraphy of the Taiyuan Formation is characterized by the sedimentary filling process of “sedimentary center migration”,“filling in”and “top cutting”. The southern part of the study area is the limestone sedimentary center,and the northern part is the clastic rock sedimentary center. (3)The development of source and reservoir in the Taiyuan Formation is controlled by sequence-sedimentary evolution,which is manifested as “third-order sequences control the development of coal-bearing source rocks,and fourth-order sequences control the vertical superposition distribution of reservoirs”. Horizontally,grain shoals are concentrated in the slope area. The study suggests that the Maoergou Section and Xiedao Section sedimentary periods in the paleogeomorphic slope area are favorable areas for natural gas exploration.

This study investigates the sequence stratigraphy,palaeogeography,and coal accumulation patterns of the coal-bearing Xishanyao Formation of the Middle Jurassic in the Taibei sag of Tuha Basin,utilizing outcrop profiles and drilling core data. The Xishanyao Formation in the Taibei sag is divided into two third-order sequences,sequence I corresponds to the first and second members of the Xishanyao Formation,while sequence II corresponds to the third and fourth members. Based on a series of contour maps of lithological parameters such as stratigraphic thickness,sandstone thickness,and sandstone-to-mudstone ratio,the palaeogeographic outlines of the two third-order sequences are reconstructed. The northern and southern parts of the Taibei sag primarily were dominated by braided river deltas and meandering river deltas,while the central area was characterized by lacustrine environment. The provenance came from the northern Bogda Mountains and the southern Juelotag Mountains. From the first and second members to the third and fourth members of the Xishanyao Formation,the Taibei sag underwent a transition from swamp-dominated(sequence I)to lacustrine conditions(sequence Ⅱ),characterizing a fluvio-lacustrine sedimentary environment. The most intensive peat accumulation occurred in the second member of the Xishanyao Formation within sequence I,with the coal accumulation center located in the northern foothills of the sag,especially in the Kekeya area,which was situated in palaeogeographic settings such as delta plains and peat swamps. In contrast,coal accumulation in sequence II was weak,with only thin or no coal seams developed. The results of this study on sequence stratigraphy,palaeogeography,and coal accumulation patterns provide a theoretical basis for coalbed methane exploration and development,as well as for the evaluation and selection of exploration blocks in the Taibei sag.

The eastern Henan Province is located at the southern edge of the North China Basin and is currently one of the main areas for coalbed methane exploration in China. The Permo-Carboniferous is the main coal-forming period in this area,and the coal measures were deposited in the marine-terrestrial transitional environments,being characterized by a wide and stable distribution. On the basis of drilling date,outcrop sections and geophysical logging date,the sequence stratigraphic framework was established for the Permo-Carboniferous coal measures in this area. Based on the regional unconformity surface,the coal-bearing series in the study area are subdivided into three third-order sequences. Combined with formation,percentages of limestones,mudstone thickness,sandstone to mudstone thickness ratios,coal thickness contour map,restore the sequence of the palaeogeographical maps,the main palaeogeographical unit with delta plain,barrier island,tidal-lagoon,and carbonate shelf. The coals in sequence I and sequence Ⅱ were mainly formed in the tidal-lagoon environment,while the coals in sequence Ⅲ were formed in the delta plain and tidal environment.Among them,the major coal seam(A-0,A-5)in sequence Ⅰ and the major coal seam(B-1)in sequence Ⅲ are well developed. The A-0 and A-5 coal seam were formed in a peat swamp developed from the offshore shelf settings,located near the initial flooding surface and the end of the HST in sequence Ⅰ where the slow rate of sea level rise and thus the slow rate of accommodation space growth was balancing with the slow rate of peat accumulation,A-0 coal seam developed well in Zhecheng area and A-5 coal seam developed well in Huaiyang area. The B-1 coal seam was formed in the peat swamp environment developed from of the fluvial-dominated shallow water delta plain,near the maximum flooding surface of sequence Ⅲ where the fast sea level rise and thus the fast growth rate of the accommodation growth was well matching the high rate of peat accumulation. The balance between the rates in peat accumulation and the rates in accommodation space creation is a key condition for coal accumulation in the sequence stratigraphic framework. The B-1 coal seam developed well in Zhecheng,Huaiyang and Taikang areas.

