Geoscience frontiers最新文献

{"title":"The daily growth band patterns of Tridacna derasa – Evidence from culture experiments","authors":"Haotian Yang ,&nbsp;Chengcheng Liu ,&nbsp;Yanan Yang ,&nbsp;Shan Liu ,&nbsp;Guozhen Wang ,&nbsp;Jun Li ,&nbsp;Pengchao Zhou ,&nbsp;Hanfeng Wen ,&nbsp;John Dodson ,&nbsp;Xuxiang Li ,&nbsp;Hong Yan","doi":"10.1016/j.gsf.2026.102265","DOIUrl":"10.1016/j.gsf.2026.102265","url":null,"abstract":"<div><div>Biogeochemical archives, such as tree rings and corals, with yearly-to-monthly resolution, have been used to reconstruct past climate change. However, they can not reconstruct weather events that occurred on daily-hourly time scales. <em>Tridacna</em>, the largest bivalve in the world, inhabiting the tropical and subtropical Pacific-Indian Ocean regions, exhibits daily growth bands measuring ∼5 to ∼60 μm and has the facility for reconstructing past extreme weather events. However, the precise daily growth band patterns across a day remain unclear, hindering any comprehensive understanding of the daily growth band patterns of <em>Tridacna</em> and their climatic implications. In this study, a 30-day controlled culture experiment on <em>Tridacna derasa</em> was carried out to address this and explore the main factors influencing the hourly Sr/Ca profiles. Results demonstrated that wide dim increments formed during daytime while narrow bright lines formed at nighttime. The hourly Sr/Ca profiles exhibited clear daily cycles synchronized with light cycles, with higher Sr/Ca at night and lower Sr/Ca values during daytime. The Sr/Ca ratios were not constant even under constant water temperature and light intensity, suggesting a limited influence of external environment factors and highlighting the role of internal biological regulation in Sr/Ca variation. A hypothesis was proposed here: During daylight, light-driven enzymatic activity coupled with H⁺ removal mechanisms regulates and lowers the Sr/Ca ratio, but the enzyme species and activities may be different, thus leading the variability of Sr/Ca at the identical light intensity; During nights, the organic matrix regulation mechanisms in extrapallial fluid (EPF) predominates, leading to higher Sr/Ca values, but the composition and concentration of organic matrix are not constant, leading to the variability of nightly Sr/Ca. Our findings provide a research foundation for paleoweather/paleoenvironment studies based on <em>Tridacna.</em></div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 3","pages":"Article 102265"},"PeriodicalIF":8.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190908","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":"Rainwater accumulation model related to tectono-stratigraphic assessment for bradyseism at Campi Flegrei, Italy","authors":"Nicola Scafetta ,&nbsp;Annamaria Lima ,&nbsp;Alfonsa Milia ,&nbsp;Frank Spera ,&nbsp;Robert J. Bodnar ,&nbsp;Benedetto De Vivo ,&nbsp;Linda Daniele","doi":"10.1016/j.gsf.2026.102256","DOIUrl":"10.1016/j.gsf.2026.102256","url":null,"abstract":"<div><div>The Campi Flegrei (CF) volcanic system near Naples, Italy, poses a significant hazard due to bradyseism — a slow vertical ground deformation resulting in either uplift or subsidence. Indeed, between January 2005 and January 2025, the urban area of Pozzuoli experienced approximately 1.4 m of uplift (GNSS RITE Station). The bradyseism is driven by a combination of hydrothermal and magmatic processes, whereby pressurized magmatic fluids generated by deep magma crystallization accumulate beneath an impermeable layer that regulates fluid exchange between upper hydrostatic and lower lithostatic systems. This study introduces a new perspective through a detailed reconstruction of the stratigraphic-tectonic architecture of the CF area that enables identification of structural controls on seismicity, deformation, and fluid migration, and the role of meteoric water. Seismicity beneath the Pozzuoli-Solfatara area occurs at shallower depths near the top of an anticline, whereas deeper earthquakes in Pozzuoli Bay occur in synclinal environments. The anticline beneath Pozzuoli facilitates hydrothermal fluid pressurization in two main reservoirs beneath two relatively impermeable units. The shallow reservoir, referred to as Unit C, is located at a depth of approximately 1.0 to 2.0 km and acts as a reservoir for meteoric water infiltration. The deeper reservoir, referred to as Unit A, occurs at a depth of about 2.0 and 4.0–4.5 km, where magmatic fluids generated by second boiling in the underlying magma accumulate. An impermeable unit of marine sediments, referred to as Unit