Sedimentary Geology最新文献

{"title":"Environmental changes during the middle to late Norian: An integrated record from the Southern Tethys, Ras Al-Khaimah, United Arab Emirates","authors":"Azeem Shah ,&nbsp;Aisha Al-Suwaidi ,&nbsp;Dominik Hennhoefer ,&nbsp;Mohammad Alsuwaidi","doi":"10.1016/j.sedgeo.2026.107061","DOIUrl":"10.1016/j.sedgeo.2026.107061","url":null,"abstract":"<div><div>The record of environmental and climatic change through the late Norian stage in paleoequatorial settings has so far received limited attention. Here we present new geochemical and sedimentological data to investigate the depositional and environmental changes through the late Norian into the earliest Rhaetian in the marine carbonate Milaha and Ghalilah Formation exposed in Wadi Milaha, Ras Al-Khaimah, UAE. The upper part of the Milaha Formation studied in Wadi Milaha, comprises sediments deposited in a shallow marine environment, with some evidence of high-energy shoal deposition. Restricted conditions are present in the basal and middle part of the Asfal member of the Ghalilah formation, followed by high diversity faunal content, indicating the development of open marine conditions in the late Norian-early Rhaetian. Development of the restricted conditions upwards suggests changes in the relative sea level. Our results show that the succession is comprised of regressive-transgressive cycles, which include minor depositional cycles influenced by changes in clastic input. Sedimentological and elemental data indicate fluctuations in clastic input throughout the sedimentary succession studied. The increase in siliciclastic input coincides with a major regressive sea level cycle during the middle-late Norian. Our results suggest that the increased coarse terrigenous input is likely due to enhanced weathering and an associated warming episode during the late Norian. Very low correlation of δ¹³C_carb and δ¹⁸O indicates little diagenetic influence on the isotopic record. The δ¹³C_carb records an overall negative trend during the middle-late Norian with small-scale fluctuations of −2.8‰ magnitude and coincides with increased clastic input. A small positive excursion in δ¹³C_carb is recorded at the Norian-Rhaetian boundary. The observed variations in sedimentary succession, relative sea level, and bulk carbonate carbon isotopic record are similar to those of other Tethyan sections. This comprehensive and comparably high-resolution record very likely indicates far-reaching or global ecological changes during the middle-late Norian.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"497 ","pages":"Article 107061"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388064","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":"Methodological framework and evaluation of aeolian system sediment state: Wahiba Dune Field, Oman","authors":"David Cousins ,&nbsp;Gary Kocurek ,&nbsp;Caroline Hern","doi":"10.1016/j.sedgeo.2026.107060","DOIUrl":"10.1016/j.sedgeo.2026.107060","url":null,"abstract":"<div><div>At the fundamental level, the existence of a dune field is determined by a set of external (allogenic) boundary conditions. At any point in time, these boundary conditions control the sediment state of the aeolian system, defined by the separate components of sediment supply, sediment availability, and the transport capacity of the wind (sensu Kocurek and Lancaster, 1999). This paper provides a methodological framework to develop an aeolian system sediment state model using the Wahiba Dune Field of Oman, a system that incorporates at least 140 ka of dune field evolution. The framework consists of (1) assembling regional proxy datasets and simulations that encompass transient allogenic forcings; (2) deriving the impacts that these forcings will have upon system parameters inherent to the dune field, such as inland sediment yield, vegetation, coastal biogenic productivity, coastal shelf exposure, and the relative strength of the wind regime components; and (3) weighing these parameters for their control on sediment supply, sediment availability, and transport capacity of the wind. Dune chronological records for the Arabian subcontinent are subsequently evaluated with reference to the predictive sediment state for the Wahiba Dune Field. Principally, the sediment state model is found to imitate high frequency allogenic forcings that largely follow from Milankovitch and small-scale cycles. Overall, there is a general agreement with previous work, however, differences emerge in the predictions of the temporal dominance of southerly Indian summer monsoon winds versus NW Shamal winds. Shifts from these opposing wind systems are speculated to have promoted major reworking and probable redefinition of the composite linear megadunes that today dominate the dune field. Additionally, the resolution of the marine isotope stage (MIS) 5 dune field is brought into question and reinterpreted. The sediment state model ultimately proves useful in informing on the generation of a geological record in a complex aeolian system.