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地球化学学报（英文版）
中国科学院地球化学研究所
地球化学学报（英文版）

中国科学院地球化学研究所

涂光炽

季刊

2096-0956

hzl@mail.gyig.ac.cn cjgc@vip.skleg.cn

0851-5891358

550002

贵州省贵阳市观水路46号地球化学研究所

地球化学学报（英文版）/Journal Acta GeochimicaCSCD北大核心EI
查看更多>>本刊由中科院地化所和中矿物岩石地球化学学会主办，科学出版社出版，荷兰VSP出版公司向世界各国发行，中外颇具影响的地学刊物，多次获全国及中科院优秀期刊奖，并被国外多家检索系统收录。
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    Experimental constraints on the formation of oxychlorine species by UV irradiation and mechanical pulverization on the lunar surface

    Jiamei LiYu-Yan Sara ZhaoHe CuiShuai-Yi Qu...
    625-637页
    查看更多>>摘要：Perchlorate and chlorate are present in various extraterrestrial celestial bodies throughout the solar system,such as Mars,the moon,and asteroids.To date,the origin mechanisms of perchlorate and chlorate on the Martian sur-face have been well-established;however,relatively little attention has been cast to airless bodies.Here,we experi-mentally investigated the potential oxidation mechanisms of chloride to chlorate and perchlorate,such as ultraviolet irradiation under H2O-and O2-free conditions and mechan-ical pulverization processes.Individual minerals,olivine,pyroxene,ilmenite,magnetite,TiO2 and anhydrous ferric sulfate,and lunar regolith simulants(low Ti,CLRS-1;high-Ti,CLRS-2)and their metallic iron(Fe0)bearing counter-parts were examined.We found that pulverization of dry matrix material-halite mixtures,even in the presence of O2,does not necessarily lead to perchlorate and chlorate forma-tion without involving water.Under photocatalytic and H2O-and O2-free conditions,olivine and pyroxene can produce oxychlorine(ClOx-)species,although the yields were orders of magnitude lower than those under Martian-relevant con-ditions.Nanophase-Fe0 particles in the lunar regolith and the common photocatalyst TiO2 can facilitate the C1Ox-forma-tion,but their yields were lower than those with olivine.The oxides ilmenite and magnetite did not efficiently contribute to ClOx-production.Our results highlight the critical role of H2O in the oxidation chloride to chlorate and perchlorate,and provide essential insights into the environmental influ-ence on the formation of oxychlorine species on different celestial bodies.
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    Features of sampling stream sediments of large river valleys under cryolithogenesis conditions in the Balygychan-Sugoy trough,North-East of Russia

    Artem S.MakshakovRaisa G.Kravtsova
    638-660页
    查看更多>>摘要：Comprehensive research has been implemented to raise the efficiency of the geochemical survey of stream sediments(SSs)that formed under the cryolithogenesis con-ditions.The authors analysed the composition,structure and specific features of the formation of exogenous anomalous geochemical fields(AGFs)identified through SSs of large river valleys of Ⅳ order.In our case,these were the valleys of Maly Ken,Ken and Tap Rivers.These rivers are located in the central and southern parts of the Balygychan-Sugoy trough enclosed in the Magadan region,North-East of Rus-sia.The authors proposed a new technique to sample loose alluvium of SSs in the large river valleys along the profiles.The profiles were located across the valleys.The AGFs of Au,Ag,Pb,Zn,Sn,Bi,Mo and W were studied.Correla-tions between elements have been established.These ele-ments are the main indicator elements of Au-Ag,Ag-Pb,Sn-Ag,Mo-W and Sn-W mineralization occurring on the sites under study.The results obtained were compared with the results of geochemical surveys of SSs.It is concluded that the AGFs recognized along the profiles reflect the com-position and structure of eroded and drained ore zones,uncover completely and precisely the pattern of element distribution in loose sediments of large water flows.The alluvium fraction＜0.25 mm seems to be most significant in a practical sense,as it concentrated numerous ore elements.Sampling of this fraction in the river valleys of Ⅳ order does not cause any difficulty,for this kind of material is plentiful.The developed technique of alluvium sampling within large river valleys is efficient in searching for diverse mineraliza-tion at all stages of prognostic prospecting.It is applicable for geochemical survey of SSs performed at different scales both in the North-East of Russia,as well as other regions with similar climatic conditions,where the SSs are formed under the cryolithogenesis conditions.
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    Rebuilding the theory of isotope fractionation for evaporation of silicate melts under vacuum condition

