Geoscience frontiers最新文献

{"title":"Sorting carbonate clay-type lithium ores using a deep learning model with adaptive spectral-texture feature fusion","authors":"Qunjia Zhang ,&nbsp;Jiacheng Mei ,&nbsp;Lujun Lin ,&nbsp;Lei Liu ,&nbsp;Hanjie Wen ,&nbsp;Le Wang","doi":"10.1016/j.gsf.2025.102185","DOIUrl":"10.1016/j.gsf.2025.102185","url":null,"abstract":"<div><div>Carbonate clay-type lithium ore holds significant potential due to its extensive reserves, broad distribution, and relatively easy extraction. However, it presents significant beneficiation challenges due to its coexistence with karst-type bauxite, which often results in mixed, low-lithium ores. For the first time, spectral–texture features derived from hyperspectral imaging (HSI) are jointly modeled with a deep learning framework to explore the feasibility of pre-sorting carbonate clay-type lithium ores. Initially, the spectral responses reflecting mineral composition and the texture features characterizing structural differences were analyzed to evaluate the feasibility of using HSI for ore sorting. Furthermore, the influence of band selection, data standardization, and water absorption regions on pre-sorting performance was systematically investigated through comparative analysis of multiple dataset configurations. Two classification schemes, primary ore types classification and multi grade classification, were employed to assess sorting accuracy and identify key influencing factors. The proposed model, A²ST-OSNet, achieves excellent results in both ore localization and classification through staged data input with varying dimensions and a modular design. Results revealed that joint modeling of spectral and texture features enables efficient and accurate pre-sorting, whereas models relying solely on either spectral or texture features were insufficient, as discriminative information for ore sorting is jointly determined by mineral composition and structural characteristics. Moreover, refined feature extraction and fusion strategies, including spectral–texture feature selection and attention mechanisms, proved critical in enhancing classification performance. The proposed approach offers valuable technical support for ore beneficiation and tailings reutilization, contributing to sustainable resource utilization and providing an effective solution for the efficient recycling of carbonate clay-type lithium ores.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 1","pages":"Article 102185"},"PeriodicalIF":8.9,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wetting of olivine by sulfide liquid: an example from the Central Asian Orogenic belt in NW China","authors":"Jian Kang ,&nbsp;Xie-Yan Song ,&nbsp;Wei Xie ,&nbsp;Yu-Feng Deng ,&nbsp;Bo Wei ,&nbsp;Stephen J. Barnes ,&nbsp;Wen Chen ,&nbsp;Wei-Dong Li","doi":"10.1016/j.gsf.2025.102183","DOIUrl":"10.1016/j.gsf.2025.102183","url":null,"abstract":"<div><div>Experimental studies have demonstrated that olivine can be wetted by sulfide liquid under specific conditions. In this study, we investigate elongated sulfide-olivine patches in lherzolite from the Dahuangshan mafic–ultramafic complex (Central Asian Orogenic Belt, NW China), which display textural evidence indicative of this phenomenon. Two-dimensional (2D) microbeam X-ray fluorescence (micro-XRF) mapping and three-dimensional (3D) high-resolution X-ray computed tomography (HRXCT) scanning reveal that the sulfide-olivine patches are 1.0‒4.8 cm long, 0.3‒2.3 cm wide and 0.2‒2.0 cm thick, and have sharp boundaries in the lherzolite matrix. These patches consist entirely of olivine (Fo₇_–_81.9) embedded within interstitial sulfides. The sulfides dominantly comprise pyrrhotite (&gt;94 vol%), minor pentlandite (&lt; 6 vol%) and trace chalcopyrite, and contain a total of 1.1‒1.9 wt.% (Ni + Cu + Co). Low olivine-olivine-sulfide dihedral angles (averaging 44.9°) indicate that olivine was wetted by the sulfide liquid in these patches. The crystal size distributions (CSDs) of the olivine grains in the sulfide-olivine patches are different from those of the olivine in the lherzolite matrix. These observations can be explained by the entrainment of pre-existing sulfide-olivine cumulates into flowing magma. The elongated shape and parallel distribution of the sulfide-olivine patches indicate that the magma flow was laminar. These findings support the hypothesis that sulfide liquid can wet olivine and under the right conditions can be transported and deposited as sulfide-olivine aggregates within magma conduits.