元素迁移的分维结构、级序路径及共轭地球化学异常存在的理论依据

微量元素在矿源岩（层）中迁移遵循严格的级序路径，并且存在两种迁移倾向。迁移的结果图象是一分维结构。两种共轭地球化学异常出现的有利环境是温度高度反差地区和大断裂系及其附近。     

甘肃南梁—华池地区三叠系延长组长三段储层物源探讨

利用稀土元素和微量元素,分析鄂尔多斯盆地南部南梁—华池地区上三叠统延长组长三段储层母岩类型和物源方向,研究表明盆地南部南梁—华池地区延长组砂岩和泥岩的稀土元素地球化学特征、REE分配模式及微量元素蜘蛛图解相同,与盆地东北缘太古代、元古代变质岩相似,但不相同;与盆地西南缘的水河地区延长组相似且不同,说明研究区与盆地东北缘和西南缘均有较好的亲缘关系。结合轻、重矿物组合和盆地周缘古陆岩矿特征,证实了研究区物源为两个主物源的混合区。     

鄂尔多斯盆地中部上三叠统延长组物源方向分析与三角洲沉积体系

首次利用稀土元素和微量化学元素,分析鄂尔多斯盆地中部上三叠统延长组母岩类型和物源方向。研究表明盆地中部延长组砂岩和泥岩的稀土元素地球化学特征、REE分配模式及微量化学元素蜘蛛图解相同,表现为轻稀土富集,重稀土亏损,铕、铈元素亏损;REE分配模式均呈“右倾斜、LREE富集、HREE平坦”型;微量化学元素蜘蛛图解具“四峰三谷一平台”型,曲线呈阶梯状分布;砂岩和泥岩的地球化学特征、REE分配模式及微量化学元素蜘蛛图解与盆地东北缘的太古代、元古代变质岩相一致,而与火成岩的重稀土富集、轻稀土亏损、“V”字型REE分配模式和“三峰两谷”型、曲线呈“W”字型分布的蜘蛛图解的特征有显著的差别。说明延长组母岩是盆地东北缘的太古代、元古代变质岩,主要物源方向为北东向。依据物源方向、沉积环境、砂岩岩石学特征、砂岩稀土元素和微量化学元素的地球化学特征,将鄂尔多斯盆地中部上三叠统延长组沉积划分为两大三角洲沉积体系,即北东向的安塞三角洲沉积体系、志靖三角洲沉积体系、安边三角洲沉积体系和北西向的盐定三角洲沉积体系。在三角洲沉积体系划分的基础上,详细阐述了不同三角洲沉积体系的岩石学特征、稀土元素和微量化学元素的地球化学特征及延长组长6-长2期三角洲沉积体系的演化过程。     

Trace Element Data on Geostandards by Mass Spectrometric Isotope Dilution Technique

The stable isotope dilution technique using solid source mass spectrometry is described. The method is capable of high sensitivity, and can yield accurate determinations of elements in trace quantities. The method enjoys freedom from interference effects and systematic errors, and because of its high absolute accuracy it is ideal for the determination of trace elements in geochemical reference samples. A compilation of isotope dilution analyses on ten trace elements in a number of international standard rock samples carried out at the Western Australian Institute of Technology is presented.     

油源对比微量元素地球化学研究进展

原油中的微量元素地球化学组成可以应用于油源对比,指标可以归纳为3类:①所含元素的聚类分析及其所反映的元素分布总体特征;②不同族、不同类型元素的组成,特别是过渡族金属元素;③稀土元素。但对于哪些微量元素可以应用于油源对比,哪些具有普遍意义,在不同地区是否具有适用性,影响其油源对比应用有效性的因素有哪些,主控因素是什么,仍然不甚清楚,由此导致很多方面的认识还不甚成熟,成功应用的实例相对常规的有机地球化学研究不多。原油中的微量元素主要来源于外部成油和运聚环境,在原油生成和运聚过程中,通过烃—水—岩之间的复杂有机—无机相互作用以金属卟啉螯合物、有机络合物或吸附态的形式聚集于原油中,并且沥青质是原油中微量元素的主要载体,元素组成在此过程中发生分异。此外,原油在自身形成与演化过程中也会发生元素组成的分异,影响因素包括油源母质类型、成熟度、次生变化等。在这些过程中,元素地球化学性质的不同会使原油中的元素组成出现差异,基本不发生/少发生变化的元素即可能是好的油源对比指标,这是应用微量元素进行油源对比的原理和理论基础。     

Canonical correlation analysis as a tool in the provenance study of overbank sediments from the small mountainous watersheds

