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This paper presents the development of a constitutive law tailored for cross-anisotropic rocks and its application on the intersection of two perpendicular unsupported galleries excavated in the the Callovo-Oxfordian (COx) claystone, considered as a potential geological formation to host an underground radioactive waste repository in France. An anisotropic Drucker-Prager elastoplastic law with shear strength hardening is developed to describe the rock matrix behaviour, and the fabric tensor method is used to account for the anisotropy of material strength related to its sedimentary layered structure. The effects of material anisotropy and in-situ stress state anisotropy on the short-term mechanical behaviour of the rock surrounding the intersection area are investigated, and the extent and shape of the plastic zone is presented for different gallery orientations and construction stages. In particular, the results indicate that the distribution of orthoradial stresses and plastic strains are mainly influenced by the anisotropic nature of the rock, leading to a preferential horizontal extension of the plastic zone regardless of the orientation of the galleries. Additionally, the zone affected by the excavation of the intersection is noticeable at a distance of maximum two diameters from the walls of the main gallery. [ABSTRACT FROM AUTHOR]

The Oriente Basin is a back-arc basin located east of the Ecuadorian Andes in South America. Evidence suggests that during the Cretaceous period, the basin's margins received a terrigenous shallow marine sedimentation. Due to regional variations in accommodation and depositional controlling factors near a shoreline, the sedimentary environments in the fluvial-marine transitional zones exhibit considerable variability. In this study, we analyzed the sedimentological characteristics of the M1 Sandstone Formation unit (∼83 Ma-72 Ma), which comprises a set of ancient estuarine deposits preserved in the northern part of the basin. We quantified the impact of mixed hydrodynamic processes on the distribution of tidal-dominated estuarine facies and discussed the development conditions and evolutionary processes of an estuarine formation under the background of persistent transgression. Core, well log, and seismic data provide evidence for reconstructing the tidal-dominated estuarine environment. In the core section, we identified 14 lithofacies and 7 major facies association types. The frequent occurrence of sedimentary structures associated with tidal currents indicates that tidal processes extensively reworked the deposits. The spatial distribution trends of facies associations reveal the evolution of mixed hydrodynamic conditions dominated by tidal processes in the estuary and allow us to divide the M1 Sandstone Formation into four depositional periods: the initial development, rapid development, decline, and the post-infilling open coast tidal flat development periods. Furthermore, through a systematic analysis of hydrodynamic conditions and sediment distributions, we identified multiple depositional centers in the tidal-dominated estuary influenced by different hydrodynamic processes. These correspond to the upstream fluvial-dominated tidal point bar depositional region, the middle mixed-energy depositional interaction zone, and the downstream tidal-dominated tidal sand bar depositional region. In these regions, the substantial accumulation of sandy deposits, represented by tidal sand bars, reflects the high accommodation space characteristic of tidal-dominated estuaries. Our findings indicate that the slow subsidence of a broad and gently sloping coastal topography, stable material transport, and sea level change dominated by marine transgression ensured the necessary accommodation for the development of the estuary in the M1 Sandstone Formation. The sedimentological study of the M1 Sandstone Formation provides a case for understanding the sedimentary evolution in fluvial-marine transitional zones. • Paleogeographic reconstruction of M1 Sandstone Fm. in the Oriente Basin reveals the potential development of estuarine sediments. • A facies model and an evolutionary model are built, hydrodynamic analysis and sequence-controlling factors involved. • Comparing to previous models of M1 Sandstone Fm., a new clastic sedimentary plan of ancient shoreline is proposed. [ABSTRACT FROM AUTHOR]

• We propose a new intelligent identification and classification strategy for GPR. • The methodology is tested on a real GPR dataset acquired on the Piscinas dunes. • Subsurface structures can be identified with an intelligent and repeatable manner. The interpretation of Ground-penetrating Radar (GPR) is commonly performed by different GPR experts, resulting in somehow subjective results, especially in complicated backgrounds like depositional sedimentary environments. In order to improve data interpretation, we propose a new intelligent identification and classification strategy based on texture characteristics of GPR to objectively describe and assess subsurface structures. We exploit a K-means++ clustering method to classify different sedimentary units, testing the methodology on a real GPR dataset acquired on the Piscinas dunes, southwestern Sardinia, Italy. The GPR dataset is fully georeferenced and we used not only amplitude data, but multi-attributes extracted using the Gabor filters. Besides, we also evaluate the applicability and feasibility of the Principal Components Analysis (PCA) dimension reduction algorithm to reduce redundant information in dataset selection. The results show that the proposed algorithm can successfully identify and classify the different typical radar facies of subsurface sedimentary structures with an intelligent, objective and repeatable manner, not only identifying sedimentary layering, but also accurately dividing the subsurface sequence in the different depositional and erosional facies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pore-scale insights into effect of clay mineral on hydrate-based CO 2 sequestration. • Hydrate formation and distribution is highly dependent on clay stability. • CO 2 storage capacity is improved by 5.8% with the presence of montmorillonite. • Clay migration will result in complex pore evolution and skeleton deformation. Geological sequestration of carbon dioxide (CO 2) in solid hydrate state beneath seafloor is an attractive option for mitigating global warming. However, as a representative geological factor in marine sediment, clay mineral still plays an ambiguous role in hydrate depositional behaviors and reservoir structural evolution, which provides an obstacle to accurately assessing the potential and security of marine CO 2 sequestration. In this work, spatiotemporal hydrate distribution and sedimentary structure evolution in the presence of two typical clay minerals with different structures and properties were investigated by low-field nuclear magnetic resonance (LNMR) technique. There was an inextricable interaction between clay-fluid migration and hydrate phase transition in porous sediments. Pore plugging owing to migration, agglomeration, and redeposition of unstable kaolinite (KIT) particles weakened final CO 2 storage capacity by 10.3% and exacerbated heterogeneous hydrate distribution. CO 2 storage capacity in montmorillonite (MMT) system was significantly improved with a water conversion of 82.7% for the high interaction potential between clay particles and favorable mass transfer conditions within the reservoir. However, clay minerals accelerated CO 2 hydrate destabilization and disrupted the initial water distribution and pore structure. Migration of MMT fluid with high viscosity and gel property during hydrate phase transition resulted in a complex pore evolution and irreversible sedimentary skeleton deformation, providing an effective warning for field implementation of geological carbon sequestration. The findings expand the understanding of pore-scale interaction between clay minerals and gas hydrates, and provide valuable support for stratigraphic adaptability evaluation of CO 2 sequestration in marine sediments. [ABSTRACT FROM AUTHOR]

The interactions of tectonics and eustasy on the stratigraphic architectural evolution of the early Eocene-early Miocene Al Jabal Al Akhdar carbonate sedimentary successions were evaluated. This evaluation was achieved through detailed analyses of microfacies, depositional interpretation, and sequence stratigraphic framework of five measured sections located within the Al Jabal Al Akhdar Uplift, northeast Libya. The study interval was subdivided into distinct microfacies based on lithological changes, grain size and components, sedimentary texture and structures, fossil contents, color, and vertical stacking pattern. Six major depositional settings were delineated: restricted lagoon, open marine lagoon, platform margin and shoals, platform-margin reefs, foreslope, and middle to lower slope. Four third-order unconformity-bounded depositional sequences were identified based on vertical and lateral facies distribution, variations in fossil contents, and diagenetic features. Each sequence is composed of a transgressive-regressive interval, except for the younger sequence, which only contains a transgressive unit. Four evolutionary stages are recognized: initiation, growth, high-relief platform, and subaerial exposure. Subsidence resulting from tectonism and sediment loading, coupled with rising sea-level, created the accommodation space for the sedimentation of the studied carbonates. Repeated eustatic sea-level fluctuations controlled the internal stratigraphic heterogeneity and sequence development. Tectonic uplift caused a major sea-level retreat, resulting in the emersion of the carbonate sequences. The pre-existing Mesozoic and Paleocene sequences that underwent major uplift during the Late Cretaceous-early Eocene formed a shallow-water positive-antecedent topography for the formation of the carbonate sediments. This study establishes a carbonate sequence stratigraphic hierarchy of different cyclic sedimentation orders and improves our knowledge of sedimentary and stratigraphic architectural evolution and depositional mechanisms of carbonate platforms in an inverted basin setting. This knowledge can aid in predicting the distribution of lithofacies and depositional systems of economic importance. • Nine microfacies defined within the Eocene-Miocene Al Jabal Al Akhdar carbonates. • Toe of slope, foreslope, margin and shoals, margin reef, restricted, and open lagoon lagoon are the major depositional settings. • Eocene-Miocene carbonates were subdivided into four depositional sequences. • Sequence evolution was mainly controlled by and tectonics and eustasy. [ABSTRACT FROM AUTHOR]