    Jie WangYun Liu
    661-676页
    查看更多>>摘要：Isotope effects are pivotal in understanding sili-cate melt evaporation and planetary accretion processes.Based on the Hertz-Knudsen equation,the current theory often fails to predict observed isotope fractionations of labo-ratory experiments due to its oversimplified assumptions.Here,we point out that the Hertz-Knudsen-equation-based theory is incomplete for silicate melt evaporation cases and can only be used for situations where the vaporized spe-cies is identical to the one in the melt.We propose a new model designed for silicate melt evaporation under vacuum.Our model considers multiple steps including mass trans-fer,chemical reaction,and nucleation.Our derivations reveal a kinetic isotopic fractionation factor(KIFF or α)αour model=[m(1species)/m(2species)]0.5,where m(species)is the mass of the reactant of reaction/nucleation-limiting step or species of diffusion-limiting step and superscript 1 and 2 represent light and heavy isotopes,respectively.This model can effectively reproduce most reported KIFFs of laboratory experiments for various elements,i.e.,Mg,Si,K,Rb,Fe,Ca,and Ti.And,the KIFF-mixing model referring that an over-all rate of evaporation can be determined by two steps jointly can account for the effects of low PH2 pressure,composition,and temperature.In addition,we find that chemical reac-tions,diffusion,and nucleation can control the overall rate of evaporation of silicate melts by using the fitting slope in ln(-lnf)versus ln(t).Notably,our model allows for the theo-retical calculations of parameters like activation energy(Ea),providing a novel approach to studying compositional and environmental effects on evaporation processes,and shed-ding light on the formation and evolution of the proto-solar and Earth-Moon systems.
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    Bulk geochemistry,Rb-Sr,Sm-Nd,and stable O-H isotope systematics of the Metzimevin high-grade iron ore deposit,Mbalam iron ore district,southern Cameroon

    Samndong Cyril TufoinCheo Emmanuel SuhTabod Charles TabodGeorge Lemewihbwen Ngiamte...
    677-706页
    查看更多>>摘要：Bulk geochemistry,Sr,Nd,and O-H isotope systematics are reported for the first time on banded iron formation(BIF)-hosted high-grade iron ore at the north-western segment of Congo Craton(CC).Located in Mbalam iron ore district,Southern Cameroon,Metzimevin iron ore deposit is a hematite-magnetite BIF system,dominated by SiO2+Fe2O3(97.1 to 99.84 wt％),with low concentrations of clastic elements e.g.,Al2O3,TiO2,and HFSE,depicting a nearly pure chemical precipitate.The REE+Y signature of the iron deposit displays strong positive Eu anomaly,strong negative Ce anomaly,and chondritic to superchondritic Y/Ho ratios,suggestive of formation by mixed seawater-high temperature hydrothermal fluids in oxidising environment.The 87Sr/86Sr ratios of the BIF are higher than the maximum 87Sr/86Sr evolution curves for all Archean reservoirs(bulk silicate earth,Archean crust and Archean seawater),indicat-ing involvement of continentally-derived components during BIF formation and alteration.The εNd(t)(+2.26 to+3.77)and Nd model age indicate that chemical constituents for the BIF were derived from undifferentiated crustal source,between 3.002 and 2.88 Ga.The variable and diverse O and H isotope data(-1.9‰ to 17.3‰ and-57‰ to 136‰respectively)indicate that the Metzimevin iron ore formed initially from magmatic plumes and later enriched by mag-matic-metamorphic-modified meteoric fluids.Mass balance calculations indicate mineralisation by combined leaching and precipitation,with an average iron enrichment factor of＞2.67 and SiO2 depletion factor of＞0.99.This is associ-ated with an overall volume reduction of 28.27％,reflecting net leaching and volume collapse of the BIF protholith.
      原文链接:
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    Metamorphic P-T conditions and ages of garnet-biotite schists in the Dahongshan Group from the southwestern Yangtze Block