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 1","pages":"Article 102183"},"PeriodicalIF":8.9,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revealing fluid dynamics in unconventional reservoir rocks: A novel approach of T1-T2 analysis","authors":"Zishuo Li ,&nbsp;Yanbin Yao ,&nbsp;Xueguang Zhu","doi":"10.1016/j.gsf.2025.102186","DOIUrl":"10.1016/j.gsf.2025.102186","url":null,"abstract":"<div><div>Fluid distribution and migration characteristics hold significant importance in evaluating the quality of reservoir rocks. Two-dimensional nuclear magnetic resonance (2D NMR) measurements have been widely applied to identify specific hydrocarbon contents within rocks. However, due to the complexity of the pore and fluid system, this<!--> <!-->technique was not fully exploited and was limited by existing data processing methods. In this study, a novel centroid method was developed to enhance the quantification of 2D NMR data for fluids in reservoir rocks. This method calculates the centroid of the 2D NMR map, which correlates with the average pore size derived from the imbibition process. To validate its effectiveness, the method was applied to analyze the <em>T</em>₁ (longitudinal relaxation time) – <em>T</em>₂ (transverse relaxation time) relationships taken during imbibition processes in three different reservoir rocks. Results demonstrate that the position of centroid can be used to analyze the dominant type of water in pores involved in the imbibition process. Besides, this method can also successfully assess state changes for different water types inside samples by tracking centroids’ movements and fluctuations in centroid <em>T</em>₁/<em>T</em>₂ ratios, as well as utilizing the 2D NMR map’s signal partitioning capacity. Compared to other approaches, it elucidates the distribution and migration characteristics of water in different types of pores and provides significant advantages in the quantitative processing and comparative analyses of 2D NMR data across various water-bearing conditions. Furthermore, it also demonstrates significant potential for investigating interactions and dynamics of multiphase fluids in unconventional reservoirs.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 1","pages":"Article 102186"},"PeriodicalIF":8.9,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First evidence of ca. 1.77 Ga S-type magmatism, Aravalli orogen: Implications for the late Paleoproterozoic geodynamic evolution of NW India","authors":"Parampreet Kaur ,&nbsp;Armin Zeh ,&nbsp;Naveen Chaudhri ,&nbsp;Prabhakar Dutta ,&nbsp;Swati Sharma","doi":"10.1016/j.gsf.2025.102182","DOIUrl":"10.1016/j.gsf.2025.102182","url":null,"abstract":"<div><div>Present models for the late Paleoproterozoic evolution of the Aravalli orogen (NW India) postulate the existence of a continental magmatic arc active between 1875 Ma and 1810 Ma, followed by a phase of post-collisional magmatism between 1730 Ma and 1700 Ma. However, the tectono-magmatic processes occurring between these two events remain cryptic. In this study, evidence for an intervening magmatic phase is revealed based on the investigation of granitoids exposed in the southern part of the Aravalli orogen. U-Pb zircon dating of these granitoids (granites to tonalites) yielded emplacement ages between 1770 Ma and 1760 Ma. Whole-rock geochemical data indicate a strongly peraluminous, S-type, high-K calc-alkaline character, with magnesian to ferroan signatures and a <em>syn</em>-collisional tectonic affinity. The REE patterns are predominantly highly fractionated, displaying depleted HREE profiles and moderate to weak negative Eu anomalies. The geochemical data further suggest derivation of the granitoids by partial melting of <em>meta</em>-greywackes at temperatures &gt; 800 °C. Subchondritic <em>ε</em>_Hf(<em>t</em>) values (−11.0 to −2.6) further indicate reworking of a heterogeneous crust. The results of this and previous studies collectively indicate that the Aravalli orogen evolved through three distinct late Paleoproterozoic tectono-magmatic phases: (1) subduction-related magmatism at 1875‒1810 Ma, (2) <em>syn</em>-collisional S-type plutonism at ca. 1770 Ma, and (3) post-collisional extension-related A-type magmatism at ca. 1720 Ma. Globally, Paleoproterozoic S-type granites were predominantly derived by anataxis of Archean crust. Additionally, the data suggest that the northern margin of proto-India collided with fragments of the Columbia supercontinent at ca. 1770 Ma, postdating Columbia’s maximum packing time (1900–1850 Ma).