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地学前缘(英文版)
地学前缘(英文版)

莫宣学

双月刊

1674-9871

geofrontier@cugb.edu.cn

010-82322283,82321855

100083

北京市海淀区学院路29号中国地质大学（北京）期刊中心

地学前缘(英文版)/Journal GEOSCIENCE FRONTIERSCSCDCSTPCD北大核心SCI
查看更多>>GEOSCIENCE FRONTIERS (GSF) is a quarterly journal that publishes in English significant original research articles and high quality reviews of recent advances in all fields of Earth Sciences — including stratigraphy and paleontology, mineralogy and petrology, economic geology and minerals and fuel exploration, structural geology, lithospheric tectonics, environmental and engineering geology, hydrogeology, astrogeology, marine geology, and geophysics and geochemistry. Technical papers, case histories, reviews, and discussions are welcomed.
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    Hot subduction in the southern Paleo-Asian Ocean:Insights from clinopyroxene chemistry and Sr-Nd-Hf-Pb isotopes of Carboniferous volcanics in West Junggar

    Yao XiaoXijun LiuWenjiao XiaoXiao-Han Gong...
    161-180页
    查看更多>>摘要：The chemical evolution and pressure-temperature conditions of subduction zone magmatism along ancient suture zones in orogenic belts can provide important information regarding plate convergence processes in paleo-oceans.Carboniferous magmatism in West Junggar is key to understanding the tectonothermal and subduction history of the Junggar Ocean,which was a branch of the Paleo-Asian Ocean,as well as the accretionary processes in the southwestern Central Asian Orogenic Belt(CAOB).We undertook a geochronological,mineralogical,geochemical,and Sr-Nd-Hf-Pb isotopic study of vol-canic rocks from the Baikouquan area of West Junggar.We used these data to determine the petrogenesis,mantle source,and pressure-temperature conditions of these magmas,and further constrain the subduc-tion and tectonic history of the Junggar Ocean.The studied volcanic rocks yielded zircon U-Pb ages of 342-337 Ma and are characterized by enrichments of large-ion lithophile elements(LILEs),and deple-tions in high-field-strength elements(HFSEs),indicative of an island arc affinity.The volcanic rocks have positive εNd(t)(5.83-7.04)and εHf(t)(13.47-15.74)values,87Sr/86Sr(t)ratios of 0.704023-0.705658,and radiogenic 207Pb/204Pb(t)and 208Pb/204Pb(t)ratios at a given 206Pb/204Pb(t)ratio,indicative of a depleted mantle source contaminated by subduction-related materials.Geochemical modeling calculations indi-cate that ≤1％of a subduction component comprising fluid and sediment melt could have generated the source of the parental melts of the Baikouquan volcanic rocks.Clinopyroxene phenocrysts in the vol-canic rocks are classified as high-and low-Ti clinopyroxene,and pressure-temperature calculations sug-gest the host rocks formed at high temperatures(～1300 ℃)and shallow to moderate depths(＜2 GPa).The magma was probably generated by hot and hydrous melting in a mantle wedge in response to sub-duction of young,hot oceanic lithosphere.The present results,combined with published data,suggest that the Baikouquan volcanic rocks record a transition in tectonic setting from normal cold to anomalous hot subduction of young oceanic lithosphere close to a mid-ocean ridge.This indicates ridge subduction began shortly after 337 Ma.Our results provide new insights into the tectonomagmatic evolution during intra-oceanic subduction prior to ridge subduction.
      原文链接:
    • NETL
    • NSTL
    • 万方数据
    • 维普

    Leucogranite mapping via convolutional recurrent neural networks and geochemical survey data in the Himalayan orogen

