Neutron Activation Analysis of Two USGS Rock Reference Samples (Granite G-2, Andesite AGV-I) and Discussion in The Light of Compiled Data

New data for 21 trace elements including eight rare-earths, determined by neutron activation analysis (NAA) in two rook reference samples (Granite G-2, Andesite AGV-1), are compared with the preferred values previously proposed. Using compiled data published in 1969 and in 1972, further comparisons are made with the preferred means calculated for different methods of trace analysis. NAA data compiled in 1969 and in 1972 and new results published since then are assembled in two tables for the 21 elements. These 1976 NAA data lead us to suggest slight revisions of the preferred values for five to ton elements in each sample.     

Experimental cpx/melt partitioning of 24 trace elements

Cpx/melt partition coefficients have been determined by ion probe for 24 trace elements at natural levels in an alkali basalt experimentally equilibrated at 1,380°C and 3 GPa. One goal was to intercompare Ds for both high-field-strength elements and rare earth elements (REE) in a single experiment. Relative to the REE spidergram, Hf and Ti show virtually no anomaly, whereas Zr exhibits a major negative anomaly. Other incompatible elements (Ba, K, Nb) fall in the range of published values, as do elements such as Sr, Y, Sc, Cr and V. Pb shows a value intermediate between La and Ce. Values for Be, Li and Ga are reported for the first time, and show that Be is as incompatible as the light REEs whereas Li and Ga are somewhat more compatible than the heavy REE.     

Experimentally determined mineral-melt partition coefficients for Sc,Y and REE for olivine,orthopyroxene, pigeonite,magnetite and ilmenite

Our current lack of understanding of the partitioning behavior of Sc, Y and the REE (rare-earth elements) can be attributed directly to the lack of a sufficiently large or chemically diverse experimental data set. To address this problem, we conducted a series of experiments using several different natural composition lavas, doped with the elements of interest, as starting compositions. Microprobe analyses of orthopyroxene, pigeonite, olivine, magnetite, ilmenite and co-existing glasses in the experimental charges were used to calculate expressions that describe REE partitioning as a function of a variety of system parameters. Using expressions that represent mineral-melt reactions (versus element ratio distribution coefficients) it is possible to calculate terms that express low-Ca pyroxene-melt partitioning behavior and are independent of both pyroxene and melt composition. Compositional variations suggest that Sc substitution in olivine involves either a paired substitution with Al or, more commonly, with vacancies. The partitioning of Sc is dependent both on melt composition and temperature. Our experimentally determined olivine-melt REE Ds (partition coefficients) are similar to, but slightly higher than those reported by McKay (1986) and support their conclusions that olivines are strongly LREE depleted. Y and REE mineral/melt partition coefficients for magnetite range from 0.003 for La to 0.02 for Lu. Ilmenite partition coefficients range from 0.007 for La to 0.029 for Lu. These experimental values are two orders of magnitude lower than many of the published values determined by phenocryst/matrix separation techniques.     

Laser Ablation and Solution ICP-MS Determination of Rare Earth Elements in USGS BIR-1G, BHVO-2G and BCR-2G Glass Reference Materials

Data are reported for rare earth elements (REE) in three geological glass reference materials (BIR-1G, BHVO-2G and BCR-2G) using a UV (266 nm) laser ablation ICP-MS system and the classical (HF-HClO₄) acid decomposition method, followed by conventional nebulisation ICP-MS. External calibration of laser ablation analyses was performed using NIST SRM reference materials with internal standardisation using ²⁹Si and ⁴⁴Ca. Replicate analyses of reference basaltic glasses yielded an analytical precision of 1-5% (RSD) for all the elements by solution ICP-MS and 1-8% (RSD) by laser ablation ICP-MS. The relative differences between the REE concentrations measured by solution and laser ablation ICP-MS compared with the reference values were generally less than 11 % for most elements. The largest deviations occurred for La determined by solution ICP-MS in BIR-1G. The results of both solution and laser ablation ICP-MS agreed well, generally better than 7%, with the exception of La, Pr and Sm in BIR-1G. The measured REE laser ablation data for BIR-1G, BHVO-2G and BCR-2G agreed with the previously published data on these basaltic reference glasses, within a range of 0-10% for most elements. No significant influences were observed for the predicted spectral interferences on some REE isotopes in the analysis of basaltic glasses.     