</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 1","pages":"Article 102182"},"PeriodicalIF":8.9,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145361149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Critical mineral supply chains and the economics of energy transition: A carbon decomposition perspective of growth and decoupling","authors":"Hu Fu ,&nbsp;Mona Alariqi","doi":"10.1016/j.gsf.2025.102181","DOIUrl":"10.1016/j.gsf.2025.102181","url":null,"abstract":"<div><div>Critical minerals like copper, lithium, cobalt, nickel, and rare earth elements form the backbone of low-carbon technologies and are central to the success of global energy transitions. Their availability and the security of their supply chains determine the scalability of renewable energy systems, electric vehicles, battery storage, and hydrogen technologies. For member countries of the International Energy Agency (IEA), which plays a pivotal role in global energy markets, ensuring resilient access to these minerals is inseparable from the broader challenge of decoupling economic growth from carbon emissions. This study examines the dynamics of energy and carbon decomposition as mechanisms for decoupling economic growth from energy-related emissions across certain IEA countries between 1995 and 2022. The analysis employs a decomposition framework that incorporates value-added carbon intensity, value-added energy intensity, and CO₂ transport and storage while accounting for the enabling role of critical mineral availability. The results reveal that improvements in energy decomposition significantly strengthen the decoupling of growth from emissions, whereas increases in carbon decomposition weaken it. Similarly, higher value-added energy intensity and carbon intensity are positively associated with decoupling, while expanded CO₂ transport and storage capacity tend to reduce its effectiveness. Notably, integrating into the analysis considerations related to mineral supply demonstrates that stable and diversified access to critical resources magnifies the benefits of energy decomposition while mitigating the risks that are linked to carbon intensity. These findings underscore the dual importance of policy frameworks that advance energy efficiency and decomposition and strategies that secure critical mineral supply chains to ensure clean technologies’ scalability.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 1","pages":"Article 102181"},"PeriodicalIF":8.9,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145361146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In situ Raman spectroscopic measurement of the 13C/12C ratio of dissolved CO2 at high temperatures and pressures: Method and implications","authors":"Yuzhou Ge ,&nbsp;Zhendong Luan ,&nbsp;Lianfu Li ,&nbsp;Shichuan Xi ,&nbsp;Zengfeng Du ,&nbsp;Xin Zhang","doi":"10.1016/j.gsf.2025.102180","DOIUrl":"10.1016/j.gsf.2025.102180","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Submarine hydrothermal activities release a large amount of greenhouse gases such as CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; into the ocean, influencing the global carbon cycle. Carrying out high-temperature and high-pressure hydrothermal experiments to simulate these geochemical processes is a prerequisite for clarifying the source of carbon-containing substances in the hydrothermal fluid. In situ monitoring of the change in carbon isotope composition of CO&lt;sub&gt;2&lt;/sub&gt; is essential for high-temperature and high-pressure simulation experiments, but it is also a great technical challenge. In recent years, laser Raman spectroscopy has attracted wide attention as a supplementary means to mass spectrometry for measuring the &lt;sup&gt;13&lt;/sup&gt;C/&lt;sup&gt;12&lt;/sup&gt;C value of CO&lt;sub&gt;2&lt;/sub&gt;. However, the existing research is limited to the Raman spectroscopy study of the carbon isotope composition of supercritical/liquid CO&lt;sub&gt;2&lt;/sub&gt;, and there is little research on dissolved CO&lt;sub&gt;2&lt;/sub&gt; in solution. In this study, we systematically studied the Raman spectral characteristics of dissolved &lt;sup&gt;13&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; and &lt;sup&gt;12&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; in the H&lt;sub&gt;2&lt;/sub&gt;O ± &lt;sup&gt;13&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; ± &lt;sup&gt;12&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; system at 25–300 °C and 10–350 bar. The results show that the peak position of the Raman characteristic band of &lt;sup&gt;13&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; (aq) is 1367–1370 cm&lt;sup&gt;−1&lt;/sup&gt;, which is 14–17 cm&lt;sup&gt;−1&lt;/sup&gt; lower than that of &lt;sup&gt;12&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; (aq), and the full width at half maximum is 2–3 cm&lt;sup&gt;−1&lt;/sup&gt; smaller than that of &lt;sup&gt;12&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt;, which indicate the &lt;sup&gt;13&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; (aq) and &lt;sup&gt;12&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; (aq) can be identified by Raman spectroscopy. On this basis, we proposed the optimal likelihood curve fitting method (OLCF) for the first time to decompose the overlapping bands and accurately obtain the peak height ratio (H&lt;sub&gt;13&lt;/sub&gt;/H&lt;sub&gt;12&lt;/sub&gt;) of dissolved &lt;sup&gt;13&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; and &lt;sup&gt;12&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt;. It has been shown that the G-factor ratios (G&lt;sub&gt;13&lt;/sub&gt;/G&lt;sub&gt;12&lt;/sub&gt;) are significantly affected by temperature and the relative content of &lt;sup&gt;13&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; and &lt;sup&gt;12&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt;. Obtaining an appropriate G-factor ratio is a prerequisite for accurately determining the &lt;sup&gt;13&lt;/sup&gt;C/&lt;sup&gt;12&lt;/sup&gt;C of dissolved CO&lt;sub&gt;2&lt;/sub&gt;. Based on the functional relationship between the H&lt;sub&gt;13&lt;/sub&gt;/H&lt;sub&gt;12&lt;/sub&gt; and the &lt;sup&gt;13&lt;/sup&gt;C/&lt;sup&gt;12&lt;/sup&gt;C, we established an empirical equation to quickly estimate the &lt;sup&gt;13&lt;/sup&gt;C/&lt;sup&gt;12&lt;/sup&gt;C value, thereby assisting in selecting an appropriate G-factor ratio. The calibrated G-factor can be well used to determine the &lt;sup&gt;13&lt;/sup&gt;C/&lt;sup&gt;12&lt;/sup&gt;C of dissolved CO&lt;sub&gt;2&lt;/sub&gt; in the hydrothermal experiments with &lt;sup&gt;13&lt;/sup&gt;C labelled. In-situ monitoring experiments show that the phase separation of the hydrothermal fluid hardly causes changes in the carbon isotope composition of dissolved CO&lt;sub&gt;2&lt;/sub&gt;. ","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 1","pages":"Article 102180"},"PeriodicalIF":8.9,"publicationDate":"2025-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145361145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbon enrichment processes in the oceanic upper mantle preserved in peridotites from Sal Island (Cape Verde)","authors":"Andrea Maffeis ,&nbsp;Maria Luce Frezzotti ,&nbsp;Rosario Esposito ,&nbsp;Marco G. Malusà ,&nbsp;Alessandro Aiuppa ,&nbsp;Andrea Luca Rizzo ,&nbsp;Simona Ferrando","doi":"10.1016/j.gsf.2025.102179","DOIUrl":"10.1016/j.gsf.2025.102179","url":null,"abstract":"<div><div>This study investigates the petrological and metasomatic processes that lead to carbon enrichment in peridotites from Sal Island, Cape Verde. Geochemical and mineralogical analyses reveal a heterogeneous lithospheric mantle, consisting of harzburgites showing ultrarefractory compositions indicative of 20 %–40 % melting degrees, as well as fertile spinel lherzolites. Evidence of metasomatism is demonstrated by the formation of reaction coronae around dissolving orthopyroxene, consisting of olivine, clinopyroxene, spinel, and interstitial phonolitic glass, together with trachytic/phonolitic glass + carbonate (calcite, aragonite, and dolomite) microveins associated with CO₂ fluid-rich melt inclusions (Type I and II) cutting through olivine and orthopyroxene. The widely differing proportions of silicate and carbonate components in inclusions likely reflect heterogeneous trapping of melt/fluid and degassing CO₂. Thermobarometric data indicate equilibration temperatures from 950 to 1060 °C in harzburgites and up to 1200 °C for reaction coronas in harzburgites and lherzolites, with pressures reaching the aragonite stability field (∼2.2–3.5 GPa, or 66–106 km depth). These observations indicate the infiltration at the base of the lithosphere of a silicate-carbonate melt enriched in alkalies, Al, and volatiles (Cl, S, F, N, P). In microveins, the silicate glass composition (e.g., K and Ti content) is consistent with experimental partial melts derived from carbonated sediments with a minor addition of a carbonated eclogite. Enrichments in major and trace elements in clinopyroxene in harzburgites and lherzolites suggest at least two significant metasomatic events involving alkali-rich silicate-carbonate melts at the base of the lithosphere, and CO₂-rich fluid, alkali-rich silicate melts in the deep lithosphere, close to pressure conditions of the carbonate ledge. The introduction of recycled carbon into the upper mantle beneath the Cape Verde archipelago likely occurred during the multiple subduction events that affected the region in the half a billion years leading to the Pangea assembly. Major mobilisation of crustal components, generation of carbonate-rich melts, and subsequent lithospheric metasomatism were triggered by the Oligocene thermal perturbation associated with the Cape Verde mantle plume.