Canonical correlation analysis (CCA) is used in this study in order to trace the lineage of overbank sediment from the initial erosion of the parent rocks down to deposition of detrital material in alluvium of the small mountainous watersheds of the Žumberak area, Croatia. It helps to elucidate relations between the hierarchically structured systems (rocks, minerals, elements) represented by the ensembles of lithological, mineralogical and geochemical variables. Taking their place in the vertical order of hierarchical complexity, geochemistry and mineralogy of the recent material are considered dependent variable regarding the related watershed lithology, with geochemical variables (major and trace elements) last in the chain. Three canonical models are built and cross-compared in order to unravel the between-level relationships and infer the basic patterns of mineral and geochemical flux from the source rocks to basin. From these, the two hierarchical (provenance) chains epitomized in recombination of the first two canonical functions have been derived highlighting complementary provenances, weathering styles, and dispersion avenues in alluvial sedimentation of the study area. The first clearly separates carbonate from siliciclastic sedimentary source while the second illuminates the origin of phyllosilicate and ferric oxyhydroxide phases with associated suite of elements in absence of clear carbonate signal.     

花岗岩锆石中的微量元素的配分特征

花岗岩锆石中的微量元素(铪、铀、钇、钍、磷)的电子探针分析表明,这些元素在花岗岩锆石中皆以类质同象形式赋存,其中最小离子半径的铪以无序固溶体形式与锆完全相溶,而钇和磷在较低温度的条件下常常呈磷钇矿与锆不完全相溶;它们在花岗岩锆石中的地球化学行为是随着结晶环境的物理化学条件的变化而分异的,因此,对它们的分析研究可以揭示花岗岩的成因特征。     

贵州西部龙场地区水系沉积物Pt、Pd异常源地球化学示踪的初步研究

以贵州龙场地区水系沉积物中的Pt、Pd异常为研究对象，选择相容性接近的7对元素比值Cr/Ni、Nb/Ta、Pd/Pt、Rb/Cs、Sr/Ba、Th/U和Zr/Hf以及CaO、TFe2O3作为地球化学示踪指标，对龙场地区水系沉积物的物质来源组成进行了示踪探讨。结果表明：（1）龙场地区水系沉积物的物质来源主要为玄武岩风化产物，其中的高含量Pt、Pd是对玄武岩层中Pt、Pd高背景的继承和进一步浓缩富集；（2）根据对分布在灰岩区的水系沉积物物质来源的地球化学示踪研究，推测部分样品的物质来源应为玄武岩和灰岩风化产物；（3）根据对红岩村的水系沉积物物质来源的示踪研究，推断有热液活动和基性－超基性侵入体的物质成分，预测该地区具有一定的找矿远景。     

Fluid source-based modeling of melt initiation within the subduction zone mantle wedge: Implications for geochemical trends in arc lavas

The GyPSM-S (Geodynamic and Petrological Synthesis Model for Subduction) scheme couples a petrological model with a 2-D thermal and variable viscosity flow model to describe and compare fundamental processes occurring within the subduction mantle wedge, including the development of a low-viscosity channel (LVC) (Hebert et al., 2009, Earth and Planetary Science Letters, v. 278, p. 243–256). Here we supplement the basic coupled model result with more sophisticated treatments of trace element partitioning in the fluid phase and melt transport regimes. We investigate the influences of slab fluid source lithology and fluid transport mechanisms on melt geochemistry, the implications of mantle source depletion related to fluid fluxing, and potential melt migration processes. This study describes two model cases that can be compared to geochemical datasets for the Izu–Bonin intra-oceanic subduction system and the Central Costa Rican part of the Central American arc. We find that there is a progression of geochemical characteristics described in studies of cross-arc and along-arc lavas that can be approximated assuming (i) limited fluid–rock interaction within the mantle wedge and (ii) that melt migration preserves the spatial distinction among melts initiated in different areas of the wedge. Specifically, volcanic front lavas have significant contributions from shallower slab fluid sources, and rear-arc lavas have significant contributions from deeper slab fluid sources. Evidence for limited fluid–rock interaction could imply either a rapid fluid transport mechanism or a fluid-dominated trace element budget within the LVC. Although we do not include a back-arc in these models, interpretations of the results lead to several potential mechanisms to explain hydrous inputs to back-arc source regions.     

