Search Results (413)

The northeastern region of India is one of the six most seismically active convergent plate tectonic areas in the world. The north–south convergence along the Indo-Tibetan Himalayan Ranges and the east–west subduction within the Indo-Burma Ranges create a complex stress regime, resulting in significant seismic activity and a history of great/large earthquakes. The region’s intricate strain patterns, active faults, and potential seismic gaps underscore the need for detailed subsurface studies to effectively assess seismic hazards and impending seismicity. Geophysical research is essential for understanding the region’s geodynamic evolution, seismotectonics, and mineral resources. This manuscript reviews the geological and tectonic settings of the region and summarizes recent geophysical studies, including seismic, gravity, magnetic, and magnetotelluric surveys conducted in the Assam Valley and adjacent areas (within latitudes 24.5–28.5° N and longitudes 89–97.5° E). The review highlights key findings on hydrocarbon-bearing sediments, the configuration of the crystalline basement, the heterogeneous structures of the crust and upper mantle, and seismic discontinuities. By synthesizing these results, the review aims to enhance the understanding of seismic hazards in Northeast India, guide mitigation strategies, and identify key knowledge gaps to direct future research efforts. Full article

The transient electromagnetic method (TEM) has a wide range of applications in the hydrogeological exploration of mining engineering. This method is highly sensitive to groundwater responses and provides reliable data for the prevention of water-related disasters, such as sudden water surges and gushes. However, there are currently a lack of comprehensive and systematic analyses and summaries regarding the characteristics of magnetic source transient electromagnetic coil devices. Based on the fixed characteristics of the field source, this paper categorizes magnetic source transient electromagnetic coil devices into fixed-source devices and moving-source devices. It provides an in-depth introduction and analysis of the working principles, technical characteristics, existing applications, and development trends of these two types of devices. This study provides important references for the selection and application of magnetic source transient electromagnetic coil devices. In the future, the development of magnetic source transient electromagnetic devices will focus on deeper measurement depths, higher lateral resolution, non-contact coupling, and efficient detection, moving towards multifunctionality, automation, and intelligence. This paper can provide a technical reference for the selection of magnetic source transient electromagnetic coil devices and their application in hydrogeological exploration of mining engineering. Full article

This study investigates the geological composition and material distribution within the Lavrion repository located in Greece through an aerial magnetometry survey using a novel aerial drone, CERBERUS, coupled with advanced data processing techniques. The deployment of drone-based magnetometry provided a high-resolution, non-invasive approach to capturing magnetic field data over complex and potentially hazardous terrain (soils highly contaminated), facilitating the rapid and precise mapping of the study area. As a final result, a 3D magnetic susceptibility model was developed, representing a detailed view of the magnetic susceptibility variations within the repository. This model enabled the comprehensive visualization of high-susceptibility zones associated with ferromagnetic materials and low-susceptibility zones correlating with diamagnetic materials like lead, arsenic, cadmium, and zinc. The combined methodologies underscore the effectiveness of drone-based aerial magnetometry in geophysical studies, highlighting its potential for mining exploration and waste management. This study demonstrates that the integration of drone technology with magnetic data processing offers a powerful tool for analysing subsurface structures in a safe, efficient, and non-invasive manner. Full article

Graphite, known for its exceptional electrical and thermal conductivity as well as its lubricating properties, is a critical mineral resource for various industrial applications. Due to these unique properties, graphite has gained increasing importance across various technological and industrial fields. Northeast China, rich in graphite deposits, faces significant exploration challenges owing to dense vegetation and limited bedrock exposure. This study provides a comprehensive analysis of the geological strata in the region, utilizing magnetic exploration to identify ore-forming strata beneath the Quaternary sediment. Additionally, self-potential methods were used to delineate areas of potential graphite mineralization. The effectiveness of these methods was evaluated across two well-tested and thoroughly studied geological profiles. The magnetic anomaly revealed three magnetic anomaly areas, with the low magnetic anomaly zone associated the Huangchagou Formation, indicating strong potential for graphite ore. Then, a self-potential survey was conducted across this anomalous zone, revealing a nearly east–west trending banded anomaly, suggesting the presence of graphite deposits. Trenching and drilling operations were subsequently carried out, confirming the existence of graphite ore, with total reserves exceeding 50,000 kt. This research demonstrates that the combination of magnetic surveys and self-potential methods offers a cost-effective geophysical approach for graphite exploration. These methods provide a promising strategy for discovering graphite deposits, particularly in the challenging terrains of Northeast China. Full article

