Forty‐Nine Major and Trace Element Concentrations Measured in Soil Reference Materials NIST SRM 2586, 2587, 2709a, 2710a and 2711a Using ICP‐MS and Wavelength Dispersive‐XRF

Excellent agreement was noted in the concentration of major and trace elements in five NIST (National Institute for Science and Technology) soil reference materials (NIST SRM 2586, 2587, 2709a, 2710a and 2711a) between measurement results from wavelength dispersive‐XRF and ICP‐MS from two independent laboratories, and NIST certificate of analysis and literature data. We describe the variability in concentrations of up to forty‐nine elements (plus loss on ignition) and provide values for up to twenty‐one elements previously uncharacterised by NIST in these soil RMs. The additional characterisation provided in this investigation can be utilised to reduce the measurement bias of custom calibration routines and improve the quality of control checks developed using these NIST RMs.     

Quaternary fossil fauna from the Luangwa Valley,Zambia

This paper describes a large collection of Quaternary fossil fauna from the Luangwa Rift Valley, Zambia. Stone Age artefacts have been recovered from stratified fluvial contexts, but no in situ fossil faunas have yet been recovered. We report on 500 fossil specimens collected from the surface of point bars exposed seasonally along the banks of the main Luangwa River channel. We used non‐destructive X‐ray fluorescence analysis of the fossils' chemical signatures to determine whether they derive from one or many primary contexts, and the relationship between chemical signature and state of preservation. Specimens are identified to taxon (genus) to reconstruct palaeoenvironments and biochronology. A relatively wide range of taxa is identified, including a fossil hominin talus, described here. None of the fossils is positively attributable to extinct species, except a femur of an extinct Theropithecus reported in 2003. Although no additional extinct taxa were identified, some of the remains were attributable to genera that are not currently found in this region. The results suggest that most of the assemblage derives from sediments which are Middle Pleistocene or later, and that past environments in the Luangwa Valley may have differed from the habitat availability found today.     

The behavior of trace elements during the chemical evolution of the H2O-, B-, and F-rich granite–pegmatite–hydrothermal system at Ehrenfriedersdorf, Germany: a SXRF study of melt and fluid inclusions

Detailed melt and fluid inclusion studies in quartz hosts from the Variscan Ehrenfriedersdorf complex revealed that ongoing fractional crystallization of the highly evolved H₂O-, B-, and F-rich granite magma produced a pegmatite melt, which started to separate into two immiscible phases at about 720°C, 100 MPa. With cooling and further chemical evolution, the immiscibilty field expanded. Two conjugate melts, a peraluminous one and a peralkaline one, coexisted down to temperatures of about 490°C. Additionally, high-salinity brine exsolved throughout the pegmatitic stage, along with low-density vapor. Towards lower temperatures, a hydrothermal system gradually developed. Boiling processes occurred between 450 and 400°C, increasing the salinities of hydrothermal fluids at this stage. Below, the late hydrothermal stage is dominated by low-salinity fluids. Using a combination of synchrotron radiation-induced X-ray fluorescence analysis and Raman spectroscopy, the concentration of trace elements (Mn, Fe, Zn, As, Sb, Rb, Cs, Sr, Zr, Nb, Ta, Ag, Sn, Ta, W, rare earth elements (REE), and Cu) was determined in 52 melt and 8 fluid inclusions that are representative of distinct stages from 720°C down to 380°C. Homogenization temperatures and water contents of both melt and fluid inclusions are used to estimate trapping temperatures, thus revealing the evolutionary stage during the process. Trace elements are partitioned in different proportions between the two pegmatite melts, high-salinity brines and exsolving vapors. Concentrations are strongly shifted by co ncomitant crystallization and precipitation of ore-forming minerals. For example, pegmatite melts at the initial stage (700°C) have about 1,600 ppm of Sn. Concentrations in both melts decrease towards lower temperatures due to the crystallization of cassiterite between 650 and 550°C. Tin is preferentially fractionated into the peralkaline melt by a factor of 2–3. While the last pegmatite melts are low in Sn (64 ppm at 500°C), early hydrothermal fluids become again enriched with about 800 ppm of Sn at the boiling stage. A sudden drop in late hydrothermal fluids (23 ppm of Sn at 370°C) results from precipitation of another cassiterite generation between 400 and 370°C. Zinc concentrations in peraluminous melts are low (some tens of parts per million) and are not correlated with temperature. In coexisting peralkaline melts and high-T brines, they are higher by a factor of 2–3. Zinc continuously increases in hydrothermal fluids (3,000 ppm at 400°C), where the precipitation of sphalerite starts. The main removal of Zn from the fluid system occurs at lower temperatures. Similarly, melt and fluid inclusion concentrations of many other trace elements directly reflect the crystallization and precipitation history of minerals at distinctive temperatures or temperature windows.     

