Geoscience frontiers最新文献

{"title":"Formation of the giant Cretaceous Jiaodong-type orogenic gold province of the North China Craton: A consequence of lithospheric multi-layer reworking","authors":"Qingfei Wang ,&nbsp;Hesen Zhao ,&nbsp;Lin Yang ,&nbsp;David I. Groves ,&nbsp;Jilong Han ,&nbsp;Kunfeng Qiu ,&nbsp;Dapeng Li ,&nbsp;Zhao Liu ,&nbsp;Rui Zhao ,&nbsp;Jun Deng","doi":"10.1016/j.gsf.2025.102047","DOIUrl":"10.1016/j.gsf.2025.102047","url":null,"abstract":"<div><div>The Cretaceous gold deposits along the margins of the North China Craton (NCC), which formed in a craton destruction setting, display geological characteristics similar to traditional orogenic gold deposits typically associated with accretionary orogeny. These deposits, known as Jiaodong-type gold deposits, have attracted considerable attention. However, the lithospheric controls and formation mechanisms of these deposits remain unclear, as they cannot be fully explained by the supracrustal metamorphic genetic model commonly applied to classic orogenic gold deposits. In this study, the compiled S-Hg-Pb isotope ratios of gold deposits on different NCC margins display compatible variations to the Sr-Nd-Hg isotope ratios of mafic dikes spatial-temporally associated with the deposits. This implies that mantle lithosphere, metasomatized by variable proportions of oceanic and continental crust, was the source for both gold deposits and mafic dikes. Increase of oxygen fugacity and zircon <em>ε</em>Hf(<em>t</em>) from pre- to <em>syn</em>-gold granites suggests continuous basic magma underplating, which could induce concentrations of Au-rich sulfides and contribute additional Au to auriferous CO₂-rich fluids derived from metasomatized mantle lithosphere and basic magma. Localization of gold deposits was controlled by craton-margin sinistral shearing induced by clockwise rotation of the craton coincident with distal emplacement of metamorphic core complexes. Thus, the Cretaceous Jiaodong-type orogenic gold deposits were derived from fertilized mantle lithosphere through such crust-mantle processes within a lithosphere thinning background.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102047"},"PeriodicalIF":8.5,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834270","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":"Experimental heating of CI chondrite: Empirical constraints on the evolution of micrometeorite O-isotopes during atmospheric entry","authors":"N.G. Rudraswami ,&nbsp;M.D. Suttle ,&nbsp;Yves Marrocchi ,&nbsp;M. Pandey ,&nbsp;Laurent Tissandier ,&nbsp;Johan Villeneuve","doi":"10.1016/j.gsf.2025.102046","DOIUrl":"10.1016/j.gsf.2025.102046","url":null,"abstract":"<div><div>Extraterrestrial dust exhibits a wide range of textural, chemical and oxygen isotopic compositions due to the heterogeneity of their precursors and modification during atmospheric entry. Experimental heating provides an opportunity to investigate the relationship between thermal processing and micrometeorite composition for a known precursor material. We conducted experiments to simulate the atmospheric entry of micrometeorites (MMs) using controlled, short-duration (10–50 s) flash heating (400–1600 °C) of CI chondrite chips (&lt;1500 µm) in atmospheric air (1 bar, 21% O₂) combined with microanalysis (textures, chemical and isotopic compositions) of the experimental products. The heated chips closely resemble natural samples, with materials similar to unmelted MMs, partially melted (scoriaceous) MMs and fully melted cosmic spherules produced. We reproduced several key features such as dehydration cracks, magnetite rims, volatile gas release, vesicle formation and coalescence, melting and quench cooling. Our parameter space allows for discriminating peak temperature and heating duration effects. Peak temperature is the first-order control on MM mineralogy, while heating duration controls vesicle coalescence and homogenization. When compared against previous heating experiments, our data demonstrates that CI chondrite dust is more thermally resistant, relative to CM chondrite dust, by approximately +200 °C. The 207 measurement of O-isotopes allows, for the first time, petrographic effects (such as volatile degassing and melting) to be correlated against bulk O-isotope evolution. Our results demonstrate findings applicable to CI chondrites and potentially to all fine-grained hydrated carbonaceous chondrite dust grains: (1) O-isotope variations arising during sub-solidus heating are dominated