Formation mechanisms and environmental influences on the crystal growth of wulfenite

In this study, we introduce a novel approach using correlative analysis techniques to unravel detailed insights into the environmental influences on crystal growth. Tabular and bipyramidal wulfenite samples from the Mežica mine in north-eastern Slovenia were analysed to combine the morphological aspects of crystal growth with the atomic-resolution reconstruction of the positions of lead (Pb) and molybdenum (Mo) atoms in the parent crystal lattice. These combined data also allow us to present the formation mechanism that enables the development of bipyramidal or tabular morphologies in wulfenite. The bipyramidal and tabular crystals are chemically pure wulfenite (PbMoO4), as confirmed by various advanced diffraction and spectroscopy techniques. However, each habit includes multiple inclusions, mostly consisting of carbonates, Pb-Fe oxides, Pb oxides and, more rarely, Pb vanadate (descloizite). The differences in the morphologies can be attributed to compositional changes during precipitation from a meteoric solution and thus, we propose a growth mechanism consisting of three different phases of growth. This innovative approach emphasises the importance of understanding the origin of crystal habits, as can help to decipher how external influences can affect the crystal structure and its surface, leading to the dissolution of preferred surfaces and the selective release of Pb and Mo.

Imaging the top of the Earth's inner core: a present-day flow model

Despite considerable progress in seismology, mineral physics, geodynamics, paleomagnetism, and mathematical geophysics, Earth's inner core structure and evolution remain enigmatic. One of the most significant issues is its thermal history and the current thermal state. Several hypotheses involving a thermally-convecting inner core have been proposed: a simple, high-viscosity, translational mode, or a classical, lower-viscosity, plume-style convection. Here, we use state-of-the-art seismic imaging to probe the outermost shell of the inner core for its isotropic compressional speed and compare it with recently developed attenuation maps. The pattern emerging in the resulting tomograms is interpreted with recent data on the viscosity of iron as the inner core surface manifestation of a thermally-driven flow, with a positive correlation among compressional speed and attenuation and temperature. Although the outer-core convection controls the heat flux across the inner core boundary, the internally driven inner-core convection is a plausible model that explains a range of observations for the inner core, including distinct anisotropy in the innermost inner core.

Radon concentration in seawater as a geochemical indicator of submarine fault activity in the Yatsushiro Sea, Japan

This study examined the relationship between radon (222Rn) concentrations in seawater and crustal activity in the Yatsushiro Sea by investigating the submarine fault zone situated at the southern end of the Futagawa-Hinagu fault zone, activated by the 2016 Kumamoto earthquake (M7.3). We conducted an analysis of 222Rn concentration in samples of bottom water just above the seafloor and pore water in sediments, utilizing multiple and piston cores from the Hakuho Maru Expedition KH18-3. The findings revealed significantly elevated 222Rn concentrations in the central sites of the Yatsushiro Sea, coinciding with a high-stress field exhibiting dense active faults. Seismicity analysis revealed heightened moment release and a low b-value post the 2016 Kumamoto earthquake, indicative of increased seismic activity and the potential for substantial earthquakes in the Yatsushiro Sea vicinity. Our results indicate that heightened concentrations of 222Rn in seawater can serve as an effective tracer for identifying and estimating submarine fault activities. Moreover, our research highlights the utility of 222Rn concentrations in detecting active submarine faults and assessing their activity. It contributes to a comprehensive understanding of the potential for significant earthquakes in the Yatsushiro Sea in the future.

CARM30: China annual rapeseed maps at 30 m spatial resolution from 2000 to 2022 using multi-source data

Rapeseed is a critical cash crop globally, and understanding its distribution can assist in refined agricultural management, ensuring a sustainable vegetable oil supply, and informing government decisions. China is the leading consumer and third-largest producer of rapeseed. However, there is a lack of widely available, long-term, and large-scale remotely sensed maps on rapeseed cultivation in China. Here this study utilizes multi-source data such as satellite images, GLDAS environmental variables, land cover maps, and terrain data to create the China annual rapeseed maps at 30 m spatial resolution from 2000 to 2022 (CARM30). Our product was validated using independent samples and showed average F1 scores of 0.869 and 0.971 for winter and spring rapeseed. The CARM30 has high spatial consistency with existing 10 m and 20 m rapeseed maps. Additionally, the CARM30-derived rapeseed planted area was significantly correlated with agricultural statistics (R2 = 0.65-0.86; p < 0.001). The obtained rapeseed distribution information can serve as a reference for stakeholders such as farmers, scientific communities, and decision-makers.

Developments of a centimeter-level precise muometric wireless navigation system (MuWNS-V) and its first demonstration using directional information from tracking detectors

Various positioning techniques such as Wi-Fi positioning system have been proposed to use in situations where satellite navigation is unavailable. One such system, the muometric positioning system (muPS), was invented for navigation which operates in locations where even radio waves cannot reach such as underwater or underground. muPS takes advantage of a key feature of its probe, cosmic-ray muons, which travel straightforwardly at almost a speed of light in vacuum regardless of the matter they traverse. Similar to other positioning techniques, muPS is a technique to determine the position of a client's muPS receiver within the coordinate defined by reference detectors. This can be achieved either by using time-of-flight (ToF) or angle of arrival (AoA) measurements. The latter configuration (AoA), called the Vector-muPS has recently been invented and the present paper describes the developments of the first prototype of a vector muometric wireless navigation system (MuWNS-V) with this new vector-muPS concept and its demonstration. With MuWNS-V, the reference tracker and the receiver ran wirelessly with fully independent readout systems, and a positioning accuracy of 3.9 cm (RMS) has been achieved. We also evaluated the outcome of measuring continuous indoor localization of a moving receiver with this prototype. Our results indicated that further improvements in positioning accuracy will be attainable by acquiring higher angular resolution of the reference trackers. It is anticipated that "sub-cm level" navigation will be possible for muPS which could be applied to many situations such as future autonomous mobile robot operations.

Climate control on the channel morphodynamics of the Sittaung River, Myanmar

The spatio-temporal development of a meandering river is controlled by its channel morphodynamics. In regions of rapid channel evolution, understanding the driving factors of meander migration is crucial in forecasting the rate and extent of morphological change. Sediment supply and fluvial discharge are the primary influences on migration rate, however climate oscillations are also integral in indirectly regulating migration rate through their control of regional precipitation, as well as the monsoon season of sub-tropical Asia. Despite this, an in-depth investigation into the impact of climate oscillations on meander bend migration remains undocumented. This study presents a satellite-based analysis of multi-decadal climatic forcing on the migration rate of the Sittaung River in Myanmar, through interpretation of the El Niño Southern Oscillation (ENSO). The mode of ENSO exerts significant climatic control on the migration rate of the meandering channels of the Sittaung River, with low-to-average migration rates recorded during dry El Niño events and peak migration rates observed during wet La Niña events. However, this climatic signal may have been obscured by certain local environmental conditions. In cases where meanders faced geological basement, the basement rock inhibited their migration through extension, forcing more rapid migration by way of seaward translation. Consequently, these translating meanders developed to be more elongate, with lower curvatures. Meanders downstream of the approximate tidal limit were less downstream skewed, indicative of tidal modulation, potentially obscuring the impact of fluvially driven climate forcing. Additionally, downstream of a major confluence, the input of sediment and fluvial discharge may have been regulated by upstream anthropogenic activities such as mining and dam construction, leading to greater variability in migration rate downstream of this confluence and further obfuscation of the climate signal.

Pore-scale simulation of low-salinity waterflooding in mixed-wet systems: effect of corner flow, surface heterogeneity and kinetics of wettability alteration

The initial wettability state of the candidate oil reservoirs for low-salinity waterflooding (LSWF) is commonly characterized as mixed-wet. In mixed-wet systems, both the two-phase flow dynamics and the salt transport are significantly influenced by the corner flow of the wetting phase. Thus this study aims at comprehensive evaluation of LSWF efficiency by capturing the effect of corner flow and non-uniform wettability distribution. In this regard, direct numerical simulations under capillary-dominated flow regime were performed using the OpenFOAM Computational Fluid Dynamics toolbox. The results indicate that corner flow results in the transport of low-salinity water ahead of the primary fluid front and triggers a transition in the flow regime from a piston-like to multi-directional displacement. This then makes a substantial difference of 22% in the ultimate oil recovery factors between the 2D and quasi-3D models. Furthermore, the interplay of solute transport through corners and wettability alteration kinetics can lead to a new oil trapping mechanism, not reported in the literature, that diminishes LSWF efficiency. While the findings of this study elucidate that LSWF does exhibit improved oil recovery compared to high-salinity waterflooding, the complicating phenomena in mixed-wet systems can significantly affect the efficiency of this method and make it less successful.

