Significance The study of the provenance of fine-grained sedimentary rocks is a crucial first step in the "source-to-sink" system theory of fine-grained sedimentary rocks. It is important for restoring the ancient sedimentary environment， understanding the formation mechanism of fine-grained sedimentary rocks， and predicting the distribution of unconventional oil and gas resources. Fine-grained sedimentary rocks are characterized by small particle size， complex composition， and difficulty in observation and research， with different material components corresponding to a variety of sources and origins. A review of the existing research results worldwide shows that currently there is a lack of systematic organization and summary of research outcomes regarding the provenance and origins of fine-grained sedimentary materials. Progress This paper synthesizes current research findings and categorizes the sources of fine-grained sedimentary rocks into three major types： terrigenous， endogenic， and volcanic-hydrothermal. It provides an in-depth summary and conclusion on the common sources and origins of fine-grained sediments， pointing out： （1） Clay minerals are of detrital weathering origin， diagenetic transformation from other minerals， transformation among clay minerals themselves， hydrolysis of submarine volcanic materials， and biologically mediated by extracellular polymeric substances； （2） Quartz mainly originates from the weathering of terrigenous materials， intra-basin biological activity， devitrification of volcanic ash materials， and authigenic formation； （3） Feldspar originates from the weathering of terrigenous detritus， input from volcanic-hydrothermal activity， and recent studies have also indicated that feldspar can be formed through microbial chemical processes； （4） Carbonate minerals are primarily endogenic， formed through chemical， bio-chemical， biological， and re-transport and deposition processes within the basin， and the input of terrigenous and volcanic-hydrothermal materials not only directly provides carbonate minerals for fine-grained sedimentary rocks but also promotes the formation of carbonate minerals within the basin； （5） Pyrite is mainly formed by the two ore-forming elements， iron and sulfur， through dissimilatory iron reduction and iron shuttling mechanisms， microbial reduction， and thermogenic reduction of sulfate within the basin； （6） Organic matter can be divided into terrigenous vitrinite， inertinite， and some liptinite， as well as endogenic liptinite， zooclastic organic debris， and secondary organic matter. ［Conclusions and Perspectives］ Future research on the provenance and origins of fine-grained sedimentary rocks will develop in a multidisciplinary and high-precision direction， and there is still an urgent need for a systematic approach suitable for the study of the provenance of fine-grained sedimentary rocks.This paper aims to clarify the provenance and origins of fine-grained sedimentary rocks， enhance the understanding of the sources and formation mechanisms of fine-grained sediments， and thus promote the development of fine-grained sedimentology theory. It provides a solid theoretical foundation and scientific basis for identifying the distribution characteristics of fine-grained sedimentary strata and predicting the distribution of unconventional oil and gas resources.

Objective Lithium rich claystone deposits with great potential for mineralization have been found in the bauxite-bearing sedimentary strata of Yunnan-Guizhou region in Southwest China， but the current understanding of the material sources and lithium enrichment mechanisms of these bauxite-type lithium rich claystones in these areas is still significantly insufficient. Methods In this study， two sets of bauxite-type lithium rich claystone systems， the Early Permian Daoshitou Formation in Yunnan and the Lower Carboniferous Jiujialu Formation in Guizhou， were analyzed in terms of their mineralogical compositions， major and trace elements， and the compositions of rare earth elements. Combined with the results of previous research， the study systematically explored the source attributes of two sets of bauxite-type lithium-rich claystone systems， which were formed in different epochs but have very similar petrographic characteristics， as well as determining the factors that led to the anomalous enrichment of lithium.［Results and Conclusions］ The results showed that the differences in source properties between the lithium rich claystones of the Jiujialu Formation in Guizhou and the Daoshitou Formation in Yunnan had a significant influence on their lithium content. In general， the development of the Jiujialu Formation， which has relatively low lithium content， is closely related to the weathering and denudation of impure dolomite in the underlying Loushanguan Group. Its original source may have been Neoproterozoic-Middle Proterozoic neutral acidic magmatism， which is significantly influenced by Mg-Fe compositions. The formation of Yunnan Daoshitou Formation claystones with relatively high lithium content was significantly influenced by the recycling of Ordovician sedimentary rocks， while the source connection with its underlying carbonate strata was weak. Their original source was dominated by neutral acidic magmatism. In addition， the lithium rich clay rocks in the Yunnan-Guizhou region were hosted by either kaolinite or illite， and the drainage of the watershed during the depositional period and the effect of coexisting ions in the water body played important roles in restricting the lithium enrichment in the clay. Analyzing the provenance of lithium rich clay rocks in the Jiujialu Formation in Guizhou and the Daoshitou Formation in Yunnan， along with the occurrence of lithium-bearing minerals， is of significant importance for understanding the ore-forming processes and controlling mechanisms of clay-type lithium deposits.