    Ziye WangTong LiRenguang Zuo
    181-192页
    查看更多>>摘要：Geochemical survey data analysis is recognized as an implemented and feasible way for lithological map-ping to assist mineral exploration.With respect to available approaches,recent methodological advances have focused on deep learning algorithms which provide access to learn and extract information directly from geochemical survey data through multi-level networks and outputting end-to-end classification.Accordingly,this study developed a lithological mapping framework with the joint application of a con-volutional neural network(CNN)and a long short-term memory(LSTM).The CNN-LSTM model is dom-inant in correlation extraction from CNN layers and coupling interaction learning from LSTM layers.This hybrid approach was demonstrated by mapping leucogranites in the Himalayan orogen based on stream sediment geochemical survey data,where the targeted leucogranite was expected to be potential resources of rare metals such as Li,Be,and W mineralization.Three comparative case studies were car-ried out from both visual and quantitative perspectives to illustrate the superiority of the proposed model.A guided spatial distribution map of leucogranites in the Himalayan orogen,divided into high-,moderate-,and low-potential areas,was delineated by the success rate curve,which further improves the efficiency for identifying unmapped leucogranites through geological mapping.In light of these results,this study provides an alternative solution for lithologic mapping using geochemical survey data at a regional scale and reduces the risk for decision making associated with mineral exploration.
      原文链接:
    • NETL
    • NSTL
    • 万方数据
    • 维普

    Mantle contributions to granitoids associated with Sn mineralization:Geochemical and isotopic evidence from the giant Dachang deposit,South China

    Tingyi WangQihai ShuXiaoping XiaChao Li...
    193-214页
    查看更多>>摘要：Major Sn deposits are commonly linked to crust-derived and highly evolved granites,with magma gener-ation aided by mantle heating.However,whether and how the mantle components contribute to Sn poly-metallic mineralization remains unclear.In this study,in combination with a compilation of equivalent data in the region,we provide new constraints on this issue based on detailed investigations on the pet-rogenesis and metallogenic significance of granitoids including the causative batholith and later granodi-orite porphyry dike in the giant Dachang Sn deposit from South China.The former has zircon U-Pb ages of 93-91 Ma and belongs to highly evolved S-type biotite granite,which experienced fractionation of mas-sive feldspar.The latter shows zircon U-Pb ages of 90 Ma and displays I-type granite features.The bath-olith was mainly derived from the dehydration melting of biotite in the metasedimentary sources,as revealed by the relatively low whole-rock Pb contents(＜30 ppm)and high Ba/Pb ratios(2.71-17.1)and initial T(ti-zr)of 790 ℃.Compared with the adjacent crust-derived S-type granites(-24.8--5.1)and 1-type granites(-11.0 to-5.2),the Dachang S-type biotite granites present higher zircon eHf(t)values(-9.1 to-2.1).Furthermore,the low magmatic zircon 618O values(6.2 ‰)and higher apatite LREE(3277-4114 ppm)and Sr(1137-1357 ppm)contents than of arc-type basic rocks were discerned.These characteristics jointly hint the contributions of mantle components.The higher initial T(ti-zr)(＞850 ℃),whole-rock Mg#(52 to 58),apatite εNd(t)(-9.2 to-6.5)and zircon EHf(t)(-7.6 to 2.5)values but lower zircon δ18O values(6.33 to 8.30 ‰)of the later granodiorite porphyry dike than those of the batholith also suggest that mantle material was involved in the generation of the dikes,which is evident by the variational features of zircon and apatite trace elements.In addition,at the zircon Hf＜12000 ppm and Eu/Eu*＞0.05,the higher zircon △FMQ values(mostly from-1.8 to 2.0)and H2O contents(100-1100 ppm)of the Dachang granitoids than the pure crust-derived S-type granites(△FMQ=mostly from-3.7 to-1.5;H2O＜100 ppm)imply that mantle materials involved are relatively rich in water and oxidized.These suggest that the addition of mantle components is conducive to the extraction of Sn from metased-imentary sources,and moderately facilitates the increase of oxygen fugacity which still maintains the incompatibility of Sn in magmas with △FMQ＜2.Also,the involvement of mantle components upgrades the H2O contents in S-type magmas,favoring the migration of ore-forming elements from magmas to hydrothermal fluids.The sediment-derived causative granites displayed higher εHf(t)and εNd(t)values with greater Sn tonnages of their associated world-class Sn polymetallic deposits,supporting the opinion that the contributions of mantle components play an important role in the generation of giant Sn deposits.
      原文链接:
    • NETL
    • NSTL
    • 万方数据
    • 维普