Metamorphic turnover at 2 Ga related to two-stage assembly of Columbia

Understanding the stabilization of cratons and how this is related to the onset of plate-tectonics is among the most important questions in geoscience. The assembly of Earth's first supercontinent Columbia represents the first lines of evidence for a global subduction network, when the oldest, deep subduction-related rocks have been reported. We combine the low-, intermediate- and high-T/P global metamorphic record with the two-stage assembly of the Nuna-Columbia supercontinent to address the significance of the oldest "cold" rocks (low-T/P) and the related emergence of bimodal metamorphic belts. For this purpose, we analyse two examples from Laurentia (including Greenland) and Australia between 2.0-1.8 Ga and 1.8-1.6 Ga. Two main observations are: (i) a first-stage (2.0-1.8 Ga) amalgamation of the megacontinent Nuna (precursor to Columbia) is characterized by bimodal metamorphism along major mobile belts suturing the megacontinent's center. In contrast, a second-stage (1.8-1.6 Ga) is dominated by the formation of soft collisional orogens during the final Columbia supercontinent assembly, recording intermediate- to high-T/P metamorphism; (ii) the metamorphic signature of the two assembly stages, featuring low- and intermediate-T/P rocks during Nuna assembly followed by their near absence during Columbia amalgamation, contrasts with the thermobaric ratios recorded by the Phanerozoic Gondwana-Pangea assembly, where intermediate and low-T/P rocks dominated the final stage of Pangea amalgamation. This discrepancy may signify substantial changes in intraplate metamorphism and minor rearrangements during Columbia assembly compared to major continent-continent collisions, such as the Appalachian-Variscan Orogen as well as production and fast exhumation of high- to ultra-high-pressure rocks during the assembly of the supercontinent Pangea. Furthermore, the variation of thermobaric ratios aligns with the concept of a two-stage mega-supercontinent formation, emphasizing differences between the potentially oldest and youngest supercontinent cycles.

Multitemporal analysis of land subsidence induced by open-pit mining activity using improved combined scatterer interferometry with deep learning algorithm optimization

Mine operational safety is an important aspect of maintaining the operational continuity of a mining area. In this study, we used the InSAR time series to analyze land surface changes using the ICOPS (improved combined scatterers with optimized point scatters) method. This ICOPS method combines persistent scatterers (PS) with distributed scatterers (DS) to increase surface deformation analysis's spatial coverage and quality. One of the improvements of this study is the use of machine learning in postprocessing, based on convolutional neural networks, to increase the reliability of results. This study used data from the Sentinel-1 SAR C-band satellite during the 2016-2022 observation period at the Musan mine, North Korea. In the InSAR surface deformation time analysis, the maximum average rate of land subsidence was approximately > 15.00 cm per year, with total surface deformation of 170 cm and 70 cm for the eastern dumping area and the western dumping area, respectively. Analyzing the mechanism of land surface changes also involved evaluating the geological conditions in the Musan mining area. Our research findings show that combining machine learning and statistical methods has great potential to enhance the understanding of mine surface deformation.

Reservoir rock typing assessment in a coal-tight sand based heterogeneous geological formation through advanced AI methods

Geoscientists now identify coal layers using conventional well logs. Coal layer identification is the main technical difficulty in coalbed methane exploration and development. This research uses advanced quantile-quantile plot, self-organizing maps (SOM), k-means clustering, t-distributed stochastic neighbor embedding (t-SNE) and qualitative log curve assessment through three wells (X4, X5, X6) in complex geological formation to distinguish coal from tight sand and shale. Also, we identify the reservoir rock typing (RRT), gas-bearing and non-gas bearing potential zones. Results showed gamma-ray and resistivity logs are not reliable tools for coal identification. Further, coal layers highlighted high acoustic (AC) and neutron porosity (CNL), low density (DEN), low photoelectric, and low porosity values as compared to tight sand and shale. While, tight sand highlighted 5-10% porosity values. The SOM and clustering assessment provided the evidence of good-quality RRT for tight sand facies, whereas other clusters related to shale and coal showed poor-quality RRT. A t-SNE algorithm accurately distinguished coal and was used to make CNL and DEN plot that showed the presence of low-rank bituminous coal rank in study area. The presented strategy through conventional logs shall provide help to comprehend coal-tight sand lithofacies units for future mining.

Structure and chronology of a star dune at Erg Chebbi, Morocco, reveals why star dunes are rarely recognised in the rock record

Star dunes are the tallest dunes on Earth and are amongst the larger and more spectacular aeolian landforms. Although they are widespread in modern sandy deserts, star dunes are rarely recognised in the rock record probably due to a lack of suitable sedimentary models. This paper presents a new sedimentary model for the structure of a star dune at Erg Chebbi in Morocco (Sahara Desert) on the basis of ground-penetrating radar (GPR) surveys. Individual sedimentary structures in star dunes are similar to those in linear or barchanoid dunes, likely leading to misidentification in the rock record. However, the suite of features described in this paper will permit identification of star dunes in future studies of the rock record. Optically stimulated luminescence (OSL) dating shows that accumulation of the Erg Chebbi star dune post-dates the end of the African Humid Period (AHP). At the base of the dune, there is an ~ 8000-year hiatus in the record. Since then, the dune has grown rapidly to create a 100 m high dune within the past 1000 years and is migrating towards the west. Changes in the cross-strata support the idea that star dune construction was accompanied by a change in the wind directions.

Experimental study on the quasi-static and dynamic tensile behaviour of thermally treated Barakar sandstone in Jharia coal mine fire region, India

In the present study, the effect of mild to high-temperature regimes on the quasi-static and dynamic tensile behaviours of Barakar sandstone from the Jharia coal mine fire region has been experimentally investigated. The experimental work has been performed on Brazilian disk specimens of Barakar sandstone, which are thermally treated up to 800 °C. The quasi-static and dynamic split tensile strength tests were carried out on a servo-controlled universal testing machine and Split Hopkinson Pressure Bar (SHPB), respectively. Microscopic and mineralogical changes were studied through a petrographic investigation. The experimental results suggest the prevalence of both, static and dynamic loading scenarios after 400 °C. Up to 400 °C, the quasi-static and dynamic tensile strengths increased due to the evaporation of water, which suggests a strengthening effect. However, beyond 400 °C, both strengths decreased significantly as newly formed thermal microcracks became prevalent. The dynamic tensile strength exhibits strain rate sensitivity up to 400 °C, although it shows a marginal decline in this sensitivity beyond this temperature threshold. The Dynamic Increase Factor (DIF) remained constant up to 400 °C and slightly increased after 400 °C. Furthermore, the characteristic strain rate at which the dynamic strength becomes twice the quasi-static strength remains consistent until reaching 400 °C but steadily decreases beyond this temperature. This experimental study represents the first attempt to validate the Kimberley model specifically for thermally treated rocks. Interestingly, the presence of water did not have a significant impact on the failure modes up to 400 °C, as the samples exhibited a dominant tensile failure mode, breaking into two halves with fewer fragments. However, as temperature increased, the failure behaviours became more complex due to the combined influence of thermally induced microcracks and the applied impact load. Cracks initially formed at the centre and subsequently, multiple shear cracks emerged and propagated in the loading direction, resulting in a high degree of fragmentation. This study also demonstrates that shear failure is not solely dependent on the loading rate but can also be influenced by temperature, further affecting the failure mode of the sandstone.

Nanoscale imaging of Fe-rich inclusions in single-crystal zircon using X-ray ptycho-tomography

We apply X-ray ptycho-tomography to perform high-resolution, non-destructive, three-dimensional (3D) imaging of Fe-rich inclusions in paleomagnetically relevant materials (zircon single crystals from the Bishop Tuff ignimbrite). Correlative imaging using quantum diamond magnetic microscopy combined with X-ray fluorescence mapping was used to locate regions containing potential ferromagnetic remanence carriers. Ptycho-tomographic reconstructions with voxel sizes 85 nm and 21 nm were achievable across a field-of-view > 80 µm; voxel sizes as small as 5 nm were achievable over a limited field-of-view using local ptycho-tomography. Fe-rich inclusions 300 nm in size were clearly resolved. We estimate that particles as small as 100 nm-approaching single-domain threshold for magnetite-could be resolvable using this "dual-mode" methodology. Fe-rich inclusions (likely magnetite) are closely associated with apatite inclusions that have no visible connection to the exterior surface of the zircon (e.g., via intersecting cracks). There is no evidence of radiation damage, alteration, recrystallisation or deformation in the host zircon or apatite that could provide alternative pathways for Fe infiltration, indicating that magnetite and apatite grew separately as primary phases in the magma, that magnetite adhered to the surfaces of the apatite, and that the magnetite-coated apatite was then encapsulated as primary inclusions within the growing zircon. Rarer examples of Fe-rich inclusions entirely encapsulated by zircon are also observed. These observations support the presence of primary inclusions in relatively young and pristine zircon crystals. Combining magnetic and tomography results we deduce the presence of magnetic carriers that are in the optimal size range for carrying strong and stable paleomagnetic signals but that remain below the detection limits of even the highest-resolution X-ray tomography reconstructions. We recommend the use of focused ion beam nanotomography and/or correlative transmission electron microscopy to directly confirm the presence of primary magnetite in the sub 300 nm range as a necessary step in targeted paleomagnetic workflows.