Vascular plants,as the major clade of land plants,represent the most important plant group that colonized the land during the Paleozoic. Fossil records demonstrate that vascular plants first appeared in the Silurian and then underwent significant radiation during the Devonian. Plants from the Silurian-Devonian periods represent the ancestors or stem groups of modern lineages such as the lycopsids,equisetopsids,filicopsids,and seed plants,foreshadowing their earliest differentiation. The total genus-level diversity of vascular plants gradually increased from the Silurian,reached the first peak during the Pragian,which was then followed by two decline-rise fluctuations,with one peak registrated during the late Givetian and another peak during the late Famennian. The vegetation types of the Silurian to Early Devonian include rhyniopsid herblands,zosterophyllopsid herblands and zosterophyllopsid-early euphyllophyte mixed herblands,with sporadic occurrences of shrubs and wetlands. During the Middle and Late Devonian,herblands,wetlands and shrubs continued to develop,while emerged new vegetation types such as cladoxylopsid forests,lycopsid forests,and progymnosperm forests. Along with the Silurian-Devonian radiation of vascular plants,the vegetation carbon stock significantly expanded,and the soil inorganic carbon stock also increased,as indicated by the dramatic increase of calcareous paleosols. Some Lower Devonian paleosols have inorganic carbon densities comparable to the modern maximum values. Since the Middle Devonian,the records of coal(paleo-histosols)gradually increased,indicating a significant rise in the amount of soil organic carbon. The increase of terrestrial carbon burial during the Silurian-Devonian was indicated by the accumulation of carbon-rich soils such as histosols and calcareous soils. Through diagenesis,carbon from surface system was converted into paleosols as a part of the lithosphere carbon stock,with an effect of long-term carbon sequestration. Future efforts,on one side,should be put into the systematics and classification of plant fossils,and as well as the study of paleobotanical community ecology and the classification of early vegetation. On the other side,the reconstruction of whole-plants and their communities,model simulations,and other methods could be conducted to estimate the vegetation carbon stocks of different time intervals. The information of surface soil carbon storage of different time intervals and burial efficiency of paleosols should be used to constrain the carbon cycle processes in Earth System models.

The Qujing and surrounding areas,Yunnan,China,is one of the earliest and more in-depth research areas of the Middle Devonian in China,and one of the ideal areas for study on the distribution of land and shallow sea in the late Middle Devonian period. According to the lithologic characteristics and the contact relationship with the underlying strata,this paper sorts out the late Middle Devonian strata in the area is better to use the Xichong Formation/Qujing Formation than the Haikou Formation. The Xichong Formation is redetermined,and its age is determined to be the late Middle Devonian(Givetian). The Middle Devonian sequence in the area,from bottom to top,consists of Chongdong,Shangshuanghe and Xichong formations or Qujing Formation(coeval but heterotrophic). Based on the lithology,contact relationship with the underlying strata and sedimentary thickness,the upper Middle Devonian in the area is divided into three distribution zones: clastic rocks,carbonate and clastic rocks mixed,and carbonates distribution areas,among which the clastic rock distribution area is divided into two subzones. Based on paleontological evidence,sedimentary characteristics and preliminary geochemical results,the characteristics of the Xichong Formation were analyzed,and it was proposed that the formation was mainly terrestrial sedimentary and developed land-sea transitional facies sedimentation. The Qujing Formation of the same period is a normal shallow marine sediment. In the late Middle Devonian,from west to east,the area showed a transition from erosional land zone to terrestrial depositional zone to interaction zone of land and shallow sea,and finally to the normal shallow sea. This land-shallow sea change is not only controlled by the palaeogeographic distribution of the region,but also by the macroscopic influence of the Caledonian tectonic movements.