    Interpreting random fields through the U-Net architecture for failure mechanism and deformation predictions of geosystems

    Ze Zhou WangJinzhang ZhangHongwei Huang
    215-230页
    查看更多>>摘要：The representation of spatial variation of soil properties in the form of random fields permits advanced probabilistic assessment of slope stability.In many studies,the safety margin of the system is typically characterized by the term"probability of failure(Pfailure)".As the intensity and spatial distribution of soil properties vary in different random field realizations,the failure mechanism and deformation field of a slope can vary as well.Not only can the location of the failure surfaces vary,but the mode of failure also changes.Such information is equally valuable to engineering practitioners.In this paper,two slope exam-ples that are modified from a real case study are presented.The first example pertains to the stability analysis of a multi-layer Su-slope while the second example deals with the serviceability analysis of a multi-layer c-φ slope.In addition,due to the large number of simulations needed to reveal the full picture of the failure mechanism,Convolutional Neural Networks(CNNs)that adopt a U-Net architecture is pro-posed to offer a soft computing strategy to facilitate the investigation.The spatial distribution of the fail-ure surfaces,the statistics of the sliding volume,and the statistics of the deformation field are presented.The results also show that the proposed deep-learning model is effective in predicting the failure mech-anism and deformation field of slopes in spatially variable soils;therefore encouraging probabilistic study of slopes in practical scenarios.
      原文链接:
    • NETL
    • NSTL
    • 万方数据
    • 维普

    Vanadium mineralization at Los Chihuidos sediment-hosted Cu-V deposit,Neuquén Basin,Argentina:An approach to vanadium ore forming processes

    Ana L.RainoldiDaniel BeaufortMarta B.FranchiniAdolfo Giusiano...
    231-252页
    查看更多>>摘要：Vanadium mineralization at Los Chihuidos deposit of the Neuquén Basin is linked to the development of a redox front system related to the inflow of hydrocarbons into the red sandstone of the Huincul Formation.Interaction of hydrocarbons with oxidized red beds and connate water generated redox reac-tions where hematite was dissolved due to iron reduction resulting in the discoloration of the red strata.At the contact between oxidized red sandstone and reduced white sandstone,precipitation of specific mineral phases resulted in the V ore with minor amounts of Cu.With the implementation of the redox interface,abundant V-montmorillonite and V-hematite precipitated at the more oxidizing conditions and Cu-V-corrensite-type at the more reducing conditions of the redox front.As the redox front advanced with fluids constantly migrating into the reservoir,more reducing conditions were stablished,promoting chloritization and minor illitization with V-Cu incorporation and continuous upgrading of the ore.Main ore mineralogy consists of clay minerals including V-bearing montmorillonite,Cu-V-corrensite-type,V-di-trioctahedral chlorite and Cu-tri-trioctahedral chlorite with minor V-illite-smectite mixed-layer minerals and associated secondary V-hematite.Chloritization over illitization was favored due to high amounts of Fe and Mg in detrital clasts and in connate fluids and by low K availability related to low amounts of detrital K-feldspar.The spatial transition of V and/or Cu bearing clay minerals observed through the mineralized redox front at Los Chihuidos deposit(kaolinite → smectite → illite/smectite →corrensite-type → di-trioctahedral-chlorite → tri-trioctahedral-chlorite)and the related variation of V-Cu concentrations in bulk rock are indicative of increasing pH and decreasing Eh of resident solutions from red to white sandstones during the hypogene mineralization process.Late influx of Cu-rich oxidized basinal brines precipitated main copper ore with Cu-sulfides in the white sandstone up to the contact with the redox front in contact with hydrocarbons.During uplift and exhumation,percolation of meteoric water promoted remobilization of V and Cu and the precipitation of oxidized V-Cu ore.
      原文链接:
    • NETL
    • NSTL
    • 万方数据
    • 维普

    Recharge and vulnerability assessment of groundwater resources in North west India:Insights from isotope-geospatial modelling approach