by the release of water from phyllosilicates, forcing the residual MM composition towards its anhydrous precursor composition. (2) Oxygen isotope compositions undergo the most significant changes at supra-solidus temperatures. As previously demonstrated and now empirically confirmed, most of these changes are driven by a mass-dependent fractionation effect caused by evaporation, which shifts residual rock compositions toward heavier values. Mixing with atmospheric air alters compositions toward the terrestrial fractionation line. Notably, these two processes do not begin simultaneously. Our data indicate that at 1200 °C, isotopic evolution is dominated by evaporative mass loss. However, at higher temperatures (1400–1600 °C), both pronounced evaporation and mixing with atmospheric oxygen become active, resulting in a more complex isotopic signature. (3) The total change in Δ¹⁷O during heating up to 1600 °C is &lt; 3‰ and in most scenarios &lt; 2‰.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102046"},"PeriodicalIF":8.5,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834167","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":"Contribution of pegmatite shells to magmatic evolution and rare metal mineralization: Insights from the Shihuiyao deposit, Inner Mongolia, Northeast China","authors":"Zhichao Zhang ,&nbsp;Zheng Ji ,&nbsp;Yusheng Zhu ,&nbsp;Hao Yang ,&nbsp;Zhenyu Chen ,&nbsp;Haoran Wu ,&nbsp;Yongzhi Wang ,&nbsp;Wenchun Ge","doi":"10.1016/j.gsf.2025.102042","DOIUrl":"10.1016/j.gsf.2025.102042","url":null,"abstract":"<div><div>Highly evolved granite associated with pegmatite shells exhibits significant potential for rare metal mineralization; however, the mechanisms through which these pegmatite shells contribute to magmatic evolution and rare metal enrichment remain poorly understood. The Late Jurassic Shihuiyao Nb–Ta–(Rb–Be–Li) deposit is one of the largest rare-metal deposits in the Southern Great Xing’an Range (SGXR), Northeast China. Exploratory trenches expose distinct layered zones from top to bottom: alternating microcline pegmatite and aplite layers (zone I), topaz lepidolite albite granite and lepidolite amazonite pegmatite (zone II), and muscovite albite granite (zone III). We conducted U–Pb dating of cassiterite, monazite, and Nb–Ta oxide, monazite Nd isotopes, and whole-rock and mineral geochemistry for the three zones. Multi-mineral U–Pb ages indicate that the three zones formed during the Late Jurassic–Early Cretaceous (147–142 Ma). Geochemical analyses of whole-rock, mica, and microcline suggest an evolutionary sequence from zone I to zone III, and finally to zone II. The Zr/Hf, Nb/Ta, Y/Ho, and K/Rb ratios combined with the rare earth element (REE) tetrad effects suggest higher degree of differentiation and fluid–melt interaction of the Shihuiyao leucogranite without a pegmatite shell compared to coeval barren granites from both Shihuiyao and the SGXR. A progressive increase in the degree of evolution is evident from the leucogranite without a pegmatite shell to the leucogranite with a discontinuous shell, and ultimately to the leucogranite with a continuous shell. The pegmatite shell acted as a geochemical barrier that facilitated the accumulation of Li and F in the underlying magma, which played a crucial role in lowering the solidus temperature of the granitic magma. This process prolonged the crystallization duration while reducing melt viscosity and density, thereby creating favorable conditions for magma differentiation and fluid–melt interaction. Rapid crystallization of the earlier water- and Be-rich melt led to the Be mineralization in the pegmatite shell. Moreover, the formation of this shell served as a barrier for Li mineralization in the underlying topaz lepidolite albite granite. This study enhances our understanding of the critical contribution of pegmatite shells to magmatic evolution and rare-metal mineralization.