Objective The Luojiawopeng Formation is a set of purplish red sand and gravel accumulation strata in the Lower Pleistocene Series in the southeastern margin of Songnen plain. The clay mineral analysis of this formation is conducive to understanding the paleoclimate characteristics in this region and defining its stratigraphic age. Methods Whole rock geochemistry， X-ray diffraction （XRD）， Scanning electron microscopy （SEM）， and High-resolution transmission electron microscopy （HRTEM） analysis of clay minerals in Luojiawopeng Formation were conducted to reveal their composition and transformation characteristics of clay minerals. Comparisons were performed on clay mineral composition between the red clays in the Chinese Loess Plateau and Luojiawopeng Formation. Results The clay mineral composition of Luojiawopeng Formation is dominated by kaolinite （content of 57%⁃73%）， followed by illite （ranging from 25% to 41%）， and the content of biotite /vermiculite mixed layer minerals is the least （average 1%）. Kaolinite shows pseudo hexagonal morphology， and its high degree of euhedral crystallinity indicates its authigenic origin， as does its high illite crystallinity （average 0.55） and illite chemical index （average 0.50）. These results， combined with the high clay to quartz ratio， indicate intense weathering characteristics. The transformation process of clay minerals is illite → kaolinite and biotite → biotite /vermiculite mixed layer minerals → kaolinite， which is consistent with the significant kaolinization trend of constant element 4Si-M⁺-R²⁺ ternary diagram. combined with the high chemical index of alteration（CIA） and hematite-to-goethite ratio of the formation， this process indicates that these minerals formed in a humid and hot environment with increasingly strong weathering. Conclusions Thus， the Luojiawopeng Formation was likely formed in a humid and hot climate， rather than through moraine accumulation as previously reported， and the stratigraphic chronology of the formation may be in the humid and hot period when the East Asian summer monsoon prevailed before the Early Pleistocene.

Significance Sepiolite is a clay mineral with a unique fibrous crystal structure； it has a significant potential application in the geological field due to its high adsorptive capacity and thermal stability. Progress The genesis types for sepiolite include direct deposition， terrestrial transport sedimentation and diagenetic alteration. Direct deposition is influenced by chemical conditions such as element concentration and pH. Terrestrial transport sedimentation is closely related to the geological environment and climatic conditions. Diagenetic alteration of sepiolite is affected by the burial depth and the properties of the hydrothermal fluids. Sepiolite is generally formed in an alkaline reducing environment rich in Mg and Si， but with a low Al content. During the thermodynamic evolution process， it undergoes mineral phase transitions and is transformed into minerals such as talc or montmorillonite， which imply different depositional and diagenetic evolutionary paths. In terms of geological applications， sepiolite has an excellent adsorptive behavior， and thus it can efficiently enrich organic matter， providing a basis for the formation of hydrocarbon source rocks with significantly enhanced oil- and gas-generating potential and quality. The diagenetic fluids of the sepiolite layer help promote the transformation of high-energy beach limestone at the edge of a depression into a high-quality dolomite reservoir， thereby giving rise to either of two oil and gas accumulation models： self-generation and self-storage， or lower generation and greater storage. In addition， the thickness and distribution of sepiolite strata inverts undulating paleolandforms and is also an effective indicator of oil and gas reservoir regions， thus providing an important basis for oil and gas exploration. In terms of paleoenvironment， the formation process of sepiolite also records a range of information （e.g.， evaporation environment， water level changes， climate evolution and anoxic events） that can be used to reveal major geological events in the region. Conclusions and prospects Sepiolite has shown significant research value in oil and gas exploration， paleogeomorphic reconstruction and paleoenvironmental restoration. Future development trends of sepiolite will include its use in defining paleoenvironmental conditions， enhancing the analytical ability of seismic data on the thickness of sepiolite strata， and developing the exploration of oil and gas in sepiolite strata.