Physics-informed W-Net GAN for the direct stochastic inversion of fullstack seismic data into facies models

Predicting the subsurface spatial distribution of geological facies from fullstack geophysical data is a main step in the geo-modeling workflow for energy exploration and environmental tasks and requires solving an inverse problem. Generative adversarial networks (GANs) have shown great potential for geologically accurate probabilistic inverse modeling, but existing methods require multiple sequential steps and do not account for the spatial uncertainty of facies-dependent continuous properties, linking the facies to the observed geophysical data. This can lead to biased predictions of facies distributions and inaccurate quantification of the associated uncertainty. To overcome these limitations, we propose a GAN able to learn the physics-based mapping between facies and seismic domains, while accounting for the spatial uncertainty of such facies-dependent properties. During its adversarial training, the network reads the observed geophysical data, providing solutions to the inverse problems directly in a single step. The method is demonstrated on 2-D examples, using both synthetic and real data from the Norne field (Norwegian North Sea). The results show that the trained GAN can model facies patterns matching the spatial continuity patterns observed in the training images, fitting the observed geophysical data, and with a variability proportional to the spatial uncertainty of the facies-dependent properties.

Tsunami deposits in Tunisia contemporaneous of the large 365 CE Crete earthquake and Mediterranean Sea catastrophic event

New field investigations along the East Tunisian coastline reveal sedimentary deposits and damaged localities that may account for a catastrophic event during the late Holocene. North of Sfax city, ~ 3.4 m high cliff coastal marine and alluvial terraces show 20 to 50-cm-thick chaotic layer with sandy coarse gravels mixed with reworked pebbles, broken shells of gastropods and molluscs, organic matter and Roman pottery. The chaotic layer truncates sandy-silty paleosol, covers Roman settlements and is overlain by fire remains, a thin sandy-silty aeolian unit and ~ 1-m-thick alluvial deposits. Charcoal samples collected at 10 cm below and 4 cm above the catastrophic deposits provide radiocarbon dating that brackets the catastrophic unit between 286 and 370 CE. Other historical investigations on the Roman sites of Neapolis (Nabeul), Hadrumete (Sousse), Thyna (Sfax), Meninx in Girba (Djerba), Wadi Ennouili (Gulf of Gabes), and Sabratha (in Libya) evidenced major damage and abandonment of sites in the fourth century (16, 41, 42, 43, 44). The new identification of catastrophic deposits, offshore-onshore correlations with turbidites and modelling of tsunami waves suggest the relationship with the 21 July 365 tsunamigenic earthquake (Mw ~ 8) of west Crete (Greece) and call for a better estimate of tsunami risk on the Mediterranean coastlines.

High spatiotemporal-resolution mapping for a seasonal erosion flooding inundation using time-series Landsat and MODIS images

Seasonal erosion flooding events present a significant challenge for effective disaster monitoring and land degradation studies. This research addresses this challenge by harnessing the combined capabilities of time-series Landsat and MODIS images to achieve high spatiotemporal-resolution mapping of flooding during such events. The study underscores the critical importance of precise flood monitoring for disaster mitigation and informed land management. To overcome the limitations posed by the trade-off between spatial and temporal resolution in current satellite sensors, we emplyedand theflexible spatiotemporal data fusion (FSDAF) methods to produce synthetic flood images with enhanced spatiotemporal resolutions for mapping by using MODIS and Landsat data from August 29 to September 3, 2016. A comparison was made between flood maps from several post-disaster forecasts based on ground-obtained time-series images of the Tumen River flood in China. According to the FSDAF approach, the input Landsat image of March 25, 2016, and the fused results had a root mean square error (RMSE) of 0.0301, average difference of 0.001, r of 0.941, and structure similarity indexof 0.939, indicating that temporal variation data had been effectively incorporated into a forecast on August 16, 2016. Results also indicated that the FSDAF forecast values are lower than those from the actual Landsat image. The results of the study also showed that the generated images could be effectively used for flood mapping. By using our newly developed simulation model, we were able to produce a comprehensive map of the inundated areas during the event from August 29 to September 3, 2016. This shows that FSDAF holds great potential for flood prediction and study and has the potential to benefit further disaster-related land degradation by combining multi-source images to provide high temporal and spatial resolution remote sensing information.

Strontium isotope proxy of sedimentological records reveals uplift and erosion in the Southeastern Neo-Tethys ocean during the late Cretaceous

The mutual interplays between plate tectonic processes, orogenesis and continental uplift, high-flux magmatism, and high sedimentation rates can affect the geochemical signatures and composition of marine sediments. Here, we examine two major disconformities, the Cenomanian-Turonian boundary (CT-ES) and the middle Turonian (mT-ES) exposure surfaces, from the Upper Cretaceous sedimentary successions of the southeastern Neo-Tethys Ocean in the Zagros Basin (Iran). The disconformities are expressed as distinct positive peaks in rubidium (Rb) contents and 87Sr/86Sr isotopic ratios of carbonates. The 87Sr/86Sr values of samples bracketing the disconformities in seven well cores give average age ranges of 94.4-93.6 Ma for the CT-ES and 91-86 Ma for the mT-ES. These ages fall in the timespan of forearc/ophiolite formation through subduction initiation in the Neo-Tethys realm (southern margin of Eurasia), high convergence velocities between Arabia and Eurasia, and blueschist exhumation. All these processes involved buckling of the Neo-Tethyan lithosphere, initiating the Neo-Tethys closure and a high erosion rate on the Eurasian margin. The first two mechanisms exerted considerable compressional forces on the adjacent carbonate platforms, reactivated basement faults, and led to the uplift and erosion of the Arabian Plate, which provided the high contents of Rb and the high 87Sr/86Sr ratios in the carbonates.

Reproducing burrows in modelled sedimentary strata

Studying bioturbated sedimentary strata is crucial; however, sampling these strata poses notable challenges. Modelling these strata has emerged as a promising solution to bridge this gap. This study introduces a workflow to model burrows utilizing the multipoint statistics (MPS) method. A key step in MPS modelling is the use of training images, and this study describes a process to create them using CT scans of rock samples contain burrows. These scans give a 3D visual representation of burrows in actual rock record. The process involves selecting suitable rock samples, CT scanning them, importing and processing the scans in Petrel™, and then transforming the scan data into training images which can be used for MPS modelling. The MPS models allow for precise replication of burrows, variations in their size and percentage, and modeling properties like porosity and permeability. This enables a more detailed analysis, paving the way for further advancements in understanding and simulating the geological implications of burrows. To guarantee reproducibility, this study has precisely documented the workflow with video guidance and provided the necessary data. This comprehensive documentation aims to encourage the broader adoption of MPS modelling for bioturbated strata, setting the stage for further advancements in the field.

Fast hybrid methods for modeling landslide susceptibility in Ardal County

Recently, machine learning models have received huge attention for environmental risk modeling. One of these applications is landslide susceptibility mapping which is a necessary primary step for dealing with the landslide risk in prone areas. In this study, a conventional machine learning model called multi-layer perceptron (MLP) neural network is built upon advanced optimization algorithms to achieve a firm prediction of landslide susceptibility in Ardal County, West of Iran. The used geospatial dataset consists of fourteen conditioning factors and 170 landslide events. The used optimizers are electromagnetic field optimization (EFO), symbiotic organisms search (SOS), shuffled complex evolution (SCE), and electrostatic discharge algorithm (ESDA) that contribute to tuning MLP's internal parameters. The competency of the models is evaluated using several statistical methods to provide a comparison among them. It was discovered that the EFO-MLP and SCE-MLP enjoy much quicker training than SOS-MLP and ESDA-MLP. Further, relying on both accuracy and time criteria, the EFO-MLP was found to be the most efficient model (time = 1161 s, AUC = 0.879, MSE = 0.153, and R = 0.657). Hence, the landslide susceptibility map of this model is recommended to be used by authorities to provide real-world protective measures within Ardal County. For helping this, a random forest-based model showed that Elevation, Lithology, and Land Use are the most important factors within the studied area. Lastly, the solution discovered in this study is converted into an equation for convenient landslide susceptibility prediction.