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"497 ","pages":"Article 107060"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388063","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":"Polymetallic nodules offshore NE Greenland: links to Fram Strait opening and local hydrothermal activity","authors":"Dmitrii Zastrozhnov ,&nbsp;John M. Millett ,&nbsp;Sverre Planke ,&nbsp;Stéphane Polteau ,&nbsp;Adriano Mazzini ,&nbsp;Derek Fabel ,&nbsp;Finlay Stuart ,&nbsp;Ana Carracedo ,&nbsp;Luigia Di Nicola ,&nbsp;Valerie Olive ,&nbsp;Nina Lebedeva-Ivanova ,&nbsp;Iakov Gogin ,&nbsp;Reidun Myklebust ,&nbsp;Ebbe H. Hartz","doi":"10.1016/j.sedgeo.2026.107033","DOIUrl":"10.1016/j.sedgeo.2026.107033","url":null,"abstract":"<div><div>This study presents the first documentation and analysis of polymetallic Fe–Mn seafloor nodules from offshore Northeast Greenland. Samples were collected from three sites by dredging and gravity coring along the slopes of both the outer and transform margin highs. The morphology, petrography, and whole-rock geochemistry of twenty-four nodules were determined. ¹⁰Be/⁹Be and (U–Th)/He dating were undertaken for representative samples to constrain the time of formation. Two nodule groups were identified in all studied sampling sites. Group 1 (<em>n</em> = 19) are light banded, primarily hydrogenetic nodules with notable enrichments in Mn and Fe, as well as several trace elements including rare earth elements (REE), V, Co, and Y. They have geochemical and textural similarities to Fe–Mn deposits from the Arctic Basin. ¹⁰Be/⁹Be age estimates suggest that growth initiated around 13,5 Ma, shortly after the opening of the Fram Strait, which influence deep-water circulation and inflow of nutrient-rich Arctic waters onto the NE Greenland shelf. Group 2 nodules (<em>n</em> = 5) are dense with high Fe (up to 64 wt% Fe₂O₃), low Mn content and little to no enrichment in trace elements and REEs. They are interpreted as hydrothermal in origin, with preliminary (U–Th)/He ages suggesting Quaternary formation under weak, diffuse fluid circulation in near-bottom environments of uncertain source. This study expands our understanding of seafloor mineralization in the Arctic–North Atlantic gateway, revealing that on the NE Greenland shelf this process reflects a long-term interplay between tectonic evolution, ocean circulation, and fluid-driven alteration.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"495 ","pages":"Article 107033"},"PeriodicalIF":2.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116410","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":"Wave-induced internal pumping as a sediment sorting mechanism and its implications for deltaic stratigraphic evolution: Insights from the Yellow River Delta","authors":"Shuyu Zhang ,&nbsp;Jiewen Zheng ,&nbsp;Pan Ji ,&nbsp;Hongjun Zhang ,&nbsp;Xiuhai Wang ,&nbsp;Yonggang Jia ,&nbsp;Xiaolei Liu","doi":"10.1016/j.sedgeo.2026.107045","DOIUrl":"10.1016/j.sedgeo.2026.107045","url":null,"abstract":"<div><div>Sediment grain size and stratigraphic evolution in river deltas are critical for understanding shoreline stability and associated engineering risks. The role of wave-induced sediment responses in regulating deltaic grain size distributions and stratigraphic organization remains poorly constrained. This study combines analyses of undisturbed sediment samples from depositional lobes of different ages with in situ wave-loading experiments in the Yellow River Delta to investigate surface grain size patterns and their sorting mechanisms. The results reveal a pronounced “older-coarser, younger-finer” configuration and a transition from cohesive to non-cohesive textures, reflecting the combined influence of external hydrodynamics and human activities. More importantly, periodic wave loading induces a significant internal seabed response, here termed internal pumping, which drives the upward migration of fine particles and produces a short-lived surface inverse fining that cannot be explained by conventional hydrodynamic sorting alone. Based on these observations, a coupled sediment-sorting framework for river deltas is proposed: hydrodynamic sorting, flow-induced shallow infiltration, and deeper internal pumping act together to regulate grain size distributions and deltaic stratigraphic evolution under conditions of reduced fluvial sediment supply and intensified nearshore energy. This mechanistic framework elucidates previously overlooked internal processes in coastal morphodynamics and provides a sedimentological basis for understanding how wave-induced sediment response governs grain size sorting and stratigraphic evolution in deltaic systems.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"495 ","pages":"Article 107045"},"PeriodicalIF":2.