Magnetic and electromagnetic techniques have a long history of application in mineral exploration to detect deposits and their surroundings. Their implementation over the last fifteen years has been affected by strong variations in the mining market in parallel with important technological developments. During this period, both methods were the subject of numerous documented case studies all over the globe, which is a sign of popularity and longevity of these techniques. Through a review of case histories from the main geophysical journals, we analyze the principal usage of these methods when applied to mineral exploration, while the majority of documented cases originate from North America, Asia, and Australia. There are more case studies describing the use of the magnetic method and we attribute this popularity to direct and indirect use of this method for mineral exploration. In particular, there is an increasing number of magnetic surveys conducted with drones. Combining magnetic and electromagnetic techniques is also common. The number of magnetic and EM technique case histories range by descending order from gold, porphyry copper, polymetallic, massive sulfides, uranium, Ni-Cu-PGE, iron ore, kimberlite, and iron-oxide copper-gold, with a number of single continent-specific applications. Full article

Porcine circovirus 3 (PCV3) is a small non-enveloped circovirus associated with porcine dermatitis and nephropathy syndrome (PDNS). It has occurred worldwide and poses a serious threat to the pig industry. However, there is no commercially available vaccine. PCV3 capsid protein (Cap) is an ideal antigen candidate for serodiagnosis. Here, a novel fully automated chemiluminescence enzyme immunoassay (CLEIA) was developed to detect antibodies (Abs) to Cap in porcine serum. Recombinant PCV3 Cap, self-assembled into virus-like particles (VLPs), was produced using baculovirus and coupled to magnetic particles (Cap-MPs) as carriers. Combined with an alkaline phosphatase (AP)–adamantane (AMPPD) system, Cap-Abs can be rapidly measured on a fully automated chemiluminescence analyzer. Under optimal conditions, a cut-off value of 31,508 was determined, with a diagnostic sensitivity of 96.8% and specificity of 97.3%. No cross-reactivity was observed with PCV1 and PCV2 and other common porcine pathogens, and both intra-assay and inter-assay coefficients were less than 5% and 10%, respectively. Prepared Cap-MPs can be stored at 4 °C for more than 6 months. Importantly, this CLEIA had a good agreement of 95.19% with the commercially available kit, demonstrating excellent analytical sensitivity and significantly reduced operating time and labor. A serological survey was then conducted, and showed that PCV3 continues to spread widely in South China. In conclusion, our CLEIA provides time and labor-saving, and a reliable tool for PCV3 epidemiological surveillance. Full article

Qing-Chengzi (QCZ) is an important silver-gold mining area in the eastern part of the Northeast China Craton. The shallow minerals in this area are almost completely depleted, leading to a demand for exploration to find deeper, concealed deposits. However, due to the rugged terrain, few high-precision ground surveys have been executed in this area, resulting in an insufficient understanding of the unexposed ores. To address this issue, this study implemented a high-precision ground magnetic survey to identify faults and potential rocks in this area. To achieve these goals, remanence was analyzed to reduce its adverse effect on processing. Then, lineament enhancement with directional derivatives was conducted on the pre-processed magnetic anomalies to highlight structural features. Based on the results, eight major and twenty-one minor faults were identified, among which three major faults correspond well to the known faults. Most of the major faults run N–S, and the others run NW/NE. Furthermore, 3D inversion was conducted to locate potential rocks. Our inversion results indicate that there are six hidden rocks in the underground, extending from a depth of a few hundred meters to no more than three km. Two of the rocks correspond well to the already mined areas. This study provides support for subsequent exploration in the QCZ area. Full article