B, is located at ∼ 2 km depth and separates Units A and C. The shallow reservoir is bounded at the top by a relatively impermeable unit mainly made up of pyroclastic deposits. We developed a simplified hydrogeological model using rainfall data dating back to 1950 to assess the role of meteoric water in bradyseism at CF. We found a strong correlation between subsurface water infiltration and vertical ground deformation observed at the Pozzuoli RITE Station, which corresponds to the crest of the anticline. Our results suggest that meteoric water contributes to interannual uplift fluctuations of up to ∼ 5 cm and accounts for over 20% of the total uplift recorded between 2005 and 2025. Furthermore, a shortening of recharge time-lag — from about four years to three years since 2010 — indicates enhanced fracturing and infiltration rates. These findings highlight the previously underestimated role of meteoric water in driving deformation and seismicity at CF. Our results also suggest that geoengineering involving targeted surface drainage interventions could mitigate ongoing ground instability and seismic hazards in the region.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 3","pages":"Article 102256"},"PeriodicalIF":8.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057338","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":"Decoding the tectonomagmatic evolution of the Ladakh Magmatic Arc, NW Himalaya: A multi-proxy geochemical and isotopic approach","authors":"Irfan M. Bhat ,&nbsp;H. Chauhan ,&nbsp;T. Ahmad ,&nbsp;T. Tanaka ,&nbsp;Tehseen Zafar ,&nbsp;Y. Asahara","doi":"10.1016/j.gsf.2026.102260","DOIUrl":"10.1016/j.gsf.2026.102260","url":null,"abstract":"<div><div>Magmatic arcs are the active locus of crustal formation, and their knowledge of spatiotemporal geochemical variation is vital for understanding the evolution of collisional systems. Here, we compare geochemical and isotopic results from the precollisional Dras-Nidar Island Arc Complex (DNIAC), pre- to syn-collisional Ladakh Batholith (LB) that formed the part of the well-known Kohistan-Ladakh Batholith, and post-collisional mafic dykes. It is observed that the long-term magmatic evolution was controlled by the Neo-Tethyan Ocean geodynamics. The Ladakh magmatic arc records three distinct magmatic stages through its geochemical and isotopic evolution. The pre-collisional DNIAC (160–110 Ma) shows tholeiitic to calc-alkaline melts with depleted mantle signatures (<em>ε</em>_Nd &gt; +5 and ⁸⁷Sr/⁸⁶Sr &lt; 0.704), transitional to syn-collisional LB granitoids and associated Khardung volcanics (103–45 Ma) reflecting enriched signatures (<em>ε</em>_Nd +2 to −4, ⁸⁷Sr/⁸⁶Sr = 0.704–0.708, La/Sm &gt; 3, Th/La &gt; 0.2) due to sediment subduction and crustal assimilation. While post-collisional mafic dykes (&lt; 45 Ma) reflect lithospheric mantle metasomatism (enriching incompatible trace elements including rare earth elements) with limited crustal interaction (<em>ε</em>_Nd +1 to +3). This demonstrates a progressive evolution from a fluid-dominated mantle wedge melting to a sediment-driven crustal influence and finally to an enriched mantle melting, highlighting the critical role of slab dynamics and crustal recycling in continental growth during arc-continent collision. Thus, we concluded that the contribution from the sediment subduction is more pronounced in the KLB compared to the DNIAC.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 3","pages":"Article 102260"},"PeriodicalIF":8.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190907","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":"Black carbon dynamics over the Northern Indian Ocean: Variability, emission sources, transport and future projections","authors":"Shyamli K. Singh ,&nbsp;Shani Tiwari","doi":"10.1016/j.gsf.2026.102263","DOIUrl":"10.1016/j.gsf.2026.102263","url":null,"abstract":"<div><div>This study presents an extensive long-term assessment of black carbon (BC) over the North Indian Ocean (NIO) by integrating multiple datasets, like reanalysis, emission inventory, satellite fire counts and trajectory model, highlighting the complex interplay among emission sources, atmospheric transport, and regional climate dynamics. The findings reveal persistent BC hotspots along the northeastern and western coast of India, particularly near the northern Bay of Bengal (BoB). These hotspots are mainly linked to intense anthropogenic activities and outflows from the Indo-Gangetic Plain (IGP). The study highlights a distinct land-to-sea gradient and strong seasonal variability in BC mass concentration, with peak values