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 1","pages":"Article 102179"},"PeriodicalIF":8.9,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145323484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling 4.5 billion years of Earth’s thermal evolution: Insights from core-mantle coupling, lithospheric viscosity, grain-size-dependent rheology, and surface boundary conditions","authors":"Petar Glišović ,&nbsp;Alexander Braun","doi":"10.1016/j.gsf.2025.102173","DOIUrl":"10.1016/j.gsf.2025.102173","url":null,"abstract":"&lt;div&gt;&lt;div&gt;We investigate Earth’s evolution through thermally coupled core-mantle models spanning 4.5 billion years. These models employ a spherical pseudo-spectral approach to solve the conservation equations for mass, momentum, and energy within a compressible, self-gravitating mantle. The methodology incorporates time-dependent treatments for core-mantle coupling, dislocation and diffusion creep mechanisms, internal heating, and thermal conductivity. Using 3-D numerical simulations, we evaluate the sensitivity of mantle cooling, viscosity structure, and inner-core growth to variations in lithospheric viscosity, diffusion viscosity, mechanical surface boundary conditions, and initial core-mantle boundary and core liquidus temperatures. Results underscore the central role of lithospheric viscosity, particularly near an effective value of ∼10&lt;sup&gt;22&lt;/sup&gt; &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mtext&gt;Pa&lt;/mtext&gt;&lt;mo&gt;·&lt;/mo&gt;&lt;mtext&gt;s&lt;/mtext&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, in producing a mantle cooling pattern consistent with petrological constraints, characterized by net warming prior to ∼3 billion years ago (Ga) followed by long-term cooling, as predicted by low-Urey-ratio thermal evolution models. Notably, one model with lithospheric viscosity allowed to vary between 10&lt;sup&gt;18&lt;/sup&gt; and 10&lt;sup&gt;24&lt;/sup&gt; &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mtext&gt;Pa&lt;/mtext&gt;&lt;mo&gt;·&lt;/mo&gt;&lt;mtext&gt;s&lt;/mtext&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; exhibits nonlinear rheological feedbacks that trigger an early-stage thermal rebound. This behavior results from a relatively abrupt increase in lithospheric viscosity which redirects the mantle onto a sustained warming trajectory that departs from the expected monotonic cooling. This example also demonstrates how nonlinear parameter interactions can produce non-monotonic thermal evolution. However, lithospheric viscosity alone cannot fully account for present-day observations of heat flux, inner-core radius, and depth-dependent viscosity profiles. We find that varying the activation enthalpy ratio for grain-growth-controlled diffusion viscosity modifies the radial viscosity structure while leaving the overall cooling pattern intact. Furthermore, surface boundary conditions permitting viscous coupling between rigid surface plates and underlying mantle flow — specifically in our plate-like (PL) model — yield the most acceptable mantle cooling rates and dynamic evolution. This PL configuration also facilitates more realistic coupling between surface kinematics and internal convection, allowing plate velocities to emerge from the flow dynamics rather than being imposed. The PL model exhibits patterns which are similar to independently estimated present-day mantle viscosity profiles, including features such as the lithosphere-asthenosphere gradient and the viscosity jump at the 660 km discontinuity. The PL model also exhibits persistent large-scale lateral temperature anomalies, consistent with previous billion-year convection studies, and illustrates how plate-like surface coupling promotes the emergenc","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 1","pages":"Article 102173"},"PeriodicalIF":8.9,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145323483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrochemistry and multi-isotopes for interpreting formation mechanisms of different-type geothermal waters in the Cuona-Woka Rift, southern Tibetan Plateau","authors":"Xingcheng Yuan ,&nbsp;Yunhui Zhang ,&nbsp;Jinhang Huang ,&nbsp;Zhonghe Pang ,&nbsp;Haoqing Huang ,&nbsp;Weibing Wang ,&nbsp;Ying Wang ,&nbsp;Ming Chang ,&nbsp;Marco Taussi ,&nbsp;Lisheng Wang","doi":"10.1016/j.gsf.2025.102170","DOIUrl":"10.1016/j.gsf.2025.102170","url":null,"abstract":"<div><div>High-temperature geothermal activities are widely distributed in rift tectonic zones, where significant volumes of geothermal waters with diverse hydrochemical characteristics are exposed. However, it is still unclear whether these geothermal waters have different formation mechanisms, which hinders