Microbial mats have existed for much of Earth's history. They represent some of the earliest evidence of life, are essential in biogeochemical cycles, and played a pivotal role in oxygenating the atmosphere. In addition, benthic microbiota impact sediment properties by enhancing the cohesion and stability of the substratum, a process known as 'biostabilization', which affects sediment dynamics and rheology. A substantial body of research has focused on experimentally quantifying biostabilization in siliciclastic sediments. This review compiles and synthesizes these studies in order to facilitate comparison of results. They, in turn, are compared with; (1) the Shields' diagram, (2) shear stress values in shallow marine environments, and (3) occurrences of microbially induced sedimentary structures in the marine stratigraphic record. The findings reveal significant variability in outcomes, with increases in the Shields' Parameter ranging from 0.1 to 4 orders of magnitude. They also demonstrate that high-energy hydrodynamic conditions, such as those above fairweather wave base, inhibit microbial colonization. Additionally, the review briefly discusses two applications of the data: (1) refining models of the Great Oxidation Event, and (2) evaluating microbial biostabilization as a response to increased coastal erosion driven by climate change. [ABSTRACT FROM AUTHOR]

Ichnological research has generally assumed that abyssal plains are dominated by quiescent, homogenous environmental conditions. Thus, deep-sea trace fossil assemblage changes have been usually linked to significant spatial and temporal environmental variations. Here, we conducted a comparative ichnological analysis between a small abyssal hill (50 m elevation) and the surrounding abyssal plain; this modest bathymetric variation is known to generate substantial environmental heterogeneity for the benthic fauna community of the Porcupine Abyssal Plain (c. 4850 m depth), Northeast Atlantic. Based on X-ray data from a 5 × 5 core grid emplaced in two box cores, we compared hill and plain bioturbational sedimentary structures, including trace fossil assemblages (e.g., ichnotaxonomy) and biodeformational structures (e.g., mixed-layer depth). We observed that topographically-enhanced near-bottom currents over the hill likely produce significant changes in depositional dynamics and sediment properties (e.g., grain size, organic matter content and degradation), and control specificities of bioturbational sedimentary structures (e.g., trace fossils, mixed layer attributes such as thickness, mottled background, discrete traces). Palaeoichnological data suggested that the abyssal plain had experienced consistent conditions during the last thousands of years while the abyssal hill recorded improving environmental conditions for the trace maker community. Our results highlight the complexity of the deep-sea environment, demonstrating that small changes in bioturbated sedimentary assemblages appear even within the same box core (m-scale), and that substantial changes can occur due to environmental heterogeneity (e.g., subtle topographic variations) at the local scale (km-scale). Considering the vast global extent of abyssal hill terrain, we suggest that their influence on the bioturbational sedimentary record may be significantly under-appreciated and require more attention in palaeoenvironmental reconstructions. • Our results highlight the complexity of deep-sea for the trace maker community. • Differences in specific ichnogenera were related to environmental features. • Ichnology shows improving environmental conditions over the abyssal hill. • Trace fossils record consistent environmental conditions at the abyssal plain. • Local (km-scale) environmental heterogeneity affect trace assemblages. [ABSTRACT FROM AUTHOR]

Cymbella janischii, an invasive species of diatom, has been broadening its geographical range in Japan since 2004, flourishing in substantial colonies in river beds. As thick and mucilaginous colonies of this diatom often cover large areas of river beds, this elicits concerns regarding the potential alteration of sedimentary bottom structures and resultant effects on the native ecosystems. The presence of the diatoms growing on the body surface of two aquatic beetles, Grouvellinus nitidus (Elmidae) and Ectopria opaca (Psephenidae) in a Japanese river was confirmed. This constitutes the inaugural documentation of invasive diatoms having a specific relationship with native aquatic insects at an individual level. [ABSTRACT FROM AUTHOR]

Many works in the last decades underline the role of evaporites, not just as a conditioning factor but as the engine for subsidence and eventually basin inversion. The western Mediterranean alpine ranges are being investigated in this regard because of the presence of discontinuous units of Permian to Triassic evaporites, deposited in the western Tethys basins. This work presents a thorough analysis of two particular structures (Cañada Vellida and Miravete anticlines) in the intraplate Maestrazgo basin (eastern Iberian Chain, Spain) in which evidence to support their reinterpretation as salt‐driven structures have been recently reported. Our analysis includes (i) a comprehensive stratigraphic and structural study of the folds along their entire trace, (ii) the compilation of thickness and distribution of evaporite–bearing and supraevaporite units, paying special attention to changes in the thickness of units in relation to anticlines, and (iii) the study of fault patterns, sometimes in relation to the mechanical stratigraphy. All three aspects are also documented and discussed on a regional scale. The new data and interpretations reported here reinforce the extensional origin of the Late Jurassic–Early Cretaceous basins, and the role of regional extensional tectonics as the responsible for the development of first‐order syn‐sedimentary normal fault zones driving the formation and evolution of sub‐basins. These basins were subsequently inverted and deformed, including the formation of complex, box‐geometry anticlines that, in their turn, controlled deposition in Cenozoic basins. The review of the arguments that support the alternative of salt tectonics for the origin of such anticlines has allowed us to delve into the sedimentary and tectonic evolution of the inverted extensional basins and to propose a specific model for the development of these faulted anticlines. The role of salt levels and other interlayered detachments in the structuring of sedimentary basins and their inversion is also pondered. The observations in the eastern Iberian Chain reported here have implications to assess ongoing reinterpretations in terms of salt tectonics in other alpine basins and ranges of the western Mediterranean. [ABSTRACT FROM AUTHOR]

While Ediacaran cap dolostones research is a hot topic, detailed sedimentological analysis of barite‐bearing cap dolostones remains scarce. Here, new data are presented from Xiangerwan in northern Three Gorges, South China, to illustrate the sedimentary characteristics, depositional environment and formation mechanism of the barite‐bearing cap dolostone. In ascending order, the succession is divided into: (i) pebbly dolostone; (ii) dolostone with unusual sedimentary structures (for example, sheet cracks and tepee structures); and (iii) barite‐bearing facies. The gravels of the pebbly dolostone record the slow relative sea‐level rise during post‐glacial transgression, with a local terrestrial influence. Sheet cracks and tepee structures represent water escape structures in the supratidal and upper intertidal zone, and gently wavy stromatolites in barite‐bearing facies are deposits typical of the upper intertidal zone. In addition, primary radial length‐slow dolomite cements were originally precipitated at the seafloor. In general, the cap dolostone was formed in a shallow‐water ramp environment. The form and sedimentary characteristics of barites indicate a primary (syngenetic) origin and help to divide the barites into bladed (Type I) and needle‐like (Type II) variants. With the ongoing melting of the Marinoan glacier and water density stratification, the cap dolostone was gradually precipitated, accompanied by exotic gravels input. The stratification persisted, and special sedimentary structures were widely developed. Phosphorus and barium ions were brought up from the deep basin by upwelling, indicated by the flourishing stromatolites and barite fan deposition. Above the sediment–water interface, the Type I barite first grew upward from substrates, then the Type II barite could grow either in the reverse 'V‐shape' cavities between and within the Type I barite clusters, forming rhythm layers with bedded dolomite, or scattered in the laminae of stromatolites or surrounding dolomite. Finally, the formation of barite fans indicates the end of cap dolostone deposition and deeper water sedimentation. [ABSTRACT FROM AUTHOR]