Exposure to arsenic and other potentially toxic elements: health risk assessment and source analysis in the Wuming Basin, Guangxi Province, China

Guangxi, China, is one of the world's largest karst regions where potential toxic elements tend to accumulate, resulting in high soil background values. This study explores the ecological risk, elemental baseline values, and sources of potential toxic elements in karst regions, expanding the research to include 21 common elements. The significance of this research lies in its implications for the management of potential toxic element pollution, the formulation of environmental quality standards, and soil remediation in karst areas. In this study, 12,547 topsoil samples (0-20 cm) were collected in the study area. Pollution assessment and ecological risk evaluation of eight potential toxic elements (Zn, Ni, Cu, Pb, Cd, Hg, Cr, and As) were conducted using the geo-accumulation index method and potential ecological risk index method. Multivariate statistical analysis was applied to analyze the total content of 21 common elements (Zn, Ni, Cu, Pb, P, Cd, Hg, Co, Mn, Cr, V, I, S, As, pH, Se, N, CaO, Corg, Mo, and F). Additionally, the potential sources of 21 soil elements were preliminarily quantitatively analyzed using the principal component analysis-absolute principal component scores-multiple linear regression receptor model. The results showed that (1) Zn, Ni, Cu, Pb, Cd, Cr, V, and As were enriched in the research area and Ca, Cd, Mn, Mo, Hg, As, and Cu might have been influenced by human activities; (2) Cr, Pb, As, and Zn were generally lightly polluted, with Hg having a moderate potential ecological risk level; and (3) Ni and Zn have contributions of 37.99% and 35.07% from geological sources, agricultural fertilization, and pesticides. Mo, V, Cr, Se, Hg, and As exhibit contributions ranging from 39.44 to 59.22% originating from geological backgrounds and human activities. Corg, S, N, and P show contributions of 45.39% to 80.33% from surface vegetation. F, Co, Mn, and Pb have contributions ranging from 31.63 to 47.93% from acidic rocks in the soil parent material, mining activities, and transportation. Cd and CaO derive 31.67% and 40.23%, respectively, from soil parent material and industrial sources. I has 31.94% from geological background and human activities, and 31.95% from soil parent material and atmospheric sources. Cu has 30.56% from geological sources. The study results can serve as a scientific basis for element research in karst areas domestically and internationally.

Radiometric characteristics of some metallic ores and nonmetallic deposits: an example, Wadi Al-Allaqi, South Eastern Desert, Egypt

Hydrothermal alteration processes are connected to many mineral formations, particularly auriferous deposits. In this study, airborne gamma-ray spectrometry (GRS) data and the analysis of radioactive materials (eU, eTh, and K) are applied to search for regions with hydrothermal alteration activity. An example is presented from Wadi Al-Allaqi, South Eastern Desert, Egypt. GRS was used to analyse various radiometric data to address potential mineral deposit areas, to map regions potentially showing metallic ore mineralisation, and to point out new geological mineral resources. The Kd (potassium deviation), "F" parameter and Th-normalisation of the K and eU anomalies were calculated, and locating new exploratory targets in the study area that exhibit high F-parameter, Kd, and K/eTh values was recommended. Additionally, the research region has a few isolated enriched spots of (K). Therefore, GRS data was used to characterise and estimate potential metallic ores, nonmetallic deposits, and gold ore zones associated with the alteration zones. Results show that most of the known mineral deposits and gold occurrences in the area, according to the metallogenic map of Egypt, are located in zones with a ratio value of (0.25-0.30) (K%/(U or Th ppm)) maps which may suggest a moderate degree of alteration. Also, most mineral deposits and gold occurrences are found in intermediate altered zones, or K-enriched sites, with a Kd% of (0.2. The work represents an attempt to map hydrothermal alteration zones associated with mineral deposits in the Wadi Al-Allaqi area. Generally, natural radiation characteristics and attributes suggest criteria that can be used globally for regional mineral exploration.

The influence of hydrocarbon generation on the sealing capability of mudstone caprock rich in organic matter

To investigate the sealing capability of mudstone caprock during the evolution of organic matter (OM)-rich mudstone, a series of hydrous pyrolysis experiments were first conducted to examine the impact of hydrocarbon generation. The pore type, pore structure, porosity, and gas breakthrough pressure of pyrolytic residual samples were analyzed by field emission scanning electron microscopy, low pressure nitrogen adsorption measurements, porosimetry, and gas breakout core experiments. To model the environment at different depths, these six experiments on hydrous pyrolysis were performed at different temperatures, lithostatic pressures, and hydrodynamic pressures, while other experimental factors such as the original sample, heating time, and rate were kept constant. The results showed that during the thermal evolution process, hydrocarbons were generated from OM in mudstone, resulting in the formation of pores within the OM. Organic acids produced by hydrocarbon generation effectively dissolved minerals, leading to the creation of numerous dissolution pores. Changes in pore type led to changes in pore structure and porosity. The volume of micropores and macropores showed an increasing trend before reaching a Ro value of 1.41%. However, after passing this threshold, they began to decrease. The volume of mesopores showed a decreasing trend before reaching a Ro value of 1.32%. After 1.32%, they began to increase. The porosity was mainly affected by the pore volumes of the mesopores and macropores. The porosity exhibited two peaks: the first occurred at a Ro value of 0.72%, with a porosity level of 4.6%. The second occurred at a Ro value of 1.41% and a porosity level of 10.3%. The breakthrough pressure was a comprehensive reflection of these influences, and its trend exhibited a negative correlation with porosity (R2 = 0.886). For two high values of porosity, the breakthrough pressure corresponded to two low values. Smaller values of the breakthrough pressure indicated a poorer sealing capability of the mudstone caprock. Overall, hydrocarbon generation in the mudstone affected the sealing capability. The mudstone in the studied area exhibited good sealing at Ro below 1.32%. However, once above the 1.32% threshold, the fluctuations of the breakthrough pressure values exhibited considerable variability, requiring a comprehensive evaluation to assess its sealing capability.

Seepage stability analysis of geogrid reinforced tailings dam

To investigate the influence of a geogrid-reinforced tailings dam on the seepage stability of the dam body, this paper was based on the field test of a reinforced tailings accumulation dam. The study utilized the finite element strength reduction method to simulate the stability of the main dam of the Fengshuigou tailings reservoir under different seepage conditions using ABAQUS software. Additionally, the paper discussed the impact of conventional heightening, dry beach length, and geogrid reinforcement on the position and safety factor of the saturation line of the dam body. The results showed that when the dam body was raised, the saturation line rose by 2.8-5.3 m, resulting in a decrease in the safety factor. The geogrid effectively reduced the height of the saturation line in the tailings dam. In comparison to the unreinforced condition (dam heightening), the saturation line of the tailings dam decreased by 0.9-2.8 m under the local reinforcement condition and by 3.2-12.5 m under the overall reinforcement condition. The geogrid significantly improved the stability of the tailings dam. Furthermore, under the local reinforcement condition, the safety factor of the dam increased by 3.8-5.5%, and under the overall reinforcement condition, it increased by 35.9-42.9%, when compared to the unreinforced condition. Increasing the dry beach length improved the stability of the tailings dam, and under normal working conditions, the safety of the tailings dam was much higher than under the minimum dry beach condition. These results served as a reference for the design of the dam and the new tailings reservoir, laying a foundation for the sustainable development and environmental protection of the tailings pond.

The impact of different preceding crops on soil nitrogen structure and nitrogen cycling in tobacco-planting soil

Soil nitrogen content, structure, and nitrogen cycling play a crucial role in tobacco growth quality, with different preceding crops having varying impacts on tobacco cultivation soil. This study conducted using field experiments, employed three treatments with different preceding crops, namely tobacco, barley, and rapeseed, to investigate the effects of different preceding crops on soil nitrogen structure and the expression levels of soil nitrogen cycling-related functional genes in tobacco cultivation soil. The results indicated that different preceding crops had varying effects on the content of different nitrogen forms in tobacco cultivation soil. Ammonium nitrogen and nitrate nitrogen were the two nitrogen forms which were most influenced by preceding crops, with the ammonium nitrogen content in soils following barley and rapeseed preceding crops increasing by 82.88% and 63.56%, respectively, compared to sole tobacco cultivation. The nitrate nitrogen content in tobacco cultivation soil was 26.97% higher following barley preceding crops and 24.39% higher following rapeseed preceding crops compared to sole tobacco cultivation. Simultaneously, different preceding crops also affected the expression levels of nitrogen cycling-related genes in tobacco cultivation soil. In the nitrification process, amoA was significantly impacted, with its expression reduced by 64.39% and 72.24% following barley and rapeseed preceding crops, respectively, compared to sole tobacco cultivation. In the denitrification process, except for the narG gene, all other genes were subjected to varying degrees of inhibition when preceded by barley and rapeseed crops. Correlation analysis between soil nitrogen structure and the expression levels of nitrogen cycling-related genes revealed that increased nitrogen levels suppressed the expression of Arch-amoA. Additionally, ammonium nitrogen strongly influenced the expression levels of most soil nitrogen cycling functional genes. In conclusion, preceding crops alter soil nitrogen structure, possibly due to changes in soil microorganisms, and different preceding crops modified the expression levels of nitrogen cycling-related genes in tobacco cultivation soil, consequently affecting the proportions of various nitrogen forms in the soil.

