Sedimentary Geology最新文献

{"title":"Sedimentary rates driven by laboratory lock-exchange turbidity currents flowing over gravel and vegetated beds","authors":"T. Serra ,&nbsp;M. Soler ,&nbsp;M. Mancini ,&nbsp;L. Solari ,&nbsp;J. Colomer","doi":"10.1016/j.sedgeo.2025.106978","DOIUrl":"10.1016/j.sedgeo.2025.106978","url":null,"abstract":"<div><div>Turbidity currents are key agents in sediment transport and bed reshaping, influencing geological records, organic carbon fluxes and pollutant transport. While extensively studied over smooth beds, their interaction with rough beds, such as gravel or vegetated substrates, remains poorly understood. Existing studies suggest bed roughness slows flow and alters deposition, but a comprehensive understanding of how grain-size affects current dynamics and sedimentation patterns is lacking. In this study, we addressed key knowledge gaps on the influence of bed roughness and vegetation on turbidity current dynamics and sedimentation by conducting a comprehensive series of lock-exchange flume experiments. Six bed grain-sizes, multiple flow depths, and sediment concentrations were tested and compared with previous experiments on simulated and real vegetation. Results demonstrate that increasing bed roughness significantly reduces turbidity current velocity and enhances near-source sediment deposition. Greater deposits close to the source result in more non-uniform sediment distribution, with less deposition along the gravel bed. Conversely, smooth beds facilitate longer sediment transport and more uniform deposition. Flow regimes were observed to shift from inertial to drag-dominated as a function of bed configuration, with vegetated and coarse-grained beds inducing comparable hydraulic resistance. Sediment deposition patterns were closely linked to bed roughness and influenced clogging processes via unimpeded static percolation. Overall, the findings reveal a strong feedback between substrate morphology and turbidity current behaviour, with important implications for turbidite formation, sedimentary structure development, and hyporheic exchange dynamics.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"489 ","pages":"Article 106978"},"PeriodicalIF":2.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative grain size analysis of fine-grained sediments: A case study of the Opalinus Clay, northern Switzerland","authors":"Géraldine Nicole Zimmerli ,&nbsp;Alicia Fantasia ,&nbsp;Stephan Wohlwend ,&nbsp;Gaudenz Deplazes ,&nbsp;Anneleen Foubert","doi":"10.1016/j.sedgeo.2025.106982","DOIUrl":"10.1016/j.sedgeo.2025.106982","url":null,"abstract":"<div><div>Grain size variability in fine-grained sediments is a critical factor influencing the physical, geomechanical, geochemical, and hydrological properties of sedimentary rocks. Even small changes in grain size can significantly alter rock behavior. Despite many decades of research on fine-grained sediments in different depositional settings, studies focusing on the comparative and quantitative calibrated analysis of grain size variations in fine-grained Mesozoic sediments are scarce. This study provides the first integrative, quantitative, comparative, and comprehensive analysis of grain size variability in the detrital fraction of the Opalinus Clay from northern Switzerland (Stadel-2 core), which serves as the designated host rock for radioactive waste disposal. The analyses include 2D image analysis, X-ray micro-computed tomography, laser particle size analysis, and sieving/decantation analysis, alongside mineralogical (X-ray diffraction, XRD) and geochemical (X-ray fluorescence, XRF) analyses. Strong correlations between grain size and elemental ratios (Si/Al, Ti/Al, Zr/Al, Zr/Rb) suggest that these ratios can serve as effective proxies for grain size variations in the Opalinus Clay, primarily controlled by the presence of quartz and phyllosilicates. Results evidence the dominance of silt-sized particles in the Opalinus Clay. Distinct trends of grain size coarsening and fining are observed based on XRF-derived grain size proxies, providing the base for further studies on sediment transport processes, including sediment provenance, flow strength, and current dynamics associated with the Opalinus Clay. Results highlight the importance of calibrating grain size variations in fine-grained sediments before their application in the understanding of rock properties and sedimentary processes.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"489 ","pages":"Article 106982"},"PeriodicalIF":2.