Geological Journal最新文献

The geochemical signatures of trace elements in coal serve as crucial indicators of material sources and depositional environments during its formation. This study focused on 13 coal seams from the Longtan Formation in the Dahebian syncline, Guizhou, China. It involved industrial analysis, sulphur measurement, elemental profiling, coal ash composition analysis, maceral identification and trace element quantification. The research explored petrological, mineralogical, sedimentological and geochemical characteristics of coal samples to evaluate the vertical evolution of coal-forming environments and variations in provenance within the Longtan Formation. The study investigated relationships between changes in depositional environments and material sources and developed a sedimentary filling model for the late Permian in western Guizhou. Key findings include: (1) The overall depositional environment of the Longtan Formation was predominantly humid and reducing, and the coal-forming plants were mainly aquatic and herbaceous. However, the depositional environment in the upper segment is more stable than that in the lower segment, with a trend towards arid and oxidative conditions in the later depositional stages. (2) Instabilities in the depositional environment of the lower segment of the Longtan Formation could be attributed to magmatic dike eruptions and volcanic ash fallout from the Emeishan region. The shift towards arid and oxidative conditions during the later stages of deposition in the Longtan Formation might be linked to extensive acidic volcanic eruptions around the periphery of South China towards the end of the late Permian.

The Liwu Group is located in the core of the Taka, Jianglang and Changqiang domes, and is an important tectono-stratigraphic unit in the southern Songpan-Ganze flysch basin. The Songpan-Ganze Orogenic Belt (SGOB) is bounded by the South China, North China and Qiangtang blocks, and forms the eastern margin of the Tibetan Plateau. The Liwu Group is mainly composed of meta-clastic/−igneous rocks. We conducted an integrated study of field geology, petrology, geochemistry, and geochronology on representative metasedimentary rocks from the Liwu Group to understand the tectonic evolution of the Songpan-Ganze Orogenic Belt (SGOB) and the western Yangtze Block. Detrital zircon U–Pb dating on the meta-clastic rocks yielded age populations of ca. 2472 Ma, 964 Ma, 791 Ma, 535 Ma and 466 Ma, constraining the maximum deposition age at ~466 Ma. Low-medium chemical index of alteration (CIA = 36–80), relatively high index of compositional variability (ICV = 0.52–1.35), and the positive Zr/Sc vs. Th/Sc correlation indicate low maturity and insignificant weathering. Whole-rock geochemical data indicate that the sediment provenance was dominated by the late Archean–Paleoproterozoic Liwu Group felsic-intermediate rocks. The sediments were likely deposited in an active continental margin setting during the early Palaeozoic. Regionally, the metasedimentary rocks in the SGOB were probably deposited in ca. 466–490 Ma, and the SGOB may have had similar early Palaeozoic geotectonic evolution in the western Yangtze Block. According to the detrital zircon U–Pb geochronology of the Liwu Group, we suggest a strong genetic link between the protolith formation and the Yangtze Block, and the features of the stratigraphic sedimentary environment and provenance in the Tethys-Himalayan Ordovician system.

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.

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.

The present-day structure of the southern Izu-Bonin arc-trench system appears to have been influenced by the partial subduction of the Ogasawara Plateau beneath the Philippine Sea Plate, which has significant tectonic consequences. Unfortunately, there is insufficient information regarding the effects of the Ogasawara Plateau collision on the geophysical and seismic characteristics of the region. Therefore, we employ the geophysical and seismic analysis on the gravity and bathymetry datasets, seismic events and earthquake moment tensors to examine the geophysical and seismic patterns of the southern Izu-Bonin subduction zone, thereby uncovering the effects of the Ogasawara Plateau subduction. The results show that the Ogasawara Plateau forms uplift/upthrusts and large fractures/faults in the outer rise region at its subduction area. Several uplifted tectonic features are observed along the southern Izu-Bonin Trench axis at the area of the Ogasawara Plateau collision, where also the bathymetry is approximately 3 km elevated compared to other sections of the trench. Several conspicuous seamounts, uplifts, depressions and ridges are visible in the outer forearc region affected by the collision of the Ogasawara Plateau. Moreover, abnormal low Bouguer gravity anomalies are detected in both the outer and inner forearc regions around the area associated with the Ogasawara Plateau subduction. An area with a scarcity of earthquakes is observed to the west of the Ogasawara Plateau, suggesting a density contrast within the subducting Pacific Plate beneath this region. A seismic gap (moderate to great magnitude [Mw > 4]) is observed in the subducting Pacific Plate at depths ranging from 200 to 500 km around the Ogasawara Plateau subduction area. This study shows that the Ogasawara Plateau subduction influences geophysical properties, seismic activity and faulting in the southern Izu-Bonin subduction system. It also improves understanding of subduction dynamics and the seismic effects associated with the subduction of large bathymetric highs.

China's rapid industrialization and economic development have significantly contributed to rising CO₂ emissions, posing a direct challenge to sustainable development objectives. This study investigates the relationship between aquaculture production, renewable energy consumption, energy intensity, and CO₂ emissions in China, with a particular focus on the role of aquaculture production and renewable energy consumption in shaping emission patterns. Employing the Method of Moments Quantile Regression (MMQREG) and Bootstrap Quantile Regression (BSQREG) approaches, the analysis explores the nonlinear dynamics across various quantiles of CO₂ emissions. The findings reveal that renewable energy consumption and energy intensity exert varying effects on CO₂ emissions across different emission levels, with the most pronounced impact observed in the lower quantiles. The study underscores the necessity of considering regional and sectoral disparities when formulating emission mitigation policies. It highlights the importance of China's ongoing transition toward renewable energy, enhanced efficiency, and region-specific policy interventions, particularly in high-emission areas. These insights contribute to the discourse on sustainable development in emerging economies, offering practical implications for policymakers and avenues for future research, particularly in regional variations and economic determinants of CO₂ emissions.