Objective Shallow-water deltas are widely observed in petroliferous basins and can form large-scale hydrocarbon reservoirs. Based on the relative proportions of mud and sand in their deposits， they can be classified into three types—sand-rich， sand-mud， and mud-rich deltas—whose geomorphological expression， depositional characteristics， sedimentary architecture， and sediment heterogeneity differ substantially. At present， systematic research on these three types of shallow-water deltas remains limited， which has severely constrained the efficient exploration and development of oil and gas resources. Methods This study employed sedimentary numerical simulation technology to reproduce the depositional evolution processes of the three types of deltas. Their sedimentary architecture and grain size models were reconstructed from the simulated depositional interfaces and grain size data. Subsequently， from a detailed analysis of the evolutionary processes， sedimentary architectural models for shallow-water deltas were established and the characteristics of sedimentary heterogeneity within this model framework were elucidated. ［Results and Conclusions ］ （1） The sediment supply ratio is a crucial influencing factor in deltaic depositional evolution， as it determines the sedimentation rate and erosion resistance of channel margins. On this basis， the evolution and ultimately the resultant architecture and heterogeneity are determined. （2） As the sand-to-mud ratio decreases， distributary channels exhibit reduced quantity， hierarchical complexity and areal proportion， as well as increased sinuosity， greater stability， diminished lateral migration capacity， and a transition from lateral migration-dominated filling to abandonment-dominated filling. （3） Sand-dominated deltas typically exhibit lobate or triangular shapes， with extensively developed distributary channels forming multistage， radial patterns. They frequently display lateral migration characteristics. Sand-mud deltas manifest as multi-fingered， branching forms with fewer distributary channels that are primarily controlled by trunk distributary channels with multi-directional bifurcations at their termini， creating multiple laterally amalgamated finger-like bar assemblages. Mud-rich deltas possess few distributary channels， being characterized by the development of narrow， sinuous， belt-like trunk distributary channels lacking lateral accretion features. These channels are predominantly infilled with muddy sediments following avulsion and abandonment. （4） Sand-rich deltas show near-continuous sand distribution with downstream fining. Coarsest grains occur in trunk channels， with finer grains in mouth bars， yielding weak planar heterogeneity but strong vertical heterogeneity due to multi-stage lateral/progradational fine-grained interbeds. Sand-mud deltas exhibit broad-banded sand bodies with coarse-grained reservoirs in trunk channels and mouth bars， weak planar heterogeneity， and strong vertical heterogeneity from muddy interbeds. Mud-rich deltas display strong planar heterogeneity， with reservoirs being restricted to mouth-bar cores that are laterally isolated by muddy channels， with weak vertical heterogeneity resulting from multi-stage muddy interbeds.

Objective The Upper Paleozoic Yanghugou Formation-Taiyuan Formation in the northwestern margin of the Ordos Basin is a good prospect for oil and gas exploration. The strata are completely developed and continuous， with large thickness changes and various types of sedimentary facies. Defining the distribution characteristics of sand bodies and clarifying the law of sedimentary evolution directly affect the selection of preferred exploration zones for oil and gas. Methods This study takes the Yanghugou Formation to Taiyuan Formation in the northwestern margin of Ordos Basin as the target horizon. Based on previous studies， through typical field profile measurement， drilling core observation， paleocurrent direction analysis， logging data， and test data analysis， the sedimentary environment， facies type characteristics， evolution， and model of the study area were evaluated. ［Results and Conclusions］ There are 19 lithofacies types and three sedimentary systems in the study area， including four sedimentary facies types， and 13 sedimentary microfacies are further divided. The Yanghugou Formation-Taiyuan Formation in the study area is supplied by the two provenance systems of the Alxa ancient land in the northwest of the basin and the Yinshan ancient land in the northeast. The Dickinson triangle plot reveals that the tectonic background of the provenance area is dominated by the recycled orogenic belt. The characteristics of heavy mineral assemblages are clear. The northwestern margin of the basin has a clear affinity with the Alashan Group （Ar₃-Pt₁）， Archean Jining Group （Ar₃）， and the Wulashan Group （Ar_1-2）. The ZTR index shows that the unstable minerals gradually decrease from north to south； analysis of the paleocurrent direction also reflects the material sources from northwest to southeast and from northeast to southwest. Based on the above provenance analysis， paleo-sedimentary environment evolution and sedimentary facies type characteristics， it is clear that the main body of the Yanghugou Formation-Taiyuan Formation in the study area is the coexistence stage of sea and land. During the sedimentary deposition of the Yanghugou Formation， under the background of the revival of Helan aulacogen and the backlog of north-south tectonics， the sea water enters rapidly. The whole study area is controlled by the delta-clastic coastal sedimentary system. The northern source supply is sufficient， resulting in the development of tidal-controlled delta deposits in the north. Affected by tides and waves， tidal flat-barrier island-desalination of lagoons-shelf sedimentary microfacies are developed in the south. During the deposition of the Taiyuan Formation， the crust continued to sink and seawater invaded. During this period， the basin became the most widely distributed period of the sea area. The sedimentary environment was similar to that of the Yanghugou Formation. The overall performance was the coexistence of tidal-controlled delta， tidal flat， desalination of lagoons-barrier island sedimentary environment， and the erosion range in the northern region was relatively reduced， the source supply continued to increase， and the tidal-controlled delta range extended wider to the south.