Drepanophycus is one of the representative early lycopsids,with a global distribution spanning from the Early to Late Devonian. New materials of Drepanophycus from the Middle Devonian Haikou Formation at the Taihe section of Qujing,Yunnan,are described and identified as Drepanophycus qujingensis Li et Edwards. Vegetative axes are preserved as lying flat or penetrating the bedding plane,with a length up to 172.0 mm. Triangular and falcate leaves,approximately 4.6 mm long,are sparsely arranged on the axes. The stomatal type observed in the cuticle of this plant is anomocytic. Research history of Drepanophycus records in China is reviewed,and taxonomic characteristics of this genus is summarized. New specimen of Drepanophycus Göppert,along with a re-examination of previous works,provides solid evidence for the occurrence of this genus in the Middle Devonian of South China. The Middle Devonian flora of South China includes both elements of the “Eophytic Flora”,such as the early lycopsid Drepanophycus and basal euphyllophytes,as well as those of the “Palaeophytic Flora”including heterosporous lycopsids and fern-like plants. Additionally,well-developed paleosols are observed in the same Haikou Formation of the same locality,in which rhizomes possibly belonging to Drepanophycus are preserved. This finding indicates that herbaceous lycopsids could have played a crucial role in soil stabilization,erosion mitigation and landscape shaping during the Middle Devonian.

The plant fossils found in the Haikou Formation in Qujing,Yunnan Province,are typical representatives of the Middle Devonian southern Chinese flora. The plant assemblage is dominated by lycopsids plants,including a large number of endemic plants,known as the Haikou flora or Xichong flora. Based on new materials from the Middle Devonian Haikou Formation of Qujing,Yunnan Province,two lycopsid plants are described,namely Lepidodendropsis zhanyiense Zheng,Wang,Li,Liu et Xue sp. nov. and Minarodendron cathaysiense (Schweitzer et Cai)Li. Lepidodendropsis zhanyiense is characterized by simple leaf bases arranged in pseudowhorls,and its false leaf scars show as shallow furrows extending laterally on thin axes,but show as a more regular M-shaped structure on thick axes. Sterile leaves are undivided and linear in shape. Sporophylls are spoon-shaped and aggregated along fertile axes,forming an extended reproductive zone up to 18 cm long. Elliptical sporangia are borne on adaxial side of sporophylls. New material of Minarodendron cathaysiense displays similar morphology of axes and leaf bases as to those described in previous studies. Based on such new materials and as well as computer-aided modelling and taphonomic simulations,the morphological variations of leaf bases with false leaf scars are discussed,demonstrating that the M-shaped structures of Lepidodendropsis zhanyiense sp. nov. and other similar plants are probably not “leaf pits”as previously suggested. The Middle Devonian lycopsids shared similar,primitive leaf bases,and some types evolved large-bodied architecture e.g. tree habit,indicating their similar evolutionary grade in vegetative structures. The Middle Devonian lycopsid floras in South China are mainly distributed in fluvial and littoral facies and show a high degree of endemism,indicating the isolated geographic position of South China. The above results further enrich the plant diversity of the Middle Devonian in South China and provide new evidence for the evolution of lycopsids.

The increase in atmospheric carbon dioxide(pCO₂)concentration is widely recognized as the primary driver of global warming. Reconstructing pCO₂ levels during geological periods is crucial for improving predictions of future climate change. The Jurassic period represents a typical greenhouse climate interval in Earth’s history. Previous studies have estimated Jurassic pCO₂ concentrations using various approaches,including climate simulations and geological proxies. However,existing reconstructions are characterized by low temporal resolution and significant discrepancies among different proxy records. In this study,we systematically compiled 1808 C₃ plant organic carbon isotope data points from the Jurassic period and applied a novel pCO₂ proxy—based on C₃ terrestrial plant organic carbon isotopes—to reconstruct a high-resolution,continuous record of atmospheric pCO₂ variation throughout the period. Our results indicate that pCO₂ levels ranged from 407×10^-6 to 7540×10^-6,which is broadly consistent with prior estimates. Furthermore,pCO₂ exhibited an overall decreasing trend punctuated by three distinct intervals of elevated concentrations,occurring in the Early and Late Jurassic. These fluctuations correlate strongly with coeval geological events,supporting the reliability of the reconstruction. Although the reconstructed pCO₂ values during the Early Jurassic Toarcian stage are higher than those derived from other proxies—likely due to regional influences on the isotopic composition of terrestrial C₃ plants—the dataset still accurately captures the long-term variation trend of pCO₂,underscoring its scientific value.