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102042"},"PeriodicalIF":8.5,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metamorphic evolution of blueschists in the Heilongjiang Complex: Implications for the subduction history of the Mudanjiang Ocean","authors":"Guang-Ming Sun ,&nbsp;Xu-Ping Li ,&nbsp;Hans-Peter Schertl ,&nbsp;Wen-Yong Duan","doi":"10.1016/j.gsf.2025.102039","DOIUrl":"10.1016/j.gsf.2025.102039","url":null,"abstract":"<div><div>The Heilongjiang Complex in northeast China (NE China) separates the Jiamusi and Songliao blocks and marks the suture zone of the former Mudanjiang Ocean, as evidenced by a variety of oceanic basalt-derived blueschists. Understanding the closure history of the Mudanjiang Ocean is crucial to unravelling the tectonic transition from the final amalgamation of the Central Asian Orogenic Belt (CAOB) to the onset of the Paleo-Pacific subduction. In this study, we investigate epidote-ferroglaucophane (Ep-Fgl) and garnet-ferrobarroisite (Grt-Fbrs) schists from the Yilan area of the Heilongjiang Complex through petrological, mineralogical, thermodynamic modelling, whole-rock geochemical, and geochronological analyses. The Ep-Fgl schists preserve a peak assemblage of ferroglaucophane + epidote + chlorite + clinopyroxene + phengite + titanite with peak P–T conditions of 13.5–15.8 kbar and 458–495 °C. On the other hand, the Grt-Fbrs schists exhibit a peak assemblage of garnet + glaucophane/ferroglaucophane + lawsonite + chlorite + phengite + rutile ± clinopyroxene ± titanite, deriving peak P–T conditions of 16.4–18.3 kbar and 457–475 °C. Both types of schist record similar clockwise P–T paths, with three metamorphic stages: a peak epidote-to-lawsonite blueschist-facies stage, a post-peak decompression stage in the epidote amphibolite-facies, and a late greenschist-facies overprint stage. The Ep-Fgl schists display alkaline OIB-like geochemical affinities, while the Grt-Fbrs schists show tholeiitic MORB-like characteristics, suggesting that the protoliths represent fragments of the Mudanjiang oceanic crust. Magmatic zircon grains from Ep-Fgl schists yield protolith ages of 276 ± 1 Ma and 280 ± 1 Ma, whereas zircon of Grt-Fbrs schists document protolith ages of 249 ± 2 Ma and 248 ± 2 Ma, indicating that the Mudanjiang Ocean existed since at least the early Permian. Reconstruction of the metamorphic P–T evolution, combined with previous magmatic and metamorphic age data from rocks of the Heilongjiang Complex and of adjacent tectonic units suggests that the subduction and eventual closure of the Mudanjiang Ocean occurred between the late Triassic and middle Jurassic, driven by a regional stress regime shift caused by the westward subduction of the Paleo-Pacific Plate beneath Eurasia.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102039"},"PeriodicalIF":8.5,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rethinking energy and policy: Driving the circular economy through renewables versus nuclear energy in OECD countries","authors":"Zhaohui Yang ,&nbsp;Danish ,&nbsp;Yiting Qiu","doi":"10.1016/j.gsf.2025.102037","DOIUrl":"10.1016/j.gsf.2025.102037","url":null,"abstract":"<div><div>The circular economy (CE) presents a promising approach to integrating industry with sustainability and circularity, which helps minimize ecological harm and preserve natural resources for future generations. This study focused on the roles of nuclear energy, renewables, and climate policies in advancing a CE. It examined the intentions of OECD countries regarding CE practices and the various factors influencing these intentions from 2000 to 2019. This study utilized second-generation panel data tools, such as slope homogeneity and stationarity tests, to assess cross-sectional dependence and heterogeneity in the panel dataset. The study employed the moment quantile regression (MM-QR) method to obtain regression estimates and analyze the conditional distribution across all quantiles. The findings indicated that the role of nuclear energy in promoting CE was negative across all quantiles. In contrast, renewable energy positively supports achieving CE in OECD countries. Climate policies assisted OECD countries in progressing toward CE in both the nuclear energy and renewable energy models. We conducted a robust check using a non-parametric panel Granger causality test, which confirmed the expected results for all other factors. The collaborative efforts for waste minimization ensure that nuclear energy systems are resilient, economically feasible, and environmentally sustainable.