Objective The Late Ordovician to Early Silurian represents a critical transition in Earth's history， characterized by the Hirnantian glaciation and the end-Ordovician mass extinction event. However， significant uncertainties persist in the chronostratigraphic framework for this interval， limiting our understanding of the mechanisms driving biotic extinction and climatic evolution. This study aims to establish a high-resolution absolute astronomical time scale for the Late Ordovician-Early Silurian through the integration of cyclostratigraphy and isotopic geochronology， providing robust temporal constraints for major geological events. Methods Three sections （Shuanghe in Chang-ning， Sichuan； Anwen in Qijiang， Chongqing； and Wangjiawan in Yichang， Hubei） were selected as study sites. High-resolution elemental data （Si， Fe， Ca， Al， Rb/Sr， etc.） were analyzed using AnalySeries and Acycle software to identify Milankovitch cycle signals. Sedimentation rates were estimated using the COCO/eCOCO and TimeOpt methods to construct floating astronomical time scales. CA-ID-TIMS zircon U-Pb dating was conducted on volcanic ash beds to obtain absolute age anchors， enabling precise conversion from the depth domain to the time domain. Results （1） Stable sedimentary cycles corresponding to 405-kyr and ~100-kyr long and short eccentricity cycles were identified in the XRF elemental series. Floating astronomical time scales of 12.2 Myr， 10.3 Myr， and 2.75 Myr were established for the Shuanghe section， Anwen section， and Wangjiawan section， respectively. （2） Given the most complete geological record preserved in the Shuanghe section， the ages of the Ordovician/Silurian （O/S） boundary and the base of the Hirnantian stage， calibrated to 442.34 ± 0.22 Ma and 443.78 ± 0.22 Ma respectively through cyclostratigraphic analysis combined with U-Pb dating of volcanic ash beds （Shuanghe section： 438.47 ± 0.17 Ma）， can serve as a candidate for future international chronostratigraphic standards. （3） The duration of the Hirnantian stage is 1.44 Myr at the Shuanghe section， but only ~0.41 Myr at the Wangjiawan section， suggesting that a sedimentary hiatus may exist in the Wangjiawan section. （4） Paleoclimatic proxies and sea-level changes exhibited long-period fluctuations of 1.2 Myr and 2.4 Myr. Conclusions The high-precision astronomical time scale established in this study significantly improves the accuracy of the chronostratigraphic framework for the Late Ordovician-Early Silurian， revealing the rapid onset of the end-Ordovician mass extinction. Astronomical cycles played a significant role in driving climate-environmental evolution during this interval， providing key temporal constraints for understanding the triggering mechanisms of the end-Ordovician mass extinction.

Objective The western Hunan region hosts extensive Neoproterozoic marine sedimentary manganese deposits. Manganese （Mn） is a typical redox-sensitive metallic element whose enrichment in sediments is strongly correlated with the redox condition of the bottom water in the basin. A detailed study of the sedimentary redox conditions of such deposits helps to explain their metallogenic mechanisms and the constraints on their marine cycling during the mineralization period， and also provides theoretical support for the assessment of regional mineralization potential. Methods This study involved mineralogical， geochemical and inorganic carbon isotope analyses of 16 manganese ore samples of various grades from the Nanhua System Datangpo Formation in the Minle area， western Hunan. Results Mineralogical and carbon isotope analyses revealed that high-grade （MnO>20%） and medium-grade （10%<MnO<20%） manganese ores consist of predominantly subhedral granular microcrystalline rhodochrosite （grain size <5 μm） and are relatively enriched in light carbon isotope （δ¹³C=-10.4‰~-8.3‰； n=10）. Conversely， low-grade （MnO<10%） manganese ores contain larger- grained （>20 μm） subhedral platy rhodochrosite enriched in heavier carbon isotope （δ¹³C=-7.4‰~-5.3‰； n=6）. Pyrite morphology and element geochemical proxies （Mo， V， Ni concentrations and Ni/Co， V/Cr ratios） indicate that the high-grade manganese ores were deposited in oxic conditions， the medium-grade ore in suboxic conditions， and the low-grade ore in anoxic conditions. Additionally， high-grade ores exhibit geochemical characteristics indicating hydrothermal deposition （e.g.， high Eu^* values and high Fe/Ti ratios）. Conclusions These findings suggest that， in the Minle area of western Hunan， the rhodochrosite in the medium- to high-grade manganese ores was formed as a result of the reaction between Mn oxides with organic matter during diagenesis， whereas in the low-grade manganese ores the rhodochrosite was probably precipitated from Mn²⁺ and CO{}_{\mathrm{3}}^{\mathrm{2}-} in highly alkaline and anoxic conditions. Submarine gas-hydrothermal activity in the deep-water basin of northeastern Guizhou most likely supplied the Mn²⁺ ions for these manganese deposits； oxidation of bottom water in the basin was the key factor determining manganese enrichment and mineralization in the region.