Geochemistry of sedimentary rocks and its relation to crustal evolution and mineralization in Southwest Yangtze Massif, China

Through a systematic study on trace elements and REE geochemistry of mudstone deposited in the basin and lower slope environments during Upper Proterozoic to Triassic in the Southwest Yangtze Mssif,three geochemical abnormal horizons of which the geochemical characteristics are quite different from those of other horizons have been established for the first time.They are the Lower Cambrian,the Upper Devonian and the Upper Permian,As compared with the crustal evolution in this area.these three geochemical abnormal horizons are corresponding to the pulling-apart periods of geotectonic cycles.which illustrates that uncommon depositional sources puring into the basin from the earth‘s interior may be one of the most important causes to originate the geochemical anomalies in these lhrizons.Thus it can be realized that the geochemistry of post-Archean sedimentary rocks has a great deal to do with the crustal evolution and it can be used as a tracer to analyze the crustal evolution.The elements in this area are mainly concentrated in these geochemical abnormal horizons,and the degree of enrichment and deficiency of trace elements in other horizons is very limited.A series of research on mineralization indicates that the main strata-bound ore deposits discovered in the Southwest Yangtze Massif occur in the Cambrian,Devonian and Permian-Trassic strata.The results of isotope tracer resarch have also proved that most of the metallogenic elements in these ore deposits came from the host strata.which illustrates that the geochemical abnormal horizons may have made great contributions to these ore-forming processes.Thus it can be concluded that it is only the particular horizons corresponding to the particular periode of earth‘s evolution that can they be the significant source beds because only in these uncommon horizons there can be highly enriched metallogeinc elements.which may be one of the most important reasons for explaining the time-bound nature of mineralization.     

临兴地区煤系泥岩微量元素特征及其地质意义

为了研究鄂尔多斯盆地东缘临兴地区煤系泥岩微量元素特征及其对沉积、物源及古气候方面的指示意义,采用ICP-MS和ICP-AES对18个泥岩样品做微量元素分析。结果表明:微量元素中Li、Sc、Nb和Th等相对富集,而Sr、Rb、Ba和Cs等相对亏损,Be、Co、Zn和Mo等元素和地壳黏土岩中元素的平均含量相当;聚类距离选择为25和11时,微量元素的"Q"型聚类结果与沉积相划分结果吻合;Th/Sc、Th/U-Th、K₂O-Rb以及多元素物源判别图等表明,研究区物源来自上地壳,以长英质物源和再旋回沉积物为主,有少量中基性物质的加入,且含砂率变化和重矿物组合的分布特征表明物源来自于临兴地区北部;利用泥岩Sr/Cu值及Sr、Ti和P等特征元素的含量变化推测,临兴地区从晚石炭世到早二叠世气候以湿润为主,且向干热转变。      

Trace element hydrochemical assessment of the Calabar Coastal Plain Aquifer,southeastern Nigeria using statistical methods

Groundwater samples from 33 locations within the Coastal Plain Sands aquifer of Calabar (Nigeria) were collected and analysed for 43 trace elements by means of ICP-MS. The aim of this study is to determine the natural background levels of trace elements as a guide for future pollution monitoring of the aquifer. Secondly, this article focuses on the pollution vulnerability of the coastal plain sand aquifer. Statistical methods have been used to determine the source(s) of these elements. Results show that the area is characterised by four types of groundwater, including: Na-HCO₃, Na-HCO₃-Cl, Na-Cl and Ca-Na-HCO₃-Cl. Secondly, all the elements considered are below normal averages. In addition, the Spearman correlation shows significant correlation especially among the lanthanide group of elements (p<0.0001). Factors analyses indicate mainly two groups of elements. The first group being due to the natural geochemical process (weathering/leaching of the basement lithology; characteristics of the elements) and the second is due to tidal flushing of the estuary. This indicates that the source of the trace element in the aquifer is due to a geogenic process and not anthropogenic. Thus, the present data set will serve as a reference source for pollution monitoring in the area.     

Variations in melting dynamics and mantle compositions along the Eastern Volcanic Zone of the Gakkel Ridge: insights from olivine-hosted melt inclusions

We present major element, trace element, and volatile concentrations from 66 naturally glassy, olivine-hosted melt inclusions erupted along the Eastern Volcanic Zone (EVZ) of the ultraslow-spreading Gakkel Ridge. Melt inclusion compositions suggest that there are systematic variations in the mantle source composition and melting dynamics from the eastern to the western end of the EVZ. This includes increasing water contents and highly incompatible trace element concentrations (e.g., Ba and Nb) and decreasing light and middle rare earth element concentrations. Ratios of light to heavy rare earth elements in the easternmost melt inclusions are relatively homogeneous, but become more variable to the west. To determine the source of the geochemical variability observed along the EVZ, we model trace elements associated with mantle melting in one- and two-component systems. We consider four possible mantle sources and a range of melting regime shapes, from a full melting triangle to a vertical melting column centered beneath the ridge axes. The observed geochemical variations can be explained by melting of a heterogeneous mantle source composed of depleted MORB mantle plus a metasomatized mantle, where the proportion of the metasomatized component and the extent of melting increases toward the west. Lower rare earth element concentrations and trace element ratios in the westernmost sites also suggest inefficient melt focusing from the outer edges of the melting region. Our results indicate that despite variations in the size of the melting zone and the composition of the mantle source along the ridge axis, the region over which the melts are pooled back to the ridge axis is relatively constant (~10–20 km), suggesting that there is a limit to the distance melts can be transported from off-axis in ultraslow-spreading environments.     