The acoustic basement of the Knipovich Ridge southeastern flank was interpreted on the time-domain CDP seismic sections and calibration of Bouguer gravity anomalies to depth was done with construction of basement structural map for the area with an oceanic crust type. On this map, to the east from Knipovich Ridge, there is a longitudinal uplift, which is the northern continuation of the Senja fracture zone and interpreted as a transverse ridge on the transform fault board. This uplift is framed by linear clusters of the off-axis seismicity epicenters, indicating the activation of this area structures. The CDP seismic data above the identified uplift show deformations of the Pliocene‒Quaternary sedimentary cover with reverse fault and shear kinematics. Physical modeling of structure formation in the area of the Knipovich Ridge clearly demonstrated the features of the main tectonic elements during oblique spreading. The result, which is especially close to reality, was obtained by conducting combined experiments with bending the weakened zone to large angles between the direction of stretching and perpendicular to the axis of the weakened zone. At the same time, the appearance of typical accretion swells and nontransform axis displacements simulating the structures of the southeastern flank of the Knipovich Ridge is close to reality. The series of experiments conducted to study the possible formation of the spreading axis jump in an easterly direction to the continuation of the Senja fracture zone showed the fundamental possibility of this structure activation, which we consider as one of the reasons for the formation of features observed in geophysical data. The current position of the active zones of the region, seismicity, the structure of the basement and the structure of the sedimentary cover indicate a shift in the activity of the main tectonic elements in the eastern direction relative to the current position of the extension axis. A likely scenario for further development of the region is the transformation of the Knipovich Ridge into one or the series of transform faults parallel to the western edge of the Barents Sea shelf and the series of short spreading segments between them. [ABSTRACT FROM AUTHOR]

Interpretation of unconsolidated Quaternary sedimentary core is difficult if key diagnostic features are obscured or not present, therefore traditional facies analysis is challenging. However, sediment texture remains a universal attribute which can be used to interpret sedimentary core. Here we present an automated classification workflow which implements Extreme Gradient Boosting and Bayesian Optimization of hyperparameters to differentiate estuarine sub‐depositional environments. We use 19 textural attributes, measured using laser particle size analysis of surface sediment samples from the Ravenglass Estuary, Cumbria, northwest England, to make unbiased classification of sub‐depositional environment and estuarine zone. Two predictive models created using the automated workflow are presented and evaluated using a suite of evaluation metrics, confusion matrices, and spatial analysis to understand their geological implications. Model 1 keeps all sub‐depositional environments discrete and has an overall accuracy of 68.96%. Model 2 merges related sub‐depositional environments to form inner‐coarse and outer‐estuary zones and has an overall accuracy of 84.14%. Both models have been applied to textural data obtained at 5 cm intervals from a Holocene core drilled through a tidal bar in the Ravenglass estuarine succession, NW England, to classify palaeo sub‐depositional environment. Predictive output of the models suggests that the core consistently experienced inner estuary deposition; all inner estuary environments are represented in the core. The workflow presented here could be applied to datasets from other marginal marine depositional systems to enhance the interpretation of their subsurface deposits. Ultimately, detailed interpretations of ancient, buried deposits could be made using models derived from analogous modern systems. Plain Language Summary: Geoscientists typically rely on characteristic sedimentary structures when interpreting core. In Quaternary core, distinguishing structures can be absent or obscured as sediment is poorly consolidated (falls apart easily). In this case, a geoscientist must rely on alternative methods that can aid core interpretation. Using proven statistical links between the size, and distribution of sand grains and sedimentary environment, we have developed a new predictive machine learning model, using freely available open source software, trained to surface sediment from a well‐studied estuary in the UK. The new surface calibrated predictive model can be used to aid a geoscientist with interpretation of core drilled into the estuary to determine how depositional environment changed with time. We have applied the predictive models to a section of core, that lacks characteristic and distinguishing features, and made subtle interpretations that had been missed during traditional sedimentary core interpretation. The use of the new predictive machine learning model permits unbiased interpretations, and should be used alongside established core interpretation methods. The models produced here are flexible and can be adapted for use as part of any classification problem that uses either numerical, or categorical data. Key Points: We propose a machine learning workflow to predict sub‐depositional environment in an estuary using sediment texture (e.g., sorting)Two surface‐calibrated predictive models are presented to automatically classify estuarine core sediment samplesApplication of the predictive models to core data allows for an unbiased interpretation of the sandy estuarine sequence [ABSTRACT FROM AUTHOR]

Hybrid event beds comprise up to five (H1-H5) vertically stacked divisions, including a basal matrix-poor turbidite sandstone (H1), overlain by a banded sandstone (H2) with alternating matrix-rich and matrix-poor bands; this gives way to a matrix-rich sandstone (H3) which constitutes the "linked debrite". Hybrid event beds include transitional flow deposits, slurry beds and matrix-rich sandstones. The Special Issue "Advances in Sedimentology and Coastal and Marine Geology" has collected significant research articles advancing the state of the art of the corresponding sub-disciplines. [Extracted from the article]

At the southernmost part of the Ryukyu subduction zone, six long-offset multi-channel seismic profiles were collected across three forearc basins and the southern Ryukyu accretionary prism during the TAIGER experiment in 2009 and the TAICRUST project in 1995. These profiles were reprocessed to generate pre-stack depth migration (PSDM) sections. In addition, two velocity-interface models were obtained by reanalyzing active source data recorded from 28 ocean-bottom seismometers during the same TAIGER experiment, in consideration of the PSDM sections and previous tomography models. Due to the northwest convergence of the Philippine Sea Plate (PSP), it is suggested that the Gagua Ridge may have been obliquely subducting northwestward beneath the Ryukyu prism and below the Nanao Basin. The PSDM sections and the velocity-interface models indicate the subducted Gagua Ridge causing the uplift of the sedimentary basement and the lower crustal structure below the Nanao Basin. The sedimentary and crustal structures near ~ 122.5° E beneath the Nanao Basin were also uplifted where shallow earthquakes had occurred by the oblique subduction of the Gagua Ridge depicted in the isopach map of the crust. Furthermore, a recent earthquake (Mw ~ 6.0) occurred near the northeast coast of Taiwan in 2018 at a depth of approximately 12 km below the Hsincheng Ridge. Our study suggests that this earthquake was caused by a thrust fault near the décollement, which might have been formed by the subduction of the PSP. [ABSTRACT FROM AUTHOR]

The rift valley of the Gakkel Ridge was divided into three segments according to sub-bottom profiling and seismoacoustic studies carried out by R/V Akademik Fedorov at the Gakkel Ridge in 2019–2020, and on seismic data of 2011–2015. West of 75° E, the rift valley crosses the Gakkel Ridge approximately in the middle, as was expected based on the assumption that the rift valley runs along the spreading axis that formed this ridge. East of 75° E, the rift valley shifts to the southwestern edge of the ridge, and, thus, it can be concluded that the spreading axis jumped to its present position relatively recently (in the Pliocene). Finally, to the south of the the Gakkel caldera (about 120° E, 81° N), the rift valley is manifested in the sections as a young graben through many kilometers of sediments. [ABSTRACT FROM AUTHOR]

Turbidity currents commonly bypass sediment in submarine channels on the continental slope, and deposit sediment lobes farther down-dip on the flat and unconfined abyssal plain. Seafloor and outcrop data have shown that the transition from bypass to deposition usually occurs over complex zones referred to as channel–lobe transition zones (CLTZs). Recognition of these zones in cores and outcrop remains challenging due to a lack of characteristic sedimentary facies and structures. This paper focuses on Unit E of the Permian Fort Brown Formation in the Karoo Basin, South Africa, in the Slagtersfontein outcrop complex, which has previously been interpreted as a CLTZ. This study integrates thin-section micrographs, sedimentary facies, bed-set and stratigraphic architecture, and palaeoflow directions to achieve a multiscale analysis of CLTZ features. A novel process-based facies scheme is developed to evaluate deposits in terms of the depositional or erosional tendencies of the flows that formed them. This scheme allows bypass to be distinguished from depositional zones by the spatial distribution of certain sediment facies. Areas of net sediment bypass were predominantly marked by erosive sediment facies and a larger variability in palaeoflow direction while depositional areas showed a lower variability in palaeoflow directions. Metre-scale structures in the bypass-dominated area reveal seafloor erosion and scour formation. Field relations suggest the presence of a ∼500 m long mega-scour in the CLTZ. The characteristic structures documented here are applicable for identifying CLTZs in sparse datasets such as outcrops with limited palaeogeographical context and sediment cores obtained from subsurface systems. [ABSTRACT FROM AUTHOR]