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrological and geochemical evidence of hematite growth and dispersal in Permo-Triassic red beds under the Pangea mega-monsoon climate, Colorado Plateau, Utah","authors":"Ondřej Bábek ,&nbsp;Hedvika Weinerová ,&nbsp;Lukáš Ackerman ,&nbsp;Daniel Šimíček ,&nbsp;Jaroslav Kapusta ,&nbsp;Ladislav Strnad","doi":"10.1016/j.sedgeo.2025.106957","DOIUrl":"10.1016/j.sedgeo.2025.106957","url":null,"abstract":"<div><div>The palaeoclimatic significance of continental red beds (CRB) is the subject of a long-standing debate. The CRBs are strikingly often found in association with arid, aeolian sediments, humid fluvial sediments and palaeosols, reflecting variable climatic regimes. In this study, diffuse reflectance spectroscopy (DRS) is used in combination with facies analysis, petrology, bulk-rock and in-situ major and trace element geochemistry, and molybdenum stable isotopes to better understand the origin and distribution of the hematite pigment in a spectrum of Permo-Triassic aeolian, fluvial and pedogenic facies of the Colorado Plateau, Utah. Their red colour is characterized by high (&gt; 30) percentage of red-band (625–700 nm) reflectance in the DRS spectra and high hematite-to-goethite peak height ratios (1.5 to 5.7) from their first derivatives. Most hematite occurs in form of submicronic to micron-sized, platy crystals in altered biotite grains, clayey grain coatings, clayey matrix, pyrite framboid pseudomorphs, and as pore-filling cement. Hematite is most abundant in palaeosols, but also present in aeolian, sand dune and damp interdune deposits, fluvial channel-fill, sandy and gravelly bars, and floodplain deposits. Iron for the hematitization was supplied from reductive release of Fe²⁺ from biotite and clay minerals. The hematitization itself occurred under oxic conditions, associated with formation of kaolinite, mobilization of V, Mo, As, U, and fractionation of rare earth elements and Mo isotopes, especially in lateritic palaeosols. Hematitization during weathering, pedogenesis, transportation and early diagenesis, and reworking and redeposition of the red material by rivers and wind is thought to be the principal mechanism of the formation of red beds in the Colorado Plateau. The processes of hematitization and the fluvial-aeolian dynamics were controlled by alternation of wetter and drier periods likely caused by the Permo-Triassic Pangean mega-monsoonal climatic regime.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"489 ","pages":"Article 106957"},"PeriodicalIF":2.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145057213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Architecture and evolution of early Pleistocene shelf margin clinoforms, northwestern South China Sea: Implications for high-frequency sequence architecture","authors":"Yueyao Chen ,&nbsp;Jiawang Ge ,&nbsp;Xiaoming Zhao ,&nbsp;Ronald Steel ,&nbsp;Kun Qi ,&nbsp;Xiaolong Tang","doi":"10.1016/j.sedgeo.2025.106984","DOIUrl":"10.1016/j.sedgeo.2025.106984","url":null,"abstract":"<div><div>The controls on cross-shelf deltaic architecture variability and high-frequency clinoform development along continental margins remain inadequately explored. Recently acquired high-resolution seismic data from the passive continental margin in the northwestern South China Sea offer an opportunity to investigate the intra-sequence architecture and shelf-edge trajectories of the early Pleistocene (2.6 to 1.8 Ma) succession in detail. Five high-frequency sequences, with an average duration of ∼160 kyr in duration (4th-order sequences), exhibit distinct intra-sequence architectures and are related to four shelf-edge trajectory types: descending, slightly ascending, steeply ascending, and backstepping. The observed correlation between shelf-edge trajectories and intra-sequence architectures under high-frequency sea-level fluctuations reflects the dynamic interplay between accommodation and sediment supply, underscoring their potential as predictive tools in depositional process analysis.</div><div>The stratal variability of early Pleistocene shelf-margin clinoforms documented in this study is controlled by a combination of factors, including sea-level fluctuations, climate, sediment supply, and tectonics. The reduced dominance of falling-stage systems tracts during the early Pleistocene compared to the late Pleistocene is attributed to the lower amplitude and more symmetrical nature of sea-level changes, which restricted the dominance of falling-stage systems tracts. The well-preserved transgressive and regressive units reflect sufficient sediment supply and paced accommodation creation. Our results emphasize that the local variations in high-frequency sequence architecture were shaped by multiple factors beyond sea-level changes in the early Pleistocene shelf-margin. Local factors such as tectonism and sediment supply can complicate the correlation of seismic sequences, even across relatively short distances.