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 Eocene represents a critical interval for understanding the evolution of the global carbon cycle. During this period,Northeast China experienced significant fluctuations in atmospheric CO₂ concentrations,ranging from 454 to 1861 μmol/mol. While these variations underscore the region’s importance in carbon cycle research,current understanding of carbon cycling in terrestrial lake systems remains limited. Most studies have focused on modern lakes since the Pleistocene,leaving a notable gap in systematic research on carbon cycling in ancient lacustrine basins such as those of the Eocene. This study integrates multiple geochemical proxies with a quantitative carbon source-sink flux model to reconstruct organic carbon burial and carbon emissions in the Yilan paleo-lake basin during the Early Eocene Climatic Optimum(EECO)and the Middle Eocene Climatic Optimum(MECO)events. The findings reveal that the Yilan Basin exhibited peak primary productivity,organic carbon burial rates,and CO₂ emissions from fossil carbon oxidation during the EECO. Despite substantial carbon release during these events,the net carbon fixed via photosynthesis(reaching 241650 Mt during the EECO)and the resulting buried organic carbon(~4028 Mt during the EECO)significantly exceeded CO₂ emissions from fossil carbon oxidation(~1448 Mt during the EECO). Therefore,the Yilan Basin functioned as a net carbon sink in Northeast China during the EECO and MECO,serving as an important natural regulator of regional climate.

In the margins of the major sedimentary basins in northern and western China,burnt rocks formed from the spontaneous combustion of coal seams are commonly found,resulting in special burnt rock landform. This landform is widely distributed in China,commonly with bright colore. However,its scientific and tourist values have been hardly focused on in literature. Few studies have involved the tourism development of such burnt rock landforms in China. Based on field investigations of outcrop sections,this study classifies these landforms into: burnt hilly landforms(including burnt red hilly landform,burnt colorful hilly landform and peak-covered landform of burnt rocks), erosional landform of burnt rocks(including gully landform,steep cliff landforms), collapse landform and loess-covering burnt rock landform according to the process of coal spontaneous combustion,landform genesis,spatial distribution and color of the burnt rocks. Among them,hilly and erosional landforms are commonly seen,while collapse landform mainly exists in areas where underground coal seams are burning. Loess-covering burnt rock landform formed with the Quaternary loess covering the burnt rocks. The formation of various burnt rock landforms is mainly controlled by such factors as coal seam thickness,stratum occurrence,tectonic movement,river erosion and paleoclimate. Burnt rock landforms should be given more attention due to its scientific value and tourism exploitation value. These burnt rock landforms have significant scientific and tourism development values and deserve appropriate attention.

Shallow-water delta front sand bodies are widely developed and represent important hydrocarbon reservoirs with high exploration potential in continental basins. However,frequent migration and avulsion of distributary channels result in vertically stacked thin interbeds and laterally interwoven distributions,leading to complex architectural patterns. Under sparse well coverage,this complexity makes reservoir prediction highly challenging and less accurate. This study takes the Member 1 of Jurassic Shaximiao Formation in the Tianfu Gas Field,Sichuan Basin,as a case example,and proposes an intelligent prediction method for thin sand bodies by integrating multi-frequency seismic attribute automated machine learning(AutoML)with waveform indication inversion(WII). Laterally,optimized frequency-decomposed seismic data were used to automatically select key attributes and integrate multi-model learning,building nonlinear mappings that improved the correlation between seismic attributes and well-derived sand thickness from 0.64 to 0.82. This enabled quantitative prediction of sand bodies under sparse well control. Vertically,WII introduced facies-controlled constraints and used uranium-free gamma ray as the inversion target,allowing stable identification of sand bodies thicker than 10 m and reliable responses from thin layers of about 4 m,and establishing seismic response templates of architectural element assemblages. Based on these results,four types of architectural elements were identified: distributary channel,residual mouth bar,levee,and interdistributary bay. Furthermore,six stacking patterns including vertical superimposition and lateral accretion were summarized. The results also reveal that,under different depositional cycles,isolated narrow channels and compound wide channels show distinct spatial distributions and vertical stacking characteristics. In three dimensions,a spatial differentiation pattern was clarified,evolving from near-source net-like distributary channels to distal tongue-shaped and lobe-shaped mouth bars. Finally,a depositional architectural model of the shallow-water delta was established. This study achieves fine-scale multi-level architectural characterization under sparse well conditions and provides new insights and methods for efficient exploration and development of complex shallow-water delta reservoirs.