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Based on the data of deep seismic sounding, which were obtained in 2003 on the R/V Mezen in the Bay of Bengal, two velocity sections have been constructed that characterize the structure of the crust in its southern part. Seismic studies have shown that, in the Bengal sector of the East Indian Ridge (EIR), a subcontinental type of crust is developed, the thickness of which reaches 19.5 km. At the western foot of the EIR, the velocity section is represented by a reduced transitional crust 13 km in thickness. Using the NGDS digitized database of the thickness of the sedimentary cover in the Indian Ocean, which is freely available on the Internet, a map of the depths of the acoustic basement is built which makes it possible to identify the morphological features of its structure. A seismostratigraphic analysis is carried out of the structure of the sedimentary cover that has developed (a) on horst blocks grouped at the foot of the western slope of the EIR, (b) on the crest of the EIR, and (c) in the adjacent part of the Central Basin. It is established that, in the Late Cretaceous–Paleogene, the Bengal sector of the EIR and horst blocks represented a single platform structure. In the latest phase of tectonic activation, which manifested itself in the late Miocene–Pliocene, the platform was divided into horst blocks, which experienced differentiated subsidence. It has been established that horst blocks play the main role in the structure of Ridge 85°. This ridge is not structurally unrelated to the Afanasy Nikitin Rise and, by its nature, is not a "tracer ridge." [ABSTRACT FROM AUTHOR]

The West Bogda Mountains separate the two largest petroliferous sedimentary basins in Northwest (NW) China and may record the evolution history of the Central Asian Orogenic Belt (CAOB). The timing of the initial uplift of the West Bogda Mountains is debated, which may provide the robust constraint on the CAOB evolution. Here we present an integrated study of sedimentology, geochemistry, and detrital zircon geochronology to constrain the timing of the initial uplift of the West Bogda Mountains. The late Lower Permian Lucaogou Formation in the West Bogda Mountains is dominated by organic-rich laminated shale, gravity flow deposits and dolomite without shallow-water sedimentary structures, suggesting a deep-water lacustrine depositional environment. The Middle Permian Quanzijie Formation is mainly composed of poorly sorted and sub-rounded conglomerate, which indicates that the depositional environment changed to an alluvial fan. The depositional environment changed to a meandering river system in the early Upper Permian Wutonggou Formation, with evidence from the widely developed cross-bedding in its sandstone and the typical 'dual structure'. The compositions of immobile elements and detrital zircon U-Pb geochronology reveal changes in sediment sources from the early to late Permian. The sediments of the late Lower Permian Lucaogou Formation were mainly sourced from the North Tianshan, while the sediments in the Middle Permian were mostly locally derived. Combining these evidences, we infer that the initial uplift of the West Bogda Mountains likely occurred in the period from the late Lower to Middle Permian (~289.8 Ma to ~265.7 Ma), and was probably caused by the intracontinental collision between Junggar Block in the north and the Tarim Block in the south. [ABSTRACT FROM AUTHOR]

The distributary channel reservoirs in the delta plain are important reservoir bodies at home and abroad, which have internal sand bodies of various shapes and sizes with a conplicated quantitative relationship. Due to the lack of systematic research on the sedimentary mode and architectural characteristics of favorable reservoirs, the development effect of natural gas is restricted to a certain extent. Based on the integrated application of modern deposit research, field outcrop anatomy, well log identification, and other related techniques, this study comes up with a method for architecture analysis and sand body description of distributary channels. This method uses modern deposit research to determine the sand body type of distributary channels, uses depositional model to study on architecture anatomy, and uses well infomation of dense well pattern to find out the scale of sand bodies, then plots typical charts showing stack modes, grain size changes, lithologic association, and logging response for different sand body types. This study also researches the development patterns and internal architechtural characteristics of different sand body types in distributary channels, and innovatively forms a technique of identifying streamlines by "beading method" and describing the association relationships between channels and different sand bodies by "mosaic method," which clarifies the formation mechanisms and internal architecture of five sand body types, as well as their distribution patterns in channels. There are mainly three results in this study. Firstly, the shape and internal architecture of the channel bars are controlled by hydrodynamic intensity. More specifically, the shape of a channel bar is constrained by the symmetry of the channel, while the scale of that is controlled by the flow intensity. Secondly, there are five types of sand bodies deposited in the distributary channels which are channel bar, convex-point bar, straight-point bar, branching-point bar, and combining-point bar. Also, the statistical results present that both the length–width ratio of bars from different channels and the width ratio of channels and bars have strong regularity. Thirdly, the widths of channel bars in distributary channels of the delta plain from Daniudi Gas Field are from 300 to 600 m, while the lengths are from 1200 to 2300 m, and the average length–width ratio is 4:1. There are great difference in various kinds of channel bars, and the main beneficial reservoir body types are channel bar, convex-point bar, straight-point bar, and branching-point bar. The method has a good guiding significance for sweet spot evaluation and effective development of fluvial sedimentary system. [ABSTRACT FROM AUTHOR]

The dual neural network (DNNW) model combines two neural networks to imitate artificial sedimentary facies division by learning the characteristics of multi-type logging curves corresponding to the sedimentary microfacies of a coring section. The model predicts many non-coring wells in the research zone through logging data. After comparing the classification performance of a fully connected neural network (FCNWW) and AutoML when dealing with three FNDA, EALS, and HRA datasets, the DNNW shows high stability and assists exploration in the Moxi gas field. Four sedimentary microfacies are identified through thin section observation, including thrombolite boundstone (MF1), laminated stromatolite boundstone (MF2), siliceous laminar boundstone (MF3), and micritic dolostone (MF4). Results suggest the fourth member of Dengying Formation in the Moxi gas field is carbonate platform facies deposition: specifically, restricted platform and platform margin. [ABSTRACT FROM AUTHOR]

The Cambrian Series 2–Miaolingian transition is a pivotal period during Earth history, which witnessed the decline of biodiversity and the reduction in biomass, i.e., the redlichiid–olenellid trilobite extinction. The notable δ13C excursion (RECE) near the Cambrian Series 2–Miaolingian boundary in east Gondwana and China apparently corresponds with the redlichiid trilobite extinction. To better understand the causal mechanism of this biotic crisis, we report the carbon isotope stratigraphy and facies changes from Cambrian Series 2–Miaolingian transition of the Mantou Formation on the southern North China Craton. The carbon isotope excursions at the Cambrian Series 2–Miaolingian transition in the study area are 0.7‰ in the Chishanhe section and −0.2‰ in the Luoquan section, respectively, showing a weak negative excursion or even no negative excursion. The sedimentary environments in the study area gradually changed through time from a clastic tidal flat to a carbonate platform across the transition, which indicated a gradual rise in sea level, with anoxic conditions occurring predominantly before the RECE δ13C excursion. Microbially induced sedimentary structures and oncoids occurred widely at the top of Cambrian Series 2. Abundant metazoan trace fossils were preserved in the Miaolingian Series of the study area. The evolution of biogenic structures across the Cambrian Series 2–Miaolingian transition indicates the emergence of harsh environments associated with the proliferation of MISS and oncoids at the RECE horizon and the recovery of benthic metazoan fauna after the RECE biotic crisis. [ABSTRACT FROM AUTHOR]

Detailed sedimentological and sequence stratigraphic analysis of the upper Paleocene–lower Eocene shallow-marine limestones exposed in the Eastern Gafsa basin in southern Tunisia provides a new insight into the sedimentary response to climate and sea-level changes revealed in the southern Tethysian margin. The 81 m thick Ayaycha Formation is composed of three units. The lower unit is built up of channelized fossiliferous limestones superposed by the sequence of alternated thin–to medium-bedded limestone and marls. The second unit is dominated by marls, and the third unit is formed by channelized limestones lying within bioclastic limestones. Based on their lithological features and strata geometries, the Ayaycha Formation exhibits seven facies evolving from offshore to intertidal environments. Clay paragenesis shows that the lower unit was accumulated under the warm and seasonally contrasting climate, or probably, repeated change of dry and humid seasons. The lower unit corresponds to the upper Paleocene deposits. The upper Paleocene-lower Eocene, middle and upper units were accumulated under warm climate and cover the time interval of global paleoecological crisis known as the Paleocene–Eocene Thermal Maximum (PETM). The consequence of this global warming was the sea level rise, which correspond to the transgressive pulse occurred prior to the Paleocene–Eocene boundary. Integrated sequence stratigraphic analysis showed that the Ayaycha Fm is formed by the stacking of thirteen third-order depositional sequences. Each depositional sequence results from a transgressive-regressive cycle in shallow marine environments. [ABSTRACT FROM AUTHOR]