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"489 ","pages":"Article 106984"},"PeriodicalIF":2.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sedimentological and ichnological characterization of tide-dominated succession during transgression in the Lower Cretaceous Zubair Formation, central Mesopotamian Basin","authors":"Zixiao Peng ,&nbsp;Jianhua Qu ,&nbsp;En Xie ,&nbsp;Chunqiang Chen ,&nbsp;Bang Zeng ,&nbsp;Dancheng Zhu ,&nbsp;Ke Zhang ,&nbsp;Yuyuan Li ,&nbsp;He Wang","doi":"10.1016/j.sedgeo.2025.106958","DOIUrl":"10.1016/j.sedgeo.2025.106958","url":null,"abstract":"<div><div>Depositional processes recorded by coastal deposits may vary rapidly during transgression due to the interactions of wave, river, and tidal processes, leading to the diversity of facies models. Reconstructing a reliable, detailed facies model associated with depositional processes remains challenging unless ichnological features are considered. Integrated sedimentological and ichnological analyses of high-resolution core samples, wireline log, and seismic data from the Lower Cretaceous Zubair Formation, central Mesopotamian Basin, are undertaken to propose a tide-dominated model within transgressive succession. The presence of sporadic river-influenced sedimentary structures, variability in ichnodiversity and bioturbation intensity, and abundant tidal physical indicators attest to the strong influence of tide-generated currents during deposition. In a transgressive upward-fining succession, seven facies associations are identified based on differences in sedimentological and ichnological indicators, and further grouped into two environments (tide-dominated estuary and open coast tidal flat), which are both considered as first-order tidal coastal environments. Deposits of estuaries are occupied by mixed <em>Cruziana-Skolithos</em> ichnofacies and dominance of channel-bar complexes, while local storm-influenced structures, higher ichnodiversity and bioturbation intensity, and well-expressed <em>Cruziana and Skolithos</em> ichnofacies clearly characterize the open coast. River-dominated paleovalley evolved into the tide-dominated estuary and then transformed into the open coast tidal flat as global sea-level rose, with increasing ichnodiversity, bioturbation intensity, and weakening fluvial influence. For the first time in the region, distinct deposits of estuary and open coast are recognized, indicating the development of facies diversity during long-term transgression. High accommodation, topographic features, limited sediment supply, and sea level rise are responsible for the spatiotemporal differential distribution of these two depositional systems. At the regional scale, tidal environments, river-influenced, and river-dominated deltas were distributed along the coastline from northwest to southeast due to the relatively increasing sediment supply from the Arabian Shield towards the southeast. The results of this study improve our understanding of regional paleogeography in the central Mesopotamian Basin, NE Arabian Plate, during the Barremian, and provide a case for understanding the diversity and sedimentary evolution of tidal facies models, which can be applied to other transgressive sequences in deep-time basins worldwide.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"489 ","pages":"Article 106958"},"PeriodicalIF":2.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145057183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cambrian reef complexes and pelmatozoan-rhynchonelliformean meadows from the Alborz Mountains, northern Iran: A reassessment of the Miaolingian–Furongian paucity of metazoan reefs paradigm","authors":"J. Javier Álvaro ,&nbsp;Aram Bayet-Goll ,&nbsp;Mehdi Daraei ,&nbsp;Blanca Martínez-Benítez","doi":"10.1016/j.sedgeo.2025.106959","DOIUrl":"10.1016/j.sedgeo.2025.106959","url":null,"abstract":"<div><div>The Alborz Mountains in northern Iran represent one of the few exceptions to the worldwide decline in Miaolingian–Furongian (Cambrian) carbonate abundance and reefal volume, likely related to the arrival of northeastern Gondwana to subtropical latitudes. This Gondwana margin recorded the stepwise nucleation of microbial and shelly carbonate factories, lithostratigraphically