Magnetic Barkhausen noise (MBN) is one of the most effective methods for determining the easy axis of ferromagnetic materials and for evaluating texture and residual stress in a nondestructive manner. MBN signals from multiple angles and different magnetization sections can be used to characterize magnetic anisotropy caused by various magnetization mechanisms. This paper reviews the development and application of magnetic anisotropy detection technology, and the MBN anisotropy models that take into account domain wall motion and magnetic domain rotation are analyzed thoroughly. Subsequently, the MBN anisotropy detection devices and detection methods are discussed, and the application of magnetic anisotropy detection technology in stress measurement and texture evaluation is reviewed. From the perspective of improving detection accuracy, the influence of composite mechanisms on magnetic anisotropy is analyzed. Finally, the opportunities and challenges faced by current magnetic anisotropy detection technology are summarized. The relevant conclusions obtained in this paper can be used to guide the MBN evaluation of magnetic anisotropy in ferromagnetic materials. Full article

The Dongzhongla deposit is a skarn-type lead–zinc ore deposit located in the eastern segment of the Gangdese metallogenic belt, situated in the Xizang province, China. The high-altitude mountainous terrain of the region poses significant challenges to ground-based exploration. To facilitate more accurate mineral exploration in the deposit and its surrounding area, a high-resolution airborne magnetic survey was conducted over the mining area and its periphery. The airborne magnetic data were processed using derivative and Euler deconvolution methods, yielding results that reflect the geological structural features of the study area. By integrating the geological characteristics of the ore deposit, we inferred that the areas of magnetic anomaly extensions and the peripheries of other magnetic anomalies are favorable zones for mineralization, providing positive leads for further mineral exploration. Full article

The exploration of porphyry deposits in Greenland has become increasingly important due to their significant economic potential. We utilized total magnetic intensity (TMI) and mobile magnetotelluric (MobileMT) airborne data to delineate potential porphyry mineralization zones. The TMI method was employed to map variations in the Earth’s magnetic field caused by subsurface geological features, including mineral deposits. By analyzing anomalies in TMI data, potential porphyry targets were identified based on characteristic magnetic signatures associated with mineralized zones. Complementing TMI data, MT airborne surveys provided valuable insights into the electrical conductivity structure of the subsurface. Porphyry deposits exhibited distinct conductivity signatures due to the presence of disseminated sulfide minerals, aiding in their identification and delineation. Integration of the TMI and MobileMT datasets allowed for a comprehensive assessment of porphyry exploration targets in Flammefjeld. The combined approach facilitates the identification of prospective areas with enhanced geological potential, optimizing resource allocation and exploration efforts. Overall, this study demonstrates the efficacy of integrating TMI and MobileMT airborne data for porphyry exploration in Greenland, offering valuable insights for mineral exploration and resource development in the region. Full article

To search for a conceptual picture describing the magnetization plateau phenomenon, we surveyed the crystal structures and the spin lattices of those magnets exhibiting plateaus in their magnetization vs. magnetic field curves by probing the three questions: (a) why only certain magnets exhibit magnetization plateaus, (b) why there occur several different types of magnetization plateaus, and (c) what controls the widths of magnetization plateaus. We show that the answers to these questions lie in how the magnets under field absorb Zeeman energy, hence changing their magnetic structures. The magnetic structure of a magnet insulator is commonly described in terms of its spin lattice, which requires the determination of the spin exchanges’ nonnegligible strengths between the magnetic ions. Our work strongly suggests that a magnet under the magnetic field partitions its spin lattice into antiferromagnetic (AFM) or ferrimagnetic fragments by breaking its weak magnetic bonds. Our supposition of the field-induced partitioning of spin lattices into magnetic fragments is supported by the anisotropic magnetization plateaus of Ising magnets and by the highly anisotropic width of the 1/3-magnetization plateau in azurite. The answers to the three questions (a)–(c) emerge naturally by analyzing how these fragments are formed under the magnetic field. Full article