    Jun-xiao MaGuang-shu YangYong-feng YanXiao-Fei Xu...
    707-718页
    查看更多>>摘要：The Dahongshan Group,situated at the south-western margin of the Yangtze Block,represents a geological unit characterized by relatively high-grade metamorphism in the region.This paper investigates the garnet-biotite schist from the Laochanghe Formation of the Dahongshan Group,employing an integrated approach that includes petrological analysis,phase equilibrium modeling,and zircon U-Pb dat-ing.The schist is mainly composed of garnet,biotite,plagio-clase,quartz,rutile,and ilmenite.Phase equilibrium mod-eling revealed the peak metamorphic conditions of 8-9 kbar and 635-675 ℃.By further integrating the prograde meta-morphic profile of garnet and geothermobarometric results,a clockwise P-T metamorphic evolution path is constructed,which includes an increase in temperature and pressure dur-ing the prograde stage.LA-ICP-MS zircon U-Pb dating and zircon Ti thermometry constrains the post-peak meta-morphic age of 831.2±7.2 Ma.Integrated with previously reported results,it is revealed that the southwestern margin of the Yangtze Block experienced a large-scale regional metamorphism during the Neoproterozoic(890-750 Ma),which is related to the collisional orogenic process.This may be associated with the late-stage assembly of the Rodinia supercontinent or with local compression and subduction processes during the breakup of the Rodinia supercontinent.
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    Hydrogeochemical and isotopic assessment of the origin of NO3-and N-NH3 contents in the aquifer located in a closed lacustrine volcano-sedimentary basin in the metropolitan area of Mexico City

    José Iván Morales-ArredondoMaría Aurora Armienta HernándezJoel Edmundo Ortega-GutiérrezElisa Cuellar Ramirez...
    719-736页
    查看更多>>摘要：To explain the presence and spatial distribution of NO3-and N-NH3 in the Aquifer of the Metropolitan Area of Mexico City(AMAMC),a hydrogeochemical and iso-topic analysis using 13CDIC(as well as the stable isotopes 18O and 2H)in groundwater was conducted.This aquifer is located in an old closed lacustrine volcano-sedimentary basin;some wells hosted in the semi-confined zone contain high N-NH3 concentrations,while others present NO3-contents in the recharge zones(hosted in an oxidizing envi-ronment).In this study,a change in the isotopic signature(primarily in 18O and 2H)was observed from the recharge zones to the basin center in some of the wells with high NO3-concentrations,this behavior can be attributed to evaporation during the incorporation of recently infiltrated water.In addition,the results for 13C(along with 2H)in wells with the highest N-NH3 concentrations exhibited an atypi-cally broad range of values.Results indicated the occurrence of hydrogeochemical and/or biochemical processes in the aquifer(in an oxidizing or reducing environment),such as organic degradation,bacterial decomposition(primarily in the ancient Lake Texcoco and which acts as a natural sink for carbon,nitrogen,sulfur,and phosphorus),besides rock weathering and dissolution,which may be responsible for a very marked isotopic modification of the 13C(and,to a lesser extent,2H).Methanotrophic bacterial activity and methano-genic activity may be related to N-NH3 removal processes by oxidation and residual water incorporation respectively,whereas the increase in the NO3-content in some wells is due to the recent contribution of poor-quality water due to contamination.
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    Unveiling Nb-Ta mineralization processes:Insight from quartz textural and chemical characteristics in the Songshugang deposit,Jiangxi Province,South China