recognized as members of the Lalun and Mila formations. The late Cambrian Epoch 2 to Miaolingian interval displays the development of oncoid-pisoid accumulations and microbial build-ups, with laminated and clotted textures, in open-sea and protected (back-barrier) settings. In contrast, the late Miaolingian and Furongian interval recorded a generalized establishment of pelmatozoan-rhynchonelliformean meadows, locally affected by horst-and-graben topographies. Hanging-wall blocks offered some protection from high-energy, shallow-water conditions, which favoured the growth of anthaspidellid-microbial reef complexes. The primary porosity recorded in the pelmatozoan-rhynchonelliformean shell beds, and the associated microboring and micritization of skeletal walls, favoured the episodic development of carbonate and iron oxyhydroxide hardgrounds. Such a singularity leads to the development of a more comprehensive global model linked to Miaolingian–Furongian progressive declines in ⁸⁷Sr/⁸⁶Sr ratios, estimated extent of carbonate platforms and reefal volume and atmospheric O₂ (punctuated by a sharp increase related to the SPICE event), coeval with relative increases in seawater calcite saturation. In some subtropical areas, such as in the Alborz margin of Gondwana, the re-occurrence of metazoan frame-builders took place in late Miaolingian times, and their subsequent reefal success was primarily controlled by tectonic activity and the nucleation of hardgrounds in highly porous pelmatozoan-rhynchonelliformean shell beds.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"489 ","pages":"Article 106959"},"PeriodicalIF":2.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145057214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Debris aggregates in debris flows and implications for debris-flow dynamics","authors":"Yi-Xi Wen ,&nbsp;Ze-Min Xu ,&nbsp;Xiao Su ,&nbsp;Bin Li ,&nbsp;Zi-Ming Ye ,&nbsp;Gui-E Shi ,&nbsp;Jing-Kai Meng","doi":"10.1016/j.sedgeo.2025.106946","DOIUrl":"10.1016/j.sedgeo.2025.106946","url":null,"abstract":"<div><div>Sediments related to debris flows consist usually of single clasts of various sizes. A kind of composite debris, i.e., elongate debris aggregates, occurring in the Jiangjia Gully debris flows in China, is reported herein. They can occur as isolated individuals, and more commonly as clusters of a few to several hundred individuals. 2,225 measured aggregates vary in maximum and minimum dimensions from 2 to 187 cm (average 17 cm) and from 2 to 107 cm (mean 12 cm), respectively. The aggregates with an elongation ratio of ≤ 0.8 make up 63%, fat ones having a flatness ratio of ≤ 0.8 represents only 37%, and at least 53% of the aggregates are prolate spheroidal. The average convexity of 0.92 illustrates that the aggregate surfaces are smooth. Massive structure (sometimes with cobble cores), concentrically banded structure, and deformation structure are developed in aggregate interiors. Slate clasts ranging in size from clay to cobbles, which originate from landslide debris in the debris-flow source areas and moving debris-flow slurries, comprise the aggregates. Field observations of more than 30 surges show that most of the aggregates belong to the objects transported by the debris flows, and rolling process is essential to their development. Fibrous palygorskite, which acts as the rock-forming mineral of the slate bedrock and is released by slate detritus, is responsible for the widespread occurrence of the aggregates. The marked presence of the elongate aggregates indicates that the debris flows can be approximated as one-dimensional, laminar flow of homogeneous single-phase yield stress fluids. Debris aggregates in debris flows merit attention because of their significant implications for debris-flow dynamics and of facilitating sediment transfer.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"488 ","pages":"Article 106946"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144912003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From Platform to Burial: Tectonic and climatic imprints on the diagenetic evolution of shallow-marine carbonate deposits (Middle Eocene), Bombay Offshore Basin, India","authors":"Sreetama Aich ,&nbsp;Cathy Hollis ,&nbsp;Sudipta Dasgupta ,&nbsp;Kumar Hemant Singh","doi":"10.1016/j.sedgeo.2025.106940","DOIUrl":"10.1016/j.sedgeo.2025.106940","url":null,"abstract":"<div><div>Conventional cores collected from a shallow tropical carbonate-ramp system reflect a diagenetic pathway that was influenced by both the globally humid, tropical climate at the middle Eocene time