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近10年来国际上用热电离质谱代替α谱仪测定不平衡铀系样品的年龄，在造礁珊瑚、洞穴堆积物、年轻火山岩和湖泊沉积物等领域已取得了显著的成果。该技术有明显的优点，如样品用量少，测试时间短，测量精度高，测年范围宽，是中更新世至全新世以来有效的测年方法之一，可为全球变化研究提供高精度和高灵敏度的年龄谱，展示了热电离质谱技术如同加速器质谱技术一样，有广阔的应用前景。我们曾用MAT－262质谱仪对国内石笋标样(GBW04412，GBW04413)和国际珊瑚标样(RKM－4)进行过测试，取得了与标准值一致的结果。 相似文献
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We present a new analytical method for U-series isotopes using the SHRIMP RG (Sensitive High mass Resolution Ion MicroProbe) mass spectrometer that utilizes the preconcentration of the U-series isotopes from a sample onto a single ion-exchange bead. Ion-microprobe mass spectrometry is capable of producing Th ionization efficiencies in excess of 2%. Analytical precision is typically better than alpha spectroscopy, but not as good as thermal ionization mass spectroscopy (TIMS) and inductively coupled plasma multicollector mass spectrometry (ICP-MS). Like TIMS and ICP-MS the method allows analysis of small samples sizes, but also adds the advantage of rapidity of analysis. A major advantage of ion-microprobe analysis is that U and Th isotopes are analyzed in the same bead, simplifying the process of chemical separation. Analytical time on the instrument is ∼60 min per sample, and a single instrument-loading can accommodate 15-20 samples to be analyzed in a 24-h day. An additional advantage is that the method allows multiple reanalyses of the same bead and that samples can be archived for reanalysis at a later time. Because the ion beam excavates a pit only a few μm deep, the mount can later be repolished and reanalyzed numerous times. The method described of preconcentrating a low concentration sample onto a small conductive substrate to allow ion-microprobe mass spectrometry is potentially applicable to many other systems. 相似文献
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Pulok K. Mukherjee Param P. Khanna Naresh K. Saini 《Geostandards and Geoanalytical Research》2014,38(3):363-379
A simple, single sample preparation involving pressed rock powder pellets was utilised to determine the trace and ultra trace abundances of petrogenetically important elements including high field‐strength elements and REEs by laser ablation‐ICP‐MS. One of the elements predetermined by XRF spectrometry served as an internal standard. The influence of sample preparation parameters (grain size, pellet compactness and amount of binding media) on analytical performance was also investigated, including sample homogeneity issues at the laser sampling scale. Line scanning with a high repetition frequency (20 Hz) and large beam diameter (200 μm) ensured ablation from a larger sample surface area, eliminating issues related to sample heterogeneity. A median grain size of about 10 μm for silicate rock powders was found to be sufficiently representative at this scale of laser sampling. Granitic rocks or samples containing resistant minerals such as zircon needed extra grinding to achieve grain sizes down to < 5 μm for better precision for elements that are concentrated in these phases. Using 137Ba as an internal standard, reasonable accuracies within 15–20% for most of the high mass trace elements were achieved; in the case of low mass elements, it may deviate up to 40%. Precision of measurements rarely exceeded 15% RSD. 相似文献
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Wilma Pretorius Dominique Weis Gwen Williams Diane Hanano Bruno Kieffer James Scoates 《Geostandards and Geoanalytical Research》2006,30(1):39-54