The global technically recoverable resources of shale oil are estimated at approximately 251.2 billion metric tons,derived from 157 organic-rich shale units across 116 basins. Internationally,shale oil exploration has largely focused on marine shale successions,whereas in China,lacustrine shales represent the primary target. The assessment of shale oil enrichment intervals is fundamentally governed by lithofacies palaeogeography. Lithofacies palaeogeographic reconstruction of lacustrine shale strata relies on quantitative datasets derived from outcrop,core,and geophysical analyses. Critical aspects of such reconstructions include considerations of temporal and spatial scales,single-factor analysis,and the application of conceptual depositional models. Recent progress in the study of shale laminae offers valuable single factors and diagnostic methods for interpreting depositional environments in palaeogeographic studies. Significant variations in reservoir properties and shale oil occurrence are observed among different lamina types. Consequently,palaeogeographic mapping based on lamina combinations and shale microfacies analysis represents an emerging research trend. Future research should aim to address the heterogeneous characteristics of lithofacies and organic matter distribution in lacustrine shale strata. Future studies should aim to resolve the heterogeneous distribution of lithofacies and organic matter in lacustrine shales,with priority given to: (1)delineating the spatial architecture of organic-rich shales within high-resolution chronostratigraphic frameworks,(2)characterizing mineral-organic composite structures,(3)establishing standardized microfacies classifications,and(4)developing depositional process simulations integrated with intelligent mapping techniques. An integrated approach combining modern sedimentological observations,sedimentary process simulations(both physical and numerical),organic petrology,and biomarker analysis is essential to reassess the sedimentary microfacies and organic enrichment mechanisms in lacustrine shale strata. This will facilitate the development of revised depositional models that accurately reflect the transport-deposition dynamics of fine-grained sediments,palaeotopographic constraints,and bioevolutionary context. By combining “inversion” and “forward modeling” methods and lever aging artificial intelligence technology,and incorporating key sweet-spot evaluation parameters,it is possible to quantitatively predict and intelligently map the spatiotemporal distribution of different lamina combinations. This methodology will allow for precise lithofacies palaeogeographic characterization of lacustrine shale strata and provide scientific guidance for the optimization of shale oil enrichment areas/layers.

Tubiphytes is a taxonomically enigmatic organism with a broad geographic distribution and an extensive stratigraphic range,documented widely in reef facies from the Late Paleozoic to the Mesozoic,making its study of significant paleoecological importance. Abundant Tubiphytes fossils have been found in the Late Pennsylvanian strata of Guizhou Province,South China. Specifically,Tubiphytes-dominated bioherms are well-developed in the Gzhelian strata of the Houchang area,southern Guizhou,providing an excellent research object for investigating the palaeoecology of this enigmatic taxon. Palaeontological analyses indicate that Tubiphytes obscurus obscurus Maslov is the dominant species in the study area,and its microstructure and paleobiological characteristics indicates that this taxon functioned as an aggregate binder and encruster,involving symbiotic associations among foraminifera and microbial communities. Quantitative analyses show that in the Tubiphytes reefs of the study area,solitary Tubiphytes exhibit a symbiotic relationship with Archaeolithoporella and the colonial coral Ivanovia cf. manchurica,while massive Tubiphytes compete with organisms such as the colonial coral Ivanovia cf. manchurica and phylloid algae. Furthermore,Tubiphytes forms micro-encrusting communities with Archaeolithoporella, and—combined with successive generations of marine cement—contributes critically to the development of the reef’s microframework,thereby assuming a primary role in reef construction. These Tubiphytes-dominated micro-encrusting communities repeatedly formed reefs in environments lacking metazoans and constitute a key component of the expansive reef systems that flourished along the Paleo-Tethyan margin.

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.

The Late Triassic Carnian Pluvial Episode(CPE,~234-232 Ma)is characterized by a sharp increase in global temperature and humidity,accompanied by significant changes in marine and terrestrial ecosystems,and is associated with the eruptions of the Wrangellia Large Igneous Province(LIP). Much of the current research on CPE has focused on marine strata with well-constrained stratigraphy,while research on the response processes of terrestrial ecosystems to CPE has been limited. Here,we review the status of terrestrial environmental,climatic,and plant changes during the CPE and explore its potential driving mechanisms. The evidence of multiple nearly synchronous negative carbon isotope excursions(CIEs),mercury(Hg)enrichment anomalies(peaks in the Hg/TOC ratio),and Hg isotopes provides direct evidence that the Wrangellia LIP was a driving factor for the significant changes in terrestrial environment,climate,and biology during the CPE. The eruption of the Wrangellia LIP released a large amount of CO₂,triggering global warming. This has led to enhanced atmospheric circulation and hydrological cycles,promoting increased global rainfall and a shift in climatic conditions from relatively warm and dry to relatively warm and humid. These conditions have resulted in the extensive development of terrestrial deltas and swamps,the rise of lake levels,the intensification of chemical weathering,the increase of hygrophytic plants and freshwater algae,and the re-emergence of global coal accumulation,as well as the origin and radiation of dinosaurs,coniferous plants,insects,crocodiles,turtles,and mammals. Terrestrial weathering,the expansion of surface water systems,and an increase in hygrophytic plants and freshwater algae have driven a significant rise in the amount of terrestrial organic carbon buried,contributing to the resurgence of global coal accumulation. The increase in the amount of organic carbon buried and the re-emergence of global coal accumulation have created negative feedback on the improvement in global atmospheric conditions. This can counteract the greenhouse effect caused by the release of greenhouse gases from the Wrangellia LIP,facilitate the gradual stabilization of the environment and climate during the CPE,and ultimately lead to the termination of the CPE. These results suggest that LIP can occur in multiple pulse forms and have a powerful ability to alter the carbon cycle,trigger environmental and climatic changes,and drive macroevolution of organisms. On the other hand,global coal accumulation plays a crucial role in climate stability.

