Search

Due to the inherent unpredictability of geological conditions, tunnelling operations are often at risk of encountering water inrushes. Such incidents can lead to construction delays, impose financial strains and pose significant safety threats to the workers involved. Water‐bearing geological formations are the main triggers for such incidents, with factors such as the positioning, water quantity and permeability distribution of these formations being key to predicting the occurrence and severity of water inrush disasters. By leveraging the complex interplay among relaxation time, P‐wave velocity and permeability within the rock's physical properties, a series of indoor tests were conducted on 40 artificial reef limestone cores to extract the necessary parameters. Through the analysis of the data, the comprehensive permeability prediction model was established, and the correlation coefficient was 0.9420 between the model's predictions and actual measurements. At the same time, through theoretical and mechanism analysis, the relationship between permeability and relaxation time and the relationship between permeability and P‐wave velocity were analysed. Finally, 10 natural reef limestone samples were used to verify the accuracy of the model. The prediction model enables an accurate evaluation of tunnel permeability, thus providing a scientific basis for the mitigation of tunnel water inrush hazards. [ABSTRACT FROM AUTHOR]

Barium (Ba) dissolution and mobilization in groundwater are predominantly controlled by sulfate because of the low solubility of barium sulfate (BaSO4) minerals. Naturally present at low concentrations in groundwater, elevated concentrations of Ba can occur as a result of anthropogenic activities, including use of barite in drill operations, and geogenic sources such as leaching from geological formations. No toxicity data exist for Ba with groundwater organisms (stygofauna) to assess the risk of elevated Ba concentrations. The present study measured Ba toxicity to two stygobiont Cyclopoida species: one collected from Wellington and the other from Somersby, New South Wales, Australia. Toxicity was measured as cyclopoid survival over 2, 4, 7, 14, 21, and 28 days in waters of varying sulfate concentration (<1–100 mg SO4/L). When sulfate was present, dissolved Ba concentrations decreased rapidly in toxicity test solutions forming a BaSO4 precipitate until dissolved sulfate was depleted. Barium in excess of sulfate remained in the dissolved form. The toxicity of Ba to cyclopoids was clearly attributed to dissolved Ba. Precipitated Ba was not toxic to the Wellington cyclopoid species. Toxicity values for dissolved Ba for the Wellington and Somersby cyclopoid species included a (21‐day) no‐effect concentration of 3.3 mg/L and an effective concentration to cause 5% mortality of 4.8 mg/L (at 21 days). Elevated dissolved Ba concentrations due to anthropogenic and/or biogeochemical processes may pose a risk to groundwater organisms. Further toxicity testing with other stygobiont species is recommended to increase the data available to derive a guideline value for Ba that can be used in contaminant risk assessments for groundwaters. Environ Toxicol Chem 2024;00:1–14. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

The Carpathian belt is one of Europe's major metallogenic provinces, where magmatic ore mineralization is associated with the past subduction environment. The upper crust is mapped for the first time in the Northeast Carpathian Volcanic Arc using magnetotelluric data inversion. The obtained 3‐D electrical resistivity model is interpreted in conjunction with geological information and magnetic anomaly data. The model illustrates the deep magmatic plumbing system including kilometer‐scale plutonic bodies at a depth of 2–7 km. The model implies that the transport of magma and fluids in the uppermost crust was controlled by pre‐existing faults and décollement horizons. Present ore mineralization, mined since historical times, can be attributed to an electrically conductive conduit that is mapped from the surface to a depth of about 30 km. It is suggested that this conduit connected a shallow magmatic chamber to a deep source region in the southeast during late Miocene time. An observed northwest deflection of the deep magmatic conduit at a depth of more than 10 km may explain the spatial gap in the distribution of the Miocene volcanic activity along the Eastern Carpathians. Plain Language Summary: The Carpathian Mountains have long been exploited for their metal ore deposits, which have been associated with the subduction of tectonic plates. Studying the natural variations of the regional electric and magnetic fields, we estimate the distribution of subsurface electrical resistivity. Subsurface electrical structures are interpreted as deep magma systems and large plutonic bodies. The interpretation implies that regional volcanic activity has been controlled by faults, large fractures in geologic formations, and detached strata. Specifically, historic mining can be attributed to a large conductive body that can be mapped from surface to about 30 km. Data suggest that this body, which could represent a pathway of magmatic fluids, connects to a deep, southeastern mantle source region. Key Points: 3‐D magnetotelluric survey in northeast Carpathian Mountains elucidates the structure of the Miocene volcanic provinceNew data reveal shallow magmatic‐hydrothermal system connected to a deep source region via an inclined conductive conduitCenturies‐old mines align with an electrically conductive layer interpreted as a clay alteration related to hydrothermal activity [ABSTRACT FROM AUTHOR]

