钾同位素的高效分离及MC-ICP-MS高精确测定

钾(K)在地球科学、生物科学、环境科学等领域有广泛应用。为了高效地从地质、生物、环境等样品中分离纯化K并进行其同位素测定，经反复实验和优化，建立了适用于不同样品中K同位素的高效分离和多接收电感耦合等离子体质谱测定方法。选取AG 50W-X8树脂(200～400目),以0.5 mol/L HNO₃为淋洗液，过柱一次，即可实现K的完全纯化分离，其回收率均大于99.9%,空白(约10 ng)。对于基体元素(Li、Na、Mg、Al、V、Cr、Ca等)含量较高的样品，建议二次过柱分离纯化。分离纯化的样品在MC-ICP-MS上采用“冷等离子体+低分辨”方法进行测定。标准物质(岩石标样、煤标样和生物质标样)的测试结果与前人分析结果一致，δ⁴¹K值的长期精度均好于0.06‰,且重现性较高。     

铁同位素的MC-ICP-MS测定方法与地质标准物质的铁同位素组成

详细报道了在低分辨和高分辨模式下运用MC-ICP-MS进行Fe同位素比值高精度测试的方法,对Fe同位素测定过程中谱峰干扰、基质效应、浓度效应、仪器测试的长期重现性等问题进行了评估,并对两种运行模式的测试结果进行了对比.在95%的可信度范围内,所建方法的外部精度优于0.5ε/ainu,达到国际同类实验室的先进水平,并且低分辨和高分辨两种模式下获得的Fe同位素测试结果是一致的.在此基础上对国家地质标准物质GBW07105(玄武岩)和GBW 07111(花岗闪长岩)进行了Fe同位素测定.相对于Fe同位素国际标样IRMM-014,GBW07105的Fe同位素成分为:ε57Fe=1.9±0.3(20),ε56Fe=1.3±0.2(2σ),ε57/56Fe=0.6±0.1(2σ);GBW 07111的Fe同位素成分为:ε57Fe=1.8±0.4(2σ),ε56Fe=1.2±0.2(2σ),ε57/56Fe=0.6±0.1(2σ).     

地质样品中高精度铬同位素分析纯化技术研究进展

随着多接收器热电离质谱仪(MC-TIMS)和多接收器电感耦合等离子体质谱仪(MC-ICP-MS)的发展,高精度铬(Cr)同位素测试已成为可能。铬同位素在地球、环境、农业生态和宇宙化学等科学领域中已显示出良好的应用潜力。然而,样品的纯化分离、干扰和仪器质量分馏的校正,依然是制约铬同位素高精度测试的重要因素。本文在近年来铬同位素分析技术最新进展的基础上,结合本课题组已有的研究,对陨石、地质和环境等各类样品中铬同位素的分离纯化方法、MC-ICP-MS测试中干扰与质量歧视校正等进行了详细综述。本文认为,阴阳离子树脂交换联用与过硫酸钾等强氧化剂的结合,可以进行低铬高基质样品的有效纯化,是一种较为普适性的纯化方法。使用铬同位素双稀释剂校正质量歧视效应,在MC-ICP-MS的中高分辨与静态测量模式下,不仅可以有效分开多原子离子的干扰,而且也可以进行高精度铬同位素分析,其δ~(53/52)Cr的分析精度与TIMS相当,可以达到0.04‰(2SD),且最低测试浓度可低至10ng,能够实现超微量铬的同位素分析。     

大型多接收等离子体质谱测定地质样品的硅同位素

使用Nu Plasma 1700型MC-ICP-MS的高分辨模式并采用标准-样品交叉法(SSB)测定Si同位素比值,以减少质谱干扰和仪器质量歧视对测定结果的影响。结果表明样品与标准样之间的Si浓度差异程度与Si同位素测量值呈正相关关系,样品与标准样的Si浓度差异低于20%时,Si同位素测量值差异小于0.04‰。测试部分国际常用标准样品的Si同位素组成,结果与文献报道值在误差范围内一致,δ~(30)Si测量精度优于0.07‰/amu。     