The Ulban terrane composed of a thick sedimentary series of Jurassic clastic deposits is located at the junction of the Mongol-Okhotsk and Sikhote-Alin orogenic belts. The results of studying the deposits assigned to the Middle Jurassic Elgon Formation are presented. The structure of the sedimentary succession and sedimentological features, which indicate sand-rich turbidite sedimentation in a setting of sandy lobe of turbidite fans or ramps, are considered and illustrated. The paleocurrent directions measured in outcrops and calculated using the anisotropy of the initial magnetic susceptibility suggest the transport of clastic material from western or southwestern sources. [ABSTRACT FROM AUTHOR]

The Paleoproterozoic Gwalior Group of central India holds carbonates at two stratigraphic levels within the Morar Formation, exposed at the Bela-Ki-Bauri and Utilla sections. Limestones are micritic/sucrosic in grain size and dominantly calcitic in mineralogy. Preservation of primary sedimentary structures, poor correlation between δ13C and δ18O values and a narrow range in isotopic values suggest preservation of near-pristine sea water signature. δ13C values for Bela-Ki-Bauri and Utilla carbonates vary between –1.1 and –2.8‰ and 0.5 to 0.1‰, respectively, with an average 2.37‰ depletion in value in Bela-Ki-Bauri carbonates. Without any significant difference in total organic carbon content between the two studied sections, the depletion in δ13C value within Bela-Ki-Bauri carbonates is correlated with influx of 12C enriched meteoric water at a shallow marine setting dominated by stromatolites and algal laminites. The 87Sr/86Sr values obtained from Gwalior carbonates (0.707403–0.711283) are well consistent with Proterozoic carbonates and a value of 0.707403 is considered composition of Gwalior seawater. Research highlights: For the first time Strontium isotopes data are reported from Paleoproterozoic Gwalior Basin. 87Sr/86Sr values from Gwalior carbonates are well consistent with other Proterozoic carbonates. Positive shift in δ13C in the Gwalior carbonate helps to infer the paleo bathymetry. [ABSTRACT FROM AUTHOR]

This study entails the characterization of the depositional environment of the Hupo Basin shelf. By means of sedimentary structure analysis, grain size, textures, sediment color, as well as optically stimulated luminescence (OSL) and accelerator mass spectrometry (AMS) ages, a sediment core (19ESDP-101, 120 m) has been interpreted to be the product of shallow-water contourites. The shallow-water (165 m) contourite deposits observed in the core are divided into seven sedimentary facies grouped into four facies associations (FA): FA1) contourite drift, FA2) contourite drift/channel transition, FA3) contourite channel/drift transition, and FA4) contourite channel. FA1 resulted from the interaction between hemipelagic fallout, low-density gravity flow, and sedimentation under low velocity bottom currents. Compared to FA1, both FA 2 and FA3 are indicative of higher velocity bottom currents, owing to their relative increase in grain size and the presence of subtle indicators of bed-load transport. FA 4 portrayed massive to slightly bedded sand, representing a contourite channel environment with high-energy conditions. Fluctuations in the bottom current activity, related to the intensification and deceleration of the North Korean Cold Current (NKCC), have caused fluctuations between contouritic and hemipelagic-dominated periods. The vertical sedimentary facies stacking patterns observed at the Hupo Basin site suggested that, over time, the depositional processes changed at the site where the core was optained. The facies association stacking pattern suggests the lateral migration of the contourite depositional system and continuous flow of the NKCC. Our findings and interpretations can serve as a much needed reference for shallow-water contourite recognition in modern environments. Moreover, our proposed model can be used to more accurately interpret shallow-water contourite deposits. [ABSTRACT FROM AUTHOR]

Changes in hydraulic properties of the flow are reflected in the vertical and/or lateral variation in sedimentary structures. In turbiditic sandstones, common sedimentary structures are grain size grading, planar lamination, and cross-lamination. This research is aimed at applying the advances in non-destructive X-ray fluorescence (XRF) mapping technology to detect various sedimentary structures in sandstones. XRF micro-imaging is able to produce in situ elemental–distribution maps of rock samples. This research applied a statistical technique of discriminant analysis to reduce the dimensionality of the variables in order to determine the key element intensity that can be used as a proxy for the observation of sedimentary structures in turbiditic sandstones. The results suggest that principal component analysis can identify the elements and elemental ratios with high loadings that explain the multivariate data. The sedimentary structures are shown in spatial elemental distribution maps and elemental ratios. The methodology here could be applied to in situ µXRF scans where the observation of sedimentary structures or grain size measurements is inaccessible such as in boreholes.

This document is a citation for the 2021 Barringer Award given to G. Osinski for his contributions to the field of impact studies. Osinski's research has focused on hypervelocity impact processes and their products, particularly in relation to impact melt-bearing lithologies. He has made significant discoveries regarding the nature of impact melt rocks and the composition of suevite deposits. Osinski has also proposed a modified working hypothesis for ejecta emplacement on terrestrial planets and has explored the relationship between impacts and the biosphere. In addition to his research, Osinski has been actively involved in public outreach, developing programs and initiatives to educate and engage the wider community. Overall, Osinski's work has made major contributions to our understanding of impact cratering processes and their effects. [Extracted from the article]

In this study, physico-mechanical properties and durability of 4 onyx-travertines from Sinincay (Ecuador) were investigated. These onyx-travertines are commonly used for decorative purposes in buildings in the Historic Center of Santa Ana de los Ríos de Cuenca. The aim of this work was to characterize these stones and determine the variation of their physico-mechanical properties, such as mass loss and water absorption, after being subjected to four durability tests: salt crystallization (S-C), freeze–thaw (F-T), thermal shock (T-S) and acid attack (A-A). In addition, Scanning Electron Microscopic (SEM) analyses were carried out to record weathering patterns and understand the deterioration mechanism. Results show that these stones' sedimentary structure is stratified. Two specimens exhibit geometrical features consistent with porous laminated facies and the remaining two have slightly porous cryptolaminated ones. Facies' structure orientation is also found to determine mechanical strength, exhibiting the normal to lamination orientation the lowest value. As for durability, the statistical interpretation of the results suggests that the level of severity of each test follows S-C > F–T > A-A > T-S. In addition, laminated facies are more vulnerable to accelerated aging tests. Impact of S-C, F–T and T-S tests is mainly explained by differences in porosity and damage produced by A-A is related to the available effective area for the reaction to take place. Thus, the onyx-travertine is more than a wonderful material, it represents an interesting case study for development of future research on heritage stone in Ecuador and the world by employing normalized tests that are rarely used or published. [ABSTRACT FROM AUTHOR]