The Paleozoic plant terrestrialization(PPT)represents a pivotal point in the evolutionary history of life on Earth. This process not only reshaped surficial geomorphological landscapes but also exerted on others biotic evolution throughout the Phanerozoic. Until now,how benthic animals respond to PPT across different depositional environments,as well as their roles in the construction of benthic ecosystems,have remained insufficiently understood. Based on the compilation and synthesis of a global trace fossil dataset,this study establishes a time-depositional environment analytical framework. Within this framework,we systematically compare the evolutionary patterns of ichnodiversity,ichnodisparity,ichnotiering,and benthic ecosystem engineering across transitional coastal,fluvial,and lacustrine settings during the process of PPT. Furthermore,we quantitatively assess the behavioral responses of benthic animals to PPT. The results show that from the Cambrian to the Permian,the behavioral evolution of benthic animals exhibits pronounced time-limited and heterogeneity. During the Ordovician,benthic animals in transitional coastal environments had already begun to show initial responses to PPT,whereas those in fluvial and lacustrine environments display a clear temporal lag. This discrepancy is closely associated with the development of plant root systems,the progression of PPT,and subsequent forest expansion. Overall,with the progressive improvement of substrate stability and organic matter availability in both continental and transitional settings driven by terrestrial plants,benthic animals gradually expanded their ecospace utilization,accompanied by increased behavioral complexity and enhanced ecosystem engineering. In turn,benthic animals exerted a positive feedback on PPT through sediment reworking and the modulation of matter and energy fluxes. In addition to the influence of terrestrial vegetation,environmental factors such as climate change and tectonic activity,and sea-level fluctuations also played significant roles in shaping benthic evolutionary trajectories. This study provides a novel ichnological perspective for understanding Paleozoic ecosystem evolution and biotic-sediment interactions.

This study investigates the shale of the upper sub-member of Member 4 of Shahejie Formation in the Minfeng subsag,Dongying sag,integrating core and thin-section observations with elemental geochemistry to reconstruct paleoenvironmental conditions. An innovative multi-method analytical framework was employed—including scanning electron microscopy coupled with cathodoluminescence(SEM-CL),focused ion beam-scanning electron microscopy(FIB-SEM),laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS),stable isotope(C,O,Sr)analysis,fluid inclusion microthermometry,and U-Pb geochronology—to systematically characterize diagenetic mineral evolution and elucidate the reservoir formation mechanism. Results indicate that deposition of the target interval occurred under an arid to semi-humid climate,within a fine-grained,brackish-deep lacustrine setting characterized by strong redox stratification. High-frequency vertical cyclicity is evident,reflecting a progressive facies transition from carbonate-rich mixed shale → mixed shale → feldspar-rich mixed shale. Total organic carbon(TOC)ranges predominantly between 1.8wt% and 6.0 wt%,with abundant organic matter accumulation attributed primarily to high sedimentation rates and robust terrigenous and/or endogenous organic input—rather than prolonged bottom-water anoxia alone. Granular calcite and fibrous calcite exhibit distinct geochemical signatures: divergent rare earth element(REE)patterns,contrasting δ¹³C and δ¹⁸O values,and significantly different U-Pb ages. Notably,columnar-to-fibrous calcite laminae oriented near-horizontally yield a broad U-Pb age spectrum(31.2±4.3 Ma to 25.1±4.2 Ma),spanning the full early-to-middle diagenetic interval. Illite comprises 80%~100% of the clay mineral assemblage;its formation is dominantly controlled by montmorillonite-to-illite transformation,while feldspar dissolution represents a major silica source for authigenic quartz precipitation. Authigenic quartz is ubiquitously observed within argillaceous laminae and calcite laminae. Under overpressured conditions,co-precipitation of authigenic quartz and recrystallized calcite effectively buffered porosity loss during cementation—thereby preserving critical pore space and facilitating subsequent pore enhancement via acidic fluid dissolution during later diagenesis. This interplay constitutes a key reservoir-quality preservation and improvement mechanism in deeply buried lacustrine shales.