Geoscience frontiers最新文献

{"title":"Long-term daily water temperatures unveil escalating water warming and intensifying heatwaves in the Odra river Basin, Central Europe","authors":"Jiang Sun ,&nbsp;Fabio Di Nunno ,&nbsp;Mariusz Sojka ,&nbsp;Mariusz Ptak ,&nbsp;Quan Zhou ,&nbsp;Yi Luo ,&nbsp;Senlin Zhu ,&nbsp;Francesco Granata","doi":"10.1016/j.gsf.2024.101916","DOIUrl":"10.1016/j.gsf.2024.101916","url":null,"abstract":"<div><p>Water temperature is a critical indicator and weathervane of aquatic ecosystems. However, the vast majority of rivers lack long-term continuous and complete water temperature datasets. In this study, ensemble models by combining NARX (nonlinear autoregressive network with exogenous inputs) and air2stream were used to reconstruct daily river water temperatures for 27 hydrological stations in the Odra River Basin, one of the largest river systems in Europe. For each hydrological station, both the NARX and air2stream models were calibrated and validated, and the better-performed model was selected to reconstruct daily river water temperatures from 1985 to 2022. The results showed that hybrid modeling by combining NARX and air2stream is promising for reconstructing daily river water temperatures. Based on the reconstructed dataset, annual and seasonal trends of water temperature and characteristics of river heatwaves were evaluated. The results indicated that annual river water temperatures showed a consistent warming trend over the past 40 years with an average warming rate of 0.315 °C/decade. Seasonal river water temperatures indicated that summer warms faster, followed by autumn and spring, and winter river water temperatures showed an insignificant warming trend. River heatwaves are increased in frequency, duration, and intensity in the Odra River Basin, and 6 out of 27 hydrological stations have river heatwaves categorized as ‘severe’ and ‘extreme’, suggesting that mitigation measures are needed to reduce the impact of climate warming on aquatic systems. Moreover, results showed that air temperature is the major controller of river heatwaves, and river heatwaves tend to intensify with the warming of air temperatures.</p></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"15 6","pages":"Article 101916"},"PeriodicalIF":8.5,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674987124001403/pdfft?md5=30eb9ab0c77e973094e7449eb0832be3&pid=1-s2.0-S1674987124001403-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151126","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":"Carbon isotope fractionation during methane transport through tight sedimentary rocks: Phenomena, mechanisms, characterization, and implications","authors":"Wenbiao Li ,&nbsp;Jun Wang ,&nbsp;Chengzao Jia ,&nbsp;Shuangfang Lu ,&nbsp;Junqian Li ,&nbsp;Pengfei Zhang ,&nbsp;Yongbo Wei ,&nbsp;Zhaojing Song ,&nbsp;Guohui Chen ,&nbsp;Nengwu Zhou","doi":"10.1016/j.gsf.2024.101912","DOIUrl":"10.1016/j.gsf.2024.101912","url":null,"abstract":"<div><p>The phenomenon of carbon isotopic fractionation, induced by the transport of methane in tight sedimentary rocks through processes primarily involving diffusion and adsorption/desorption, is ubiquitous in nature and plays a significant role in numerous geological and geochemical systems. Consequently, understanding the mechanisms of transport-induced carbon isotopic fractionation both theoretically and experimentally is of considerable scientific importance. However, previous experimental studies have observed carbon isotope fractionation phenomena that are entirely distinct, and even exhibit opposing characteristics. At present, there is a lack of a convincing mechanistic explanation and valid numerical model for this discrepancy. Here, we performed gas transport experiments under different gas pressures (1–5 MPa) and confining pressures (10–20 MPa). The results show that methane carbon isotope fractionation during natural gas transport through shale is controlled by its pore structure and evolves regularly with increasing effective stress. Compared with the carbon isotopic composition of the source gas, the initial effluent methane is predominantly depleted in ¹³C, but occasionally exhibits ¹³C enrichment. The carbon isotopic composition of effluent methane converges to that of the source gas as mass transport reaches a steady state. The evolution patterns of the isotope fractionation curve, transitioning from the initial non-steady state to the final steady state, can be categorized into five distinct types. The combined effect of multi-level transport channels offers the most compelling mechanistic explanation for the observed evolution patterns and their interconversion. Numerical simulation studies demonstrate that existing models, including the Rayleigh model, the diffusion model, and the coupled diffusion-adsorption/desorption model, are unable to describe the observed complex isotope fractionation behavior. In contrast, the multi-scale multi-mechanism coupled model developed herein, incorporating diffusion and adsorption/desorption across multi-level transport channels, effectively reproduces all the observed fractionation patterns and supports the mechanistic rationale for the combined effect. Finally, the potential carbon isotopic fractionation resulting from natural gas transport in/through porous media and its geological implications are discussed in several hypothetical scenarios combining numerical simulations. These findings highlight the limitations of carbon isotopic parameters for determining the origin and maturity of natural gas, and underscore their potential in identifying greenhouse gas leaks and tracing sources.