during winter (up to 3.20 μg/m³) and post-monsoon seasons (up to 2.05 μg/m³) due to reduced atmospheric dispersion. BC levels increased notably during the rapid economic expansion in the 1990s and 2000s (up to 0.036 μg m⁻³ yr⁻¹) but flattened after 2011, particularly in eastern coastal regions, suggesting the substantial impact of emission control and air quality regulations policies. Regional discrepancies remain, with areas like sub-regions R1 experiencing both sharp increases and significant recent declines, highlighting heterogeneous emission patterns and the effects mitigation policies. Atmospheric processes, particularly long-range transport, extensively influence BC distribution. Cluster analyses of airmass back trajectories further confirm that the BC over the BoB predominantly originates from the Indian landmass, while the Arabian Sea (AS) receives BC loading from both India and the Middle East, along with ship emissions. Agricultural fires and forest degradation contribute significantly to BC emissions, with highest fire occurrences observed between 2001 and 2010 followed by a decline, except for a fire surge in 2021. Future projections of BC mass concentration using the Seasonal Autoregressive Integrated Moving Average (SARIMA) model suggest an increasing trend during 2023–2032 across all the sub-region (up to 0.035 μg m⁻³ yr⁻¹) except sub-region R3 where almost negligible decreasing trend is found (−0.002 μg m⁻³ yr⁻¹). Thus, present study concludes that effective BC mitigation demands integrated emission controls, targeted regional policies, and continuous monitoring to address both local sources and transported pollution, which is crucial for improving climate and air quality in South Asia and the NIO.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 3","pages":"Article 102263"},"PeriodicalIF":8.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191029","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":"Insights into the final closure of the Mongol-Okhotsk Ocean (eastern segment): Implications from Mesozoic granitoids in the Northern Great Xing'an Range, NE China","authors":"Chao Li ,&nbsp;Tao Ren ,&nbsp;Zigao Zhou ,&nbsp;Jianguo Huang ,&nbsp;Hongyang Zhou ,&nbsp;Jun Guo","doi":"10.1016/j.gsf.2026.102259","DOIUrl":"10.1016/j.gsf.2026.102259","url":null,"abstract":"<div><div>The Mongol-Okhotsk suture signifies the closure of the Mongol-Okhotsk Ocean between the Siberian Craton and the Erguna Block (also known as the Amuria Block), a process that was pivotal in shaping the Mesozoic tectonic evolution of East Asia. While a scissor-like, west-to-east diachronous closure mechanism is widely accepted, considerable debate persists regarding the exact timing of final suturing in the eastern segment and the underlying geodynamic processes. Granitic rocks provide critical insights into crustal growth and reworking, and supercontinental cyclicity. Notably, magmatic activity in the Mongol-Okhotsk suture zone is relatively subdued compared with the adjacent Northern Great Xing'an Range (NGXAR), which is widely attributed to the evolution of the Mongol-Okhotsk Ocean. To elucidate the evolution of the Mongol-Okhotsk Ocean, we investigate the Tayuan granitoids in the Erguna Block of the NGXAR and conduct a comparative analysis with the published Early Jurassic–Early Cretaceous granitoid data from the region. Zircon U–Pb geochronology constrains the Tayuan granitoid emplacement to the Late Jurassic (ca. 152–148 Ma). They are characterized by high Sr content and Sr/Y ratio, together with low Mg# and Y-Yb contents, showing low-Mg# adakitic affinity. Given its weakly depleted Sr–Nd–Hf isotopic signatures (⁸⁷Sr/⁸⁶Sr(<em>t</em>) = 0.70516–0.70624; <em>ε</em>_Nd(<em>t</em>) =  −1.28 to + 1.4; <em>ε</em>_Hf(<em>t</em>) = +2.1 to +7.3), the Tayuan adakitic granitoids are inferred to have sourced from the juvenile, thickened lower crust.</div><div>The Early to Late Jurassic low Mg# adakitic granitoids in the NGXAR suggest a substantial crustal thickening event, which is attributed to the southward subduction of the Mongol-Okhotsk oceanic plate. Our calculations reveal that the crust attained its average thickness (∼60 km) during the Jurassic (200–155 Ma). The Late Jurassic witnessed the coeval emergence of not only low-Mg# adakitic granitoids but also A-type granites and high-Mg# adakitic granitoids. This petrogenetic shift tightly constrains the final suturing to 155 Ma and marks a pivotal tectonic transition from compressional to extensional regimes. Subsequently, during the Early Cretaceous, the widespread emplacement of calc-alkaline, non-adakitic volcanic and granitic rocks signifies regional lithospheric extension accompanied by significant crustal thinning, with estimated thicknesses of approximately 40 km. This extensional phase and associated thinning were primarily driven by slab rollback and subsequent break-off following the final closure of the Mongol-Okhotsk Ocean.