The United States Geological Survey granitic and granodioritic reference materials G‐2 and GSP‐2 were decomposed in high‐pressure bombs using both HF‐HNO3 and HF‐HNO3‐HClO4 in order to evaluate the feasibility of characterising the entire suite of geologically relevant trace elements through direct analysis with a high‐resolution inductively coupled plasma‐mass spectrometer (HR‐ICP‐MS). The digested samples were diluted to the appropriate levels and analysed at low, medium and high resolution depending on the required sensitivity and potential interferences for each element. Memory effects during analysis of the high field strength elements (HFSE) were negligible when analysed using an all‐Teflon, uncooled sample introduction system and combined with adequate wash times with 4% v/v aqua regia + 0.5% v/v HF between samples. The concentration of the remaining lithophile elements was determined with a conventional, cooled, Scott‐type spray chamber using a wash solution of 1% v/v HNO3. Total procedural blanks contributed between 0.01 to 0.5% to final sample concentrations and blank subtractions were typically unnecessary. Abundances for Li, Hf, Ba, Zr, Ga, Rb, Sr, La, Ce, Th and U were systematically higher, while those for the heavy rare earth elements (HREEs), Cu and Y were systematically lower in this study compared to USGS values for G‐2 and GSP‐2. This is likely to be related to, respectively, higher recoveries from more efficient digestion of refractory phases (i.e., zircon, tourmaline), and better resolution of interferences when using a HR‐ICP‐MS. Sample digestion experiments also showed that perchloric acid digestion in high pressure bombs resulted in superior recoveries and better precision for the bulk of the trace elements analysed. The concentration of the remaining elements overlapped within uncertainty with recommended reference values and with values determined in other studies using isotope‐dilution TIMS, ICP‐MS and XRF. Concentrations for the elements Cd, Sn, Sb, Ta, Bi, Tb, Ni and Mo are also reported for G‐2 and GSP‐2 reference materials. Our study shows therefore that it is feasible to determine thirty‐nine geologically relevant trace elements accurately and directly in granitoid sample digests when using a HR‐ICP‐MS, thereby negating the need for ion exchange or isotopic spiking. 相似文献
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应用同位素稀释法热电离质谱(TIMS)技术测定珊瑚礁的高精度铀系年龄。通过对BarbadosⅢ、Ⅳ阶地等样品分析,RendezvousHil和Curacao+6m的TIMS年龄分别为129.2±1.2kaB.P.和125.4±1.1kaB.P.,对应深海沉积物氧同位素第5期5e段的高海面;Kendal山阶地为208.1±1.9kaB.P.,可能代表7c间冰期高海平面的时代。该结果与Edwards等测定同一阶地的年龄一致,与α谱法数据在误差范围内吻合。另外,探讨了初始铀同位素比值的变化,并对TIMS年龄的可靠性做了评价。 相似文献
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稀土稀有稀散元素现代仪器测试全新方法的建立 总被引：1，自引：0，他引：1
本文系统总结了自2011年以来在三稀矿产实验测试方面取得的新进展。重点介绍了离子相稀土单元素浸泡提取实验研究、稀土原产地Nd同位素与微量元素示踪技术研究、离子吸附型稀土样品野外现场快速定性定量手持X射线荧光(XRF)分析研究成果。结果表明,采用25%硫酸铵浸泡提取,电感耦合等离子体光、质谱(ICP- AES、ICP- MS)测定,可以清晰反映出各稀土元素的浸泡提取率;采用高精度多接收电感耦合等离子体质谱仪(MC- ICP- MS)进行稀土矿石中Nd143/Nd144同位素比值测定,其比值差异可以示踪不同稀土矿石产地;通过精确测试分析不同产地稀土精矿样品中的稀土和其他微量元素含量,并进行数据相关性分析和数据分类分析,通过Y、Be和Bi三种元素含量的比较,可以判断稀土精矿来源;野外现场快速分析,20分钟可完成1件样品测试,不仅可定性判断是否为离子吸附型稀土,同时可定量各离子相稀土单元素含量,与室内精确分析结果符合性良好,可为我国离子吸附型稀土矿床的找矿快速筛查提供技术支撑。 同时介绍了混合酸微波分解样品- 电感耦合等离子体光、质谱(ICP- AES、ICP- MS)同时测定钨矿石、钼矿石、铌钽矿石中的多种稀有稀散稀土元素含量的方案。该方案的特点在于采用了耐氢氟酸体系,尤其对高含量W、Nb、Ta样品更具优势,否则易产生水解,导致测定结果系统偏低。同时梳理总结了我国常见三稀矿石地质样品的特点,针对不同矿种、不同矿床样品类型与基体特点,以及所测试元素种类的不同,研究建立了专门针对“稀有、稀散、稀土元素”现代仪器分析的10个全新的配套方法及其相应的技术指标(准确度、精密度、检出限),可满足地质矿产实验室测试质量管理的规范要求,而且为我国三稀金属矿产资源的战略调查、国家重点研发计划“深地锂资源探测”和四川甲基卡等地找矿突破做出了贡献。 相似文献
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High Precision Hf-W Isotopic Measurements in Meteoritic Material Using Negative Thermal Ionisation Mass Spectrometry (NTIMS) 总被引：1，自引：0，他引：1
Ghylaine Quitté Jean-Louis Birck Françoise Capmas Claude J. Allègre 《Geostandards and Geoanalytical Research》2002,26(2):149-160