Acer Linn. represents a significant component among the northern temperate broad-leaved forests,with a wide geographical distribution across the northern temperate regions and occasionally extending into certain subtropical zones. In this study,we document nine leaf fossils and two samara fossils of Acer from the Laoliangdi Formation in Chifeng,Inner Mongolia. These fossils were identified as A. cf. sinense of section Palmata and A. cf. buergerianum of section Oblonga based on detailed morphological observations and comparisons. Furthermore,we reconstructed the dispersal routes of these two sections using the fossil record. During the Paleocene,section Palmata was restricted to East Asia. By the Late Eocene,it expanded into Europe via the Turgai Strait. During the Oligocene and Miocene,this section became widespread across Eurasia. In the Pliocene and Pleistocene,its distribution was again limited to East Asia. However,during the Holocene,section Palmata expanded from East Asia to North America,resulting in the current disjunct distribution between these two continents. Section Oblonga likely migrated from the high latitudes of North America to the mid-latitudes of East Asia via the Bering Land Bridge during the Late Eocene. After the Miocene,this section disappeared from North America and persisted exclusively in East Asia,where it remains widely distributed today. The distinct dispersal histories of sections Palmata and Oblonga highlight the need for further investigation into the biogeographical pathways of Acer species across different sections. Additionally,by integrating the current climatic parameters of the habitats of A. sinense and A. buergerianum with those of the reported Early Miocene plant fossils in Chifeng,Inner Mongolia,we estimate that the mean annual temperature in Chifeng during the Early Miocene ranged from 10.6 to 18.2 ℃,with annual precipitation ranging from 950 to 1492 mm. These data indicate a warm and humid climate in the Early Miocene. This study further enriches the plant diversity in Early Miocene eastern Inner Mongolia and provides new evidence for the climate of this region during the Early Miocene.

To reduce the subjectivity in indicator weighting and the fuzziness of grading criteria in favorable area evaluation of tight sandstone reservoirs,we develop an integrated method that couples combined weighting with a normal cloud model,and apply it to the X subunit of the Member 3 of the Qingshankou Formation(Q3)in the Qianshen Block,southern Songliao Basin. First,subjective weights are derived from expert judgment using the Analytic Hierarchy Process(AHP). Objective weights are then obtained from the dataset using the CRITIC method. The two sets of weights are finally integrated to produce combined weights,improving both geological rationality and data-driven objectivity. Meanwhile,a normal cloud model is introduced to characterize uncertainty during grade assignment. Standard cloud parameters—expectation(E_x),entropy(E_n),and hyper-entropy(H_e)—are determined from the score intervals of evaluation grades under constraints of a boundary membership threshold,enabling a flexible mapping between evaluation grades and measured data. Results show that sedimentary facies belt,oil-bearing property,and effective thickness are the dominant controls on favorable areas,with combined weights of 0.253,0.182,and 0.124,respectively. Evaluation of 20 wells identifies 12 wells for Class Ⅰ,five wells for Class Ⅱ,and three wells for Class Ⅲ wells;the outcomes show 95% agreement with previous interpretations,with a Cohen’s kappa coefficient(κ)of 0.91. The method therefore provides a practical and reliable tool for favorable area evaluation of tight sandstone reservoirs.