Geological formations with fractures are frequently encountered in various research fields. Accurately characterizing these fractured media is of paramount importance when it comes to tasks that demand precise predictions of liquid flow and solute transport within them. Since directly measuring fractured media poses inherent challenges, data assimilation (DA) techniques are typically employed to derive inverse estimates of media properties using observable state variables. Nonetheless, the considerable difficulties arising from the strong heterogeneity and non‐Gaussian nature of fractured media have diminished the effectiveness of existing DA methods. In this study, we formulate a novel DA approach known as parameter estimator with deep learning (PEDL) that harnesses the capabilities of DL to capture nonlinear relationships and extract non‐Gaussian features. To evaluate PEDL's performance, we conduct three case studies, comprising two numerical cases and one real‐world case. In these cases, we systematically compare PEDL with three widely used DA methods: ensemble smoother with multiple DA (ESMDA), iterative local updating ES (ILUES), and ES with DL‐based update (ESDL). Notably, in the problems characterized by highly non‐Gaussian features, ESMDA and ILUES produce significantly divergent results. Conversely, employing the DL‐based update, ESDL demonstrates improved performance. However, its estimation uncertainty remains high, potentially attributable to ESDL's updating mechanism. Comprehensive analyses confirm PEDL's validity and adaptability across various ensemble sizes and DL model architectures. Moreover, even in scenarios where structural difference exists between the accurate reference model and the simplified forecast model, PEDL adeptly identifies the primary characteristics of fracture networks. Key Points: A deep learning‐based data assimilation method, named parameter estimator with deep learning (PEDL), is proposed to characterize fractured media with highly non‐Gaussian featuresPEDL outperforms three popular data assimilation methods based on deep learning or the Kalman formulaComprehensive analyses confirm PEDL's validity and adaptability across various ensemble sizes and DL model architectures [ABSTRACT FROM AUTHOR]

The Archean Superior craton was formed by the assemblage of continental and oceanic terranes at ∼2.6 Ga. The craton is surrounded by multiple Proterozoic mobile belts, including the Paleoproterozoic Trans‐Hudson Orogen which brought together the Superior and Rae/Hearne cratons at ∼1.9–1.8 Ga. Despite numerous studies on Precambrian lithospheric formation and evolution, the deep thermochemical structure of the Superior craton and its surroundings remains poorly understood. Here we investigate the upper mantle beneath the region from the surface to 400 km depth by jointly inverting Rayleigh wave phase velocity dispersion data, elevation, geoid height and surface heat flow, using a probabilistic inversion to obtain a (pseudo‐)3D model of composition, density and temperature. The lithospheric structure is dominated by thick cratonic roots (>300 km) beneath the eastern and western arms of the Superior craton, with a chemically depleted signature (Mg# > 92.5), consistent with independent results from mantle xenoliths. Beneath the surrounding Proterozoic and Phanerozoic orogens, the Mid‐continent Rift and Hudson Strait, we observe a relatively thinner lithosphere and more fertile composition, indicating that these regions have undergone lithospheric modification and erosion. Our model supports the hypothesis that the core of the Superior craton is well‐preserved and has evaded lithospheric destruction and refertilization. We propose three factors playing a critical role in the craton's stability: (a) the presence of a mid‐lithospheric discontinuity, (b) the correct isopycnic conditions to sustain a strength contrast between the craton and the surrounding mantle, and (c) the presence of weaker mobile belts around the craton. Plain Language Summary: We introduce a new model of the temperature and composition of the Superior Craton, a stable and ancient (>2.5 billion years old) geological formation, and its neighboring areas, by using an advanced and novel imaging technique. The central aim of the study is to use the present‐day structure (from the surface to 400 km depth) to understand how the craton's lithosphere (the rigid outer layer of the Earth) has evolved over time, and how its deep roots have persisted over billions of years of geological processes. The Superior Craton displays well‐preserved cores with a distinct chemical composition beneath its eastern and western arms, which likely contribute to its long‐term preservation. Isopycnicity (a state of density equilibrium) within the lithosphere is a likely controller of long‐term stability. Additionally, the presence of layering in the lithosphere and weaker structures (e.g., mountain belts, rifts, hotspot tracks) surrounding the edges of the craton emerge as critical factors contributing to the resilience and endurance of the Superior Craton's lithosphere. These findings significantly advance our understanding of the mechanisms governing the evolution and stability of cratonic regions. Key Points: First integrated multi‐observable probabilistic thermochemical model of the lithosphere beneath the Superior craton and environsThe Superior craton shows well‐preserved depleted cores beneath its eastern and western armsLong‐term craton stability is likely controlled by isopycnicity, and the presence of mid‐lithospheric discontinuities and mobile belts [ABSTRACT FROM AUTHOR]