New ICP‐MS Results for Trace Elements in Five Iron‐Formation Reference Materials

Iron formations (IFs) typically contain low mass fractions of most trace elements, including the rare earth elements (REE), and few publications describe analytical methods dedicated to this matrix. In this study, we used bomb and table‐top acid dissolution procedures and ICP‐MS to determine the mass fractions of trace elements in IF reference materials FER‐1, FER‐2, FER‐3, FER‐4 and IF‐G. The full digestion of the IF samples with the bomb procedure required the addition of a small amount of water together with the acids. The results obtained by this method mostly agreed statistically with published values. The most remarkable exception was the higher values obtained for the heavy REE in FER‐3. The recoveries of the REE obtained with the table‐top procedure were slightly higher than those of the bomb digestion, except for the values of the heavy REE in FER‐3 and FER‐4, which were up to 30% lower than published values. Sintering of the samples with sodium peroxide was performed to determine the REE, but the results tended to be lower than those derived following acid digestion. On the whole, the recoveries showed dependence on the conditions of digestion, but subtle differences in trace mineral composition between samples also exerted influence on the analytical results for trace elements.     

Determination of zircon/melt trace element partition coefficients from SIMS analysis of melt inclusions in zircon

Partition coefficients (^zircon/meltD_M) for rare earth elements (REE) (La, Ce, Nd, Sm, Dy, Er and Yb) and other trace elements (Ba, Rb, B, Sr, Ti, Y and Nb) between zircon and melt have been calculated from secondary ion mass spectrometric (SIMS) analyses of zircon/melt inclusion pairs. The melt inclusion-mineral (MIM) technique shows that D_REE increase in compatibility with increasing atomic number, similar to results of previous studies. However, D_REE determined using the MIM technique are, in general, lower than previously reported values. Calculated D_REE indicate that light REE with atomic numbers less than Sm are incompatible in zircon and become more incompatible with decreasing atomic number. This behavior is in contrast to most previously published results which indicate D > 1 and define a flat partitioning pattern for elements from La through Sm. The partition coefficients for the heavy REE determined using the MIM technique are lower than previously published results by factors of ≈15 to 20 but follow a similar trend. These differences are thought to reflect the effects of mineral and/or glass contaminants in samples from earlier studies which employed bulk analysis techniques.D_REE determined using the MIM technique agree well with values predicted using the equations of Brice (1975), which are based on the size and elasticity of crystallographic sites. The presence of Ce⁴⁺ in the melt results in elevated D_Ce compared to neighboring REE due to the similar valence and size of Ce⁴⁺ and Zr⁴⁺. Predicted ^zircon/meltD values for Ce⁴⁺ and Ce³⁺ indicate that the Ce⁴⁺/Ce³⁺ ratios of the melt ranged from about 10⁻³ to 10⁻². Partition coefficients for other trace elements determined in this study increase in compatibility in the order Ba < Rb < B < Sr < Ti < Y < Nb, with Ba, Rb, B and Sr showing incompatible behavior (D_M < 1.0), and Ti, Y and Nb showing compatible behavior (D_M > 1.0).The effect of partition coefficients on melt evolution during petrogenetic modeling was examined using partition coefficients determined in this study and compared to trends obtained using published partition coefficients. The lower D_REE determined in this study result in smaller REE bulk distribution coefficients, for a given mineral assemblage, compared to those calculated using previously reported values. As an example, fractional crystallization of an assemblage composed of 35% hornblende, 64.5% plagioclase and 0.5% zircon produces a melt that becomes increasingly more enriched in Yb using the D_Yb from this study. Using D_Yb from Fujimaki (1986) results in a melt that becomes progressively depleted in Yb during crystallization.     