Soil temperature forecasting using a hybrid artificial neural network in Florida subtropical grazinglands agro-ecosystems

Soil temperature is a key meteorological parameter that plays an important role in determining rates of physical, chemical and biological reactions in the soil. Ground temperature can vary substantially under different land cover types and climatic conditions. Proper prediction of soil temperature is thus essential for the accurate simulation of land surface processes. In this study, two intelligent neural models-artificial neural networks (ANNs) and Sperm Swarm Optimization (SSO) were used for estimating of soil temperatures at four depths (5, 10, 20, 50 cm) using seven-year meteorological data acquired from Archbold Biological Station in South Florida. The results of this study in subtropical grazinglands of Florida showed that the integrated artificial neural network and SSO models (MLP-SSO) were more accurate tools than the original structure of artificial neural network methods for soil temperature forecasting. In conclusion, this study recommends the hybrid MLP-SSO model as a suitable tool for soil temperature prediction at different soil depths.

Experimental analysis of low-dip reverse fault dislocation effects on tunnel site models with different soil properties

The fortification system of the tunnel structure spanning the active fault, such as the failure mechanism and fault-resistant design (measures), has not been thoroughly established. In this study, the self-developed cross-fault large-scale bedrock dislocation loading device platform is utilized to carry out the model test of the tunnel structure and soil site of sand and cohesive soil when the low-angle reverse fault dislocation occurs, based on the earthquake damage. The results demonstrate that: (1) When the fault is staggered, the segmented flexible joint tunnel segment is more favorable in the cohesive soil site. (2) When compared to the cohesive soil tunnel structure site, the strain change of the tunnel structure in the sandy soil site is greater, with the vault increasing by roughly two times and the arch bottom increasing by nearly six times. After the tunnel is buried, the uplift range of the sand cover layer grows, revealing uneven deformation, and the rupture zone migrates to the footwall; hence, the sand site plays a "add seismic" role in the cross-fault tunnel structure. (3) Knowing the location and shape of the rupture range of the overburden soil caused by bedrock dislocation under different inclination angles and soil properties is required in the design in order to place the buried depth and segment length of the tunnel reasonably and take fault-resistant measures.

Experimental study of true triaxial high pressure subcritical water impact fracturing

A new fluid alternative to slick water for fracturing shale gas can reduce the waste of water resources and improve the extraction efficiency, enabling volumetric fracturing. For the new fracturing technique, the experiments of different release pressures under pre-injection and for pre-injection were conducted using a self-designed true triaxial experimental system, and the pressure pulse curves were plotted to analyze the fracturing principle. The experimental results showed that: (1) the pressure rise curve in the reactor can be divided into five stages: initial reaction, linear pressure rise, rate slowdown, instantaneous pressure release, and residual pressure stages; (2) Pre-filling fracturing requires a smaller expansion ratio, weaker pressure degradation, resulting in better fracturing effect; (3) The increase in the initial fracture length leads to an increase in the pressure required to extend the fracture, and high-pressure subcritical water impact fracturing achieved fracture extension at a lower fluid pressure; (4) The fractal dimension has a strong linear relationship with fracture complexity, which is a new option when evaluating the fracturing effect. Volumetric fracturing allows for the creation of more tiny trenches that increase reservoir permeability, leading to better recovery of the reservoir's energy resources.

An experimental and numerical study of the strength development of layered cemented tailings backfill

The behaviour of a stratified backfilled stope in terms of strength development and stress distribution has not been well established in the field of rock engineering. Yet, the mining industries with massive ore bodies are looking into high production with a high standard of safety which is mainly governed by large excavation with backfill as a support system. It is difficult to fill these large excavations at one time. Therefore, a subsequent backfilling of the stope layer by layering is adopted, which results in a layered backfill structure. The purpose of this study was to explore the strength development, stress distribution and deformation across the stope supported by both layered and non-layered backfill. It has been observed that the backfill support system gain its strength with time, however, the layered backfill support system loses its strength when more layers are introduced, this is due to the shearing effect around the interfaces of the backfill layers. The impact of layering was validated by 3D numerical simulation. It is therefore concluded that non layered backfill support system are more suitable for stoping mining methods rather than layered support system.

Effect of intensity of sedimentary cover deformation on hydrocarbon accumulation in Dongying Sag, Bohai Bay Basin, China

The developmental phase of the fault deformation zone denotes the zone of weak deformation (with strong concealment) that evolves within the sedimentary cover of the basin. Recent studies have unveiled the objectively existing tectonic phenomenon of weakly deformed tectonic belts within the sedimentary basin cover, closely intertwined with oil and gas accumulation. To elucidate the deformation intensity and hydrocarbon accumulation scale within the cap cover deformation zone, a pivotal concern in oil and gas geology, this study focuses on the Dongying Sag. The structural physical simulation experiment method, incorporating variable caprock thickness and variable shear strength, is employed to scrutinize the impact of basement fault strike-slip activity on the development of faults in the sedimentary caprock of the basin and dyed oil is charged. In conjunction with sag examples, Early R shear single-channel migration-isolated aggregation, Early and mid-term R shear main channel migration-geese and beaded aggregation, P shear main channel migration-intermittent zonal aggregation, Full channel migration-continuous belt aggregation accumulation models of basement faults are established. It is emphasized that the R shear pressurized deformation section and the R and P shear intersection section in the deformation zone are favorable target areas for oil and gas exploration.

Evaluation of rock and fluid intermolecular interaction between asphaltene and sand minerals using electrochemical, analytical spectroscopy and microscopy techniques

Long-time contact of heavy crude oil with rock leads to an adsorption phenomenon, which causes the rock surface to become oil-wet and appears as a barrier to the fluid flow in the porous media. However precise understanding of how asphaltene fractions influence sand wettability is lacking. The wetness of neat and asphaltene-aged sandstone was calculated using two relative permeability and contact angle methods. Then the molecular interaction between asphaltene and sand minerals was systematically analyzed using Fourier-transform infrared spectroscopy. Furthermore, the zeta potential was representative of electrostatic properties and surface charge alteration of the sand after these phenomena. Scanning electron microscopy with energy-dispersive X-ray (EDX) analysis also showed elemental mapping and dispersion of asphaltene particles on the rock surface. According to contact angle and EDX analyses of asphaltene samples, the contact angle rises from 115° to 141° by an increase in carbon adsorption on the sand surface from 8.23 to 41.56%. Spectroscopy results demonstrated that hydrogen-bonding, π-bonding, and sulfur-containing compounds such as sulfoxide improve asphaltene adsorption onto the sand surface. The higher the aromaticity index and hydrogen potential index of asphaltene, the greater the ability of asphaltene to change wettability. Adsorption of surface active components would make the surface charge of the sand more negative. The presence of nitrogen/sulfur-containing functional groups on the sand surface changed the electrostatic properties, as a sand surface coated with asphaltene would reduce the percentage of metal cations.

3D density imaging using gravity and gravity gradient in the wavenumber domain and its application in the Decorah

Density imaging is a method that uses the inversion of the gravity and gravity gradient spectra in the wavenumber domain to create accurate 3D reconstructions of subsurface density distributions. This approach offers computational efficiency and rapid calculations. This research used preliminary inversions to examine the spectral characteristics of gravity and gravity gradient anomalies, as well as the resulting models, were scrutinized through preliminary inversions. 3D density imaging of gravity and gravity gradient was performed in the wavenumber domain using depth weighting on both noise-added and theoretical data, producing a density model that was consistent with the theoretical one. The technique was then used in the Decorah region of the United States, where 3D density imaging was performed and an examination of the properties of gravity and gravity gradient anomalies was conducted. The results showed where high-density Decorah complexes, low-density siliceous intrusive rocks, and high-density intrusive rock masses, were the distributed within the surrounding rock. Each of these provided comprehensive insights into the intrusive pathways to the rock mass. Thus, the appropriateness and effectiveness of the density imaging method were confirmed, supporting a deeper understanding of the structural division and geological evolution in the region.