The Guxiang–Tongmai segment of the Jiali fault is situated northeast of the Namche Barwa Syntaxis in northeastern Tibet. It is one of the most active strike‐slip faults near the syntaxis and plays a pivotal role in the examination of seismic activity within the eastern Himalayan Syntaxis. New study in the research region has yielded a 1:200000 gravity dataset covering an area 1500 km2. Using wavelet transform multiscale decomposition, scratch analysis techniques, and 3D gravity inversion methods, gravity anomalies, fault distributions, and density structures were determined across various scales. Through the integration of our new gravity data with other geophysical and geological information, our findings demonstrate substantial variations in the overall crustal density within the region, with the fault distribution closely linked to these density fluctuations. Disparities in stratigraphic density are important causes of variations in the capacity of geological formations to endure regional tectonic stress. Earthquakes are predominantly concentrated within the density transition zone and are primarily situated in regions of elevated density. The hanging wall stress within the Guxiang–Tongmai segment of the Jiali fault exhibits a notable concentration, marked by pronounced anisotropy, and is positioned within the density differential zone, which is prone to earthquakes. [ABSTRACT FROM AUTHOR]

High‐resolution 2D and 3D data remotely acquired by SuperCam's Remote Micro‐Imager and Mastcam‐Z aboard the Perseverance rover enabled us to characterize the stratigraphic architecture and sedimentary record of the Kodiak butte, an isolated remnant of the western delta fan of Jezero crater. Using these data, we build up on previous interpretations of the butte interpreted as a prograding Gilbert‐type deltaic series. We characterize three individual stratigraphic Units 0 to 2 on the eastern and northern faces of the butte. Each Unit displays the same vertical succession of prodeltaic/lacustrine bottomsets, delta slope toesets and foresets, and fluvially influenced topsets of a deltaic plain with a braided river pattern, shown by 11 individual sedimentary facies. We infer that these individual Units record the formation of three distinct deltaic mouth bars successively across time and space. For the first time on another planet than Earth, we are able to construct a precise sequence stratigraphic framework to highlight lake‐level fluctuations at the time the Kodiak butte was emplaced, during the latest stages of deltaic activity. We identify four hydrogeological cycles indicated by alternating rises and falls of the lake‐level on the order of 5–10 m. These were most probably linked to climatic events and variations controlling lake water inputs in probable relation to an astronomical control. Plain Language Summary: Kodiak butte is an isolated remnant of the main western sedimentary fan of Jezero crater. It displays the characteristic structures of a Gilbert‐type delta, a structure that shows deposition of fluvial material into a standing body of water, here interpreted to be a lake within Jezero crater. 11 individual sedimentary facies (textures, grain‐sizes, and structures) of the rocks exposed at Kodiak suggest that the depositional environments ranged from the fluvial plain to a steep subaqueous slope and into the bottom of the shallow Jezero lake. Our observations further show that Kodiak butte is organized into three distinct stratigraphic Units (0–2), each displaying the same vertical succession of bottomsets, toesets, foresets and topsets. This architecture is interpreted as reflecting three distinct deltaic packages, formed consecutively and not at the same time. Using these facies and stratigraphic architecture data, we are able for the first time on another planet than Earth, to precisely construct a sequence stratigraphic framework for the formation of Kodiak. This framework illustrates with unprecedented precision successive episodes of rises and falls of the paleo‐lake‐level (in the order of 5–10 m) involved in the construction and evolution of the western Jezero delta. Key Points: New observations on the Kodiak delta remnant were carried out to characterize its detailed facies and stratigraphic architectureThree deltaic mouth bars are identified showing 4D succession of depositional settings ranging from deltaic plain to slope to shallow lakeThe first ever sequence stratigraphic framework on Mars shows four cycles of alternating rises and falls of the lake‐level within 5–10 m [ABSTRACT FROM AUTHOR]