</p></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"15 6","pages":"Article 101912"},"PeriodicalIF":8.5,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674987124001361/pdfft?md5=76eb148fdb9ebd685957c1f186eb11f1&pid=1-s2.0-S1674987124001361-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142006337","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":"The upstream rare earth resources of Malaysia: Insight into geology, geochemistry, and hydrometallurgical approaches","authors":"Syed Muhammad Ibad ,&nbsp;Haylay Tsegab ,&nbsp;Numair Ahmed Siddiqui ,&nbsp;Monera Adam ,&nbsp;Santosh Mishra ,&nbsp;Syahrir Ridha ,&nbsp;Nisar Ahmed ,&nbsp;Afifa Azmi","doi":"10.1016/j.gsf.2024.101899","DOIUrl":"10.1016/j.gsf.2024.101899","url":null,"abstract":"<div><p>Peninsular Malaysia is already well known for having rare earth (RE) resources. However, pertinent data and information on upstream RE resources and reserve potential in Malaysia are yet to be established. It is vital to identify opportunities and challenges for value addition to rare earth elements (REEs) deposits in Malaysia. Therefore, this study evaluates the potential of Malaysian geological formations to serve as repositories for RE resources, such as rare earth minerals (REMs) and REEs, by elucidating the geological processes that are considered critical to the formation of the various deposit types. This paper concisely reviews possible REE mineralization in alkaline igneous rocks, pegmatites, placer deposits: monazite and xenotime, marine sediments, river and lake sediments, ion adsorption clays (IAC) deposits, and shale/coal deposits found in Malaysia. Comparisons between Malaysian deposits revealed that these deposits are potentially enriched with RE resources showing geological formations across the world. The paper reviews the methods and flowsheets used for the recovery of REMs and REEs from primary, secondary as well as alternative resources, with special consideration to the hydrometallurgical procedures comprising of leaching with acids and alkalis tailed by ion exchange, solvent extraction, or precipitation. The REEs ecosystem of Malaysia has also been discussed by considering the latest information from the Malaysian Investment Development Authority (MIDA), the REEs processing center, the Academy of Science of Malaysia (ASM), the People’s Republic of China (PRC), Lynas Malaysia Sdn. Bhd. (Lynas), Ministry of Energy and Natural Resources (NRECC), Jabatan Mineral &amp; Geosains (JMG), Ministry of Science, Technology, and Innovation (MOSTI), and the Malaysian Chamber of Mines. The information on upstream RE resources and recent hydrometallurgical approaches provided in this study will contribute to developing and enhancing midstream and downstream RE-based manufacturing and processing operations in Malaysia.</p></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"15 6","pages":"Article 101899"},"PeriodicalIF":8.5,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674987124001233/pdfft?md5=ea3d72f2f9b4820518bb613ef0890c18&pid=1-s2.0-S1674987124001233-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142006336","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":"Deep recycling of volatile elements in the mantle: Evidence from the heterogeneous B isotope in intra-plate basalts","authors":"Yan-Qing Li ,&nbsp;Hiroshi Kitagawa ,&nbsp;Chang-Qian Ma ,&nbsp;Eizo Nakamura ,&nbsp;Chie Sakaguchi ,&nbsp;Katsura Kobayashi ,&nbsp;Xiang-Yun Hu","doi":"10.1016/j.gsf.2024.101900","DOIUrl":"10.1016/j.gsf.2024.101900","url":null,"abstract":"<div><p>Volatiles in the mantle are crucial for Earth’s geodynamic and geochemical evolution. Understanding the deep recycling of volatiles is key for grasping mantle chemical heterogeneity, plate tectonics, and long-term planetary evolution. While subduction transfers abundant volatile elements from the Earth’s surface into the mantle, the fate of hydrous portions within subducted slabs during intensive dehydration processes remains uncertain. Boron isotopes, only efficiently fractionating near the Earth’s surface, are valuable for tracing volatile recycling signals. In this study, we document a notably large variation in <em>δ</em>¹¹B values (−14.3‰ to +8.2‰) in Cenozoic basalts from the South China Block. These basalts, associated with a high-velocity zone beneath East China, are suggested to originate from the mantle transition zone. While the majority exhibit <em>δ</em>¹¹B values (−10‰ to −5‰) resembling the normal mantle, their enriched Sr-Nd-Pb isotope compositions and fluid-mobile elements imply hydrous components in their source, including altered oceanic crust and sediments. The normal <em>δ</em>¹¹B values are attributed to the dehydration processes. Remarkably high <em>δ</em>¹¹B values in the basalts indicate the presence of subducted serpentinites in their mantle source. A small subset of samples with low <em>δ</em>¹¹B values and radiogenic isotope enrichments suggests a contribution from recycled detrital sediments, though retaining minimal volatile elements after extensive dehydration. These findings provide compelling evidence that serpentinites within subducted slabs predominantly maintain their hydrous nature during dehydration processes in subduction zones. They may transport a considerable amount of water into deep mantle reservoirs, such as the mantle transition zone.</p></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"15 6","pages":"Article 101900"},"PeriodicalIF":8.5,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674987124001245/pdfft?md5=47e5d4c6df11d7be54e16d76ae136a45&pid=1-s2.0-S1674987124001245-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142058511","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":"Towards an improved prediction of soil-freezing characteristic curve based on extreme gradient boosting model","authors":"Kai-Qi Li ,&nbsp;Hai-Long He","doi":"10.1016/j.gsf.2024.101898","DOIUrl":"10.1016/j.gsf.2024.101898","url":null,"abstract":"<div><p>As an essential property of frozen soils, change of unfrozen water content (UWC) with temperature, namely soil-freezing characteristic curve (SFCC), plays significant roles in numerous physical, hydraulic and mechanical processes in cold regions, including the heat and water transfer within soils and at the land–atmosphere interface, frost heave and thaw settlement, as well as the simulation of coupled thermo-hydro-mechanical interactions. Although various models have been proposed to estimate SFCC, their applicability remains limited due to their derivation from specific soil types, soil treatments, and test devices. Accordingly, this study proposes a novel data-driven model to predict the SFCC using an extreme Gradient Boosting (XGBoost) model. A systematic database for SFCC of frozen soils compiled from extensive experimental investigations via various testing methods was utilized to train the XGBoost model. The predicted soil freezing characteristic curves (SFCC, UWC as a function of temperature) from the well-trained XGBoost model were compared with original experimental data and three conventional models. The results demonstrate the superior performance of the proposed XGBoost model over the traditional models in predicting SFCC. This study provides valuable insights for future investigations regarding the SFCC of frozen soils.</p></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"15 6","pages":"Article 101898"},"PeriodicalIF":8.5,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674987124001221/pdfft?md5=76e5873ce2a825ba0e2599974ea033a8&pid=1-s2.0-S1674987124001221-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141963204","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":"","authors":"Yajun Liu,&nbsp;Jinjian Wu,&nbsp;Shigang Zhang","doi":"10.1016/j.gsf.2024.101897","DOIUrl":"10.1016/j.gsf.2024.101897","url":null,"abstract":"","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"15 6","pages":"Article 101897"},"PeriodicalIF":8.5,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S167498712400121X/pdfft?md5=1ff8f3268ca3b3347ec9de5cc99aa591&pid=1-s2.0-S167498712400121X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141997795","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":"Exploring the impact of green technology, renewable energy and globalization towards environmental sustainability in the top ecological impacted countries","authors":"Arshian Sharif ,&nbsp;Uzma Bashir ,&nbsp;Sumera Mehmood ,&nbsp;Calvin W.H. Cheong ,&nbsp;Muhammad Farhan Bashir","doi":"10.1016/j.gsf.2024.101895","DOIUrl":"10.1016/j.gsf.2024.101895","url":null,"abstract":"<div><p>Green environmental technologies, renewable energy and globalization are interconnected pillars that impact economies and societies. By effectively fostering these resources, environmental policies can help achieve economic prosperity, sustainable development and environmental protection. The current study seeks to address environmental and economic predicaments by empirically examining the role of green technology and renewable energy in influencing the load capacity factor and ecological footprint with the highest ecological impact. Given that these nations are also significant players in the global economy, we also examine the impact of Globalization and economic growth within econometric investigation. The current study uses moments quantile regression (MMQR) as an econometric strategy to report that while innovations in green technology and renewable energy positively influence load factor capacity and help reduce ecological footprint, certain facets of globalization worsen the ecological footprint, thereby unsettling its load factor capacity. These findings underscore the pressing need for policymakers to prioritize integrating environmental and trade policy agreements to ensure progress towards long-term environmental goals.