Simple models for dynamic melting in an upwelling heterogeneous mantle column: Analytical solutions

Several lines of evidence suggest that the melt generation and segregation regions of the mantle are heterogeneous, consisting of chemically and lithologically distinct domains of variable size and dimension. Partial melting of such heterogeneous mantle source regions gives rise to a diverse range of basaltic magmas. In order to better assess the role of source heterogeneity during mantle melting, we have undertaken a theoretical study of trace element distribution and fractionation during concurrent melting and melt migration in an upwelling, chemically heterogeneous, two-porosity double lithology melting column. Analytical solutions for the abundance of a trace element in the matrix and channel were obtained under the assumptions that the porosity, melt and solid velocities, and solid-melt partition coefficients are constant and uniform. For simplicity, we neglected diffusion and dispersion in the melt. Chemical source heterogeneities of arbitrary size and shape were integrated into the simple melting models by allowing trace element abundance in the source region to vary as a function of time and space. Concurrent melting and melt migration in an upwelling heterogeneous mantle may be approximated as a quasi-steady state problem in which time-dependent concentration patterns produced by melting of heterogeneous source regions are superimposed on a reference steady-state concentration distribution established by melting of the ambient or background mantle. Chromatographic fractionation is especially important for the matrix melt and solid when chemical heterogeneities are involved during melting and melt migration in the mantle, giving rise to significant phase-shift between two incompatible trace elements in the matrix melt and scattered correlations among incompatible trace elements in residual peridotites. Mixing is the chief mass transfer process in the dunite channel where the chromatographic effect is negligible for most of the incompatible trace elements. The lack of chromatographic fractionation among incompatible trace elements and isotopic ratios in MORB suggests either most MORB are channel melts or mixing in magma conduit and chamber is very efficient such that the phase-shift is averaged out during magma transport and storage processes. Advection brings melt produced by smaller-degree of melting in the deeper part of the melting column to the overlying melting region, increasing the incompatible trace element abundance in the matrix and the channel. This advection-induced self-enrichment is especially important when heterogeneous sources are involved and may account for some of the enriched incompatible trace element patterns observed in residual peridotite that were previously interpreted to be a result of mantle metasomatism. Systematic studies of high-resolution spatially correlated mantle samples may help to constrain the melting history and the size and nature of chemical heterogeneities in the mantle.     

中国煤中有害微量元素含量的空间分布

煤中有害微量元素对生态环境和人体健康的潜在影响是地球化学和能源环境领域研究的热点之一,地球化学制图对深刻理解地球化学过程及其变化规律具有重要作用。目前,尚缺乏中国煤中有害微量元素含量的空间分布图。通过对中国煤炭样品中1 167个Be、1 315个Co、1 406个Cu、1 191个Mo、1 247个Th 和1 390个Zn含量数据进行统计分析,测算中国煤中Be、Co、Cu、Mo、Th 和 Zn 的平均含量,并利用ArcGIS技术绘制中国煤中Be、Co、Cu、Mo、Th、Zn的含量地球化学空间分布地图。结果表明:中国煤中有害微量元素含量跨度大,数据分布呈正偏性,不符合正态分布特征;中国煤中Be、Co、Cu、Mo、Th和Zn 的平均含量分别为2.10、5.53、21.36、2.19、7.35和30.02 mg/kg;各元素含量的空间分布极不均匀;煤中有害微量元素含量空间分布格局是多种因素综合作用的结果,如物源区母岩、热液作用、水运移作用等,其中热液作用是煤中有害微量元素异常富集的典型特征。研究成果可为煤中微量元素研究和环境管理提供直观有效的参考。      

A comparison of selective extraction soil geochemistry and biogeochemistry in the Cobar area, New South Wales