This paper presents a two-stage anion-exchange procedure for tungsten extraction, an improved mass spectrometric procedure for tungsten analysis and a simplified chemical separation and TIMS procedure for the determination of Hf concentrations. The chemical separation of tungsten is based on its complexing properties with HF and H2 O2 . The blank level for a sample size of 300 mg is about 80 pg for tungsten. The procedure is designed for the high sensitivity of negative thermal ionisation mass spectrometry (NTIMS) provided by the use of Mg oxide as an emitter on Ir filaments. Tungsten can be readily measured with a high precision in various meteoritical material and especially in small W-poor silicate fractions. Samples containing as little as a few ng g-1 tungsten can be analysed reliably with this method. 相似文献
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岩石样品中低含量铂族元素和锇同位素比值的高精度测量方法 总被引：9，自引：1，他引：9
铂族元素（Os,Ir,Pt,Ru,Rh,Pd)具有强亲铁性和强亲铜性，为一组地球化学性质相近的相容元素，铂族元素包含两个同位素衰变体系（^190Pt-^186Os和^187Re-^187Os)。近年来，铂族元素和Re-Os同位素在研究各类不同地持作用过程中，尤其是在地幔岩石的研究中，作用独特，效果显著。由于地幔岩石的铂族元素含量较低，因此高精度，高灵敏度的分析测试方法的研究就显得十分重要。以往的分析方法（如常规的ICP－MS和中子活化分析方法），对含10^-9-10^012级低含量铂族元素的产品分析精度一般较差（＞15％－100％）。所采用的分析流程通常也无法同时获得样品的铂族元素含量和Os同位素比值。本文采用新的熔样方法（HAP－S高温高压釜酸溶法），新的化学流程（溶剂萃取和阴离子交换树脂柱）和新的分析仪器（多接收等离子体质谱MC－ICPMS和负离子热电离质谱N－TIMS）。用同位素稀释法对低含量地幔橄榄岩样品同时测定的铂族元素含量和Os同位素比值，获得了高精度的分析结果。对所分析的地橄榄样品中的铂族元素分配曲线和Os同位素组成的地质意义进行了初步探讨。 相似文献
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A new method integrating high-precision U-Pb geochronology with zircon trace element analysis (U-Pb TIMS-TEA) 总被引：1，自引：0，他引：1
Increased precision in isotope-dilution thermal ionization mass spectrometry (ID-TIMS) U-Pb geochronology has revealed age complexities in zircon populations that require new tools for understanding how the growth of zircon is related to geologic processes. U and Pb are routinely separated from other elements in dated minerals by ion exchange separation prior to TIMS isotope measurement. We develop a method in which trace elements in the exact same volume of zircon are redissolved and analyzed using solution nebulization inductively coupled plasma sector-field mass spectrometry with matrix-matched external liquid calibration. Using <0.5 ml solution, resulting concentrations are between <1 ppt for elements such as Ti, Nb and Ta and tens of ppb for Zr. By analyzing a series of standard solutions, zircons and procedural blanks, we show that accurate measurements are performed on Zr, Hf, Y, Sc, and the HREE while low-concentration elements can be measured accurately to <5 ppt. We performed combined U-Pb ID-TIMS geochronology with trace element analysis (here called U-Pb TIMS-TEA) on zircons from eight volcanic rocks comprising several volcanic systems and one metamorphic sample. Similar to previous in situ trace element analyses, zircon geochemistry is distinct between different samples and records petrogenetic processes such as fractional crystallization, assimilation and/or magma mixing. Unique from in situ analysis, U-Pb TIMS-TEA can trace geochemical evolution in accessory minerals with adequate age precision to resolve magmatic processes in rocks at least 200 million years old. This provides a means to identify auto-, ante- and xenocrystic zircon and lead to more robust age interpretations in ID-TIMS U-Pb geochronology. One suite of Cretaceous andesitic zircons shows correlations in geochemistry and absolute time that record evolution of a magmatic system over ∼250 ka prior to eruption. Future work will combine U-Pb TIMS-TEA with solution isotopic analysis of Nd, Sr and Hf and will be applied to a host of datable minerals such as monazite, sphene, apatite, rutile, xenotime, and baddeleyite. These combined tools will provide access to an improved understanding of a wide range of igneous and metamorphic processes as a function of time. 相似文献