and the subsequent onset of Himalayan mountain building. Detailed optical, cathodoluminescence-petrographic and non-isotopic geochemical analyses were used for the study. The eogenetic processes, e.g., micritization, pyritization, isopachous and micritic cementation, early marine dolomitization, and the early stages of mechanical compaction, happened during and soon after deposition in the marine-phreatic environment. During the late Eocene, as the global climate cooled, the relative sea level fell, and the carbonate ramp underwent subaerial exposure, leading to the meteoric-phreatic diagenetic processes, e.g., neomorphism, dissolution (phase-1), pendant cementation (vadose zone), and significant calcite spar cementation (C-1). With ensuing deposition above through the early Oligocene, the effects of compaction affected the formation by truncation and fragmentation of grains, condensed packing, developing various (point-tangential, concavo-convex, and sutured) grain contacts, pressure dissolution and stylolite generation, fracturing, corrosion (phase-2 dissolution), and burial-calcitic (C-2) and non-calcitic (NC) cementation. After the early Oligocene, the basin tilted westward, a far-field consequence of the Indo-Eurasian collision. This tectonic reorganisation caused the Paleogene carbonate strata to undergo a partial exhumation and thus, they were susceptible to the influence of meteoric water mainly through the reactivation of pre-existing faults. These tectonic readjustments led to the reopening of the stylolite sets, telogenetic fracturing, and another dissolution episode (phase 3). Hence, the diagenetic pathway manifesting itself at the microscopic scale posits a clear connection with the basin's evolution. Further, the diagenetic reconstruction also corroborates the global climatic transition, from a greenhouse to a cooler ice-house condition, that took place across the Eocene-Oligocene boundary, making the study significant from a regional to global scale.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"488 ","pages":"Article 106940"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144916613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new sedimentary record from the Tabernas Basin: Implications for the Messinian Salinity Crisis in the Western Mediterranean","authors":"Gustavo Kenji Lacerda-Orita ,&nbsp;Fernando Pérez-Valera ,&nbsp;Jesús M. Soria ,&nbsp;Hugo Corbí ,&nbsp;Jingjing Liu ,&nbsp;Núria Sierra-Ramirez ,&nbsp;Enrique Gomez-Rivas ,&nbsp;Luis Gibert","doi":"10.1016/j.sedgeo.2025.106947","DOIUrl":"10.1016/j.sedgeo.2025.106947","url":null,"abstract":"<div><div>The Tabernas Basin (SE-Spain), renowned for its Tortonian turbidites, also records thick Messinian successions (&gt;200 m) that offer valuable insights into the Messinian Salinity Crisis (MSC). Yet, the stratigraphic correlation of the Tabernas sediments with the classic successions of the nearby Sorbas Basin remains unclear. This study presents a composite stratigraphic section (named Yesón Alto) that covers the pre-evaporitic, syn-evaporitic, and supra-evaporitic stages of the MSC recorded in Tabernas Basin, offering detailed paleoenvironmental and chronostratigraphic characterization. We provide new constraints on the connections between two marginal basins of the Betic Cordillera and on the paleoenvironmental changes that took place in the Western Mediterranean during the MSC. During the Late Messinian pre-evaporitic phase, siltstones and shales alternating with distal turbidites recorded shifts between warm-oligotrophic and cold-eutrophic planktonic foraminiferal assemblages, indicating the influence of precession-driven climatic fluctuations on the water column. Progressive basin restriction led to the development of an incipient hybrid carbonate shelf, subjected to significant siliciclastic influx. 16 key planktonic foraminifera bioevents and a magnetic reversal (C3An.1n to C3r at 6.035 Ma) have been identified and correlated with the astronomically calibrated cycles of the Sorbas Basin, suggesting the possible synchronous onset of the MSC in both basins. The evaporitic stage in Tabernas is represented by four selenitic gypsum beds intercalated with siliciclastic and carbonate deposits. Facies analysis and gypsum isotopic compositions (δ³⁴S_sulfate and δ¹⁸O_sulfate) suggest that evaporites represent the initial cycles of the Primary Lower Gypsum (PLG) of the MSC Stage 1 in the Mediterranean. Below gypsum bed PLG 4, an inter-evaporitic level rich in marine fauna indicates the episodic re-establishment of near-normal marine conditions