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146172543","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 machine-learning approach for classifying fluvial sandbody types from vertical facies sequences using geological analogues","authors":"Luca Colombera ,&nbsp;Soma Budai ,&nbsp;Nigel P. Mountney","doi":"10.1016/j.sedgeo.2026.107047","DOIUrl":"10.1016/j.sedgeo.2026.107047","url":null,"abstract":"<div><div>Machine-learning tools exist for classifying sedimentary units according to objective and verifiable labels (e.g., lithological types), but the role of geologists in interpretive facies analyses is considered irreplaceable. This study presents a machine-learning method for automating interpretations of fluvial sandbodies following an approach that mirrors the application of classic one-dimensional facies models presented as idealized vertical facies sequences. Ensemble decision-tree models were trained on descriptors of facies sequences (sandbody thickness, average facies thickness, facies proportion, and vertical thickness trend), documented in many geological analogues studied by different research groups, reflecting global sedimentological thinking. The data were synthesized in two alternative datasets of contrasting dimensionality (50 vs 26 features). Up to 1222 facies sequences were used for model training and testing, with data splits operated in different ways: (i) using a partition algorithm, with options to exclude data from two-dimensional outcrop panels and to prevent the same sedimentary bodies from occurring in both splits; (ii) by arbitrarily picking sandbodies that are thought to be easily misinterpreted. Four ensemble machine-learning models were applied to perform binary classifications of (i) fluvial sandbody types according to their general channel or overbank origin, and (ii) channel sandbody types according to the interpreted planform style of their formative rivers (‘low-sinuosity or braided’ vs ‘meandering’). Across all training approaches, the models for general sandbody classification yield accuracy values ranging between 0.76 and 0.87: on average only 16% of sandbodies are misclassified. Comparable predictive power (accuracy: 0.75–0.91) is seen for models classifying formative river patterns from channel-body facies sequences, a result that challenges the much-cited notion that interpreting river planforms from vertical profiles of channel deposits is futile. A benchmark comparison against interpretations by eight sedimentologists demonstrates that cases of model misclassification are in line with errors by human geologists. The outcomes support the possibility of automating sedimentological interpretations of borehole observations (e.g., image logs) using models trained on geological analogues.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"495 ","pages":"Article 107047"},"PeriodicalIF":2.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146172542","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":"Unravelling organic rich shale formation using geochemical proxies in the Doushantuo Formation, South China","authors":"Junfeng Zhang ,&nbsp;Detian Yan ,&nbsp;Zeyu Lu","doi":"10.1016/j.sedgeo.2026.107042","DOIUrl":"10.1016/j.sedgeo.2026.107042","url":null,"abstract":"<div><div>The black shale of the Doushantuo Formation provides important insights into the Ediacaran geological environment and organic carbon enrichment with shale gas potential and exploration. As a typical marine shale with high organic carbon content and considerable thickness, it also holds significant resource potential. In this study, shale samples from multiple water depths and depositional environments across the middle Yangtze block, were examined by well log analysis, field surveys, and lithological divisions. We identified four distinct systems tracts within the second member of Doushantuo Formation (DST-2). High-resolution total organic carbon (TOC) profiles recorded several discrete enrichment pulses. These pulses vary systematically across systems tracts and water depths. This pattern suggests changes in organic-matter supply and preservation and these changes are driven by shifts in water-column redox structure. They are also linked to episodic upwelling. Together, these factors control organic carbon accumulation. Enrichment occurred primarily during transgressive phases, driven by varying water column redox conditions and persistent upwelling. Notably, deeper-water shales showed stronger organic matter enrichment than shallow-water shales did, highlighting the importance of deep-water environments for shale gas exploration. By integrating a sequence-stratigraphic framework with high-resolution TOC data across a nearshore–offshore transect, we constrain the timing and controls of episodic organic carbon enrichment in DST-2. The results highlight transgressive-phase enrichment driven by redox stratification and persistent upwelling; and demonstrate that deep-water settings consistently hosted higher TOC and thicker organic-rich intervals, thereby refining most prospective facies and intervals for shale-gas exploration.