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区域化探样品元素测定几个问题的探讨 总被引：4，自引：0，他引：4
化探样品元素测定的要求,因任务的不同而异。区测与普查相比其要求不同。在普查(及详查)阶段,工作限定在较小的范围内,可能发现的矿种有限或可以预测,测定元素的数目也相应较少(约20种元素)．普查的测网较密,主要是圈出含量和衬度较高的异常内带,对灵敏度和准确度要求可以低些。区域化探主要是发现强度低、衬度低而范围大的区域地球化学异常,而且做为地球化学基础资料,是按分幅扫面,最后要拼缩成全国性的地球化学图。由于图幅间的对比拼接,要求较高的灵敏度和准确度。在区测中凡是能形成独立矿产的元素(包括稀有分散元素)以及有指示意义的伴生元素都要测定。区测化探不但用于找矿,目前日益为区域地质、自然区划、环境保护和农林畜牧的研究,提供重要的地球化学资料。目前测定的元素包括成岩特征元素在内已达39种。文中还探讨了在我国目前化验水平和能力的情况下,完成区测化探样品测定的方法和工作步骤。 相似文献
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较低稀释比熔片制样X射线荧光光谱法测定磷矿石中12种主次痕量组分 总被引：4，自引：4，他引：0
当前应用X射线荧光光谱熔片制样技术分析测定较低含量、低荧光产额氟组分时,准确度较低,精密度较差、检出限较高。本文运用5:1较低稀释比熔样制片技术,采用波长色散X射线荧光光谱法测定磷矿石中12个主次量组分(F、Na2O、MgO、Al2O3、SiO2、P2O5、K2O、CaO、TiO2、MnO、TFe2O3和痕量SrO)。采用磷矿石、岩石国家一级标准物质、磷矿石管理样品和人工配制标准样品校准,经验系数法进行基体校正,结果表明12个组分分析方法的精密度和准确度较好,检出限较低,未知样品的分析结果比较满意;氟的精密度、准确度和检出限均好于文献中10:1熔样稀释比得出的结果。该方法解决了压片制样测定氟组分,熔片制样测定其他主次量组分的技术问题,同时也降低了熔片制样技术测定氟的检出限。 相似文献
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微量陨石激光熔样稀有气体测定方法是一种可以在微米尺度上对几毫克陨石样品进行准确稀有气体同位素分析的方法,克服了传统全岩熔融法在测量时存在样品用量大、前处理过程复杂和样品稀有气体分布不均导致不同组分的宇宙射线暴露历史无法进一步区分等问题。但是由于该方法所用样品体积小和样品用量低,要求实验室具有超低本底的稀有气体提取系统,目前国内在微量陨石稀有气体分析技术方面尚处于起步阶段。本文采用金刚石激光样品窗成功研制了超低本底的气体提取系统,通过系统体积标定和天平称量误差、热本底、干扰元素、质量歧视及质谱灵敏度等参数的校正,在中国科学院地质与地球物理研究所建立了微量陨石激光熔样稀有气体测定方法,并对毫克级微量钙长辉长无球粒陨石Millbillillie粉末标样进行了稀有气体同位素含量和比值测定,计算获得准确一致的宇宙暴露年龄。该方法的建立,将为我国迅速发展的比较行星学和深空探测提供重要技术支撑。 相似文献
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Elizabeth Keegan Stephan Richter Ian Kelly Henri Wong Patricia Gadd Heinz Kuehn Adolfo Alonso-Munoz 《Applied Geochemistry》2008
Elemental and isotopic ratio analyses of U ore concentrate samples, from the 3 operating U mining facilities in Australia, were carried out to determine if significant variations exist between their products, thereby allowing the U ore concentrate’s origin to be identified. Elemental analyses were conducted using inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence spectrometry (XRF). Lead isotope ratios were measured using ICP-MS and U isotope analyses were conducted using thermal ionisation mass spectrometry (TIMS). Minute quantities of sample, such as that obtained from a swipe, were also examined for elemental concentrations using secondary ion mass spectrometry (SIMS). The results of multivariate statistical analysis show clear patterns in the trace elemental composition of the processed U ores, indicating that it is possible to use this feature as a unique identifier of an Australian U ore concentrate’s source. Secondary ion mass spectrometry analyses also allow individual particles to be differentiated using this ‘fingerprinting’ technique. Isotope ratios determined using TIMS reveal that there is a significant difference in the n(234U)/n(238U) isotope ratio between the U ore concentrate from each mine. 相似文献
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NIU Yaoling 《《地质学报》英文版》2003,77(1):44-58
The authors measured Pb isotope compositions of seven USGS rock reference standards, i.e. AGV-1, AGV-2, BHVO-1, BHVO-2, BCR-2, BER-1/1 and W-2, together with NBS 981 using a micromass isoprobe multi-collector inductively-coupled plasma mass spectrometer (MC-ICP-MS) at the University of Queensland. 203Tl-205Tl isotopes were used as an internal standard to correct for mass-dependant isotopic fractionation. The results for both NBS 981 and USGS rock standards AGV-1 and BHVO-1 are comparable to or better than double- and triple-spike TIMS (thermal ionization mass spectrometry) data in precision. The data for BHVO-2 and, to a lesser extent, AGV-2 and BCR-2 are reproducibly higher for 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb than double-spike TIMS data in the literature. The authors also obtained the Pb isotope data for BIR-1/1 and W-2, which may be used as reference values in future studies. It is found that linear correction for Pb isotopic fractionation is adequate with the results identical to those corre 相似文献