In parts of the deeply weathered and semi-arid environments of the Cobar area (NSW, Australia), detection of mineralisation using conventional soil sampling and total metal analysis is impeded. This is due to the intense leaching of trace elements within the weathered profile, discontinuous coverage of transported materials and the existence of diffuse regional geochemical anomalies of ill-defined source. Selective chemical extractions, applied to various regolith components, and biogeochemistry offer a means of isolating localised geochemical patterns related to recent dispersion of trace elements through the overburden. Lag geochemical patterns across the McKinnons deposit (Au) and Mrangelli prospect (Pb–Zn–As) reflect mechanical dispersion processes and minor hydromorphic effects. Concentrations of more mobile elements tend to be higher in the non-magnetic fraction, due to higher proportions of goethite and poorly crystalline hematite than in the magnetic fraction. The subdued soil geochemical responses for metals extractable by cold 40% hydrochloric acid (CHX) and for total element concentration reflect the leached nature of the residual profile, low grade of mineralisation, dilution by aeolian components and disequilibrium of fine fractions with coarser, relict Fe-oxides. The stronger contrast for CHX for most metals, compared with total extraction, indicates surface accumulation of trace elements derived from underlying mineralisation. Enzyme leach element anomalies are intense but generally located directly over bedrock sources or major structural breaks, irrespective of the nature of the overburden. Though mechanisms for the dispersion of trace elements extracted by enzyme leaching are not well established, the lack of lateral transport suggests vertical migration of volatile metal species (atmimorphic dispersion). The strong, multi-element response to mineralisation in cypress pine needles indicates significant metal recycling during the present erosional cycle. However, a comparison of the trace element concentrations in vegetation (cypress pine needles) and selective extractions of soils indicates that recycling by the plants is not the dominant mechanism for transportation of metals through the overburden. The vegetation may be responding to hydromorphic dispersion patterns at depth. The use of selective extractions may be useful in detecting mineralisation through deeply leached profiles, but offers even greater potential when integrated with biogeochemistry to detect targets buried by significant thickness of transported cover.     

西湖凹陷平北地区泥岩地球化学特征及其地质意义

为了研究西湖凹陷平北地区泥岩微量及稀土元素的分布特征及其地质意义,采用ICP—MS对研究区25个泥岩样品进行了稀土元素和微量元素分析,研究表明：（1）研究区泥岩稀土元素主要来自陆源碎屑矿物,源岩主要为沉积岩及碱性玄武岩;（2）始新世末构造运动揭示的构造沉积界线在研究区留下了证据,微量元素比值、稀土总量等参数在此界面上存在明显的突变,界线十分明显,并且此界线亦是研究区平湖组与花港组的沉积界面,界面以下以三角洲沉积为主,界面之上主要为河流相沉积,这一沉积相转换面在研究区P1井尤为明显;（3）利用Sr／Cu比值推测平北地区始新世中晚期．早渐新世经历了较为明显的气候变化,总体上有逐渐变温湿趋势,并且研究区北部要温湿于南部。     

Application of major and trace elements as well as boron isotopes for tracing hydrochemical processes: the case of Trifilia coastal karst aquifer,Greece

The Trifilia karst aquifer presents a complex hydrochemical character due to the intricate geochemical processes that take place in the area. Their discernment was achieved by using the chemical analyses of major, trace elements and boron isotopes. Major ion composition indicates mixing between seawater and freshwater is occurring. Five hydrochemical zones corresponding to five respective groundwater types were distinguished, in which the chemical composition of groundwater is influenced mainly due to the different salinization grade of the aquifer. The relatively increased temperature of the aquifer indicates the presence of hydrothermal waters. Boron isotopes and trace elements indicate that the intruding seawater has been hydrothermally altered, as it is shown by the δ¹¹B depleted signature and the increased concentrations of Li and Sr. Trace elements analyses showed that the groundwater is enriched in various metallic elements, which derive from the solid hydrocarbons (bitumens), contained in the carbonate sediments of the Tripolis zone. The concentration of these trace elements depends on the redox environment. Thus, in reductive conditions As, Mn, Co and NH₄ concentrations are high, in oxidized conditions the V, Se, Mo, Tl and U concentration increases while Ni is not redox sensitive and present high concentration in both environments.     

上置晕与物质的“类气相”垂向迁移

阐明了上置晕的术语概念,指出文献中术语运用的失当之处,归纳出以上置晕为基础的各类隐伏矿化探方法。按传统的观念,上置晕主要是由不同形式的水迁移作用造成的。地气法、ＭＦＥ法和离子晕法的出现,揭示出在覆盖层中存在着一种新的元素迁移机制,即元素以非常细小的固相微粒随地气流迁移。一系列实验和实测结果表明,这种固相微粒可能是纳米粒径的物质,它们具有类气相的性状,故可将这种迁移机制称为物质的类气相垂向迁移。这一机制可以说明按传统机制难以解释的现象,对相应化探方法的研制、改善和应用有理论和实践上的指导意义。