Objective The Taiyuan Formation of Permian System in Ordos Basin has the characteristics of large thickness， wide distribution， and rich types of oil and gas resources， which indicates a substantial potential for exploration. At present， the study of this formation is mainly concentrated in the eastern part of the basin， while the exploration and study of Taiyuan Formation in the western part of the basin need to be further discussed due to the complex and variable tectonic pattern and sedimentary evolution. Methods The detrital material source， tectonic setting and paleogeographic evolution of Taiyuan Formation in western Ordos Basin are systematically studied by means of outcrop observation， drilling sample collection， detrital zircon U-Pb dating and paleo-flow analysis. Results The sediments in the northeastern part of the study area （Group A） are mainly from the Yinshan Orogenic Belt under the collision-compressional tectonic background， with strong provenances. The delta plain， delta front， tidal sand ridge and tidal sand bar are successively developed in the middle of the basin. The sediments in the northwest （Group B） are derived from the Alxa Block under the collisional compression and convergent orogenic tectonic background， and the delta plain， delta front and lagoon-tidal flat develop successively towards the middle of the basin. The sediments in the southern （Group D） area came from the North Qilian and North Qinling tectonic belts under the extension-subduction-collision tectonic environment of the Paleo-Tethyan Ocean. The central paleo-uplift of the Taiyuan Period was slow， the provenance-supply was weak， and the mainly developed barrier island-barrierisland-lagoon-tidal flat deposits. Conclusions The northern part of the study area is characterized by high uplift and strong provenance supply in the context of collision and convergence orogenic structures， and large tide-delta complex system， while the southern part is characterized by weak provenance supply in the context of tensile extension structures， and is dominated by tidal flat and lagoon. This study not only deepens the understanding of the sedimentary system and provenance supply mechanism in the western Ordos Basin， but also provides a new perspective and reference for the reconstruction of the tectono-sedimentary evolution process and paleogeographic pattern in the western Ordos Basin.

Objective The formation of sedimentary systems within straits is intricately linked to the unique topographical constraints that influence both facies characteristics and sediment distribution patterns. Although current research mainly focuses on narrow straits （less than 50 km wide） ， where sedimentation is dominated by tidal processes， wider straits introduce more complex hydrodynamic dynamics， leaving many aspects of the sedimentation processes yet to be fully understood. Methods This study focuses on the Bohai Strait （a shallow strait with a width of 106 km） and is based on an extensive dataset of surface sediment grain sizes， combined with four shallow seismic profiles， to characterize the sedimentary environment within the Bohai Strait. Additionally， a regional ocean modeling system （ROMS） simulation was employed for winter （December 2020⁃February 2021） to better understand the hydrodynamic processes influencing sediment dynamics and control over sediment distribution within and surrounding the Bohai Strait. Results Our results reveal significant differences in sediment dynamics between the northern and southern parts of the strait. The northern region exhibits a high-energy environment dominated by erosion， whereas the southern region displays a lower-energy environment conducive to deposition. Surface sediment types vary spatially， with coarser grains predominating in the north and narrow regions， with finer grains observed on both sides （east⁃west） and in the south. A large-scale， sandy flood-tidal delta appears around the Laotieshan Channel in the north. The asymmetric tidal currents flowing in and out of the channel are likely responsible for this feature， and ebb-tidal delta is not prominent. In contrast， the southern part of the strait exhibits two distinct sedimentary systems：（1） Shandong mud wedge： This system lies along the coast of the Shandong Peninsula， shaped by the substantial sediment supply from the Yellow River and the influence of coastal currents. （2） Scour troughs and sandy tidal deltas： These smaller features are attributed to the protective effect of islands present in the southern strait， combined with the abundant supply of fine-grained sediments. Conclusions This study highlights the critical role of the complex topography of the strait in the confinement in shaping regional sediment transport dynamics and the resulting distribution of sedimentary systems.