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 3","pages":"Article 102259"},"PeriodicalIF":8.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191031","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":"Long term evolution of deep banner banks offshore Brittany (France): paleo-coast line markers and interactions between hydrodynamics and seafloor morphology","authors":"Paul Daguinos ,&nbsp;Pascal Le Roy ,&nbsp;Gwenael Jouët ,&nbsp;David Menier ,&nbsp;Nicolas Le Dantec ,&nbsp;Axel Ehrhold ,&nbsp;Christophe Prunier ,&nbsp;Pauline Dupont ,&nbsp;Marcaurelio Franzetti","doi":"10.1016/j.gsf.2026.102250","DOIUrl":"10.1016/j.gsf.2026.102250","url":null,"abstract":"<div><div>This study focusses on the development and evolution of a banner banks set located offshore the Britanny coast (Iroise Sea, France) using multibeam bathymetric data, high-resolution seismic data, and grab samples. It aims to provide a comprehensive understanding of environmental parameters underpinning the long-term evolution and preservation of these major morpho-sedimentary bedforms. These banks have developed on a highly dispersive tide-and-storm-dominated shelf. Despite their very contrasting morphologies, the base of each of them lies at a similar depth range (100 to 90 m). The presence of dunes superimposed on the banks suggests that they remained active until today excepting for the Armen bank. Five seismic units have been also distinguished within each bank, separated by pronounced erosional unconformities. The surfaces are interpreted as the product of the gradual flooding of the bedrock outcropping across the shelf that modified the prevailing tidal conditions and directions of sediment transport. It thus appears that correlation between sea-level rise, the opening of straits across the shelf and the intensification of tidal currents are the key parameters of the long-term sand bank evolution offshore Brittany. The stepped morphology of the bedrock also appears to be a crucial factor in the initiation of the bank and its lasting anchoring between external and internal shelf. The preservation of their original nucleus indeed attests to their low lateral migration. With the exception of the silico-clastic basal unit, the banks are biogenic and fed by a process of self-recycling the sand within the sedimentary cell controlling the preservation of the bank. This study sheds light on the mechanisms of the formation and the deep anchorage of these deep banner banks, as well as their inherent link. It also highlights the dynamic nature of these large deep bedforms that are sustained by a fossil sedimentary stock.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 3","pages":"Article 102250"},"PeriodicalIF":8.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057339","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":"The source-to-surface journey of volatile-flooded magmas: The archetypal case of the Campi Flegrei unrest Caldera","authors":"Ilenia Arienzo ,&nbsp;Bruna Cariddi ,&nbsp;Carlo Pelullo ,&nbsp;Claudia D’Oriano ,&nbsp;Etienne Deloule ,&nbsp;Massimo D’Antonio ,&nbsp;Roberto Moretti","doi":"10.1016/j.gsf.2026.102262","DOIUrl":"10.1016/j.gsf.2026.102262","url":null,"abstract":"<div><div>We attempt to reconstruct the architecture of the magmatic feeding system of the Campi Flegrei volcanic field, currently experiencing an unrest phase threatening several hundred thousand people, to shed light on the processes interplaying during magma evolution and transfer to the surface. To this aim, we provide, for the first time, a complete chemical dataset (major, trace and volatile elements, including hydrogen isotopes) of melt inclusions and their host pyroxenes. Case studies are the Campanian Ignimbrite eruption (∼40 ka) and explosive events that occurred in a short time-span (from ∼5 ka to ∼4 ka), in sectors of the Campi Flegrei caldera identified as having the highest probability of future eruptive activity.</div><div>Melt inclusions point to high dissolved volatiles content (H₂O ≈ 0.5–2.9 wt.%; CO₂ ≈ 120–2600 ppm; Cl ≈ 4000–10600 ppm; F ≈ 1400–3400 ppm; SO₃ ≈ 0.2–0.05 wt.