The microstratigraphy and depositional environments of Lida Ajer and Ngalau Gupin, two fossil-bearing tropical limestone caves of west Sumatra

Lida Ajer and Ngalau Gupin are karstic caves situated in the Padang Highlands, western Sumatra, Indonesia. Lida Ajer is best known for yielding fossil evidence that places the arrival of Homo sapiens in Southeast Asia during Marine Isotope Stage 4, one of the earliest records for the region. Ngalau Gupin recently produced the first record of hippopotamid Hexaprotodon on the island, representing the only globally extinct taxon in Pleistocene deposits from Sumatra. Microstratigraphic (micromorphological) analyses were applied to unconsolidated fossil-bearing cave sediments from these two sites. We use micromorphology as part of a micro-contextualised taphonomic approach to identify the diagenetic processes affecting fossils and sediments within these caves, through phases of their depositional history. The fossil-bearing sediments in Lida Ajer have been subjected to a suite of natural sedimentation processes ranging from water action to carnivore occupation, which would indicate the fossils underwent significant reworking prior to lithification of the deposit. The results demonstrate that the base of the unconsolidated fossil-bearing sediments in Ngalau Gupin were derived from the interior of the cave, where the matrix was partially phosphatized as a result of guano-driven diagenesis. These observations can be used to test hypotheses about the integrity of incorporated vertebrate remains and to aid in local palaeoenvironmental reconstructions. The methods employed in this research have not previously been applied to cave sediments from sites in the Padang Highlands and provide key new insights into the palaeontological and natural history of the western region of Sumatra.

Platinum and microspherule peaks as chronostratigraphic markers for onset of the Younger Dryas at Wakulla Springs, Florida

Anomalous peak abundances of platinum and Fe-rich microspherules with high-temperature minerals have previously been demonstrated to be a chronostratigraphic marker for the lower Younger Dryas Boundary (YDB) dating to 12.8 ka. This study used Bayesian analyses to test this hypothesis in multiple sequences (units) of sandy, weakly stratified sediments at Wakulla Springs, Florida. Our investigations included platinum geochemistry, granulometry, optically stimulated luminescence (OSL) dating, and culturally dated lithics. In addition, sediments were analyzed using scanning electron microscopy and energy dispersive x-ray spectroscopy to investigate dendritic, iron-rich microspherules previously identified elsewhere in peak abundances at the onset of the Younger Dryas (YD) cool climatic episode. Our work has revealed this abundance peak in platinum and dendritic spherules in five sediment sequences at Wakulla Springs. A YDB age of ~ 12.8 ka for the platinum and spherule chronostratigraphic datum in these Wakulla Springs sequences is consistent with the archaeological data and OSL dating. This study confirms the utility of this YDB datum layer for intersequence correlation and for assessing relative ages of Paleoamerican artifacts, including those of likely Clovis, pre-Clovis, and post-Clovis age and their possible responses to environmental changes known to have occurred during the Younger Dryas cool climatic episode.

The first identification of cronstedtite in Cu-Ni-PGE ores of the Talnakh intrusion

We present new mineralogical data of cronstedtite from the Southern-2 orebody, located in the South-Western branch of the Talnakh intrusion (Noril'sk area) composed of massive sulfides in which the total amount of oxides and silicates does not exceed 1-3 vol%. The petrographic and mineralogical features of these ores indicated occurrence of fine-grained, fibrous needle like clusters < 50-µm-sized grains of cronstedtite (7.09 Å along its c-axis). This mineral confirmed by a number of analytical techniques (powder X-ray diffraction of balk samples, transmission electron microscopy, scanning electron microscopy, Raman and Infrared spectroscopy). Cronstedtite sporadically contains signals of Al, Ni, Ca and filling the cracks and cavities between sulfides of copper (chalcopyrite) and iron (pyrrhotite, pentlandite). In some cases, cronstedtite contains micron-sized PGM, and associates with magnetite. According the X-ray diffraction analysis of the bulk massive ores besides cronstendtite are established kaolinite, gypsum, calcite, quartz, and cristobalite. The findings of cronstedtite in Noril'sk area have never been mentioned publicly before. Its occurrence is the northernmost known locality in the world. Our results imply that the formation of cronstedtite in the Talnakh intrusion could be possible by the active participation low-temperatures fluids within the relatively near-surface (< 2 km of paleosurface) conditions of intrusion emplacement, in contrast to other deep-seated supergiant Cu-Ni-PGE deposits in the world. The conditions of formation in isolated cavities in fresh pyrrhotite-pentlandite-chalcopyrite massive ores of deep level of the Talnakh intrusion could be favorable for the formation of cronstendtite.

Tiny stresses are capable of triggering earthquakes and tremors in Arunachal Himalaya

The Arunachal Himalaya has been hosting some notable events in the recent past. The tectonic history of Arunachal Himalaya is complex and has been influenced by several major tectonic events, including the 1950 Mw8.6 Assam-Tibet earthquake. In this study, we explored the effect of dynamic stresses generated by teleseismic events on the triggering of seismicity in the region. We analyzed 34 large teleseismic events since 2010 and found triggering during six events. The change in seismicity was also confirmed by analysis with the STA/LTA method. The triggering in the region occurred in the form of earthquakes and tremors. The dynamic stress as low as 1 kPa was found capable of triggering. The back-azimuth angle does not play an important role in the triggering. The angle direction of incoming waves with respect to the fault ~ 60° and ~ 120° is the possible reason for triggering in the region. The triggering occurred in the Mishmi and Main Central Thrust regions. The largest triggered event, ML2.3, was triggered 7.5 h after the 2012 Indian Ocean earthquake of Mw8.6. The region is tectonically very sensitive and tiny stresses are capable of triggering seismicity in Arunachal Pradesh.

Effect of freeze-thaw manipulation on phytostabilization of industrially contaminated soil with halloysite nanotubes

The latest trends in improving the performance properties of soils contaminated with potentially toxic elements (PTEs) relate to the possibility of using raw additives, including halloysite nanotubes (HNTs) due to eco-friendliness, and inexpensiveness. Lolium perenne L. was cultivated for 52 days in a greenhouse and then moved to a freezing-thawing chamber for 64 days. HNT addition into PTE-contaminated soil cultivated with grass under freezing-thawing conditions (FTC) was tested to demonstrate PTE immobilization during phytostabilization. The relative yields increased by 47% in HNT-enriched soil in a greenhouse, while under FTC decreased by 17% compared to the adequate greenhouse series. The higher PTE accumulation in roots in HNT presence was evident both in greenhouse and chamber conditions. (Cr/Cd and Cu)-relative contents were reduced in soil HNT-enriched-not-FTC-exposed, while (Cr and Cu) in HNT-enriched-FTC-exposed. PTE-immobilization was discernible by (Cd/Cr/Pb and Zn)-redistribution into the reducible fraction and (Cu/Ni and Zn) into the residual fraction in soil HNT-enriched-not-FTC-exposed. FTC and HNT facilitated transformation to the residual fraction mainly for Pb. Based on PTE-distribution patterns and redistribution indexes, HNT's role in increasing PTE stability in soils not-FTC-exposed is more pronounced than in FTC-exposed compared to the adequate series. Sphingomonas, Acidobacterium, and Mycobacterium appeared in all soils. HNTs mitigated FTC's negative effect on microbial diversity and increased Planctomycetia abundance.

Freshwater fish diversity in the western Amazon basin shaped by Andean uplift since the Late Cretaceous

South America is home to the highest freshwater fish biodiversity on Earth, and the hotspot of species richness is located in the western Amazon basin. The location of this hotspot is enigmatic, as it is inconsistent with the pattern observed in river systems across the world of increasing species richness towards a river's mouth. Here we investigate the role of river capture events caused by Andean mountain building and repeated episodes of flooding in western Amazonia in shaping the modern-day richness pattern of freshwater fishes in South America, and in Amazonia in particular. To this end, we combine a reconstruction of river networks since 80 Ma with a mechanistic model simulating dispersal, allopatric speciation and extinction over the dynamic landscape of rivers and lakes. We show that Andean mountain building and consequent numerous small river capture events in western Amazonia caused freshwater habitats to be highly dynamic, leading to high diversification rates and exceptional richness. The history of marine incursions and lakes, including the Miocene Pebas mega-wetland system in western Amazonia, played a secondary role.