In the past few decades, there has been a notable technological advancement in geophysical sensors. In the case of magnetometry, several sensors were used, having the common feature of being miniaturized and lightweight, thus idoneous to be carried by UAVs in drone-borne magnetometric surveys. A common feature is that their sensitivity ranges from 0.1 to about 200 nT, thus not comparable to that of optically pumped, standard fluxgate or even proton magnetometers. However, their low cost, volume and weight remain very interesting features of these sensors. In fact, such sensors have the common feature of being very inexpensive, so new ways of making surveys using many of these sensors could be devised, in addition to the possibility, even with limited resources, of creating gradiometers by combining two or more of them. In this paper, we explore the range of applicability of small tri-axial magnetometers commonly used for attitude determination in several devices. We compare the results of surveys performed with standard professional geophysical instruments with those obtained using these sensors and find that in the presence of strongly magnetized sources, they succeeded in identifying the main anomalies. Full article

Autosomal dominant polycystic kidney disease (ADPKD) is the predominant hereditary factor leading to end-stage renal disease (ESRD) worldwide, affecting individuals across all races with a prevalence of 1 in 400 to 1 in 1000. The disease presents significant challenges in management, particularly with limited options for slowing cyst progression, as well as the use of tolvaptan being restricted to high-risk patients due to potential liver injury. However, determining high-risk status typically requires magnetic resonance imaging (MRI) to calculate total kidney volume (TKV), a time-consuming process demanding specialized expertise. Motivated by these challenges, this study proposes alternative methods for high-risk categorization that do not rely on TKV data. Utilizing historical patient data, we aim to predict rapid kidney enlargement in ADPKD patients to support clinical decision-making. We applied seven machine learning algorithms—Random Forest, Logistic Regression, Support Vector Machine (SVM), Light Gradient Boosting Machine (LightGBM), Gradient Boosting Tree, XGBoost, and Deep Neural Network (DNN)—to data from the Polycystic Kidney Disease Outcomes Consortium (PKDOC) database. The XGBoost model, combined with the Synthetic Minority Oversampling Technique (SMOTE), yielded the best performance. We also leveraged explainable artificial intelligence (XAI) techniques, specifically Local Interpretable Model-Agnostic Explanations (LIME) and Shapley Additive Explanations (SHAP), to visualize and clarify the model’s predictions. Furthermore, we generated text summaries to enhance interpretability. To evaluate the effectiveness of our approach, we proposed new metrics to assess explainability and conducted a survey with 27 doctors to compare models with and without XAI techniques. The results indicated that incorporating XAI and textual summaries significantly improved expert explainability and increased confidence in the model’s ability to support treatment decisions for ADPKD patients. Full article

Magnetotelluric (MT) sounding is a geophysical technique widely utilized in mineral resource surveys, where conductivity and magnetic permeability serve as essential physical parameters for forward modeling and inversion. However, the effects of conductive anisotropy and non-zero magnetic susceptibility are usually ignored. In this study, we present a three-dimensional (3D) MT modeling algorithm using Coulomb-gauged electromagnetic potentials, incorporating a mixed nodal and edge-based finite element method capable of simulating MT responses for conductive anisotropic and magnetic anomalies. Subsequently, the algorithm’s accuracy was validated in two steps: first, it was compared with analytical solutions for a 1D magnetic model; then, a comparison was made with previously published numerical results for a 3D generalized conductive anisotropic model. The results of two tests show that the maximum relative error is below 0.5% for both models. Furthermore, representative models were computed to comprehensively analyze the responses of MT. The findings illustrate the relationship between anisotropic parameters and electric fields and emphasize the significance of considering the impact of magnetic susceptibility in magnetite-rich regions. Full article

A reinforced earth wall is a structure in which reinforcement materials are placed in an embankment to build a vertical or nearly vertical wall surface. Such walls have been widely used in roads and in developed land since around 1960. Reinforcement materials have a set service life of 100 years and fall into two types: steel and geosynthetics. To ensure long-term durability, steel reinforcement materials are plated, while geosynthetics are designed with a limit strength designed to resist fracture for 100 years under the conditions of a given load placed on the reinforcement materials. However, owing to the difficulty of assessing the condition of reinforcement materials in soil, this paper proposes solutions based on non-destructive methods. Specifically, it proposes a method of assessing the amount of strain through an embedded optical fiber in the case of geosynthetic reinforcement materials, or magnetic surveying to investigate the degree of corrosion in the case of steel reinforcement materials. This paper demonstrates that it is possible to non-destructively assess the state of either type of reinforcement material. Full article