%) which suggest that magma differentiation and degassing took place at pressures ranging approximately between 645 MPa and 74 MPa. In fact, one of the major outcomes of the paper is the temporary coexistence, at pressures higher than 200 MPa of felsic magma batches with mafic magmas. Modelling of gas release shows that trachytic magmas formed due to crystallization in a system featured by a mean oxidation state with Fe³⁺/Fe_tot = 0.15, under variable but high initial volatile contents: total volatiles exceed 5 wt.%, with not less than 2 wt.% CO₂. The high volatile elements content in the deep feeding system is possibly responsible for repeated fluxing events that may prompt the ascent of differentiated magmas to the shallowest reservoirs. Water-loss, due to the combination of repeated crystallization and CO₂ fluxing events in crustal reservoirs, satisfactorily explains the <em>δ</em>D variability in melt inclusions, producing multiple paths approaching the <em>δ</em>D of the local magmatic water discharged from present-day, low-temperature fumaroles. Our findings suggest that: (1) the studied eruptions were fed by trachytic magma inputs in equilibrium with a gas phase featured by <em>X</em>CO₂ ∼0.9 at pressures greater than 250 MPa; (2) <em>X</em>CO₂ decreases nearly continuously while pressure decreases; and (3) the obtained pressures cannot be simply converted into crystallization/storage depths. Conversely, local overpressure associated with gas fluxing must be considered. The overpressure can explain the ascent of differentiated, trachytic magmas that enter the uppermost plumbing system levels with an excess of volatiles, which may drive further magma crystallization and eruption. The final stage of magma ponding and degassing, between ∼200 MPa and ∼74 MPa, may represent the ultimate engine of the unrest phases at Campi Flegrei that precede volcanic eruptions.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 3","pages":"Article 102262"},"PeriodicalIF":8.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190380","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":"The transport and enrichment of rhodium (III) in chloride-rich fluids: Implications for seafloor hydrothermal systems","authors":"Haibo Yan ,&nbsp;Jing Xu ,&nbsp;Weidong Sun ,&nbsp;Xing Ding","doi":"10.1016/j.gsf.2026.102257","DOIUrl":"10.1016/j.gsf.2026.102257","url":null,"abstract":"<div><div>Hydration and complexation are crucial processes for dissolving metal elements and transporting metal complexes in hydrothermal fluids. However, the impact of hydration and complexation on the transport and enrichment of metal elements, such as those involving rhodium and chloride, has not been thoroughly evaluated. Here, this study employed a hydrolysis experiment of K₃RhCl₆ at 200–600 °C and 100 MPa to determine the controlling factors and thermodynamics of Rh-Cl complexes in chloride-rich fluids. The results show that the dominant Rh-Cl complex is <span><math><mrow><msubsup><mtext>RhCl</mtext><mrow><mtext>6</mtext></mrow><mtext>3-</mtext></msubsup></mrow></math></span> at 200–400 °C, gradually converting into Rh(III)–OH-Cl complexes over 400 °C. The hydrolysis equilibrium constant (LnK) of <span><math><mrow><msubsup><mtext>RhCl</mtext><mrow><mtext>6</mtext></mrow><mtext>3-</mtext></msubsup></mrow></math></span> at 200–400 °C affected by temperature (<em>T</em> (K)) is calculated as: <span><math><mrow><mi>lnK</mi><mo>=</mo><mrow><mfenced><mrow><mn>49.06</mn><mo>±</mo><mn>7.01</mn></mrow></mfenced></mrow><mo>-</mo><mrow><mfenced><mrow><mn>48802</mn><mo>±</mo><mn>3896.0</mn></mrow></mfenced></mrow><mo>/</mo><mi>T</mi><mo>.</mo></mrow></math></span> Accordingly, the <span><math><mrow><msub><mrow><mi>Δ</mi></mrow><mrow><mi>r</mi></mrow></msub><msubsup><mrow><mi>H</mi></mrow><mrow><mi>m</mi></mrow><mrow><mi>Θ</mi></mrow></msubsup></mrow></math></span> and <span><math><mrow><msub><mrow><mi>Δ</mi></mrow><mrow><mi>r</mi></mrow></msub><msubsup><mrow><mi>S</mi></mrow><mrow><mi>m</mi></mrow><mrow><mi>Θ</mi></mrow></msubsup></mrow></math></span> of the hydrolysis reaction were obtained to be 405.8 ± 32.39 kJ·mol⁻¹ and 407.9 ± 58.30 J·mol⁻¹·K⁻¹, respectively. Thermodynamic parameters reveal the dependence of the stability of Rh-Cl complexes on temperature in chloride-rich fluids. For instance, the formation constants (lnβ) of <span><math><mrow><msubsup><mtext>RhCl</mtext><mrow><mtext>6</mtext></mrow><mtext>3-</mtext></msubsup></mrow></math></span> vary from 0.0184 ± 0.0022 to −0.0079 ± 0.0012 as the temperature rises from 150 to 400 °C. Geochemical modeling illustrates that low-temperature and acidic fluids can enhance the stability of Rh-Cl complexes, which can be dominated by Cl concentration (over 0.5 wt.