</p></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"15 6","pages":"Article 101895"},"PeriodicalIF":8.5,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674987124001191/pdfft?md5=506be48658ac7f53401aa6a22b30756b&pid=1-s2.0-S1674987124001191-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141842411","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":"Assessing the palliative aspects of green innovations in the non-linear tendencies of environmental sustainability-financial globalization nexus among West African states","authors":"Mohammed Musah ,&nbsp;Stephen Taiwo Onifade ,&nbsp;Elma Satrovic ,&nbsp;Joseph Akwasi Nkyi","doi":"10.1016/j.gsf.2024.101893","DOIUrl":"10.1016/j.gsf.2024.101893","url":null,"abstract":"<div><p>A reconciliation of the disagreement on whether financial globalization (FG) affects ecological footprint through the scale, technique and composition effects cannot be achieved without an explicit understanding of the direct and indirect interactions of FG with environmental sustainability. Hence, the novel perspective of this study lies in the investigation of how green innovations moderate the non-linear tendencies in the FG-environmental sustainability link among western African states given the abundance of natural resources and the prevailing pace of economic growth. The core findings are obtained from robust analysis based on cross-sectional autoregressive distributed lag (CS-ARDL) technique, the augmented mean group (AMG) technique, and the common correlated effects mean group (CCEMG) advanced estimators. Firstly, the beneficial ecological impacts of green innovations were observed. As per direct impact, enhanced financial globalization (FG) exhibits non-linear detrimental ecological effects. However, green innovations cushion the observed adverse ecological effects of FG. Furthermore, resource rents reduce ecological footprint within the moderating framework of green innovation as the environmental Kuznets curve (EKC) is validated among the states. Additionally, a bidirectional causal link between financial globalization, green innovations, economic growth, natural resources, and ecological footprint was observed. Thus, the significant policy implication is for the West African states to decisively increase their investments in green innovations while strategically encouraging the share of ecologically friendly resources in total resource utilization to guarantee a more sustainable environment.</p></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"15 6","pages":"Article 101893"},"PeriodicalIF":8.5,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674987124001178/pdfft?md5=0a05975eebc3b235b269b0c03b83988f&pid=1-s2.0-S1674987124001178-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141714223","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":"Gravitational and elastic energies stored in crustal volumes activate normal versus strike-slip and thrust seismogenic faults","authors":"Carlo Doglioni","doi":"10.1016/j.gsf.2024.101894","DOIUrl":"10.1016/j.gsf.2024.101894","url":null,"abstract":"&lt;div&gt;&lt;p&gt;Shallow crustal faults are passive features mobilized by the dissipation of the potential energy and the shear stress accumulated in the brittle volume surrounding them. However, the stored energy in the volume differs from the tectonic setting, i.e., it is mainly gravitational in extensional tectonic settings, whereas it is elastic in strike-slip and contractional tectonic environments. In extensional settings, below about 1 km, the horizontal tensile stress is overwhelmed by the confining pressure of the lithostatic load, and it becomes positive, i.e. compressive. Therefore, there is no horizontal tension in extensional tectonic settings and the pro-gravity motion of the crustal volume is provided by the lithostatic load, which is the vertical maximum principal stress. The elastic energy is rather accumulated by the maximum horizontal principal stresses, i.e., iso-gravity in transcurrent settings and counter-gravity in contractional tectonic settings. The different relation with the gravitational force in the different tectonic settings generates several relevant differences in the three main tectonic environments. The extensional tectonic settings, both in continental and oceanic rift zones generate normal fault-related earthquakes, i.e., pro-gravity movements, or graviquakes. They differ from the other tectonic setting because are marked by (i) lower energy and lower differential stress to activate faults with respect to strike-slip and contractional tectonics; (ii) lower maximum earthquake magnitude; (iii) a larger