    Annadasankar RoySitangshu ChatterjeeUday Kumar SinhaAnil Kumar Jain...
    253-268页
    查看更多>>摘要：Recent studies indicate dwindling groundwater quantity and quality of the largest regional aquifer sys-tem in North West India,raising concern over freshwater availability to about 182 million population residing in this region.Widespread agricultural activities have resulted severe groundwater pollution in this area,demanding a systematic vulnerability assessment for proactive measures.Conventional vul-nerability assessment models encounter drawbacks due to subjectivity,complexity,data-prerequisites,and spatial-temporal constraints.This study incorporates isotopic information into a weighted-overlay framework to overcome the above-mentioned limitations and proposes a novel vulnerability assessment model.The isotope methodology provides crucial insights on groundwater recharge mechanisms(18O and 2H)and dynamics(3H)-often ignored in vulnerability assessment.Isotopic characterisation of precipitation helped in establishing Local Meteoric Water Line(LMWL)as well as inferring contrasting recharge mechanisms operating in different aquifers.Shallow aquifer(depth＜60 m)showed significant evaporative signature with evaporation loss accounting up to 18.04％based on Rayleigh distillation equa-tions.Inter-aquifer connections were apparent from Kernel Density Estimate(KDE)and isotope correla-tions.A weighted overlay isotope-geospatial model was developed combining 18O,3H,aquifer permeability,and water level data.The central and northern parts of study area fall under least(0.29％)and extremely(1.79％)vulnerable zones respectively,while majority of the study area fall under moderate(42.71％)and highly vulnerable zones(55.20％).Model validation was performed using ground-water NO3-concentration,which showed an overall accuracy up to 82％.Monte Carlo Simulation(MCS)was performed for sensitivity analysis and permeability was found to be the most sensitive input param-eter,followed by 3H,18O,and water level.Comparing the vulnerability map with Land Use Land Cover(LULC)and population density maps helped in precisely identifying the high-risk sites,warranting a prompt attention.The model developed in this study integrates isotopic information with vulnerability assessment and resulted in model output with good accuracy,scientific basis,and widespread relevance,which highlights its crucial role in formulating proactive water resource management plans,especially in less explored data-scarce locations.
      原文链接:
    • NETL
    • NSTL
    • 万方数据
    • 维普

    Major,trace element and Sr-Nd isotope evidence for a sublithospheric mantle source for the Umkondo large igneous province