Rare earth elements in ‘Younger’ granites,Northern Portugal

Rare earth elements (REE) were determined in two suites of Hercynian ‘Younger’ granodiorites and granites, one massive and the other porphyritic. Within each suite, the REE abundances decrease towards the more felsic granite while the REE patterns are almost identical. The patterns of the porphyritic types are only slightly more fractionated than those of the massive rocks. Negative Eu-anomalies are observed in all rocks although those of the granodiorites are smaller than those of the granites. Modeling of the data indicates that the granitic magmas may be derived, by partial melting, from the greywackes and pelites of the orogenic belt, the melts being in equilibrium with a residuum composed of quartz, plagioclase, garnet, orthopyroxene or cordierite, and, possibly, biotite.     

基于机器学习的洋岛玄武岩主量元素预测稀土元素

地学共享数据库(如GEOROC、PetDB等)可为地球科学研究提供重要基础数据。然而,这些数据库均存在一个明显缺陷:样品的9种主量元素(SiO2、TiO2、Al2O3、CaO、MgO、MnO、K2O、Na2O和P2O5)均有准确数据,但稀土元素(rare earth elements,REE)数据大量缺失。鉴于REE在地球化学领域的重要作用,我们尝试为数据库缺失的REE值提供一个补全方案,即利用机器学习中的随机森林方法实现由9种主量元素预测REE值。以洋岛玄武岩(ocean island basalt,OIB)为例,把从GEOROC库中搜集到的1 283组OIB数据按8∶2的比例分为两组,其中80%的数据作为训练数据集用于建模,20%的数据作为测试数据集验证模型。比较了随机森林和多元线性回归方法对相同数据进行建模和预测的效果差异,发现无论是回归建模还是预测,随机森林方法都优于多元线性回归,且随着输入参数与输出参数之间关系的复杂化,这种优势更加明显。随机森林对测试数据集的预测效果整体较好,只是随着REE原子序数的增大,预测效果逐渐减弱。这一方面可能是因为原子序数大的REE与主量元素的关系更弱;另一方面可能是由于原子序数大的REE与主量元素的关系更加复杂。其次,随机森林方法预测的REE配分曲线与实际配分曲线吻合度较高,且预测所得配分曲线的区分能力较强,能够反映实际配分曲线之间的相对差异,这一点对推断地球化学过程尤为重要。随机森林方法随着训练数据的增多,其建立的模型也将越稳定,预测结果也会更精确。因此,随着数据库的不断完善,对数据库中REE值的预测也将更为可信、可行。     

Sequential Inductively Coupled Plasma Determination Of Some Rare-Earth Elements in Five French Geostandards

Experimental data for eleven rare-earth elements (REE) obtained by inductively coupled plasma spectrometry (ICP) in five French geochemical reference standards (BE-N, BR, DR-N, GS-N and FK-N)are presented. The method is based on acid digestion of the sample and cation-exchange separation from matrix elements.
Together with these new determinations an updated compilation of these reference materials are presented. Good agreement between the present results and previously preferred and published values obtained by various analytical techniques is observed. The values obtained in the present work corroborate the validity of the outlined method.     

中国不同类型钨矿床稀土元素地球化学研究成果综述

钨矿的稀土元素地球化学可以反映成矿作用的条件和过程,为矿床成因提供有效的信息。中国钨矿床稀土元素地球化学的研究硕果累累,从单矿种角度进行全国性的系统总结十分必要。本文统计了1990年至2016年间不同类型钨矿床钨矿石矿物及与成矿有关岩体的稀土元素300多组数据。通过总结可知,不同类型钨矿床钨矿石矿物及与成矿有关花岗岩中稀土元素的总量和稀土配分曲线不同,这与成矿原始物质及成矿时物理化学条件的不同有关。不同类型钨矿床大部分具有Eu负异常的特征,显示成矿条件为较高温的还原环境;黑钨矿及其成矿岩体的稀土分配模式之间存在一定的依从关系,但是,黑钨矿中的稀土元素并没有随着岩浆-流体的结晶分异而富集。     

Rare earth elements in vivianite from Lake Åstrum

The rare carth elements are determined in vivianite concretions and surrounding clay sediments. Approximately 3/4 of the rare earth elements in the clay is present in adsorbed state. The concentration of REE in the pore water is calculated from the composition of the vivianite, assuming a diffusion model for the formation of the concretions and lower solubility of the rare earth elements above the concretions than in the pore water at some distance from the concretions. The concentrations thus calculated are similar to published values for ocean water.     