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"494 ","pages":"Article 107042"},"PeriodicalIF":2.9,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079586","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":"Sedimentary evolution under high-frequency sea-level oscillations of the lower Triassic carbonate-evaporite system in Xuanhan area, Sichuan Basin: Implications for the genesis of polyhalite minerals","authors":"Fanfan Zuo ,&nbsp;Yongsheng Zhang ,&nbsp;Baoling Gui ,&nbsp;Kui Su ,&nbsp;Enyuan Xing ,&nbsp;Xinsheng Niu ,&nbsp;Yuan Peng ,&nbsp;Yan Xue","doi":"10.1016/j.sedgeo.2026.107032","DOIUrl":"10.1016/j.sedgeo.2026.107032","url":null,"abstract":"<div><div>Polyhalite is a common potassium-bearing mineral of many ancient evaporitic systems, which can provide important ore resources for agricultural development. However, the genesis of polyhalite is still debated, especially for the origin of primary type. In order to provide novel perspectives and evidence for the genesis of polyhalite minerals, detailed sedimentological and sequence stratigraphic analyses, combined with sulfur isotope stratigraphy, were carried out using Lower Triassic core data in the Xuanhan area, northeastern Sichuan Basin. Fifteen microfacies grouped into six microfacies associations were identified. Furthermore, facies cycle types were recognized and the target intervals were subdivided into six fourth-order sequences and multiple parasequences within them. The result of fourth-order sequences was further validated by sulfur isotope chemostratigraphy. Sedimentary models in the study area and a formation model for primary polyhalite were established consequently. The coupled effects of paleoenvironmental conditions, tectonic activities, and provenance supply caused by sea-level fluctuations collectively led to the precipitation of primary polyhalite in the Sichuan Basin during the Early Triassic. Specifically, primary polyhalite occurs when K⁺- and Mg²⁺-enriched concentrated brine within halite saltern mixes with external influxes carrying Ca²⁺ and SO₄²⁻ ions, a process regulated by the dynamic fluctuations of multi-order sea-levels, especially the high-frequency ones. Moreover, the margins of the halite saltern and the gypsum saltern, as well as the spatial transition zone between them, created an ideal setting that can meet the above-mentioned geochemical conditions for the precipitation of polyhalite. These results contribute to the supplementation and refinement of the formation mechanisms of polyhalite minerals, especially for the primary ones.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"494 ","pages":"Article 107032"},"PeriodicalIF":2.9,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079588","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":"Sedimentology and sequence architecture of the inner shelf siliciclastic‑carbonate succession of the Lower to Middle Jurassic Shusha Formation, Gebel El-Maghara, North Sinai, Egypt","authors":"Mounir H. El-Azabi","doi":"10.1016/j.sedgeo.2026.107031","DOIUrl":"10.1016/j.sedgeo.2026.107031","url":null,"abstract":"<div><div>The sedimentological characteristics of Lower to Middle Jurassic deposits are poorly defined in the southern Tethys. These deposits represent shallow marine siliciclastic‑carbonate facies in Gebel El-Maghara, North Sinai, marked by vertically stacked meter-scale cycles; their origin remains unclear. They include a well-preserved example of Aalenian sediments, which are not so ubiquitous around the Tethys. An integrative sedimentological and sequence stratigraphic study provides new insights into the sedimentation patterns and stratal architecture of the siliciclastic‑carbonate cycles, representing the first cyclostratigraphic research on Uppermost Toarcian–Lower Bajocian deposits in the southern Tethys. The siliciclastic facies include shale and sandstone of barrier-island/lagoon, estuary, and beach-ridge strandplain, developed along a northwestward-dipping coast on an inner shelf during transgressive and early regressive events. The carbonate facies comprise limestone and dolostone, which formed during falling sea levels, marking late regressive events. Facies characteristics indicate the development of a passive-margin shelf in North Sinai during the latest Early Jurassic, earlier than previously assumed. The transgressive-regressive cycles reflect reciprocal sedimentation of alternating siliciclastic and carbonate systems, a relatively uncommon pattern in the geologic record. At intervals, deep incisions, along with dolomitization and ferribands, interrupt these cycles, leading to the formation of incised valleys filled with fluvial sandstones and estuarine sands deposited during sea-level rise. The incised valleys and other discontinuities divide the transgressive-regressive cycles into five distinct depositional sequences, each separated by boundaries linked to short-term eustatic sea-level falls. These falls, combined with a humid climate, largely controlled the initiation of incised valleys, resulting in sequence incompleteness, variations in cycle numbers and durations within equivalent sequences, and the preservation of lowstand deposits along the inner shelf. The clear record of global eustatic sea-level changes preserved on the passive-margin shelf enables more accurate dating of these sequences, revealing that the enclosed low-amplitude, high-frequency cycles have average durations of 54–400 kyr. These fourth- to fifth-order cycles were likely driven by climatic variations within the Milankovitch frequency band and are probably linked to global cooling intervals during the Aalenian and Bajocian.