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102037"},"PeriodicalIF":8.5,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatiotemporal analysis of AGB and BGB in China: Responses to climate change under SSP scenarios","authors":"Chuanmei Zhu ,&nbsp;Yupu Li ,&nbsp;Jianli Ding ,&nbsp;Jiexin Rao ,&nbsp;Yihang Xiang ,&nbsp;Xiangyu Ge ,&nbsp;Jinjie Wang ,&nbsp;Jingzhe Wang ,&nbsp;Xiangyue Chen ,&nbsp;Zipeng Zhang","doi":"10.1016/j.gsf.2025.102038","DOIUrl":"10.1016/j.gsf.2025.102038","url":null,"abstract":"<div><div>Aboveground biomass (AGB) and belowground biomass (BGB) are key components of carbon storage, yet their responses to future climate changes remain poorly understood, particularly in China. Understanding these dynamics is essential for global carbon cycle modeling and ecosystem management. This study integrates field observations, machine learning, and multi-source remote sensing data to reconstruct the distributions of AGB and BGB in China from 2000 to 2020. Then CMIP6 was used to predict the distribution of China under three SSP scenarios (SSP1-1.9, SSP2-4.5, SSP5-8.5) from 2020 to 2100 to fill the existing knowledge gap. The predictive accuracy for AGB (<em>R</em>² = 0.85) was significantly higher than for BGB (<em>R</em>² = 0.48), likely due to the greater complexity of modeling belowground dynamics. NDVI (Normalized Difference Vegetation Index) and soil organic carbon density (SOC) were identified as the primary drivers of AGB and BGB changes. During 2000–2020, AGB in China remained stable at approximately 10.69 Pg C, while BGB was around 5.06 Pg C. Forest ecosystems contributed 88.52% of AGB and 43.83% of BGB. AGB showed a relatively slow annual increase, while BGB demonstrated a significant annual growth rate of approximately 37 Tg C yr⁻¹. Under the low-emission scenario, both AGB and BGB show fluctuations and steady growth, particularly in South China and the northwestern part of Northeast China. Under the moderate-emission scenario, AGB and BGB show significant declines and increases, respectively. In the high-emission scenario, both AGB and BGB decline significantly, particularly in the southwestern and central regions. These results provide valuable insights into ecosystem carbon dynamics under climate change, emphasizing the relatively low responsiveness of AGB and BGB to climatic variability, and offering guidance for sustainable land use and management strategies.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102038"},"PeriodicalIF":8.5,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A plate geodynamic game changer: Effects of the 66 Ma Chicxulub asteroid collision","authors":"Amit Segev ,&nbsp;Nadav Wetzler ,&nbsp;Craig O’Neill ,&nbsp;Gideon Rosenbaum","doi":"10.1016/j.gsf.2025.102032","DOIUrl":"10.1016/j.gsf.2025.102032","url":null,"abstract":"<div><div>At the end of the Cretaceous period, 66 million years ago, the 7 − 19 km diameter Chicxulub asteroid hit the Yucatan Peninsula in Mexico, triggering global catastrophic environmental changes and mass extinction. The contributions of this event towards changes in plate and plume geodynamics are not fully understood. Here we present a range of geological observations indicating that the impact marked a tectonic turning point in the behavior of mantle plume and plate motion in the Caribbean region and worldwide. At a regional scale, the impact coincides with the termination of seafloor spreading in the Caribbean Ridge. Shortly after the Cretaceous–Paleogene transition, magmatism associated with the Caribbean Large Igneous Province waned, and intensive Paleogene volcanism was initiated. These events happened synchronously with anomalously high mid-ocean ridge magmatism worldwide and an abrupt change in the relative motion of the South American and North American tectonic plates. The evidence for such abrupt changes in plate kinematics and plume behavior raises the possibility that the Chicxulub impact triggered a chain of effects that modified melt reservoirs, subducting plates, mantle flows, and lithospheric deformation. To explain how an asteroid impact could modify tectonic behavior, we discuss two end-member mechanisms: quasi-static and dynamic triggering mechanisms. We designed a numerical model to investigate the strain field and the relative plate motion before and after the impact. The model predicts an enhanced deformation associated with the impact, which surficially tapers off ∼ 500 km from the crater. The impact modifies the subjacent mantle flow field, contributing to long-term mantle-driven dynamic changes. Additionally, deformation associated with seismic effects may have contributed to far-field effects and global changes. We conclude that large asteroid impacts, such as the Chicxulub collision, could trigger cascading effects sufficient to disrupt and significantly modify plate geodynamics.