Progressive climate change may have unpredictable consequences for the Arctic environment. Permafrost catchments off the west coast of Svalbard, described as "thin" and "warm," are particularly sensitive to climate change. The interdisciplinary research on the hydrochemical response of surface and underground water functioning within a small permafrost catchment area focused on the determination of the impact of meteorological conditions (temperature (T), precipitation (P)) on the mean daily discharge (Q), and the lowering of the groundwater table (H). We determined physical and chemical properties (pH and SEC) and concentrations of major elements (Ca, Mg, Na, K) and 23 trace elements (i.a. Cd, Cu, Hg, Pb, Zn) in 280 water samples. The results of the correlation matrix showed that an increase in the average air temperature in the summer of 2021 had a significant impact on the hydrochemistry of both types of waters operating in the catchment. In response to increase in T, the lowering of the H (0.52 < r < 0.66) and a decrease in Q (−0.66 < r < −0.68) were observed what in consequence also leads to changes in water chemistry. The principal component analysis (CA) indicates that chemical weathering and binding of elements to DOC are processes influencing water chemistry. Results of statistical analysis showed that the resultant of the hydrometeorological conditions that prevailed in that season and the type of geological formations on which they were located had a significant impact on the water chemistry at individual measurement points. Significant differences in the concentrations of elements between points on the same geological formations were also found. [ABSTRACT FROM AUTHOR]

Geologic carbon sequestration requires CO2 injection into the storage formation at high‐injecting pressure. Such high pressure could induce choked flow accompanying huge variations in thermodynamic properties of CO2 at a converging‐diverging (CD) fractures in the storage formation. In this study, high‐velocity CO2 transport through CD fractures was investigated to quantify the effect of fracture morphology on occurrence of both choked flow and shockwave that constrain the mass flow rate of fluid. In addition, variations in thermodynamic CO2 properties including Mach Number (Ma), defined by the ratio of fluid velocity to sound speed, and shock properties were investigated. The morphological characteristics of CD fractures were determined by nine properties, such as throat diameter, throat length, inlet diameter, outlet diameter, throat diameters of two‐connected CD fractures, fracture wall curvature, roughness amplitude, and frequency. As a result, the throat diameter crucially affected choked flow occurrence and maximum Ma. When the inlet and outlet diameters varied, the profiles for Ma variation were consistent in the converging and diverging segments, respectively. In addition, regardless of change in the throat length, the position of maximum Ma was nearly constant with showing the position length ratio of 0.13–0.14. However, roughness of fracture wall significantly influenced the Ma variation and occurrence of shock. In particular, backflows segregated from the main CO2 flow were observed near the wall roughness. Plain Language Summary: Choked flow is a fluid‐mechanical process that restricts the mass flow rate of fluid and it can be occurred when fluid velocity overcomes its sound speed. When CO2 is injected into the targeted geologic formation, choked flow can occur due to highly pressurized flow within the fractures located near the CO2 injection well. Once choked flow occurred, the shock, which accompanies substantial changes in the thermodynamic properties of CO2, follows in the fractures. In the study, choked flow is generated within the converging‐diverging (CD) fracture which serves as a pathway of injected CO2, and its cross‐sectional area decreases and increases again after the "throat." We assumed that the CD fractures have various morphologic properties and analyzed the relationship between the fracture morphology and shock properties. The results highlighted that the throat diameter and fracture roughness mainly affected choked flow occurrence and shock properties. Findings here are applicable to other site‐specific studies, such as volcanoes, geysers, geothermal fields, and underground hydrogen storage sites where highly compressed fluid often migrates through subsurface fractures or any types of geologic conduits. Key Points: CO2 flow within the fracture was simulated to evaluate the effect of fracture morphology on choked flow and shock generationMorphologic properties including throat diameter and length, inlet and outlet diameter, number of throats, and wall roughness were variedThroat diameter influenced the Mach number (Ma); a complicated trend of Ma and backflow were observed owing to wall roughness [ABSTRACT FROM AUTHOR]