Parentage Identification of Differentiated Achondritic Meteorites by Hand‐held Energy Dispersive X‐Ray Fluorescence Spectrometry

We evaluate the potential of a hand‐held energy dispersive XRF spectrometer for the preliminary classification of non‐chondritic differentiated meteorites. The studied achondrites include nine lunar meteorites, seventeen Martian meteorites, five angrites and eighteen meteorites from asteroid 4 Vesta. Analytical precision and accuracy was tested on thirty‐nine terrestrial igneous rock slabs with a wide range of composition. Replicate analyses, performed on the studied meteorites, show that Fe/Mn values together with Si and Ca/K ratio can be used in the discrimination of different achondrite groups. Fusion crust's Fe/Mn values of meteorites from Vesta and Mars are indistinguishable from those of the interior implying that even measurements on the fusion‐crusted external surface could be sufficient to pigeonhole non‐chondritic meteorites. Hand‐held energy dispersive XRF spectrometer is a non‐destructive but very effective technique for preliminary classification of achondrites in the field and in laboratory and for the identification of mislabelled meteorites in museum collections.     

一种改进的X荧光分析基体效应校正方法及软件实现

在能量色散 Ｘ 荧光谱分析中,使用罗兹方程法校正基体效应,存在一定的局限性。为了获得最佳校正效果,本文提出了一种改进的基体效应校正法。该法是以罗兹方程为基础,在校正模型中引入特散比,并加强待校正元素在模型中作用的一种经验系数法。为了能够快速地对地质样品进行批量分析,在 Ｗ ｉｎｄｏｗ ｓ９８ 平台上,运用 Ｖ Ｃ＋ ＋ ５．０ 工具编制了分析软件,由其完成全部校正分析过程。     

锶矿X荧光勘查技术研究与应用

研究了找锶矿的Ｘ荧光勘查技术,包括：野外Ｘ荧光测量、数据处理、成果图编制方法,以及异常评价模式。应用该技术在四川大足、渠县等地寻找隐伏锶矿中取得良好效果。     

X射线荧光光谱法测定碳酸锶产品中锶钡钙镁组分含量

采用人工配制系列标准样,硼酸镶边垫底粉末压片方法制样,建立X射线荧光光谱法测定SrCO3产品中锶钙钡镁含量的定量分析曲线。由于SrCO3产品中锶含量极高,按照仪器给定的测量条件进行测量会产生谱峰饱和现象,造成计数率溢出,分析结果误差较大;文章对锶的分析条件进行了研究,提出降低锶的测定功率来降低计数率,以达到测量目的。同时还对自成特性很差的SrCO3产品的压片条件进行了讨论。使用α经验系数法校正基体效应,通过对实际样进行检验,测量值与化学分析值结果吻合。方法的检出限和准确度均满足分析要求。方法的RSD分别为Sr0.029%,Ba0.17%,Ca0.89%,Mg0.20%。     

Quantitative micro‐X‐ray fluorescence scanning spectroscopy of wet sediment based on the X‐ray absorption and emission theories: Its application to freshwater lake sedimentary sequences

Micro‐X‐ray fluorescence scanning spectroscopy of marine and lake sedimentary sequences can provide detailed palaeoenvironmental records through element intensity proxy data. However, problems with the effects of interstitial pore water on the micro‐X‐ray fluorescence intensities have been pointed out. This is because the X‐ray fluorescence intensities are measured directly at the surfaces of split wet sediment core samples. This study developed a new method for correcting X‐ray fluorescence data to compensate for the effects of pore water using a scanning X‐ray analytical microscope. This involved simultaneous use of micro‐X‐ray fluorescence scanning spectroscopy and an X‐ray transmission detector. To evaluate the interstitial pore water content from the X‐ray transmission intensities, a fine‐grained sediment core retrieved from Lake Baikal (VER99‐G12) was used to prepare resin‐embedded samples with smooth surfaces and uniform thickness. Simple linear regression between the linear absorption coefficients of the samples and their porosity, based on the Lambert–Beer law, enabled calculation of the interstitial pore spaces and their resin content with high reproducibility. The X‐ray fluorescence intensities of resin‐embedded samples were reduced compared with those of dry sediment samples because of: (i) the X‐ray fluorescence absorption of resin within sediment; and (ii) the sediment dilution effects by resin. An improved micro‐X‐ray fluorescence correction equation based on X‐ray fluorescence emission theory considers the instrument's sensitivity to each element, which provides a reasonable explanation of these two effects. The resin‐corrected X‐ray fluorescence intensity was then successfully converted to elemental concentrations using simple linear regression between the data from micro‐X‐ray fluorescence scanning spectroscopy and from the conventional analyzer. In particular, the calculated concentration of SiO₂ over the depth of the core, reflecting diatom/biogenic silica concentration, was significantly changed by the calibrations, from a progressively decreasing trend to an increasing trend towards the top of the core.     

便携式X射线荧光元素分析仪的应用

利用NITON XL3t 500型便携式X射线荧光光谱仪,选择云南会泽县金牛厂铅锌矿区进行样品分析条件试验.试验中分别对实验室分析与X射线荧光光谱仪分析结果,以及不同湿度条件下分析结果进行了对比研究,确定了最佳的应用条件.结果表明,实验室分析与X射线荧光光谱仪分析结果相近,但湿度因素会降低元素含量.所以应用便携式X荧光光谱仪进行试验不失为一种方便快捷和行之有效的方法.