Disentangling Jenny's equation by machine learning

The so-called soil-landscape model is the central paradigm which relates soil types to their forming factors through the visionary Jenny's equation. This is a formal mathematical expression that would permit to infer which soil should be found in a specific geographical location if the involved relationship was sufficiently known. Unfortunately, Jenny's is only a conceptual expression, where the intervening variables are of qualitative nature, not being then possible to work it out with standard mathematical tools. In this work, we take a first step to unlock this expression, showing how Machine Learning can be used to predictably relate soil types and environmental factors. Our method outperforms other conventional statistical analyses that can be carried out on the same forming factors defined by measurable environmental variables.

Azarshahr travertine compression strength prediction based on point-load index (Is) data using multilayer perceptron

Azarshahr County in the northwest of Iran is predominantly covered by Azarshahr travertine, a prevailing sedimentary rock. This geological composition has led to extensive open-pit mining activities, particularly in the western and southwestern parts of the county. The rock's drillability and resistance to excavation play a pivotal role in determining its overall durability and hardness, crucial factors that influence the mining process. These attributes are intimately tied to the compressive strength of the rock. Accurate assessment of rock strength is vital for devising reliable excavation methodologies at mining sites. However, conventional approaches for analyzing rock strength have limitations that undermine the precision of strength estimations. In response, this study endeavors to leverage artificial intelligence techniques, specifically the Multilayer Perceptron (MLP), to enhance the prediction of travertine's compressive strength. To formulate a robust model, a comprehensive database containing data from 150 point-load index (Is) tests on Azarshahr travertine was compiled. This dataset serves as the foundation for the development of the MLP-based predictive model, which proves instrumental in projecting rock compressive strength. The model's accuracy and efficacy were rigorously assessed using the Receiver Operating Characteristic (ROC) curve, employing both training and testing datasets. The modeling outcomes reveal impressive results. The estimated R-squared coefficient attained an impressive value of 0.975 for axial strength and 0.975 for diametral strength. The overall accuracy, as indicated by the Area Under the Curve (AUC) metric, stands at an impressive 0.968. These exceptional performance metrics underscore the efficacy of the MLP model in accurately predicting compressive strength based on the point-load index of samples. The implications of this study are substantial. The predictive model, empowered by the MLP approach, has profound implications for excavation planning and drillability assessment within the studied region's travertine deposits. By facilitating accurate forecasts of rock strength, this model equips mining endeavors with valuable insights for effective planning and execution.

Research on the comparison of impact resistance characteristics between energy absorption and conventional hydraulic columns in fluid-solid coupling

Rock burst disaster affects underground mining safety. The energy-absorbing hydraulic support for preventing tunnel impact has been implemented in rock burst mines. In order to compare the impact resistance characteristics of conventional columns and energy-absorbing columns, based on the derivation of energy theory, the CEL fluid-solid coupling simulation algorithm is used to simulate the process of static load 1000 kN superimposed impact load 1500 kN on φ180 mm type conventional column and energy-absorbing column. Combined with the static-dynamic combined test of the 6500 kN impact testing machine on the column, the accuracy and reliability of the CEL simulation column impact response are verified. The results showed that compared with conventional columns, the reaction force of energy-absorbing columns is reduced by 32.55%. The stress and expansion of the cylinder are significantly reduced. The acceleration of the mass movement has been reduced by 59.46%. The addition of the energy-absorbing device enhances the system's energy absorption by 33.46%, thereby reducing the energy absorption of the column itself to 23.58%. Additionally, the deformation of the energy-absorbing device increases the effective displacement by 239.45%. This also prolongs the impact duration, ensuring sufficient time for the safety valve to open, safeguarding the support from damage, and enhancing the overall integrity of the tunnel.

Sediment deposition within cascade reservoirs: a case study of Baihetan Reservoir in the lower Jinshajiang River, China

Sediment deposition in cascade reservoirs is not only related to the utilization efficiency of the reservoir itself but also to the boundary conditions for the operation of other reservoirs in the same group. The Baihetan Reservoir is the largest hydropower project with the highest unit capacity in the world, and it is necessary to consider sediment deposition within it, as this affects the comprehensive operation of cascade reservoirs in the lower Jinshajiang River. In this study, the input water, sediment, and deposition characteristics were analyzed based on both field hydrological and topographic data of the Baihetan Reservoir during its initial impoundment period. The results showed that water entering Baihetan Reservoir was mainly derived from the upper main stream, and approximately 41% was concentrated in the third quarter. Ten times the amount of sediment derived from the main stream was received from tributaries and uncontrolled areas of the reservoir, and these are the main sediment input sources. The fluctuating backwater area influenced by the upstream Wudongde Reservoir was slightly eroded, and siltation mainly occurred in the dead storage capacity (below 765 m) of the main stream and tributary estuaries in the perennial backwater area; approximately 15.8 times that in the regulating storage capacity (between 765 and 785 m). The differences between the results of this study and those from the reservoir demonstration stage indicate that was a lack of understanding about how climate change, human activities, and uncontrolled areas would affect siltation patterns. In future projects, research focusing on climate trend analyses and the comprehensive consideration of human activities should be combined with extensive sediment production monitoring and model parameter calibration.

Mine pressure behavior law of isolated island working face under extremely close goaf in shallow coal seam

In order to study the mining pressure characteristics of the shallow buried coal seam with the same silo working face under the very close mining void zone and the overlying coal rock body, the theoretical analysis is used to determine whether the open-cutting eye bearing layer belongs to the mining under the very close mining void zone or not, based on the numerical simulation of FLAC3D and on-site measurement of the working resistance at the end of the cycle of the working face's hydraulic bracket, It is proposed to divide the mining stress of the working face based on the advancing length of the working face, that is, the high-pressure zone, the transition zone and the low-pressure zone. The results of the study show that: FLAC3D software was used to analyze the stress intensity of the "C" island working face when it was mined back to 50 m, 100 m, 150 m, and 180 m (one time "square"), and the simulation results were imported into the Origin software, which was used to analyze the stress intensity of the working face. The simulation results were imported into Origin software, and the influence range of mining stress was divided into four areas: high-stress area, stress transition area, low-stress area, and "square" stress concentration area. According to the on-site measurement of the working resistance at the end of hydraulic support cycle, the initial pressure step of the working face under the overlying coal rock body is 48.9-55.7 m, with the peak value of 38 MPa, the cycle pressure step is 9.0-23.3 m, with the peak value of 36 MPa, and the dynamic load factor of the working face is 1.14-1.16; relative to the overlying coal rock body, the average decrease of the cycle pressure step is nearly 10% and the average increase of dynamic load factor is 1.14-1.16; compared with that under the overlying coal rock body, the average decrease of the cycle pressure step is nearly 10% and the average increase of dynamic load factor is 1.14-1.16. Compared with the overlying coal rock body, the average decrease of the cycle pressure step under the overlying mining zone is nearly 10%, the average increase of the dynamic load factor is 20%, and there is no obvious regularity and periodicity in the direction of strike, and the working face is divided into three parts along the direction of strike: high-pressure zone, transition zone, and low-pressure zone. Therefore, in the process of mining under the overlying coal rock body, we should strengthen the roadway peripheral rock support and roof and floor management, which is of guiding significance to the mining of similar working faces and mine safety production.

Applying the improved stratigraphic modified Lorenz technique for dividing the highly heterogeneous clastic reservoirs into hydraulic flow units

The present study applies the improved stratigraphic modified Lorenz (ISML) technique to divide the Matulla Formation in Muzhil Oil Field in the Gulf of Suez into some hydraulic flow units (HFUs) and to check the flow efficiency contribution of each hydraulic flow unit (HFU) to the total bulk flow capacity of the reservoir in 3 wells (Muzhil-4, 7, and 8). The output of the ISML plot is applied in integration with the vertical plot of the porosity (∅), permeability (k), and effective pore radius (R35) against depth to measure the efficiency of each HFU contribution to the total flow capacity of the Matulla reservoir, and to delineate the main attributor to the flow capacity. It is indicated that the Matulla sandstone reservoirs can be subdivided into 7 HFUs to the NW of the field, while it is subdivided into four and five HFUs in the center and to the SE of the field; i.e., its heterogeneity increases to the NW at Muzhil-7 well. On the other side, the best reservoir quality is assigned to the southeast at Muzhil-4 well (av. ∅ = 20.8%, av. k = 596.6 md, and R35 = 12.1 μm). The efficiency of the obtained HFUs was estimated and described both mathematically and graphically. Also, the measured porosity and permeability values indicate relatively low reservoir properties to the NW of the field. The reservoir heterogeneity is also measured using the Dykstra-Parsons technique which indicates extremely high heterogeneity (0.89 ≤ V ≤ 0.98).