Precise Determination of Ultra-Low (sub-ng g-1) Level Rare Earth Elements in Ultramafic Rocks by Quadrupole ICP-MS

We present a new method that determines precisely and accurately rare earth elements (REE) at the sub-ng g^-1 level in ultramafic rocks based on acid dissolution and quadrupole ICP-MS with systematic interference corrections on each sample. The method is demonstrated by analyses of the international geochemical reference materials, PCC-1 (peridotite), DTS-1 (dunite) and DTS-2 (dunite) provided by the United States Geological Survey (USGS), and JP-1 (peridotite) issued by the Geological Survey of Japan (GSJ). Detection limits, as rock equivalent, were calculated to be 0.01-0.08 ng g^-1 for our instrument, which is sufficiently low compared to the REE concentrations of ultramafic rocks. In addition, procedural blanks of the proposed method were 0.2-5 pg, which is negligible even for the ultra-low level REE determinations. Reproducibility obtained from separate dissolutions and measurements of USGS DTS-2 and GSJ JP-1 was 3-6%, which corresponds to the high-precision data obtained by ID-TIMS or magnetic sector field ICP-MS with a desolvating nebuliser. The REE data determined exhibit smooth chondrite-normalised REE patterns for all of the tested geochemical reference materials, and the abundances are in good agreement with recently published data.     

Inductively Coupled Plasma Determination Of Nine Rare-Earth Elements In Sixty International Geochemical Reference Samples

Data for nine rare-earth elements (REE) determined by inductively coupled plasma spectrometry (ICP-AES) in sixty international geochemical reference samples (igneous and sedimentary rocks, soils and sediments) are presented. The method is based on acid digestion of the sample and cation-exchange separation from matrix elements. Good agreement is generally achieved between the results of this work and the recent compilation values. The present paper includes analytical data on several reference materials for which existing data are rather scarce or even inexistent     

DETERMINATION OF RARE EARTH ELEMENTS IN SIXTEEN SILICATE REFERENCE SAMPLES BY ICP-MS AFTER TM ADDITION AND ION EXCHANGE SEPARATION

This study reports the results of thirteen rare earth elements (REE) in sixteen geochemical reference samples. The analytical procedure involved dissolution of a whole rock or mineral separate, spiking with Tm, and separation of the REE using a simple ion-exchange chromatography procedure. The resulting REE solutions were analysed by ICP-MS. The results are compared with literature values. The agreement between our data and recommended or ID-TIMS values is very favorable. The precision of the technique is better than 5% (2) for all the REE.     

Reference Materials for Geochemical Studies: New Analytical Data by ICP-MS and Critical Discussion of Reference Values

Abundances of twenty four trace elements, including Y and fourteen rare earth elements (REE), are reported for eighty six geological reference materials and four proficiency testing samples. Analytical data were obtained by ICP-MS using solution nebulisation after mixed acid digestion (HF-HClO₄) under pressure. Analysed samples cover a wide range of element concentrations and mineralogical compositions, including samples for which there are few previously published data. Precision for elemental determinations in nearly 90% of the samples analysed is better than 5%. Accuracy, estimated by comparison with data from compilations is better than 6% for well characterized reference materials. Results obtained for samples that are low in trace elements are often significantly lower than compiled reference values. A critical discussion of the compiled data sets, especially for Y and the REEs, indicates that some reference values seem to be erroneous.     

Determination of Rare Earth Elements in Geological Reference Materials: A Comparative Study by INAA and ICP-MS

Data was obtained for the rare earth elements (REE) by instrumental neutron activation analysis (INAA) and inductively coupled plasma-mass spectrometry (ICP-MS) in twenty geological reference materials. In general, the precision obtained by ICP-MS is better for the light REE, decreasing with increasing atomic number. This is partly a result of the occurrence of the heavy REE at low concentrations. The precision of the data obtained by INAA is good (5% RSD). The data obtained also showed that for the elements determined by both methods, the accuracy is similar for the light REE and better for the middle and heavy REEs by INAA. Higher uncertainty is achieved by ICP-MS mainly for elements at very low concentrations, occurring at about ten times the chondritic values.     