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102032"},"PeriodicalIF":8.5,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Implications of the newly discovered Triassic suites from the eastern segment in the giant Tongshan porphyry Cu deposit, northeast China","authors":"Chenglin Bai ,&nbsp;Guiqing Xie ,&nbsp;Yang Liu ,&nbsp;Jie Chen ,&nbsp;Qiaoqiao Zhu ,&nbsp;Wei Li","doi":"10.1016/j.gsf.2025.102034","DOIUrl":"10.1016/j.gsf.2025.102034","url":null,"abstract":"<div><div>The Tongshan porphyry Cu deposit is well known as one of the most economically significant porphyry deposits in northeast China. Recently, Tongshan has become the largest porphyry Cu deposit in northeast China with the successful exploration of the concealed ore zone V. Ore zone V has the largest Cu tonnage (562 Mt @ 0.50% Cu) and extends into the eastern segment at Tongshan. Compared with ore zones I–III, which are hosted within granitic rocks in the western segment, the ore zone V mainly occurs in Duobaoshan volcanic rocks and the roof pendants of newly discovered intrusions. Here, we conducted a study of the understudied eastern ore zone and found that copper mineralization is associated with the newly discovered suites in the eastern segment at Tongshan. Two periods of ore-bearing quartz veins with different widths have been recognized, including quartz-chalcopyrite-pyrite veinlets (0.1–0.2 cm) and quartz-chalcopyrite-polymetallic sulfide wide veins (&gt;0.5 cm). The latter veins can be divided into four stages (I–IV) of mineralization and alteration, which are closely related to the newly discovered granodiorite and dacite porphyry. Our new zircon U–Pb ages show that the granodiorite and dacite porphyry were developed between 228–223 Ma, suggesting that the overprinting porphyry copper mineralization occurred in the Triassic. The Triassic suites have adakite-like character with high Sr/Y, and show no or minimal negative Eu anomalies, indicating early dominant amphibole with limited plagioclase fractionation. For the Triassic intrusions, the high zircon Eu/Eu* (0.67–0.89), Δ_FMQ (1.04 ± 0.53; where Δ_FMQ is the log <em>f</em>O₂ difference between the sample value and the fayalite-magnetite-quartz mineral buffer), hygrometer values (∼7.19 wt.% H₂O) and high whole-rock Fe₂O₃/FeO, Sr/Y, V/Sc and 10,000×(Eu/Eu*)/Y ratios together indicate the Triassic magmas were oxidized and hydrous. These contents and ratios of the Triassic suites are significantly higher than those of the Ordovician suites (Δ_FMQ = 0.74 ± 0.26, ∼5.90 wt.% H₂O), suggesting that the newly discovered Triassic magmas are more oxidized and hydrous, with high potential for porphyry copper mineralization. Based on the investigation of mineralization and the above results, we proposed that multiple superimposed mineralizations can help form a large-scale deposit and the southeastern segment is a favorable exploration area at Tongshan.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102034"},"PeriodicalIF":8.5,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143611723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a comprehensive framework for wetland ecosystem assessment and management","authors":"Manob Das ,&nbsp;Arijit Das ,&nbsp;Suman Singha","doi":"10.1016/j.gsf.2025.102036","DOIUrl":"10.1016/j.gsf.2025.102036","url":null,"abstract":"<div><div>This study focuses on the assessment of ecosystem health (EH), ecosystem services (ES), and ecosystem risk (ER) in East Kolkata Wetland (EKW). A comprehensive framework on the EH, ES and ER has been developed using remote sesning and geo-spatial techniques for the year 2000, 2005, 2010, 2015, and 2020. The study also assessed ecosystem structure and fragmentation using landscape metrics calculated using fragstats, which showed a significant influence of land use and land cover (LULC) changes on the wetland’s ecological integrity. The study revealed that 6.86% of EKW fallen under a very low EH zone, while 20% was categorized as having very high EH. Spatio-temporal analysis of ES indicated that 30% of the area had very low ES value, with only 8% exhibiting very high ES. ER assessment revealed that 7% of the study area was highly ER, while 12% identified within a high ER zone, reflecting frequent LULC changes. The correlation analysis highlighted strong negative relationships between landscape deviation degree (LDD) and EH (−0.971), and between normalized difference water index (NDWI) and normalized difference vegetation index (NDVI) (−0.991). Additionally, landscape metrics such as the number of patches (NP) and the largest patch index (LPI) exhibited significant correlations, emphasizing the impact of fragmentation on EH and resilience. This comprehensive assessment underscores the importance of integrated approaches to monitor and manage wetland ecosystems, particularly in urban areas facing significant environmental stressors. The findings are crucial for informed decision-making and sustainable management of the wetland ecosystems, particularly in the cities of the global south.