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.