Recently, the carbon nanoparticles with defined architecture, small particle diameter and large mesopore size, have aroused people's enormous interests on account of their laudable properties. Here, it is novel mesoporous carbon nanoparticles (MCNs) that have been successfully fabricated in a neoteric oil-water microemulsion system, which is developed to synchronously adjust the surface roughness, particle diameter, and large mesopore size through accommodating the emulsion polarity. Besides, pentanol as a cosurfactant not only significantly affects the evolution of mesopore size but also acts an vital role in the interfacial interaction between carbon precursors and soft templates, leading to the fluffy growth of particles. Interestingly, an extended swelling-penetration mechanism is subtly put forward to explain the formation and transformation of MCNs, which would provide a simple and unique ingenuity for this material species. Remarkably, to fulfill the multifunctional properties of such MCNs, MCNs-2 is further utilized as a fluorescent probe platform to detect mutated nucleic acids with high selectivity and low detection limit, as well as a medical carrier to work well in drug delivery system with high adsorption/release properties and extremely low cytotoxicity, which would empower it with luciferous prospects for the applications in biosensor and biomedical fields. Schematic illustration of double-duty MCNs-2 and MCNs with different morphologies. The N-doped large mesoporous carbon nanoparticles with synchronously tunable surface roughness, particle diameters and pore sizes have been triumphantly fabricated via a novel oil-water microemulsion assembly strategy in one pot. Interestingly, this method permits adjusting the external morphology and internal architecture through regulating the synthesis parameters. On the one hand, the more ethanol is added, the larger particle diameters, the smaller pore sizes, and the less surface roughness. On the other hand, the fluffy MCNs are eventually fabricated when increasing the input of pentanol, which not only significantly affects the evolution of mesopore size but also acts an vital role in the interfacial interaction between carbon precursors and soft templates. Furthermore, an extended swelling-penetration mechanism is innovatively proposed to explain the formation of such MCNs with large mesopores and rough surface. Encouragingly, MCNs-2 can be applied as a fluorescent probe platform to detect mutated nucleic acids with high selectivity and low toxicity. Moreover, it also illustrates extraordinary performance as a drug carrier to improve the dissolution and release rate of insoluble drugs, which can afford a blueprint for the biomedical application. [Display omitted] • MCNs are first fabricated via a facile microemulsion assembly strategy. • MCNs possess synchronously tunable diameters, pore sizes and surface roughness. • Pentanol can construct fluffy structure as a sedimentary template. • An extended swelling-penetration mechanism is innovatively expounded. • MCNs-2 manifests superior performance in drug release and DNA variants detection. [ABSTRACT FROM AUTHOR]

A uniform approach to ichnotaxonomy has been for the most part positively received by the scientific community. We carry it further here, presenting a revised treatment of trace fossil groups. These should include cololites and regurgitalites as well as root traces. Signs of human technology may be seen as traces; however, they should not be named following the principles of zoological taxonomy and rules of zoological nomen)clature. Microbially induced sedimentary structures are not considered as traces and neither are structures resulting from bioclaustration. The latter, also known as galls and embedment structures, may be named as cecidotaxa (cecidofamilies, -genera, -species; briefly cfam., cgen., csp.) and, as such, they are governed by the International Code of Zoological Nomenclature. Cecidotaxa do not compete for synonymy with ichnotaxa, other parataxa or biotaxa. A revised list of ichnotaxobases includes the arrangement of subunits as well as (in a restricted way) size and bioglyphs. The principal type of substrate may serve as an ichnotaxobase, especially in bioerosion traces, but its sole use should be avoided, unless informed by knowledge about the behaviour of specialist producers. For the purpose of the nomenclatural code, we further propose to define ‘fossil’ as ‘not demonstrably postdating the beginning of the Holocene’ and provide a revised definition of ‘ichnotaxon’. [ABSTRACT FROM AUTHOR]

The sand bodies formed by braided fluvial fan deposits have a certain distinctiveness. They not only have the characteristics of fluvial facies sandbodies but also follow the distribution law of alluvial fan sand bodies. The variation law of sandbodies that are present along and perpendicular to a channel is relatively complex. Therefore, constraints in the modeling process of sand–mudstone facies of this type of reservoir are essential. This study selects the second member of the Shanxi Formation reservoir formed by a braided fluvial fan in the middle of Ordos Basin to perform sand–mudstone facies modeling. First, by studying the lithology and sedimentary structure of the area, the sedimentary characteristics and sand body distribution law of braided river fan are analyzed. Then, the original data points are analyzed, the variation function with high convergence is obtained, and the sand–mud facies model under the constraint of sedimentary facies is established using the random modeling method. Finally, the accuracy of the established random model is tested via single-well thinning, multi-well thinning, and random seed model similarity. The test results confirm that the distribution law of the sand and mudstone in the model is highly similar to that of the actual stratum. And it also conforms to the sedimentary model of braided fluvial fan. The accuracy of the model established by this method is reliable, and the method can be used to predict sand body distribution in areas with low well pattern density. [ABSTRACT FROM AUTHOR]

Lakes provide habitat for a diverse array of species and offer a wide range of ecosystem services for humanity. However, they are highly vulnerable as they are not only impacted by adverse actions directly affecting them, but also those on the surrounding environment. Improving knowledge on the processes responsible for community assembly in different biotic components will aid in the protection and restoration of lakes. Studies to date suggested a combination of deterministic (where biotic/abiotic factors act on fitness differences amongst taxa) and stochastic (where dispersal plays a larger factor in community assembly) processes are responsible for structuring biotic communities, but there is no consensus on the relative roles these processes play, and data is lacking for lakes. In the present study, we sampled different biotic components in 34 lakes located on the South Island of New Zealand. To obtain a holistic view of assembly processes in lakes we used metabarcoding to investigate bacteria in the sediment and surface waters, and eukaryotes in the sediment and two different size fractions of the water column. Physicochemical parameters were collected in parallel. Results showed that deterministic processes dominated the assembly of lake communities although the relative importance of variable and homogeneous selection differed among the biotic components. Variable selection was more important in the sediment (SSbact and SSeuks) and for the bacterioplankton (Pbact) while the assembly of the eukaryotic plankton (SPeuks, LPeuks) was driven more by homogeneous selection. The ease of human access to the lakes had a significant effect on lake communities. In particular, clade III of SAR11 and Daphnia pulex were only present in lakes with public access. This study provides insights into the distribution patterns of different biotic components and highlights the value in understanding the drivers of different biological communities within lakes. [ABSTRACT FROM AUTHOR]

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The second Member of the Funing Formation in the Haian Sag of the Subei Basin is a set of organic‐rich fine‐grained sedimentary rocks, which is a key interval for shale oil exploration. Under the premise of establishing a high‐frequency sequence framework, the fine description of the lithofacies change characteristics of the continental fine‐grained sedimentary rocks is the basis for the prediction of shale oil favourable areas and the optimization of the production horizons. This study is established through wavelet transformation of the natural gamma curve of the high‐frequency sequence framework of the second Member of the Funing Formation, using thin‐section observation, total organic carbon analysis, and X‐ray diffraction experiments to study the lithofacies types and characteristics of fine‐grained sedimentary rocks, and discuss the combination of lithofacies under the high‐frequency sequence framework Mode and influencing factors. The results show that the second Member of Funing Formation is composed of three‐level sequence of low‐level system tract (LST), transgressive system tract (TST), and early high‐level system tract (EHST), corresponding to 6 fourth‐level sequences and 10 fifth‐level sequences. According to the division scheme of "abundance of organic matter + mineral composition + sedimentary structure", it is found that 12 types of lithofacies were developed in the fine‐grained sedimentary rocks of the second Member of Funing Formation. The lithofacies type is affected by the palaeoenvironment. The organic matter facies are mainly controlled by palaeo‐water depth and palaeo‐redox conditions, the components are mainly controlled by palaeo‐water depth and palaeo‐salinity, and the tectonic facies are mainly controlled by palaeo‐redox and palaeo‐salinity. The lithofacies are regularly superimposed in the high‐frequency sequence framework, and three combination modes of A, B, and C are developed. Among them, the type A lithofacies are developed in the low‐stand system tract, and the type B lithofacies are developed in the transgressive system. The C‐type lithofacies assemblage developed near the largest flooding surface and the early highstand system tract, and combined with palaeoenvironment analysis to establish a lithofacies sedimentary model. [ABSTRACT FROM AUTHOR]

