Geological Journal最新文献

Understanding the elemental concentration and distribution in coal has significant importance in assessing its mobility and behaviour during utilisation processes. The depositional environment of coal controls the concentrations of elements that can adversely affect human health and the environment. Thus, this study investigates the detailed mineralogy and elemental composition of Talcher coal, the largest coalfield in India, in order to gain insight into the mode of occurrence of elements and palaeodepositional conditions. The coal is enriched in detrital mineral matter and exhibits a high detrital/authigenic index. Quartz and kaolinite are abundant, while siderite, calcite, plagioclase, goethite, illite, dolomite, apatite, and Ti-oxide have also been identified. This coal is enriched with Hg, Mo, Cr, and Th concerning the world hard coal. The Ti, Na, Cu, Cr, Rb, U, and Th have a strong association with silicate minerals. The Sr, K, Mg, Ca, and P exhibit both carbonate and phosphate affinities, whereas Fe, S, and Co are mostly associated with organic matter. Similarly, Mn, Ba, Ni, Zn, Pb, Cd, Mo, As, and Nb display both organic and inorganic affinities. The inorganic matters in coal are predominantly derived from intermediate rocks and have undergone strong weathering. Various elemental proxies suggest that the coal is formed predominantly in a freshwater depositional environment under a fluctuating oxygenating conditions. The Sr/Cu and Rb/Sr ratios have implied the prevalence of a warm humid climate with intermittent transitional warm to dry climatic conditions during coal formation. This research will be helpful in future palaeowetland research as well as understanding the behaviour of trace elements during coal utilisation.

This paper aims to address the controversy surrounding the occurrence state, enrichment and precipitation mechanism of gold in the Shuiyindong gold deposit, which has been extensively discussed by several authors. To this end, pyrite and arsenopyrite in the high-grade ores of the deposit were considered as the research objects. Scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) were used to determine the morphology and elemental content of the growth zonal of pyrite and arsenopyrite–pyrite aggregates. The occurrence and distribution of Au was analysed, and its enrichment and precipitation mechanisms are discussed herein. The findings of this paper indicate that gold mainly occurs in the growth annulus of pyrite and arsenopyrite of the pyrite–arsenopyrite aggregate. Furthermore, the emergence of ‘giant grains’ (200 μm) of ‘native gold’ was observed. Gold primarily participates in the lattice structure of pyrite and arsenopyrite in the form of Au⁺, but also occurs less commonly as Au⁰. Moreover, ‘giant grains’ of natural gold were observed in host rocks exhibiting dolomitisation and/or calcilisation, and in quartz veinlets. Notably, Au⁺ mainly replaces the S of pyrite and arsenopyrite by isomorphism in a relatively closed environment, whereas Au⁰ and native gold form by the rapid precipitation of Au-rich saturated and supersaturated hydrothermal fluids in a relatively open environment.

Since the Mesozoic, the southern margin of the Sichuan Basin has experienced multiple deformations due to the far-field effects of geological events, including the westward subduction of the Paleo-Pacific Plate and the collision between the Indian and Eurasian plates; it serves as a natural laboratory for investigating intracontinental deformation. Through detailed geological surveys, analysis of over 500 vector datasets, and paleostress inversion, we identified three significant deformations in this region during the Meso-Cenozoic. Low-temperature thermochronology data constrain the timing of these deformation and cooling-exhumation events. The first phase occurred during the Late Mesozoic; in the early deformation stage, trough-like folds developed outside the basin, accompanied by medium- to high-angle SE-dipping thrust faults in the cores of the anticlines, while a widely developed planar conjugate shear joints formed within the basin. In the later stage of deformation, the NW-SE compression rotated to N-S due to boundary fault activation, resulting in the formation of nearly E-W trending folds within the basin. The deformation was likely induced by multiple NW-directional detachments and progressive compression in the Xuefeng orogenic belt. The second phase, characterised by NW-trending box folds and SW-dipping, moderate- to high-angle thrust faults, took place from the Eocene to early Miocene, induced by compressional forces from the India–Eurasian plate collision, leading to NE-SW compression and significant exposure in the Dalou and Daliang Mountains, with some involvement of basin strata. The third phase, characterised by NE-trending tight anticlines and high-angle reverse faults NW dipping in the core of the anticlines since the mid-Miocene, is linked to the eastward lateral extrusion of crustal material from the Tibetan Plateau towards the northwest margin of the Sichuan Basin, resulting in strong NW-SE compression that likely impacts the basin's southern edge. These multiple deformations indicate two major shifts: the transition from the Marginal-Pacific tectonic domain to the Tethys-Himalayan domain, and the phased outward expansion of the Himalayan tectonic domain due to changes in the Tibetan Plateau's internal geodynamic setting since the Miocene. Understanding these deformations is crucial for elucidating the mechanisms of intracontinental deformation in the context of plate collision.