Neutron Activation Determination of The Fourteen Rare-Earth Elements In Five Rock Standards

Five geochemical reference samples. Granite GA and Basalt BK from CRPG, Diorite DR-N and Serpentine UB-N from ANRT and Andesite AGV-1 from USGS were analysed for their rare-earth element (REE) contents. All the fourteen REE were determined using neutron activation analysis. The results are presented and compared with published data.     

Chemical Characterisation of NIST Silicate Glass Certified Reference Material SRM 610 by ICP-MS, TIMS, LIMS, SSMS, INAA, AAS and PIXE

National Institute of Science and Technology (NIST) silicate glass SRM 610 is widely used as a certified reference material for various micro-analytical techniques such as SIMS or laser ablation ICP-MS. SRM 610 has been nominally doped with sixty one trace elements at the 500 μg g⁻¹ level, but certified concentration data exist for only a few of these elements. This study reports concentration data for fifty nine trace elements obtained by ICP-MS, SSMS, LIMS, TIMS, INAA, AAS, and PIXE analyses of two different SRM 610 wafers. Most elements fall within a 10% band around a median value of about 440 μg g⁻¹. The REE concentrations are shown to be constant to 3% (1 σ), thus emphasizing the value of SRM 610 as a reference material for REE analyses.
Comparison of our values with published data suggests that different SRM 610 wafers are, within errors, chemically identical for most elements. Exceptions to this general rule appear to be restricted to elements which were partly lost during the production of the glass, e.g. Ag and Br. On the basis of six independent determinations of Rb concentrations, which are systematically lower by a few percent than the reported NIST value, we argue that the certified Rb concentration may not be representative for all distributed SRM 610 wafers.     

Consistent patterns of rare earth element distribution in accessory minerals from rocks of mafic-ultramafic complexes

This paper summarizes analytical data accumulated in the world literature and other materials about the regularities of the REE distribution in minerals contained in ultramafic and mafic rocks as accessory phases. These minerals are tentatively divided into two groups. The first includes garnets, zircons, apatites and perovskites, which can accumulate increased amounts of REE in their structure. The second consists of minerals whose structure can accumulate only limited contents of these trace elements. These are chrome-spinels, ilmenites, and micas. These minerals, in respect of REE geochemistry, are studied to a varying degree because of the different levels of accumulations of these elements, different degrees of occurrence in rocks, tiny sizes of their grains and other reasons. The analytical database formed on their basis includes about 600 original analyses. The overwhelming majority of presently available data on REE geochemistry in accessory minerals from ultramafic and mafic rocks have been published only in the recent 15 years. The studies became possible due to the development and introduction of new highly sensible microprobe analyses allowing detection of REE and many other trace elements in minerals grains directly in thin sections. The greatest numbers of these analyses were performed for garnets and zircons, fewer for apatites, and the fewest for chrome-spinels, ilmenites, micas, and perovskites. In general, the regularities of REE distribution in these minerals from ultramafic and mafic rocks are less studied compared to the rock-forming minerals from ultramafic and mafic rocks. Among the analytical methods, which were used to study the REE composition of accessory minerals, the most efficient was the mass-spectrometry with inductively coupled plasma (ICP-MS).     

The Behaviour of Rare—Earth Elements（REE） During Weathering of Granites in Southern Guangxi,China

The behaviour of the rare-earth elements(REE)during the weathering of granites was studied in southern Guangxi,China.Based on the study of the weathering profiles,the soil,weathered and sub-weatereb zones are identified with different REE geochemical behaviours throug the weathering profiles of granite.The Ce anomalies of the weathering profiles cover a large range of values with most falling between 1.02 and 1.43in the soil zone and 0.16and 0.40in the weathered and sub-weathered zones.Light rare-earth elements(LREE) and heavy rare-earth elements(HREE)are enriched to varying degree in the weathering profiles as compared to host granites.In the soil zone,more HREEs are leached than LREEs,and HREEs are more enriched than LREE in the weathered and sub-weathered zones.It is considered that infiltration and adsorption on clays are two processes controlling the enrichment and formation of REE deposits in the weathering profiles of granite.