Abstract—The geoelectric structure of the junction region between three largest segments of the East European Craton (EEC)–Volga–Uralia, Sarmatia, and Fennoscandia—is studied. We analyze electrical conductivity anomalies within the Orsha depression revealed by synchronous array magnetotelluric (MT) and magnetovariational (MV) crustal soundings. The study is based on the data from deep MT/MV survey acquired in 2018–2020 under the SMOLENSK experiment in the vicinity of the Orsha depression and the results of similar studies carried out since 2007 in the previous KIROVOGRAD experiment east on the slope of the Voronezh crystalline massif (VCM). The data are interpreted in the class of two-dimensional (2D) geoelectrical models constructed on the long latitudinal geotraverses combining the soundings from the SMOLENSK array in the west and KIROVOGRAD array in the east. Interpretation of MT/MV data within the Orsha depression is substantially complicated by intricate interference of deep and shallow responses. The latter are determined by current systems within the conductive sedimentary cover, ~2 km thick at the center of the depression and having an integrated longitudinal conductance of ~1000 S. Shallow quasi 3D effects obscure responses of crustal conductive features in a wide range of periods, challenging their analysis in the scope of 2D interpretation of impedance data. Important role in overcoming these obstacles is played by MV tipper data which are immune to surface distortions. To develop the strategy of joint MT/MV interpretation, we carried out experiments on inverting synthetic data calculated in a series of 2D models simulating possible geoelectric structure of the study region. The numerical results demonstrated the effectiveness of using the REduced Basis OCCam's (REBOCC) algorithm in the two-stage successive 2D-inversion scheme which inverts at the first stage the electric (TE) mode MT/MV data alone, and at the second stage incorporates the magnetic (TM) mode impedance data. This technique reliably identifies deep conductive structures beneath thick sedimentary strata. The importance of using a priori information about the geoelectric structure of sedimentary cover when constructing the starting inversion model is demonstrated. The joint 2D inversion strategy worked out on the synthetic MT/MV data was used to interpret observations along three combined profiles of the SMOLENSK and KIROVOGRAD arrays. The interpretation refined the structure of the Kirov–Baryatino crustal anomaly on VCM western slope, revealed complex architecture of crustal anomalies beneath the Orsha depression, and allowed preliminary conclusions about the nature of conductivity anomalies and their connection with ancient and recent geodynamic processes. [ABSTRACT FROM AUTHOR]

The current strategy for detecting evidence of ancient life on Mars—a primary goal of NASA's ongoing Mars 2020 mission—is based largely on knowledge of Precambrian life and of its preservation in Earth's early rock record. The fossil record of primitive microorganisms consists mainly of stromatolites and other microbially influenced sedimentary structures, which occasionally preserve microfossils or other geochemical traces of life. Raman spectroscopy is an invaluable tool for identifying such signs of life and is routinely performed on Precambrian microfossils to help establish their organic composition, degree of thermal maturity, and biogenicity. The Mars 2020 rover, Perseverance, is equipped with a deep-ultraviolet (UV) Raman spectrometer as part of the SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) instrument, which will be used in part to characterize the preservation of organic matter in the ancient sedimentary rocks of Jezero crater and therein search for possible biosignatures. To determine the deep-UV Raman spectra characteristic of ancient microbial fossils, this study analyzes individual microfossils from 14 Precambrian cherts using deep-UV (244 nm) Raman spectroscopy. Spectra obtained were measured and calibrated relative to a graphitic standard and categorized according to the morphology and depositional environment of the fossil analyzed and its Raman-indicated thermal maturity. All acquired spectra of the fossil kerogens include a considerably Raman-enhanced and prominent first-order Raman G-band (∼1600 cm−1), whereas its commonly associated D-band (∼1350 cm−1) is restricted to specimens of lower thermal maturity (below greenschist facies) that thus have the less altered biosignature indicative of relatively well-preserved organic matter. If comparably preserved, similar characteristics would be expected to be exhibited by microfossils or ancient organic matter in rock samples collected and cached on Mars in preparation for future sample return to Earth. [ABSTRACT FROM AUTHOR]

A mid-Permian (late Kungurian) micro-dolerite dyke/sill complex located at Kinghorn Point intruded into the then unconsolidated upper Wandrawandian Siltstone of the lower Shoalhaven Group, southeastern Sydney Basin. The dark grey siltstone was deposited in the deeper part of a coastal seaway characterised by northward-directed paleocurrents, with a Cruziana ichnofacies, crinoid stem fossils and abundant glendonites indicating a cold climate. Thin periodic storm deposits, or tempestites, of fine-grained sandstone of volcanogenic origin are scattered through the siltstone. These paler sandy beds were probably derived from island volcanoes to the south or southeast, indicating that regional volcanism was pervasive during this glacial episode. Evidence for penecontemporaneous igneous emplacement into mid-Permian wet unconsolidated shallow marine sediments includes: destruction of primary sedimentary structures caused by extensive interaction and intermingling between the sedimentary and igneous materials, the presence of brecciated contacts and peperite, angular and rounded dolerite fragments in the siltstone, fluidisation and entrainment of the sediments into cooling and flow fractures in the magma, and the presence of tube-like flow features. There are also hyaloclastite and baked sediments along the contact margins, fumaroles and vesicles within both the sediment and magma. High vesiculation is characteristic of intrusion near the surface, and possibly extrusion at the sediment–water interface. The geochemistry of the intrusion, especially key element ratios of the high-field-strength, major and trace elements, is very different from that of the shoshonites of the nearby Permian (mid Wordian to Capitanian) Gerringong Volcanics, having much lower Zr/TiO2, Nb/Y, Nb/Zr, K2O, P2O5, Rb, Th, U, Y, Zr and Nb, and higher MgO, suggesting they are unrelated. This indicates that the Kinghorn Point intrusion was associated with an earlier intermediate pre-Gerringong Volcanics phase, or it may be distinctive and unrelated. Magmatic geochemical comparisons further afield along the northern Sydney Basin and Tamworth Fold Belt boundary coasts show that volcanism was pervasive during the Wandrawandian glacial episode and that regional mid-Permian mafic volcanism was well evolved in the southern Sydney Basin during sedimentation. A mid-Permian syndepositional dolerite intrusion at Kinghorn Point shows classical peperite and soft-sediment deformation features. Previously unreported mafic tuffaceous sandstone beds within the Wandrawandian Siltstone were probably derived from island volcanoes to the south or southeast. Geochemistry of the intrusion shows that it is not related to the mid Wordian to Capitanian Gerringong Volcanics. Regional volcanism was pervasive during the Wandrawandian glacial episode along the southeast Panthalassan margin of Gondwana. [ABSTRACT FROM AUTHOR]

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The Yellow River Estuary is a typical constructive delta with a complex sedimentary structure. To analyze the physical, mechanical properties, and structural characteristics of the surface sediments in the delta, reveal the sedimentary environment and avoid geological hazards, cone penetration test (CPT) is used for nautical in situ testing and evaluating effective internal friction angle (φ'). Four typical areas formed by the diversion of the Yellow River Estuary in different periods are selected as the research objects to perform the in situ CPT, particle size analysis test, scanning electron microscopy, and triaxial test, building calculation model. The main conclusions are as follows: (1) The sediment given priority to are silt and silty clay, where the stratigraphic distribution difference is more significant, accompanied by soft interlayer or alternating layers of hard. (2) Hard soil in the sediments cause abrupt changes and fluctuations in the cone tip resistance and sleeve friction resistance. (3) The empirical formulas proposed by Berezantsev, Khristoforov, and Golubkov, Kulhawy and Mayne, and Mayne are used to predict φ' and the effect of inversion is good. (4) The coefficients of formulas are significantly improved, modified according to site variability. [ABSTRACT FROM AUTHOR]

Conventional well logs cannot detect fractures in hydrocarbon reservoirs. Drilling core data are costly and this puts a significant limitation on data acquisition. The image logs, with their specific technology and by implementing electrical and sonic characteristics of the formation, can recognise various features in the borehole wall, including bedding, fracture, sedimentary structures, faults, condition of fractures, whether mineral-filled, etc. This investigation uses image logs (FMI, OBMI, and UBI) of five wells in different Iranian oil fields. The studied area is located in the central part of the northern Dezful embayment. The fracture values in each zone of the Asmari Formation of studied wells were calculated, and each zone's fracture density histogram was drawn. The maximum and the minimum number of fractures were recognised, and reservoir zones with a high production potential were defined. Mud loss and cumulative oil production data were converted to histograms and compared with fracture density histograms. The results showed that there was a good correlation between the three histograms. Based on these research results, well log image diagrams can determine the exact location and calculate the fractures density to determine the appropriate reservoir zones. [ABSTRACT FROM AUTHOR]