Study on correlation between TBM tailings gradation and granitic gneiss surrounding rock stability

In the process of double-shield TBM excavation, it is difficult to directly observe and test the characteristics of the surrounding rock. In this paper, the screening test of the different type tailings in the wet state was carried out to obtain the gradation curve and curve evaluation index. Combining with the excavation parameters and the surrounding rock characteristics of the tailings, a comprehensive analysis was carried out to establish the evaluation system among with the tailings gradation characteristics, lithology characteristics and excavation parameters. The results showed that: Sparsely fissured rock: the tailings are extensional fractures, the tailings gradation curve is inverse "S" type and gentle, and the evaluation index value: (1.50 > lg(Cu) > 1.35), (1.90 > Cc > 1.10). Broken surrounding rock: the curve is "L" type and steep, the content of coarse particles is much more than that of fine particles and (1.10 > lg(Cu) > 1.00), (2.60 > Cc > 2.40). Fractured rock: the curve is "Step" type, the tailings particles lack the middle particle size, the minerals are mostly weathered, (2.15 > lg(Cu )> 1.95), (0.09 > Cc > 0.07). The research results have good applicability to the surrounding rock stability evaluation of the example tunnel, which verifies the feasibility of the method.

3D structural modeling using seismic data and well logs for Khatatba reservoir in Matruh-Shushan Basin, North Western Desert, Egypt

Middle Jurassic reservoirs present challenges in the northern segment of the Western Desert due to geometric uncertainties arising from structural configurations, lateral facies variations, diverse lithologies, and heterogeneous reservoir quality. Consequently, this study employed an intricate approach, constructing detailed 3D geostatic models by amalgamating diverse datasets, including 2D seismic sections and digital well-logs. The focus of these 3D models was on the Khatatba Formation (Upper-Safa Member, Kabrit Member, and Lower-Safa Member) in Matruh-Shushan Basin in the North Western Desert. The objectives encompassed assessing hydrocarbon potential, precisely estimating reserves, formulating development and exploration strategies, and identifying prospective drilling locations. The resultant structural model revealed a compartmentalized region marked by major and minor NE-SW trending normal faults, establishing structurally advantageous locations for hydrocarbon trapping within the study area. Petrophysical analyses highlighted the promising potential of the Upper-Safa Member as a reservoir, featuring porosity values ranging from 10 to 18%, peaking in the northeast sector, volume of shale (Vsh) between 15 and 24%, water saturation (Sw) spanning from 18 to 53%, and increased sand thickness towards the eastern section. Similarly, the Lower-Safa Member demonstrated favorable reservoir attributes, including porosity values ranging from 10 to 16%, with higher values in the southeastern part, Vsh between 17 and 28%, and Sw varying from 15 to 47%. The study findings underscored the hydrocarbon potential in the northeast block of the study area for the Middle Jurassic Khatatba Formation. These insights contribute valuable information for decision-making in exploration and production endeavors within the basin.

Pre-earthquake anomaly extraction from borehole strain data based on machine learning

Borehole strain monitoring plays a critical role in earthquake precursor research. With the accumulation of observation data, traditional data processing methods struggle to handle the challenges of big data. This study proposes a segmented variational mode decomposition method and a GRU-LUBE deep learning network based on machine learning theory. The algorithm enhances data correlation during decomposition and effectively predicts borehole strain data changes. We extract pre-earthquake anomalies from four-component borehole strain data of the Guza station for two major earthquakes in Sichuan (Wenchuan and Lushan earthquakes), obtaining more comprehensive anomalies than previous studies. Statistical analysis reveals similar abnormal phenomena in the Guza station's borehole strain data before both earthquakes, suggesting shared crustal stress accumulation and release patterns. These findings highlight the need for further research to improve earthquake prediction and preparedness through understanding underlying mechanisms.

Geochronological results from the Zhela Formation volcanics of the Tethyan Himalaya and their implications for the breakup of eastern Gondwana

The relationship between the Kerguelen mantle plume and the breakup of eastern Gondwana is still debated. The new Zircon SHRIMP U-Pb dating of 139.9 ± 4.6 Ma, as well as previous ages from the Zhela Formation volcanic rocks in the Tethyan Himalaya, show that the studied Zhela Formation volcanic rocks formed during the Late Jurassic-Early Cretaceous, rather than the Middle Jurassic. The calculated volume of the Comei-Bunbury igneous rocks is ~ 114,250 km3, which is compatible with the large igneous provinces and, consequently, the typical mantle plume models. The new date results, along with existing dates, show that the volcanism attributed to the Kerguelen mantle plume in the Tethyan Himalaya ranges from ca.147 Ma to ca.124 Ma, with two peaks at approximately 141 Ma and 133 Ma. This new finding, together with geochemical and palaeomagnetic data obtained from the Comei-Bunbury igneous rocks, indicate that the Kerguelen mantle plume contributed significantly to the breakup of eastern Gondwana and that eastern Gondwana first disintegrated and dispersed at ca.147 Ma, the Indian plate separated completely from the eastern Gondwana before ca.125 Ma.

Laser scanner and UAV digital photogrammetry as support tools for cosmic-ray muon radiography applications: an archaeological case study from Italy

The use of light detection and ranging technologies, i.e. terrestrial laser scanner (TLS), airborne laser scanner (ALS) and mobile laser scanner (MLS), together with the unmanned aerial vehicles digital photogrammetry (UAV-DP) and satellite data are proving to be fundamental tools to carry out reliable muographic measurement campaigns. The main purpose of this paper is to propose a workflow to correctly plan and exploit these types of data for muon radiography aims. To this end, a real case study is presented: searching for hidden tombs in the Etruscan necropolis of Palazzone (Umbria, Italy). A high-resolution digital elevation model (DEM) and three-dimensional models of the ground surface/sub-surface of the study area were created by merging data obtained using different survey methods to achieve the most accurate three-dimensional environment. Indeed, the simulated muon flux transmission used to infer relative transmission values, and the estimated density distribution, depends on the reliability of the three-dimensional reconstructed ground surface model. The aim of this study is to provide knowledge on the use of TLS and UAV-DP data and GPS-acquired points within the transmission-based muography process and how these data could improve or worsen the muon imaging results. Moreover, this study confirmed that muography applications require a multidisciplinary approach.

Imaging overpressurised fracture networks and geological barriers hindering fluid migrations across a slow-deformation seismic gap

There is an ongoing debate on the processes producing background seismicity and deformation transients across seismic gaps, i.e., regions that lack historical large-magnitude earthquakes. Essential missing elements are geophysical images that resolve sources of geophysical unrest. Here, we apply seismic scattering and absorption tomography to data recorded during the 2010-2014 seismic sequence within the Mt. Pollino seismic gap region (Southern Italy). The tomographic models show high sensitivity to fluid content, deformed fractured structures, and impermeable layers stopping fluid migrations. They bridge the gaps between geological and geophysical models and provide a highly-resolved image of the source of seismic and deformation unrest within this seismic gap. High absorption topping the western Pollino seismic volume appears pressurized between the low-Vp/Vs and low-scattering San Donato metamorphic core and a deep basement. Absorbing fluids can only migrate laterally to the east, blocked in the west and southwest by deep low-scattering barriers associated with east-dipping faults and to the north and southeast by saturated overpressurized low-scattering basins. This eastern migration is only partially effective, producing seismicity across the lowest boundary of the high-absorption volume. Our results showcase the potential of seismic scattering and absorption when imaging structures causing geophysical unrest processes across fault networks.

Experimental production of K-rich metasomes through sediment recycling at the slab-mantle interface in the fore-arc

Sediment contribution to the mantle is the key step for the generation of orogenic magmatism to produce its isotopic and geochemical inventory. Even though they are exceptional for the post-collisional settings, there are worldwide examples of arc-related ultrapotassic mafic magmas which require complex multi-stage processes along with sediment melting e.g. in Italy or Pontides of Türkiye. To understand the metasomatism leading mantle to produce ultrapotassic mafic melts, we simulated the reactions of depleted (harzburgite) and fertile (lherzolite) mantle with subducted carbonate-rich sediment at relatively cold (800-850 °C) and shallow (2 GPa, 60-80 km) slab-mantle interfaces. The melting of sediments can trigger the formation of immiscible and conjugate carbonatitic and silicic melts which flux the mantle to develop hydrous minerals and dolomitic melt. The metasomatic growth product is a wehrlite composed of clinopyroxene, phlogopite, carbonate minerals and amphibole, representing a source of choice for Si-undersaturated ultrapotassic lavas. The occurrence of conjugate carbonatitic and silicic melts and their potential physical separation, offer a possibility for fractionation of several canonical trace element ratios such as Th/La, observed in Si-saturated ultrapotassic lavas. The synergy between peridotite-melt interaction and the physical separation of the carbonatitic and extremely K-enriched silicic melts are essential for the compositional evolution of ultrapotassic orogenic magmas and their mantle sources.