%). Hydrothermal fluids with low pH and high Cl content, typically occurring in the mid-ocean ridge, promote Rh transport and subsequent enrichment in encrustations and minerals by substituting Mn and Fe for isomorphism, or in the form of alloys, forming a substantial Rh reservoir in the ocean.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 3","pages":"Article 102257"},"PeriodicalIF":8.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076998","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":"Potassium isotope characteristics of typical salt lake in key tectonic zones, China: Sources and evolutionary models","authors":"Zhengyan Li ,&nbsp;Yuanyuan Cheng ,&nbsp;Maoyong He ,&nbsp;Jiangdi Zhou ,&nbsp;Xueqin Wen ,&nbsp;Li Deng ,&nbsp;Binkai Li","doi":"10.1016/j.gsf.2026.102261","DOIUrl":"10.1016/j.gsf.2026.102261","url":null,"abstract":"<div><div>Potassium isotopic compositions (<em>δ</em>⁴¹K) have emerged as sensitive tracers in modern environmental processes. Lakkor Co Salt Lake, situated within a critical tectonic zone of the Qinghai-Tibet Plateau (the Bangong-Nujiang tectonic belt), stands as a leading example of applying stable potassium isotopes to decipher diverse geochemical cycles in tectonically active regions. The results demonstrated that the potassium concentration in Lakkor Co can reach up to 2901 mg/L. A distinct potassium isotope fractionation is observed across the system. The <em>δ</em>⁴¹K values vary from −0.82‰ to −0.05‰ in recharge rivers, which are lower than the global riverine range reported in previous studies (−0.59‰ to −0.08‰). In contrast, the surface brine of Lakkor Co exhibits <em>δ</em>⁴¹K values between −0.30‰ and + 0.05‰, falling within the ranges of both modern seawater (−0.01‰ to + 0.14‰) and chloride-dominated brines in the Qaidam Basin (−0.57‰ to + 0.22‰). In combination with hydrochemical, <em>δ</em>¹¹B and <em>δ</em>⁷Li data, the potassium in the Lakkor Co area is sourced from surface rock weathering and geothermal fluid. Moreover, weathering of ultra-high pressure metamorphic zones formed by deep subduction of oceanic crust may represent an additional source, which is supported by the anomalously low <em>δ</em>⁴¹K values observed in the lake basin. This study investigates the sources, geochemical behavior and evolution process of potassium in the Lakkor Co Salt Lake; provide a theoretical basis for subsequent exploration and development of analogous salt lakes; and explore the elemental behavior of subducting oceanic crust.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 3","pages":"Article 102261"},"PeriodicalIF":8.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191030","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":"Knowledge-based data-driven prediction of shield tail clearance under karst geological condition","authors":"Wengang Zhang ,&nbsp;Han Han ,&nbsp;Weixin Sun ,&nbsp;Yunhao Wang ,&nbsp;Zhihao Wu ,&nbsp;Peng Xiao ,&nbsp;Yumiao Yan","doi":"10.1016/j.gsf.2025.102221","DOIUrl":"10.1016/j.gsf.2025.102221","url":null,"abstract":"<div><div>Precise control of shield tail clearance is a critical factor influencing the safety and quality of shield tunneling construction. Although various methods exist for accurately measuring shield tail clearance, predictive capabilities remain insufficient. This study is based on a shield tunnel project in the karst region of Longgang, Shenzhen, China. By integrating geological parameters obtained from advanced geological prediction with shield construction monitoring data, a predictive calculation method for shield tail clearance is developed, grounded in the spatial relationship between the shield machine and the pipe segments. A knowledge-based data-driven prediction approach is proposed using a Transformer-LSTM deep learning model. Case analysis demonstrates that the proposed Transformer–LSTM model consistently outperformed baseline models such as GRU, LSTM, and pure Transformer. The predicted <em>R</em>² values for the four positions of the shield tail—top, bottom, left, and right—reached 0.990, 0.901, 0.976, and 0.908, respectively, while error indicators (MAE, RMSE, and MAPE) were also minimized. These results confirm that the proposed hybrid approach effectively captures both global dependencies and temporal dynamics, enabling accurate prediction of shield tail clearance and offering practical engineering significance for guiding shield tunneling construction.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"17 2","pages":"Article 102221"},"PeriodicalIF":8.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145748664","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}