    Ben HayesLewis D.AshwalKhulekani B.KhumaloLinda M.Iaccheri...
    269-291页
    查看更多>>摘要：The Mesoproterozoic(1.11 Ga)Umkondo large igneous province(LIP)in southern Africa and Antarctica was emplaced in＜5 Myr and is dominated by low-Ti tholeiitic doleritic-gabbroic sills.It is of particular interest because it is the least studied LIP in southern Africa with both sublithospheric and lithospheric mantle sources proposed and it coincides with the early assembly of Rodinia,so it has importance in understanding the nature of magmatism and tectonics in and around the Kalahari craton during the Mesoproterozoic.In this study,we compiled a large database of existing(～750)and new(～100)major and trace element data for the Umkondo province,as well as 42 new Sr-Nd isotopic measurements,to provide constraints on its magma sources and geochemical evolution.Major element compositional vari-ations in the low-Ti tholeiites are explained by low-pressure(1 kbar)three-phase fractional crystallisa-tion(olivine,clinopyroxene and plagioclase)of a parent magma with～10 wt.％MgO in oxidising conditions(QFM+1).Inverse models show that the low-Ti tholeiitic magmas were derived as residual melts after the crystallization of 12％-33％olivine from primary komatiitic-basaltic magmas(up to～20 wt.％MgO)in equilibrium with mantle olivine(Fo90).Low Sm/Yb and TiO2/Yb-Nb/Yb indicate that the primary magmas were derived by 2％-20％ shallow(40-50 km)partial melting of spinel lherzo-lite.High Sm/Yb is restricted to dyke swarms and may imply limited magma production from deeper(up to～70 km)garnet lherzolite-like sources.The low-Ti tholeiites of the Umkondo province are enriched in large ion lithophile elements(Rb-Sr-Cs-K)and depleted in high-field strength elements(Zr-Hf-Nb-Ta),indicating the involvement of crustal material and/or the subcontinental lithospheric mantle.This is supported by covariations in Th/Nb,Nb/Yb,Nb/La and Ce/Sm with generally negative△Nb.Sr-Nd isotopes lend support to the notion that the Umkondo magmas were derived from depleted and/or enriched sublithospheric mantle sources and subsequently contaminated by enriched lithospheric material during emplacement(initial(at 1.11 Ga)87Sr/86Sr between 0.704820 and 0.737464 and εNd between-8.9 and+5.3).The Vredefort sills are significant as they display the most depleted Sr-Nd iso-topic signatures(average initial 87Sr/86Sr of 0.705342 and average εNd of 0.4)and are the least contam-inated magma suite in the Umkondo province.Because of(i)the large volume of low-Ti magmas,(ii)evidence of a primary hot and MgO-rich(komatiitic)magma,and(iii)the short duration of magma-tism,we suggest that the Umkondo province was formed by plume-induced melting of the sublitho-spheric mantle beneath the Kalahari craton in an extensional setting.This contrasts with previous suggestions that the heat source developed in response to the"thermal insulation"of the mantle beneath a thickened Kalahari craton in the absence of a mantle plume.There is further evidence from the elevated Zn/Fe that the sublithospheric mantle was lithologically heterogeneous and consisted of mixed peridotite and pyroxenite domains.There is a general lack of ultramafic cumulates in the low-Ti magma suite that may imply there was deeper ponding and storage of the primary magmas that fractionated large quan-tities of ultramafic rocks.There is also a paucity of high-Ti rocks in the Umkondo province that may reflect limited direct melting of the lithospheric mantle or that they are simply not as well-preserved in this province compared to the Karoo province.The similar trace element and Sr-Nd isotopic composi-tions of the Umkondo sills in southern Africa with the Borgmassivet sills in Antarctica support the con-cept that the Kalahari craton and Grunehogna terrane were adjoined at 1.11 Ga.The timing of the Umkondo province indicates there was localised lithospheric extension and upwelling asthenospheric mantle during a time of dominantly compressional tectonics on Earth at the end of the'boring billion'.
      原文链接:
    • NETL
    • NSTL
    • 万方数据
    • 维普

    Extreme exposure of fluoride and arsenic contamination in shallow coastal aquifers of the Ganges delta,transboundary of the Indo-Bangladesh region

    Dipankar RuidasSubodh Chandra PalTanmoy BiswasAsish Saha...
    293-310页
    查看更多>>摘要：Globally,shallow aquifer groundwater(GW)has been severely affected in recent decades for both geo-genic and anthropogenic reasons.The hydro-geochemical characteristics of the GW change inconsistently with the addition of unwanted inorganic trace elements into the GW aquifer of the Indo-Bangladesh delta region(IBDR),such as arsenic(As)along with fluoride(F-)contamination.Contaminated GW can have a negative impact on drinking water supplies and agricultural output.GW pollution can have serious adverse effects on the environment and human health.Thus,the GW quality of this region is deteriorat-ing progressively,and human health threatening by various life-threatening disorders.Hence,the current study concentrated on the GW quality evaluation and prediction of possible health issues in the IBDR due to elevated contamination of As along with F-within GW aquifers by considering sixteen causative.Field survey-based statistical methods such as entropy quality index(EWQI)combined with health risk index(HRI)was implemented for evaluating the As and F-sensitivity with the help of correlation testing and principal component analysis.The study's outcome explains that a substantial portion of the IBDR has been vastly experiencing inferior GW quality,environmental issues,and health-related problems in dry and wet seasons,correspondingly for As and F-exposure.Piper diagram verified the suitability of water that almost 55％of GW across the study area's aquifers are unfit for drinking as well as cultivation of crops.Sensitivity analysis and the Monte Carlo simulation method were also applied to assess the con-taminant's concentration level and probable health risk appraisal.The present study concludes that the elevated exposure of As and F-pollution has to be monitored regularly and prevent unwanted GW con-tamination through implementing sustainable approaches and policies to fulfil the sustainable develop-ment goal 6(SDG-6)till 2030,ensuring the most basic human right of clean,safe,and hygienic water.
      原文链接:
    • NETL
    • NSTL
    • 万方数据
    • 维普