The relative lake level is fundamental for constructing the sequence stratigraphy. However,considering the difficulty of ensuring the location of the lake level and the complexity of lacustrine rift basins,using traditional methods to establish the sequence stratigraphy is quite difficult. Thus,we introduced‘trajectory analysis’ in this study. We used well logging,lithological association,and seismic data to establish sequence stratigraphy of the lower part of the Second Member of Dongying Formation(corresponding to SQd₂)in the western part of Bozhong sag. Prograding sigmoidal clinoforms,prograding oblique clinoforms,small-scale mouth-shaped reflection,and parallel to sub-parallel reflection developed in SQd₂ of Bozhong sag. We interpreted four types of seismic reflection into three sedimentary systems,including river deltas,sub-lacustrine fans,and lakes. According to the direction of migration and the shape of shorelines,there are four types of shoreline trajectories identified,which are called ascending regression with convex-upward curvature(type-1),ascending regression with concave-upward curvature(type-2),descending regression with convex-upward curvature(type-3)and ascending transgression with concave-upward curvature(type-4),respectively. These four types of shoreline trajectories were related to the lowstand systems tract(LST),highstand systems tract(HST),falling stage systems tract(FSST),and transgressive systems tract(TST). Large-scale deltas developed during the late stage of SQd₂. The ascending regression with concave-upward curvature reflects the normal regression and large-scale deltas with‘thick topsets and thick foresets’ developed during this stage. Then,small-scale sub-lacustrine fans may develop due to gravity. The descending regression with convex-upward curvature is related to forced regression. During the stage,large-scale deltas with thin topsets and thick forestes developed. Thus,more sediment was transported into the deep lake,and large-scale sub-lacustrine fans were developed. In conclusion,we introduced‘trajectory analysis’ to divide an entire third-order sequence into four systems tracts. Then,we highlighted the importance of forced regression and the large-scale,rich sand sediment developed during this stage. Additionally,sub-lacustrine fans with relatively high sand ratios are always associated with rich-sandy deltas. The deltas and sub-lacustrine fans during the FSST are significant for reservoirs and lithologic traps.

The channel network structure of shallow delta is complex. In the previous studies on the morphological characterization of distributary channels,there was a lack of quantitative data support for the spatial continuity of river width. This paper focuses on the quantitative characterization of channel morphological parameters and studies the spatial continuous variation characteristics of the width of the distributary channels in the Ganjiang Delta,aiming to provide constraints on the spatial variation of channel width for reservoir configuration research,and then improve the reservoir configuration characterization method system. Based on the Google Earth Engine big data cloud computing platform,this paper improves the RivWidthCloud river width extraction algorithm,realizes the automated extraction of continuous width data of the Ganjiang Delta distributary channel,and reveals the spatial continuous variation law of the width of the distributary channel in the shallow delta plains. The results show that: (1)the river width data extracted after algorithm optimization have significant correlation with the measured values(R²=0.84),which verifies the reliability and applicability of this method in river morphology monitoring;(2)the seasonal variation of the width of the main branch of Gan River is significant(the average river width in the dry season is 444.85 m,and the average river width in the rainy season is 650.75 m,an increase of 46%),which is significantly higher than that of the other two tributary channels;(3)There is a significant spatial coupling relationship between channel width and bifurcation frequency: the width of the upstream section of the bifurcation mouth increases sharply,and the width of the secondary channel decreases significantly after bifurcation;(4)According to the continuous channel width curve(the trend line of continuous river width data points),the width data of the distributary channels has an overall decreasing trend towards the downstream of the delta,but still shows an oscillating change with multiple levels of fluctuations. (5)70% of the quasi-central-bar development areas present a width variation pattern of “wide beach head,narrow beach neck,and wider beach tail”,and the corresponding river channel width curve shows a three-stage feature of “high-low-higher”. The continuous river width quantification method provides a new tool for the study of modern delta sedimentation. The law of distributary channels scale variation revealed by it can provide a quantitative basis for fine characterization of the scale of distributary channels,geometric constraints for reservoir architecture modeling,compilation of small-scale sedimentary facies maps.