The imperative shift toward renewable energy sources is driven by escalating climate change concerns and the depletion of fossil fuels. Microbial fuel cells (MFCs) present a promising solution by converting organic matter into electricity through microbial metabolism. This study aims to develop a portable MFC capable of powering soil moisture sensors to enhance sustainable agricultural practices in remote regions of Malaysia. Cow manure and human waste were employed as substrates due to their high organic content and microbial diversity, which emphasises their potential in sustainable energy generation. Carbon sheet electrodes of varying sizes (7 cm × 5 cm and 3 cm × 5 cm) were tested to optimise electrochemical performance. Experimental results demonstrated that MFCs utilising cow manure with smaller electrodes (3 cm × 5 cm) exhibited superior performance, achieving an initial open-circuit voltage of 0.495 V and stabilising at approximately 0.314 V after 120 h. The peak power density reached 5207 μW/m², significantly outperforming the human waste MFCs. The enhanced performance is attributed to the effective substrate degradation and efficient electron transfer facilitated by the cow manure substrate and optimised electrode surface area. While a single MFC unit does not generate sufficient current to directly power standard soil moisture sensors, strategic improvements such as increasing electrode dimensions, optimising chamber volume, and incorporating energy storage and voltage boosting circuits can render the system practical. This work underscores the potential of MFC technology in addressing energy scarcity in rural agricultural regions, aligning with global efforts toward renewable energy adoption and sustainable waste management. Future advancements in MFC design and integration hold promise for broader applicability in precision agriculture and beyond.

Landslides pose a serious threat, especially in mountainous regions, where they can severely impact human life, property and economic activities. This hazard has been particularly challenging in the Himalayan region, particularly in the Sikkim Himalayas. In this study, hybrid models are used to generate landslide susceptibility maps (LSMs) in the South Sikkim Himalaya region of India that could significantly help in reducing the risk. To construct an accurate susceptibility map, a detailed 163 landslide inventories were created using historical data, Google Earth and field investigations. A Random Forest (RF) model was employed to identify relevant factors that revealed 15 significant variables, out of which, distance from road and rainfall emerged as the primary drivers of landslide risk. The Stacking Ensemble model combines three classic machine learning models, such as Artificial Neural Networks (ANNs), Support Vector Machines (SVMs) and Gradient Boosting Decision Trees (GBDTs) to avoid overfitting and improve generalisation. For modelling, landslide data were randomly divided into training (70%) and validation (30%) subsets. The models were evaluated using the receiver operating characteristic (ROC) curve and statistical metrics. The results showed that the ANN had the highest individual prediction performance with an area under curve (AUC) value of 0.92, followed by GBDT (0.89), SVM (0.83) and the Stacking method (0.89). However, the Stacking model performed best in generalisation and class-specific accuracy, particularly in very high (0.54%) compared to other models. The results of this study highlight the Stacking model's promise as a reliable tool for landslide susceptibility mapping by showing that it performs better than alternative methods in precisely identifying landslide-prone locations. The combination of many machine learning methods inside a hybrid framework markedly improves the dependability and accuracy of these maps. The utilisation of hybrid models enhances understanding of landslide dynamics and establishes a scientific foundation for formulating efficient risk reduction methods. This improvement offers critical insights for policy-making focused on reducing landslide risks and supports long-term regional growth and sustainability, especially in geologically vulnerable and mountainous areas.

The contradiction between the irreplaceability of critical metallic resources in economic development and national defence security, and their relatively small reserves and uneven distribution in nature, highlights the significance of exploring new types of mineral resources. The discovery of critical metals in coal has made it possible for coal to become an alternative source of these resources. This study provides geochemical and mineralogical data of the No. 13 coal in Xiegou Mine, Hedong Coalfield, North China, focusing on the occurrence and enrichment mechanisms of lithium (Li) and rare earth elements and yttrium (REY). The No. 13 coal is a high-volatile bituminous coal with low ash yield and high total sulphur content. The kaolinite, pyrite and calcite are the main minerals, with a small amount of anatase, zircon, illite and REY-bearing minerals. Compared to world hard coals, the studied coal samples have high Li and REY content; in addition to Li and REY, Ga and Zr (Hf) may also be of potential economic significance. Li occurs predominantly in kaolinite or Ti-bearing kaolinite, and REY occurs dominantly in phosphate minerals (LREY is mainly related to goyazite). The geochemical parameters and mineral assemblages indicate that the Yinshan Oldland is the main sediment source of coal and host rocks. In addition, the geochemistry and mineralogy of the parting indicate that it is the product of alkaline felsic volcanic ash. The high content of Li and REY in the No. 13 coal is the result of alkaline volcanic ash input and the late modification of multi-stage fluids.