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"494 ","pages":"Article 107031"},"PeriodicalIF":2.9,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079587","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":"Influence of geomorphological dynamics and associated mineralogical structures on carbon mineralization processes within different surfaces of sand ramps","authors":"Mohsen Kargarian,&nbsp;Neda Mohseni,&nbsp;Reza Hosseinzadeh","doi":"10.1016/j.sedgeo.2026.107029","DOIUrl":"10.1016/j.sedgeo.2026.107029","url":null,"abstract":"<div><div>Sand ramps are recognized as critical archives for reconstructing Late Quaternary environmental changes, including sediment supply, paleoclimate, and soil carbon dynamics. We investigated the influence of geomorphic processes, weathering, and mineralogical dynamics on the mechanisms controlling the sequestration and mineralization of soil organic carbon (SOC) within falling and climbing sand ramps. Analyses including XRD, XRF, SEM, granulometry, physicochemical attributes, and weathering indices were conducted on sand ramps in central Iran. The abundance of carbonate minerals, sand-sized sediments, well-sorted clastic aggregates, and symmetrical grain distribution, combined with high roundness and minimal quartz corrosion, suggests that falling surfaces remain relatively intact with limited evidence of weathering. Despite the presence of carbonate minerals on falling sand ramps, the lower proportion of clay minerals and fine particles resulted in weaker organic matter binding compared to climbing surfaces. Conversely, the higher frequency of secondary clay minerals, poor sediment sorting, high angularity, and the formation of micro-scale features on granites indicate long-term exposure of climbing surfaces to chemical weathering. The elevated presence of illite, kaolinite, montmorillonite, as well as Fe₂O₃ and Al₂O₃ oxides, supported pedogenic processes and promoted microaggregate-associated carbon, rendering SOC less accessible to microbial mineralization. The findings indicate that climbing sand ramps represent a stabilized, pedogenically altered colluvial-aeolian apron overlying the granite, where primary sedimentary structures have been obscured by chemical weathering and clay illuviation. This contrasts with the structurally intact, gravity-dominated falling ramps. These results suggest that localized variations in geomorphic and weathering processes, alongside mineralogical composition, significantly influence the biogeochemical mechanisms controlling SOC mineralization throughout the evolution of sand ramps, offering valuable insights into carbon dynamics in arid and semi-arid regions.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"494 ","pages":"Article 107029"},"PeriodicalIF":2.9,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982104","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":"Mud volcanoes and synsedimentary deformation structures in Miocene lacustrine deposits over evaporites: Evidence of seismite interpretation","authors":"M.E. Sanz-Montero ,&nbsp;C. Giraldo ,&nbsp;J.P. Rodríguez-Aranda","doi":"10.1016/j.sedgeo.2026.107043","DOIUrl":"10.1016/j.sedgeo.2026.107043","url":null,"abstract":"<div><div>In continental tectonic basins, evaporite paleokarst and soft sediment deformation structures can occur together. However, distinguishing between the effects of tectonism and karst-related dissolution is challenging. Highly deformed beds overlying an evaporite paleokarst in the Miocene deposits of Madrid Basin have been studied in exceptional and laterally continuous outcrops. The paleokarst overburden is mudstone-dominated and displays closely packed fluid seepage structures in the form of mud breccias, tubes, fractures and veins networks connected to surface. At fault intersections, these features dip inwards decametric bowl-shaped to funnel-like structures bounded by circular fractures. This supports that these depressions represent collapsed mud volcanoes built at the surface by the fluid seepage features. They developed in periods of high pore pressures favoured by compressional regimes. Associated fluidization structures including in situ breccia, plastic intrusions, convolute and load forms support that earthquakes are the triggering mechanism.</div><div>The network of conduits is lithified by carbonate cements, including slickenfibers of aragonite, as well as by oxides of rare earths and iron‑manganese. The calcite and aragonite cements are highly depleted in ¹⁸O in comparison with the hosts suggesting overpressured aquifers as the source of freshwater fluids.</div><div>This analogue provides clues to identifying ancient, sagged beds as evolved fluid seepage systems and help to recognizing seismic events in lacustrine environments. Interpretations of sagging structures, common in worldwide-evaporitic paleokarst as purely dissolution-driven should be revisited considering the potential tectonic controls behind their rapid and extensive formation.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"494 ","pages":"Article 107043"},"PeriodicalIF":2.9,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079589","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}