    Hengsong ZhangShaohao ZouXilian ChenDeru Xu...
    737-753页
    查看更多>>摘要：The Songshugang deposit is a large Ta-Nb deposit in South China,with Ta-Nb mineralization associ-ated genetically with the granite and pegmatite.A diversity of quartz from topaz-albite granite,quartz-mica pegmatite,quartz-feldspar pegmatite,and quartz-fluorite pegmatite at Songshugang was studied by CL and LA-ICP-MS in order to constrain enrichment mechanisms of Nb and Ta and to find geochemical indicators of quartz for rare metal deposits.Cathodoluminescence image illuminates a canvas of com-plexity,the quartz from topaz-albite granite,quartz-mica pegmatite,quartz-feldspar pegmatite,and quartz-fluorite pegmatite,exhibits numerous dark CL streaks,patches,and a series of healed fractures.These textures suggest that the rocks were fractured because of deep crustal pressure,and underwent later hydrothermal metasomatism and quartz filling.The quartz from quartz-fluorite pegmatite present limited patches or fractures but distinct growth bands,indi-cating that the melt fluid composition during the formation of quartz at this stage varies greatly and is less affected by mechanical fragmentation.The LA-ICP-MS analysis of quartz shows that there is a positive correlation between Al and Li in the quartz from topaz-albite granite,quartz-mica pegmatite,quartz-feldspar pegmatite,to quartz-fluorite pegmatite,indicating that Al mainly enters the quartz lat-tice through charge compensation substitution mechanism with Li.However,our data deviate from the theoretical Li:Al mass ratio of～1:3.89 in quartz,indicating that there may be competition between H+and Li in a water-rich magmatic environment.The quartz from topaz-albite gran-ite is enriched in K and Na elements,and the quartz from quartz-fluorite pegmatite is enriched in fluorite with a low Ca content in quartz,further elucidating that these rocks were subjected to hydrothermal metasomatism.From topaz-albitite granite to quartz-fluorite pegmatite,Al,Li and Ge content and Al/Ti,Ge/Ti,Sb/Ti ratios in quartz gradually increased,but Ti content gradually decreased,reflecting the high evolution of magma,which can enrich rare metal ele-ments.Based on the characteristics of quartz CL textures and trace elements in topaz-albite granite,quartz-mica pegmatite,quartz-feldspar pegmatite,and quartz-fluorite pegmatite,combined with the albitization and K-feldspa-thization of rocks,it is suggested that the Nb-Ta minerali-zation in Songshugang may be influenced by the combined action of magmatic crystallization differentiation and fluid metasomatism.By comparing the quartz in the Songshugang pluton with the quartz in the granite type and pegmatite type rare metal deposits recognized in the world,the Songshu-gang pegmatite share similarities with the LCT-type peg-matite.Combined with previous studies,the Ge/Ti＞0.1 and Ti＜10 ppm,as well as Al,Li,Ge,Sb,K,Na contents and Al/Ti,Sb/Ti ratios in quartz have the potential to be a power-ful exploration marker for identifying granite-like pegmatitic Nb-Ta deposits in other places.
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    Melting geodynamics reveals a subduction origin for the Purang ophiolite,Tibet,China

    Tao RuanZhong-Jie BaiWei-Guang ZhuShi-Ji Zheng...
    754-773页
    查看更多>>摘要：The debate regarding whether the Yarlung-Zangbo ophiolite(YZO)on the south of the Qinghai-Tibet Plateau,formed in a mid-ocean ridge(MOR)or a supra-sub-duction zone(SSZ)setting has remained unresolved.Here we present petrological,mineralogical,and geochemical data associated with modeling melting geodynamics of the mantle peridotites from the Purang ophiolite in the west-ern segment of the Yarlung-Zangbo Suture Zone(YZSZ)to explore its tectonic environment.The Purang lherzolites are characterized by the protogranular texture and have abyssal-peridotite-like mineral compositions,including low Cr#(20-30)and TiO2 contents(＜0.1wt％)in spinel,high Al2O3(2.9wt％-4.4wt％)and CaO(1.9wt％-3.7wt％)contents in orthopyroxene and LREE-depletion in clinopy-roxene.Compositions of these lherzolites can be modeled by～11％dynamic melting of the DMM source with a small fraction of melt(-0.5％)entrapped within the source,a similar melting process to typical abyssal peridotites.The Purang harzburgites are characterized by the porphyroclastic texture and exhibit highly refractory mineral compositions such as high spinel Cr#(40-68),low orthopyroxene Al2O3(＜2.2wt％)and CaO(＜1.1wt％)contents.Clinopyroxenes in these harzburgites are enriched in Sr(up to 6.0 ppm)and LREE[(Ce)N=0.02-0.4],but depleted in Ti(200 ppm,on average)and HREE[(Yb)N＜2].Importantly,the more depleted samples tend to have higher clinopyroxene Sr and LREE contents.These observations indicate an open-system hydrous melting with a continuous influx of slab fluid at a subduction zone.The modeled results show that these har-zburgites could be formed by 19％-23％hydrous melting with the supply rate of slab fluid at 0.1％-1％.The lower clinopyroxene V/Sc ratios in harzburgites than those in lher-zolites suggest a high oxidation stage of the melting system of harzburgites,which is consistent with a hydrous melting environment for these harzburgites.It is therefore concluded that the Purang ophiolite has experienced a transformation of tectonic setting from MOR to SSZ.
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    Formation and growth of nanophase iron particles on the surface of Mercury revealed by experimental study