Anomalous solute migrations in fractured rocks are governed by geometric characteristics and flow regimes. Although existing inverse models can describe this behavior, the underlying physics for quantifying key transport coefficients remains largely unexplored. Here, we investigate the quantitative impacts of geometric heterogeneity and flow regimes on solute transport in rock fractures. We conduct numerical experiments to simulate water flow and conservative solute transport in 3D fractures with varying geometric features and Reynolds numbers. Our results show that the non‐Fickian transport is prevalent across the entire flow regime, with Darcy flows attributed to geometric heterogeneity and non‐Darcian flows influenced by additional eddy zones. We employ the mobile‐immobile (MIM) domain model and continuous time random walk (CTRW) model to inversely model simulated breakthrough curves. Inverse analyses demonstrate that both models effectively characterize anomalous transport behaviors. The fitted transport coefficients of the MIM model exhibit stronger quantitative relationships with aperture and roughness parameters, as well as Reynolds number, compared to the CTRW model. By incorporating parameterized transport coefficients, we propose physics‐ and statistics‐based models to directly predict anomalous transport behaviors under different flow regimes. These prediction models accurately reproduce solute transport processes of all simulated cases with acceptable errors. The feasibility of directly predicting solute transport under varying flow regimes using geometric information is thus validated. Our study not only supports the study of substance migration based on geometric structure features, but also serves as a foundation for investigating geological activities based on substance migration information. Plain Language Summary: The migration of substances within geological formations is governed by their geometric pore structure, while information about substance migration can reveal the geometric characteristics of these formations. In this context, these two aspects form an interdependent feedback system. Investigating quantitative relationships and models between the geometry of geological formations and substance migration is thus crucial for understanding various geological processes related to geometric structure changes and hydrogeochemical signals (i.e., chemical information carried by groundwater or surface water, which reflects various natural and anthropogenic geological processes) evolution. Here, we explore the impact of both geometric structure and hydrodynamic conditions on solute transport in rock fractures. We conduct extensive direct numerical simulations to determine the inherent quantitative relationships between key transport coefficients and geometric parameters under different flow regimes. Based on these relationships, we establish upscaling models for directly predicting solute transport processes using only geometric parameters within both physics‐ and statistics‐based frameworks. This research has significant implications for predicting solute migrations using measurable physical properties and offers potential applications for studying geological activities related to fractured rocks through analyzing released hydrogeochemical signals. Key Points: Non‐Fickian transport behaviors in 3D fractures under different Re were characterized within physics‐ and statistic‐based frameworksTransport coefficients within mobile‐immobile and continuous time random walk frameworks were systematically parameterized by geometric and hydrodynamic parametersDirectly predicting solute transport via geometric parameters under different Re is feasible in both physics‐ and statistic‐based frameworks [ABSTRACT FROM AUTHOR]

Zircon U‐Pb‐He double dating (ZDD) provides the opportunity to derive high temperature crystallization ages and low temperature cooling ages from the very same mineral grain, making it especially attractive for zircon provenance studies. We present the combination of in situ detrital zircon U‐Pb‐He double dating and Raman spectroscopy‐based heavy mineral analysis on different tributaries of the Inn river system applying a new grain embedding technique. The Inn river catchment drains a well‐studied complex nappe pile of the Eastern Alps exposing Austroalpine and Penninic crystalline basement rocks. Igneous formations of different emplacement ages, as well as various metasedimentary units, have experienced Alpine and diverse pre‐Alpine metamorphic overprints. This makes the area ideally suited for testing the sensitivity and potential of ZDD for fingerprinting various lithologically contrasting units with contrasting thermal histories. Results demonstrate that both high‐ and low‐temperature age distributions reflect the major sources and thermotectonic pulses, respectively. More specifically, the rocks of the Tauern Window with Miocene (U‐Th)/He ages as well as the Permian metagranitoids from the Tauern and the Err‐Bernina nappe in the uppermost Inn valley are recorded in the downstream Inn sample. The main mass of zircons in the lower Inn, however, derives from the Ötztal and Silvretta crystalline basement rock with Cadomian U‐Pb and Cretaceous (U‐Th)/He ages. The abundance of heavy minerals derived from metamafic formations shows no correlation to the area of such lithologies on the catchments and the different zircon fertility resulted in the overrepresentation of zircon U‐Pb ages from the Variscan igneous suites. Plain Language Summary: The provenance analysis of sediments addresses the question of their origin, which geological formations were the sources of for example, sand bodies. For this so‐called heavy minerals are used that are specific for some rock types and help identify the major lithologies of the source region. The other method is the determination of the age of the detrital zircon crystals that commonly occur in many rock types and sand samples. In our study, we used a relatively new method that determines both the crystallization age and the cooling age in each individual zircon crystal that is highly specific for the source formations of the sediment. Both the heavy mineral analysis and the zircon "double dating" technique were performed on sand samples from the Alpine Inn river to test the reliability of these methods as the catchment of the river is well known and thus it can be used as a reference region. Key Points: Detrital zircon U‐Pb‐He double dating (DD) can accurately specify the sources of sediment—our test performed on well‐studied Alpine catchmentsCombination of DD and Raman‐based heavy mineral analysis applied to modern sands of the Alpine Inn riverComparison of predicted and measured detrital mineralogy and age spectra [ABSTRACT FROM AUTHOR]