the efficient exploitation and utilization of geothermal resources. Hence, this study investigates 41 geothermal water samples from the Cuona-Woka Rift (CWR) on the Tibetan Plateau to elucidate their hydrogeochemical evolutions and formation mechanisms. These geothermal waters are distributed along normal faults (N–S) and thrust faults (E–W), with discharge temperatures ranging from 34.0 to 85.5 °C. Self-organizing map classification identifies three distinct hydrochemical groups: Group 1 (Cl-Na and Cl·HCO₃-Na), Group 2 (HCO₃·Cl-Na), and Group 3 (SO₄·Cl-Ca·Na). The <em>δ</em>D and <em>δ</em>¹⁸O values indicate that meteoric and snow-melt waters are the dominant recharge sources for geothermal waters, with magmatic water contributions ranging from 18 % to 24 % (Group 1) and 12 % to 21 % (Group 2). The hydrochemical composition is primarily controlled by silicate and carbonate mineral dissolution, gypsum leaching, and cation exchange, with a higher contribution rate than the mixing of magmatic waters. All geothermal waters originate from the same deep sources, with Groups 2 and 3 undergoing mixing with 68 %–88 % and 57 %–70 % shallow cold groundwater, respectively. The significantly enriched trace alkali elements (Li, Rb, and Cs) in Group 1 are attributed to the input of crustal magma melts. Deep reservoir temperatures are estimated at 251–270 °C (Group 1), 226–229 °C (Group 2), and 189–194 °C (Group 3) based on empirical chemical geothermometers, silica-enthalpy mixing model, and geothermometric modeling. The maximum circulation depths are 4.8–5.2 km, 4.3–4.4 km, and 3.5–3.6 km, respectively. Three genesis conceptual models controlled by rift structures are proposed: melt intrusion heating type, hot–cold mixing heating type, and steam heating type. These findings will enhance the understanding of the origin of rift-type geothermal waters and provide valuable insights for the global exploitation and utilization of high-temperature geothermal resources.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 6","pages":"Article 102170"},"PeriodicalIF":8.9,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145332900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatiotemporal analysis of the FWI over Europe and North Africa: Historical trends and climate projections under RCP4.5 and RCP8.5","authors":"Fabio Di Nunno,&nbsp;Francesco Granata","doi":"10.1016/j.gsf.2025.102178","DOIUrl":"10.1016/j.gsf.2025.102178","url":null,"abstract":"<div><div>Wildfires represent an escalating environmental threat across Europe and North Africa, increasingly exacerbated by climate-driven shifts in temperature, precipitation, and drought patterns. However, there is still limited large-scale, methodologically consistent research that simultaneously assesses historical patterns and future projections of fire danger across these regions, particularly in terms of both frequency and duration of risk under different climate scenarios. This study addresses this gap by providing a high-resolution, spatiotemporal assessment of fire weather conditions, with the aim of offering critical insights to support climate-adaptive fire management strategies, extended preparedness frameworks, and the integration of future fire weather projections into land-use and risk governance policies. To achieve this, we investigate historical (1979–2021) and projected (2000–2098) trends in fire danger using the Canadian Fire Weather Index (FWI), based on ERA5 reanalysis data and outputs from five Global Climate Models (GCMs) under RCP4.5 and RCP8.5 scenarios. Over 50,000 land grid cells were analyzed to assess the frequency and duration of six FWI danger classes. Different metrics were used to quantify the agreement between historical reanalysis data and GCM outputs, while the Seasonal Kendall (SK) test was applied to detect trends. Results reveal a substantial decline in the duration of the very low FWI class, from 36 to 23 months, and significant increases in both the duration and frequency of the extreme FWI class, reaching up to 6.38 months and 14.42% under the RCP8.5 scenario. Correlation coefficients exceed 0.8 across much of Southern Europe and North Africa, indicating strong temporal agreement. Trend analyses reveal statistically significant increases in fire danger across southern latitudes, while Northern Europe shows mixed or decreasing trends. These findings project a dramatic intensification and expansion of fire-prone conditions, particularly under high-emission scenarios.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 6","pages":"Article 102178"},"PeriodicalIF":8.9,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145332899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}