The middle sub-member (Es3z) within the third member (Es3) of the Eocene Shahejie formation is the main source of the generation and accumulation of hydrocarbons in the lacustrine deltas of Bonan depression. Exploration and research work in different blocks is carried out separately. Types of sedimentary facies, and their vertical and lateral evolution in Es3z are not studied in detail. To fill this knowledge gap, we did a detailed analysis of facies and lithological characteristics through integrative studies of cores, well logs and seismic data. Identification of sedimentary structures and lithology of the reservoir zone from cores are calibrated with high-quality well logs and seismic data. Depositional facies in Es3z reservoirs are identified through analysis of sedimentary structures, grain size, log's trends and seismic sections. Es3z was deposited in the fan delta front setting where five facies associations are found, among them distributary channels consisting of MCS, CSg, PCSs, MS, RCL, WCS, PBSs, RCS and GBS lithofacies, natural levee containing DFs, and furthermore, sheet sand are associated to CBS and SSM lithofacies. GM, GGM and DGM lithofacies are related to inter-distributary deposits, whereas mouth bars consist of PLS, CS and CFS. Depositional history, flow direction of the sediments, and facies distribution are investigated through detailed facies mapping and cross-section profiling to show that the sediments were sourced from southeast to northwest. We found thicker succession of sedimentary profiles towards north and north-west directions. Belt distributary channel deposits, covering a wide range of areas, act as potential reservoirs along with mouth bar deposits, while mudstones in interdistributary channels act as a good source and seal rocks. The methodology adopted has great potential to explore the reservoirs of fan delta front in lacustrine deltas. [ABSTRACT FROM AUTHOR]

The heterogeneity of sedimentary aquifers can be characterized by parameters related to the underlying sedimentary structure such as physical attributes of sediments (e.g., volume proportions and lengths of facies types). These parameters often reflect multiscale variability typically observed in the hydraulic conductivity field and the resulting fluid velocity. Although there have been many studies of solute transport processes (e.g., dispersion, mixing, and dilution) in heterogeneous media, there is still a lack of understanding of the controlling influence of sedimentary architecture on the time‐evolution of the solute plume's spreading and mixing behavior and their uncertainty. In this work, we used high‐resolution and three‐dimensional numerical simulations to investigate the time‐evolution of the effective dispersion and mixing behavior of the solute through a heterogeneous aquifer that displays multiscale sedimentary architecture. Transport simulations are performed by using the random walk particle tracking method. Our numerical experiments allow us to understand which scale of sedimentary architecture is most relevant to explaining effective dispersion and mixing. We further analyze whether or not the uncertainty in solute spreading and mixing are equally affected by the different spatial organization of sedimentary facies types. We also perform an extensive parametric study to better understand the effect of physical sediment attributes and univariate statistics of hydraulic conductivity (e.g., mean and variance) at the facies scale on both effective dispersion and mixing. Our results indicate that meter‐scale heterogeneity plays a major role in controlling solute transport processes. Moreover, the effective dispersion is more sensitive to the spatial organization of sedimentary facies type. Key Points: Geometry of larger‐scale facies types is most relevant to explain effective dispersion and mixing processesThe effect of sediment properties and univariate statistics of K on mixing and effective dispersion and their uncertainty are evaluatedDispersion process is more realization dependent than mixing process [ABSTRACT FROM AUTHOR]

Marine Isotope Stage (MIS) 5 is the best documented warm period besides the Holocene, but storm events during this time remain largely underexplored. This study investigates unique anticline-shaped "hummocky" structures on the SD area of the Xisha Islands in the South China Sea, providing valuable insights into storm dynamics during that period based on detailed sedimentological works and available U Th dating data. The primary diagnostic features of these structures include: (1) internal structure characterized by gentle dip angles of less than 5°; (2) grain-size features dominated by medium carbonate sand, moderate sorting, negative skewness, and high kurtosis; and (3) empirical discriminant analyses, all of which classify these deposits as beach-ridge rather than aeolian deposits. Evidence suggests that these deposits were influenced by paleostorm events, supported by two key aspects: (1) distinct sedimentary structures, such as seaward- and landward-dipping stratifications and hummocky cross-stratification (HCS); and (2) foraminifera anomalies, marked by a sudden increase in fossil abundance and the simultaneous appearance of shallow water and offshore species. These sedimentological indicators suggest that these "hummocky" structures are storm-induced beach ridges. Available U Th dating results suggest these deposits likely formed during MIS 5. Two distinct beach-ridge models were further established. The first model describes low-angle beach ridges formed by the constructive action of storm waves during a cold period with low sea levels, where storm surges provided a sufficient and consistent sediment supply with no significant erosion. In contrast, the second model features high-angle beach ridges with erosional truncations. These beach ridges, influenced by more intense storm surges, were initially formed through rapid deposition and subsequently altered by erosion during a warm period with rising sea levels. The development of these beach-ridges highlights that strong paleostorm events or increased storm intensity during MIS 5 likely coincided with relatively warm periods featured by high sea levels or transitions from cold to warm episodes. This study reveals the crucial role of storm events in shaping coastal sedimentary records and provides new insights into the patterns of paleostorm development during interglacial period. • The anticlinal "hummocky" structures are storm-induced beach-ridges formations. • Two beach-ridge types vary greatly in geomorphology and internal structure. • Beach-ridge system records distinct changes in storm magnitude. • Intense storms during MIS 5 likely correspond to warm or transition periods. [ABSTRACT FROM AUTHOR]

The calcareous deposits were affected by syn-sedimentary (lamination, bedding, convolute, ripple marks, pseudo-nodule) and post-sedimentary structure (diaclase, fault, and desiccation crack). Lamination and bedding expressed by color variation and granulometry are linked to a calm period of sedimentation and seasonal fluctuations and are periodically affected by seismic shocks giving the convolute bedding and pseudo-nodules. The presence of symmetrical ripple marks and desiccation cracks indicate respectively back and forth water movements and periodic phases of emersion characteristics of lacustrine to swampy environments. According to geochemistry data, the major element composition classifies the studied samples as shales and wackes. High LREE/HREE ratios (9.07–13.08; average: 11.77); slight positive and negative Eu anomaly (0.98–1.11); Al2O3/TiO2 ratios (16.52–21.87; average: 19.73), Th/Co ratios (1.24–4.18; average: 2.26), La/Sc versus Th/Co and Zr versus TiO2 plots indicate sediments derived from felsic rocks. The K2O/Na2O ratios (0.24–1.90; average: 1.01); index of compositional variability (0.88–1.35); PIA (64.94–98.42) and the Zr/Sc versus Th/Sc diagram indicate that the source rocks have experienced globally a moderate recycling and sorting as well as moderate weathering. The chemical index of alteration values and the SiO2 versus $\mathrm{Al}_{2}\mathrm{O}_{3} + \mathrm{K}_{2}\mathrm{O} + \mathrm{Na}_{2}\mathrm{O}$ diagram could indicate relatively warm and arid to semi-arid climate during deposition of sediments. The Sr/Ba (0.22–2.01; average: 0.58) ratios indicate a variant salinity. The Y/Ho ($

Hydrate-based CO 2 sequestration (HBCS) under seafloor with huge storage capacity and long-term mechanical stability is attractive for large-scale carbon reduction. However, as representative geochemical constituents of marine sediments, swelling clay minerals still play ambiguous roles in hydrate phase transition and sedimentary structure stability. In this study, pore-scale behaviors of hydrate deposition and reservoir structure evolution in the presence of montmorillonite (MMT), a representative swelling clay, was investigated using low-field nuclear magnetic resonance (LNMR) technique. Total inter-particle interaction energy of 195.4 K b T ensured the dispersion of clay in 0.5 wt% MMT system, which facilitated homogeneous hydrate formation by providing nucleation sites and surface electric fields, improving hydrate conversion from 78.2 % to 89.6 %. Weak water activity caused by strong water absorption of swelling clay resulted in a 14.4 % reduction in CO 2 storage capacity of high-concentration (10.0 wt%) MMT reservoir. Hydrate phase transition accompanied by the migration of MMT particles and liquid water synergistically contributed to sedimentary structure evolution. Migration of MMT-rich fluid with high viscosity could cause irreversible geologic damages by exacerbating sedimentary skeleton deformation. This work reveals the interaction between swelling clay and CO 2 hydrate at microscopic scale, providing new perspectives for effective implementation of CO 2 geologic sequestration in marine sediments. [Display omitted] • Revealing the interaction of swelling clay with CO 2 hydrate from the pore scale. • The presence of montmorillonite improves the homogeneity of hydrate distribution. • Concentrated clay fluids provide mass transfer resistance for hydrate formation. • Clay agglomeration and migration can cause irreversible damage to the reservoir. • A small amount of clay allows for homogeneous and dense hydrate-based CO 2 storage. [ABSTRACT FROM AUTHOR]