after periods of evaporite precipitation. The Supra-evaporitic unit, comprising deltaic-fluvial conglomerates and sandstones, reflects a regional regressive trend and marks the continentalization of the basin's margins. The progradation of these continental deposits over the evaporitic basin was favored by an eastward uplift trend in the Betic Cordillera, ultimately leading to exposure of the Tabernas Basin before or during Stages 2 and 3 of the MSC. The paleoenvironmental evolution of the Tabernas Basin indicates that marine connections with the Sorbas Basin persisted before and during the early MSC and that tectonics associated with climatic factors played a key role in the evolution of its sedimentary systems.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"487 ","pages":"Article 106947"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144865276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-frequency sequence patterns in lacustrine basins: Insights from delta-hyperpycnal flow systems in the Middle Jurassic shale interval, Sichuan Basin, China","authors":"Haocheng Shi ,&nbsp;Benzhong Xian ,&nbsp;Yichen Liu ,&nbsp;Zhiyun Yu ,&nbsp;Lin Zhao ,&nbsp;Junyang Geng ,&nbsp;Rongheng Tian ,&nbsp;Qianran Wu ,&nbsp;Li Liu ,&nbsp;Yujie Shuai ,&nbsp;Yi Shu","doi":"10.1016/j.sedgeo.2025.106948","DOIUrl":"10.1016/j.sedgeo.2025.106948","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Unlike marine sedimentary basins, lacustrine sedimentary basins are more sensitive to small-scale climatic changes (fourth-order and higher sequences: spanning thousands to tens of thousands of years), and exhibit characteristics such as rapid sedimentary facies transitions and strong heterogeneity. Frequent changes in the sedimentary environment significantly influence the development of sedimentary systems and the formation of sequence structures. These factors present new challenges for understanding the sequence architecture and sedimentary evolution in deep-water zones in lacustrine depression basins. Taking the Middle Jurassic Lianggaoshan Formation in the eastern Sichuan Basin, China, as an example, in this paper, we integrate data from cores, well logs, element geochemistry, and 3D seismic surveys. By applying the transgression–regression cycle theory and high-frequency sequence stratigraphy of lacustrine depression basins, we analyze the genetic mechanisms and distribution patterns of different types of sandstone interlayers within the shale interval and investigate the effect of high-frequency climatic changes on sedimentary processes in lacustrine basins. A high-frequency sequence pattern for lacustrine depression basins is established. The results indicate that within the third-order sequence of the Lianggaoshan Formation, during the shale-deposition interval (maximum water abundance period), the lacustrine depression basins were controlled by the 405 ka (fourth-order sequence) climatic cycle, which still demonstrates basin-scale expansion and contraction. In the shale interval, climate-driven lake transgression-regression cycles within fourth-order sequences promoted frequent interbedding of high sedimentation rate, coarse-grained deposits (e.g., deltaic deposits and hyperpycnal flow deposits) and low sedimentation rate, fine-grained deposits (e.g., suspension settling: shallow-water mudstone and deep-water shale). This reveals a high-frequency sequence stratigraphy pattern that demonstrates the coupling mechanism between the sedimentary processes and climatic forcing in lacustrine depression basins. Within the fourth-order sequences, the early transgressive systems tract and late regressive systems tract are characterized by shallow water and arid conditions, which resulted in the development of organic-poor mudstones, while deltaic sandstones prograde into the center of the basin. In contrast, the late transgressive systems tract and early regressive systems tract are marked by deep water and humid conditions, which led to the formation of organic-rich shales, accompanied by hyperpycnal flow sandstones entering the center of the basin. This resulted in the formation of multiple sets of strongly heterogeneous interbedded organic-poor mudstone and organic-rich shale assemblages. The findings establish a high-frequency sequence pattern for these basins, elucidate their internal depositional and facies evolution processes, an","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"487 ","pages":"Article 106948"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144889096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}