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Precise and accurate in situ Pb-Pb dating of apatite, monazite, and sphene by laser ablation multiple-collector ICP-MS 总被引：3，自引：0，他引：3
B.J.A WilligersJ.A Baker E.J KrogstadD.W Peate 《Geochimica et cosmochimica acta》2002,66(6):1051-1066
To evaluate in situ Pb dating by laser ablation multiple-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS), we analysed apatite, sphene, and monazite from Paleoproterozoic metamorphic rocks from West Greenland. Pb isotope ratios were also determined in the National Institute of Standards and Technology (NIST) 610 glass standard and were corrected for mass fractionation by reference to the measured thallium isotope ratio. The NIST 610 glass was used to monitor Pb isotope mass fractionation in the low Tl/Pb accessory minerals. Replicate analyses of the glass (1 to 2 min) yielded ratios with an external reproducibility comparable to conventional analyses of standard reference material 981 by thermal ionisation mass spectrometry (TIMS). Mineral grains were generally analysed with a 100-μm laser beam, although some monazite crystals were analysed at smaller spot sizes (10 and 25 μm). The common Pb isotope ratios required for age calculations were either measured on coexisting plagioclase by LA-MC-ICP-MS or could be ignored, as individual crystals exhibit sufficient Pb isotopic heterogeneity to perform isochron calculations on replicate analyses of single crystals. Mean mineral ages with the 204Pb ion beam measured in the multiplier were as follows: apatite, 1715 ± 23 m.y.; sphene, 1789 ± 11 m.y.; and monazite, 1783 to 1888 m.y., with relative uncertainties on individual monazite ages of <0.2% but highly reproducible age determinations on single monazite crystals (?1%). Isochron ages calculated from several mineral analyses without assumption of common Pb also yield precise age determinations. Apatite and monazite Pb ages determined by in situ Pb isotope analysis are identical to those determined by conventional TIMS analysis of bulk mineral separates, and the analytical uncertainties of these short laser analyses with no prior mechanical or chemical separation are comparable to those obtained by TIMS. Detailed examination of the sphene in situ age data does, however, show a small discrepancy between the LA-MC-ICP-MS and TIMS ages (∼1% younger). High-resolution mass scans of the sphene during ablation clearly showed several small and as yet unidentified isobaric interferences that overlap with the 207Pb peak at the resolution conditions for measurement of isotope ratios. These might account for the age discrepancy between the LA-MC-ICP-MS and TIMS sphene ages. LA-MC-ICP-MS is a rapid, accurate, and precise method for in situ determination of Pb isotope ratios that can be used for geochronological studies in a manner similar to an ion microprobe, albeit currently at a somewhat degraded spatial resolution. Further modifications to the LA-MC-ICP-MS system, such as improved sensitivity, ion transmission, and LA methodology, may lead to this type of instrument becoming the method of choice for many types of in situ Pb isotope dating. 相似文献