    Geophysical evidence of a large occurrence of mud volcanoes associated with gas plumbing system in the Ross Sea(Antarctica)

    Martina BusettiRiccardo GelettiDario CivileChiara Sauli...
    311-331页
    查看更多>>摘要：Seafloor and buried reliefs occur along continental margin of the Ross Sea(Antarctica).These features are several kilometres wide and tens of metres high,exhibiting cone or flat-top dome shapes.Previous stud-ies have proposed a volcanic or glacial origin for these formations,but these hypotheses do not account for all the available evidence.In this study,we use morpho-bathymetric data,intermediate resolution multichannel seismic and high resolution chirp profiles,as well as magnetic lines to investigate these clusters of mounds.By employing targeted processing techniques to enhance the geophysical characterization of the seafloor and buried reliefs,and to understand the underlying geological features,we propose that the reliefs are mud volca-noes.Some of these formations appear to be associated with a plumbing system,as indicated by acoustic anomalies linked to sediment containing gas.These formations are likely fed by clayey source rocks of Miocene age.Additionally,other reliefs might be the result of mud mobilisation caused by gravity insta-bility and fluid overpressure.
      原文链接:
    • NETL
    • NSTL
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    • 维普

    The formation and growth mechanisms of young back-arc spreading ridges from high-resolution bathymetry:The Marsili Seamount(Tyrrhenian Sea,Italy)

    Eugenio NicotraSalvatore PassaroGuido Ventura
    333-346页
    查看更多>>摘要：The formation and growth mechanisms of Mid-Ocean Ridges(MOR)are relatively well known,whereas those of back-arc spreading ridges are comparatively less known because geophysical,geochemical,and morphological data are scarce and of low density.Here we present a high-resolution bathymetry of the Marsili Seamount(MS;1 Ma-3 ka),which represents the inflated spreading ridge of the 2 Ma old Marsili back-arc basin associated to the subduction of the Ionian Sea below the Calabrian Arc and Tyrrhenian Sea.MS is 70 km long,30 km wide,and its height reaches about 3000 m from surrounding seafloor.Our new digital bathymetric model has a 5 m grid cell size resolution and covers the MS bathymetry from-1670 mbsl to the top at-491 mbsl.We conduct morphometric and morphological analyses of the bathymetry and recognize landforms due to volcanic,tectonic,hydrothermal and gravity processes.MS consists of volcanoes related to fissural and central-type activity,this latter located at the northern and southern tips of the main dike swarms.Dike swarms represent the surface expression of different ridge segments whose strikes are controlled by the larger scale back-arc spreading processes and by the local occurrence of an active hydrothermal field.This latter develops in a flat area between two partly overlapping ridge segments where historical volcanism and extensional processes concentrate.Such ridges represent the embryonic stage of the formation of transform-like faults.Central volcanoes,the northern of which is characterized by a caldera,form at the tips of MS because the decrease in width of the major volcanic fissures promotes vent localization associated with the formation of sill-like reservoirs from which central-type vents may develop.Gravity processes affecting the MS flanks are due to shallow seafloor sliding.Caldera collapses affecting the northernmost central-type polygenic volcano must be included in the evaluation of the hazard related to potential tsunami.Inward dipping faults characterize the MS eastern flank suggesting a moderately asymmetric growth of the spreading ridge possibly associated with the eastward opening of the Marsili back-arc.The Marsili back-arc spreading rate is similar to those of MOR slow spreading ridges.However,the MS morphology resembles that of fast spreading ridges.These two features also characterize more extended back-arc spreading ridges(e.g.the Mariana in Western Pacific).We conclude that,independently from the spatial scale,the increase in the ridge accretion rate is related to the progressive addition of a subduction-related component to a pure spreading mantle source.
      原文链接:
    • NETL
    • NSTL
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    • 维普