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102036"},"PeriodicalIF":8.5,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cobalt enrichment in Paleoproterozoic African and Brazilian manganese deposits","authors":"Evilarde Carvalho Uchôa Filho ,&nbsp;Felipe Holanda dos Santos ,&nbsp;Douglas Teixeira Martins ,&nbsp;Wagner da Silva Amaral ,&nbsp;José Alberto Rodrigues do Vale","doi":"10.1016/j.gsf.2025.102035","DOIUrl":"10.1016/j.gsf.2025.102035","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This study highlights a new by-product source for cobalt by recycling Paleoproterozoic Mn deposits. We present a geochemical modeling approach utilizing Principal Component Analysis (PCA) for available geochemical data of Paleoproterozoic manganese deposits found in Africa and Brazil, which exhibit anomalous cobalt contents (up to 1200 ppm) along with other metals such as copper, nickel, and vanadium. The PCA results for the correlation coefficient matrix of the Enrichment Factor (EF) values of major and trace elements from samples of eight Mn deposits found in Africa and Brazil (Kisenge-Kamata, Moanda, Nsuta in Africa, and Azul, Buritirama, Lagoa do Riacho, Morro da Mina, and Serra do Navio in Brazil) yielded a cumulative variance of 53.3% for PC1 (34%) and PC2 (19.3%). In PC1, the highest positive loadings correspond to the variables Mn&lt;sub&gt;EF&lt;/sub&gt;, Ni&lt;sub&gt;EF&lt;/sub&gt;, and Co&lt;sub&gt;EF&lt;/sub&gt;, while the highest negative loadings correspond to the variables Si&lt;sub&gt;EF&lt;/sub&gt;, Fe&lt;sub&gt;EF&lt;/sub&gt;, K&lt;sub&gt;EF&lt;/sub&gt;, Ti&lt;sub&gt;EF&lt;/sub&gt;, Cr&lt;sub&gt;EF&lt;/sub&gt;, and Zr&lt;sub&gt;EF&lt;/sub&gt;. PC2 exhibits the highest positive loadings for the variables Ca&lt;sub&gt;EF&lt;/sub&gt;, Mg&lt;sub&gt;EF&lt;/sub&gt;, and P&lt;sub&gt;EF&lt;/sub&gt;, while the highest negative loadings are for Cu&lt;sub&gt;EF&lt;/sub&gt; and V&lt;sub&gt;EF&lt;/sub&gt;. The biplot diagram representation showed that clusters of vectors Mn&lt;sub&gt;EF&lt;/sub&gt;, Ni&lt;sub&gt;EF&lt;/sub&gt;, Co&lt;sub&gt;EF&lt;/sub&gt;, V&lt;sub&gt;EF&lt;/sub&gt;, and Cu&lt;sub&gt;EF&lt;/sub&gt; influence samples of Mn-carbonate rock, Mn-carbonate–silicate rock, Mn-silicate rock, and Mn-carbonate-siliciclastic rock, all with high Co&lt;sub&gt;EF&lt;/sub&gt; values (up to 414). The cluster of vectors Ca&lt;sub&gt;EF&lt;/sub&gt;, Mg&lt;sub&gt;EF&lt;/sub&gt;, and P&lt;sub&gt;EF&lt;/sub&gt; significantly influence carbonate rock and dolomite marble, which have low Co&lt;sub&gt;EF&lt;/sub&gt; values (close to 0). The cluster of vectors Si&lt;sub&gt;EF&lt;/sub&gt;, Fe&lt;sub&gt;EF&lt;/sub&gt;, K&lt;sub&gt;EF&lt;/sub&gt;, Ti&lt;sub&gt;EF&lt;/sub&gt;, Cr&lt;sub&gt;EF&lt;/sub&gt;, and Zr&lt;sub&gt;EF&lt;/sub&gt; strongly influences siliciclastic rock, which exhibits low Co&lt;sub&gt;EF&lt;/sub&gt; values. On the other hand, the cluster of vectors Cu&lt;sub&gt;EF&lt;/sub&gt; and V&lt;sub&gt;EF&lt;/sub&gt; influences oxidized Mn ore, which exhibits Co&lt;sub&gt;EF&lt;/sub&gt; values of up to 108. The results reveal a dichotomy regarding the origin of cobalt and other metal enrichments in these deposits linked to the Mn redox cycle. This process involves the formation of Mn-oxyhydroxides with the adsorption of Co and other metals under oxic conditions, followed by the burial of these Mn oxides in an anoxic diagenetic environment, where microbial sulfate reduction leads to the nucleation of Mn-carbonates and the formation of metal-rich sulfides (Fe, Co, Ni, V). Additionally, detrital input and sulfide phases (e.g., framboidal pyrite) for the formation of Mn-rich siliciclastic rocks associated with Mn-carbonate rocks are evidenced by proxies Si&lt;sub&gt;EF&lt;/sub&gt;, Fe&lt;sub&gt;EF&lt;/sub&gt;, K&lt;sub&gt;EF&lt;/sub&gt;, Ti&lt;sub&gt;EF&lt;/sub&gt;, Cr&lt;sub&gt;EF&lt;/sub&gt;, and Zr&lt;sub&gt;EF&lt;/sub&gt;. This new exploration approach, supported by geochemical modeling through PCA, enha","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102035"},"PeriodicalIF":8.5,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}