number of low magnitude earthquakes in extensional settings because the crust moves downward as soon as it can move, whereas contractional settings require larger accumulation of energy to move counter-gravity; (iv) consequently, the &lt;em&gt;b&lt;/em&gt;-value of the Gutenberg-Richter is higher than 1 and the aftershocks are more numerous and last longer in extensional settings; (v) the downward motion of the hangingwall determines more diffuse cataclastic deformation with respect to the other tectonic settings because the lithostatic load works everywhere, whereas in the other tectonic settings is concentrated where the elastic energy accumulates; (vi) in extensional settings the volume dimension is determined by thickness of the brittle layer, and its length is in average three times the seismogenic thickness; in strike-slip and contractional settings dominates the elastic energy (elastoquakes), and the mobilized volume may be ten to thirty times longer in a single seismic sequence, being its size proportional both to the brittle thickness and the relative speed of plates. These differences characterize the seismic cycle of graviquakes with respect to the elastoquakes. The bigger the volume, the wider the seismogenic fault in all tectonic settings. The interplay between the horizontal tectonic forces and the lithostatic load, which is ubiquitous, varies in the three main tectonic settings, generating different seismotectonic style","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"15 6","pages":"Article 101894"},"PeriodicalIF":8.5,"publicationDate":"2024-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S167498712400118X/pdfft?md5=8cf0e7e9dd0d7de86fea8084e438ad0b&pid=1-s2.0-S167498712400118X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141689478","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":"Extreme geochemical fractionation during mantle melting: Insights from Hf-Nd isotopically ultra-depleted eclogite","authors":"Kun Zhou ,&nbsp;Yi-Xiang Chen ,&nbsp;Yong-Fei Zheng ,&nbsp;Ren-Xu Chen ,&nbsp;Yueheng Yang","doi":"10.1016/j.gsf.2024.101892","DOIUrl":"10.1016/j.gsf.2024.101892","url":null,"abstract":"<div><p>Extreme fractionation of elements and isotopes in mafic igneous rocks is abnormal in deciphering the source nature and melting conditions of mafic magmatism. Especially, identification of geochemically ultra-depleted mafic melts and their mantle sources has great bearing on the property of crust-mantle differentiation at plate margins. This is illustrated by extreme Hf-Nd isotope fractionation in ultrahigh-pressure eclogites from the Sulu orogen in east-central China. In addition to the previous finding of ultrahigh <em>ε</em>_Nd(0) values, we report here new data of whole-rock trace elements and Lu-Hf isotopes in eclogites and related rocks from the same region. The present results show extremely high Lu/Hf ratios and abnormally high <em>ε</em>_Hf(0) values of up to 576 for the eclogites, significantly different from the garnet amphibolites and other eclogite-facies metamorphic rocks in the same orogen. This feature is coupled with the ultrahigh <em>ε</em>_Nd(0) values as well as the severe depletion of light rare earth elements (LREE) and high field strength elements (HFSE). Because HFSE and LREE are immobile in aqueous solutions and the effect of melt extraction is insignificant during the continental deep subduction, the extreme fractionation of Lu/Hf and Sm/Nd indicate their origination from a geochemically ultra-depleted mantle source. These eclogites have the depleted mantle Hf model ages of 1.27 Ga to 1.61 Ga, similar to the depleted mantle Nd model ages of 1.39 Ga to 1.67 Ga as previously reported. This suggests that the protolith of the extremely high <em>ε</em>_Hf-<em>ε</em>_Nd eclogites was a kind of mafic igneous rocks derived from fractional crystallization of geochemically ultra-depleted mafic melts, which were produced by partial melting of the highly refractory lithospheric mantle during a series of seafloor spreading initiation-failure cycles at a divergent plate margin after the breakup of supercontinent Columbia in the Early Mesoproterozoic. The mafic igneous rocks were located in a passive continental margin in the Late Paleozoic and experienced deep subduction and exhumation in the Triassic, giving rise to the presently studied eclogites. The ancient geochemical signatures were retained without considerable influence by mantle convection, providing insights into the nature of crust-mantle differentiation during the tectonic transition from supercontinental breakup to seafloor spreading beneath the sub-ridge lithospheric mantle.</p></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"15 6","pages":"Article 101892"},"PeriodicalIF":8.5,"publicationDate":"2024-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674987124001166/pdfft?md5=34b794962b91e1284a8e620aafea41e2&pid=1-s2.0-S1674987124001166-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141690209","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}