The paleogeography and kinematic evolution of the Lhasa terrane during the Cenozoic time are key aspects to understanding the tectonic evolution of the Tibetan Plateau. Previous studies have focused on the paleolatitude reconstruction of the Lhasa terrane before and during the onset of the initial India–Asia collision. However, there exists an important gap between the period immediately after the onset of the India–Asia collision and the precise time at which the Lhasa terrane reached its present-day latitude in terms of its kinematic evolution throughout the Cenozoic time. To this end, we performed an integrated study including paleomagnetism and isotopic geochronology on the Paleogene sediments of the Niubao (NB) Formation to provide a new constraint on the late Eocene paleolatitude of the Lhasa terrane. In combination with rock magnetic and petrographic results, our obtained results show that 91 inclination-shallowing corrected characteristic remanent magnetizations (ChRM) are of pre-folding origin and have passed the reversal test, indicating their primary nature. Based on these inclination-shallowing corrected 91 filtered ChRM directions from sediments, the paleopole was calculated as λ_p = 77.2° N, φ_p = 308.2° E, with dp/dm = 3.0°/5.1°. This new result indicates that the Lhasa terrane was at 21.7° ± 3.0° N for the reference site at ca. 38 Ma, suggesting that the Lhasa terrane was still underway to its northward motion before its final arrival at present-day latitude. This further suggests that a total magnitude of ca. 1700 km crustal shortening was partitioned within Asia since 38 Ma to the present day.

Solar saltworks often face challenging production conditions, including drastic thermodynamic condition changes. The major ionic evolution of the inland brine in Chott Melrhir saltwork has been studied with an indoor polythermal and isothermal at 35°C evaporation simulation, using phase diagrams and forward geochemical modelling. Hydrochemical and mineralogical analysis indicated that the brine under investigation exhibits an oceanic chemical character and follows a metastable evaporation path similar to that of seawater at 35°C. During the transport to the surface, the brine undergoes a drastic concentration, depositing major calcium content as gypsum. Evaporation yields significant quantities of kainite, magnesium sulphate salts and halite, the latter of which precipitates predominantly at the outset of the process along with minimal gypsum contents. Raw salt and washing brine analysis indicated that the interstitial brine was the source of the major ionic impurity, along with clay and sand, while gypsum and calcium ions were identified as solar evaporation impurities. The use of PHREEQC (pH-Redox Equilibrium C-programme) geochemical simulation software and Pitzer's database has enabled the precise proposal of a shift in pumping densities for solar evaporation feed brine of approximately 1.221 and for washing brine of approximately 1.227. This methodology may be tested for the purpose of overcoming significant challenges posed by major ionic impurities that producers may encounter during production in such environments. Moreover, the results have the potential to facilitate the expansion of production through the separation of other salts that may possess greater economic value, such as kainite in this case.

The potential resources of potassium and lithium in the underground brine of the Qaidam Mahai Basin are considerable. However, the research on the mineralization regularity of lithium-rich clay layer brine lacks a theoretical basis. This article takes the shallow intercrystalline brine of Dezong Mahai as the research object and employs hydrochemical and isotope geochemical methods to discuss the salinization and mineralization characteristics, evolution patterns, and the sources of brine-forming fluids of the underground brine. The shallow intercrystalline brine deposits in the study area belong to alkaline brines with high salinity, and the hydrochemical type is mainly the magnesium sulfate subtype. The contents of K⁺ and Li⁺ are relatively high, attaining the minimum industrial grade and the boundary grade respectively, and thus possess mining value. The Hydrochemical analysis reveals that the water chemical composition of the shallow intergranular brine in the study area is dominated by evaporation and crystallisation. Under the effect of evaporation and crystallisation, minerals such as gypsum, rock salt, mirabilite, glauberite, sylvite, carnallite and bischofite are precipitated. Under the water-rock interaction, carbonate rock precipitates are generated, evaporite and silicate rock minerals are dissolved, and the main ion sources of the brine are enriched. The hydrogen and oxygen isotope analysis indicates that the shallow intergranular brine in the study area has a meteoric water origin, with a recharge elevation of approximately 3440 m, and is replenished by the meteoric water and snowmelt water from the Seshten Mountain and Nanbaxian Mountain. The strontium isotope analysis demonstrates that the material source of the shallow intergranular brine in the study area is multi-sourced, and there are certain supplies of rock salt leachate water, deep fluid, and water from the Yuqia River. There exists a close relationship between the genesis of the shallow intercrystalline brine in the study area and factors such as atmospheric precipitation, infiltration of surface water, admixture of deep fluids, evaporation and concentration, and water-rock interaction.