    Ronghua PangYang LiChen LiPengfei Zhang...
    774-784页
    查看更多>>摘要：Space weathering is a primary factor in altering the composition and spectral characteristics of surface mate-rials on airless planets.However,current research on space weathering focuses mainly on the Moon and certain types of asteroids.In particular,the impacts of meteoroids and micro-meteoroids,radiation from solar wind/solar flares/cosmic rays,and thermal fatigue due to temperature variations are being studied.Space weathering produces various transfor-mation products such as melted glass,amorphous layers,iron particles,vesicles,and solar wind water.These in turn lead to soil maturation,changes in visible and near-infrared reflectance spectra(weakening of characteristic absorption peaks,decreased reflectance,increased near-infrared slope),and alterations in magnetism(related to small iron particles),collectively termed the"lunar model"of space weather-ing transformation.Compared to the Moon and asteroids,Mercury has unique spatial environmental characteristics,including more intense meteoroid impacts and solar thermal radiation,as well as a weaker particle radiation environment due to the global distribution of its magnetic field.There-fore,the lunar model of space weathering may not apply to Mercury.Previous studies have extensively explored the effects of micrometeoroid impacts.Hence,this work focuses on the effects of solar-wind particle radiation in global magnetic-field distribution and on the weathering transfor-mation of surface materials on Mercury under prolonged intense solar irradiation.Through the utilization of high-valence state,heavy ion implantation,and vacuum heating simulation experiments,this paper primarily investigates the weathering transformation characteristics of the major mineral components such as anorthite,pyroxene,and olivine on Mercury's surface and compares them to the weathering transformation model of the Moon.The experimental results indicate that ion implantation at room temperature is insuf-ficient to generate np-Fe0 directly but can facilitate its for-mation,while prolonged exposure to solar thermal radiation on Mercury's surface can lead directly to the formation of np-Fe0.Therefore,intense solar thermal radiation is a crucial component of the unique space weathering transformation process on Mercury's surface.
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    Nitrogen isotope stratigraphy of the Early Cambrian successions in the Tarim Basin:Spatial variability of nitrogen cycling and its implication for paleo-oceanic redox conditions

    Bi ZhuXuefeng LiLu GeYongquan Chen...
    785-801页
    查看更多>>摘要：The Early Cambrian represents a critical time period characterized by extraordinary biological innovations and dynamic redox conditions in seawaters.Nitrogen iso-topic signatures of ancient sediments have the potential to elucidate the evolutionary path of marine redox states and the biogeochemical nitrogen cycle within the water column of the Early Cambrian ocean.While existing research on this topic has predominantly focused on South China,the explo-ration of other continental margins has been limited,leaving contradictory hypotheses untested.In this study,paired δ15N and δ13Corg analyses were performed on the Lower Cam-brian successions from the Shiairike section(inner ramp)and Well Tadong 2(deep shelf/basin)in the northwestern and eastern Tarim Basin,respectively.Our data from the Shiairike section reveal a discernible shift in the operation of different nitrogen cycles for the black chert-shale unit,also referred to as the black rock series in Chinese literature,of the Yurtus Formation(Fortunian stage to lower Stage 3).Oscillating δ15N values for its lower part are suggestive of alternating anaerobic assimilation of NH4+and denitrifica-tion/anammox.This is likely attributed to a shallow,unsta-ble chemocline consistent with the upwelling and incur-sion of deep,anoxic waters during a major transgression.In contrast,aerobic nitrogen cycling,indicated by positiveδ15N values of＞2‰,dominated the upper part alongside a reduction in upwelling intensity.On the other hand,theδ15N signatures of Xishanbulake and Xidashan Formations of Well Tadong 2,which encompass a time interval from the Cambrian Fortunian Age to Age 4,are indicative of N2 fixation by diazotrophs as the major nitrogen source.The two studied intervals,although not time-equivalent,exhibit separated states of nitrogen cycling at least during the depo-sition of the Yurtus black rock series.The spatially different nitrogen cycling of the studied sections is compatible with a redox-stratified ocean during the deposition of the Yur-tus black rock series.The build-up of a NO3-reservoir and aerobic nitrogen cycling in seawater was largely restricted to near-shore settings whereas anaerobic nitrogen cycling dominated by N2 fixation served as the main nitrogen uptake pathway in off-shore settings.
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