大型高分辨率多接收等离子体质谱准确测定地质标样的铁同位素组成

使用AGMP-1M阴离子交换树脂提纯样品中的Fe同位素,利用Nu1700大型多接收等离子体质谱在高分辨率模式下测定铁同位素比值,采用标样-样品交叉法校正仪器的质量歧视效应,对回收率、化学流程本底、酸度效应、浓度效应进行了检验,建立了可靠的高精度铁同位素分析技术。本文测定了常用地质标准样品(BCR-2,BHVO-2,AGV-2,GSR-2,GSR-3)的Fe同位素组成,测定结果与文献报道值在误差范围内一致,其测试精度优于(BCR-2,BHVO-2,AGV-2,GSR-3)0.03‰(2SD)。GSR-2可能受Fe含量较低(TFe_2O_3=4.95%)和均一性的影响,获得的δ~(56)Fe和δ~(57)Fe的测试精度分别为0.05‰和0.07‰(2SD)。     

铈同位素研究进展

铈作为一种重要的稀土元素,广泛存在于各种地质储库,并参与到成岩成矿作用。铈是少数具有可变价态(Ce³⁺,Ce⁴⁺)的稀土元素,由此导致的铈异常被广泛应用于示踪氧化还原条件变化。随着质谱技术的不断发展,铈同位素的高精度测量得以实现,并在地质测年、示踪氧化还原状态等方面取得了重要进展。本文在前人研究的基础上,对铈同位素的测试方法进行了小结。铈同位素测试主要利用热电离质谱(TIMS)和多接收电感耦合等离子体质谱(MC-ICP-MS)完成,测试精度最高可达到0.02‰(2SD)。随后结合最新的研究成果,较全面的总结了铈同位素在不同地质储库(如天体、海洋等)中的组成特征以及不同环境条件下(如低温、不同pH值等)的分馏机制,指出铈同位素在不同温度体系下的分馏机制仍然缺少模拟实验的验证和理论计算的支持。最后梳理了铈同位素在示踪物质来源、沉积环境以及地质测年等方面的应用,显示了铈同位素具有较大的应用潜力。     

高分辨电感耦合等离子体质谱法测定地质样品中稀土元素的氧化物干扰研究

电感耦合等离子体质谱(ICP-MS)用于测定稀土元素经常会引起M+、MO+、MOH+离子的质谱重叠干扰,其中制约分析准确度和精密度的主要因素是多原子离子干扰,尤其是轻稀土元素的氧化物和氢氧化物对重稀土元素的干扰,以及钡的7个天然同位素形成的氧化物和氢氧化物对轻稀土元素的干扰.本文采用高温高压密闭消解地质样品,高分辨电感耦合等离子体质谱法(ICP-MS)测定其中的痕量稀土元素,研究了低、中、高三种分辨率模式下氧化物的干扰情况,确定了最佳的测定同位素和合适的分辨率.分析结果表明,在低、中分辨率模式下,轻稀土元素Ce、Pr、Nd、Sm的氧化物和Ba的氧化物干扰明显,Gd元素的测定值严重偏离;在高分辨模式下,Ba氧化物对Eu的干扰以及大部分轻稀土元素氧化物对重稀土元素的干扰基本可以消除,无需进行校正,而只有157Gd受到141pr16O的干扰突出,当样品中Pr/Gd的浓度比值大于100时,Gd的测量值必须进行数学校正.     

钙同位素化学分离方法研究

报道了在本实验室建立的地质样品钙同位素化学分离方法。通过对比不同离子交换柱类型、树脂体积、淋洗酸浓度及类型、上样量及样品岩性等影响化学分离效果的因素,确定了采用AG MP-50(100-200目)树脂及HCl淋洗的化学分离流程。该流程在确保高回收率的条件下实现了Ca与K、Sr等干扰元素的有效分离和质谱测量过程中基体效应的有效控制,经这套化学分离方法提纯的NIST SRM 915a、IAPSO大西洋标准海水及一些USGS标样的测试结果与文献值在误差范围内一致,表明本文建立的化学分离流程可满足热电离质谱(TIMS)高精度测定地质样品钙同位素的要求。     

铅锌矿床地质样品的Ge同位素预处理方法研究

目前Ge同位素研究主要局限于地球有机质(煤等)、火成岩及陨石样品,作为Ge重要储库之一的铅锌矿床,其Ge同位素的研究涉及较少。铅锌矿床样品中Ge的化学分离及提纯是Ge同位素研究的基础。本文详细考察了陨石样品中Ge同位素预处理方法(分离和提纯)对铅锌矿石样品的适用性。阴离子条件实验说明,目前普遍采用的离子交换树脂单柱法虽然对铅锌矿样品中Fe、Se等元素的剔除效果理想,但无法有效剔除其中的Zn,当Zn/Ge比值大于3时,样品必须经过阳离子交换树脂柱作进一步处理剔除Zn。通过对闪锌矿标准样品、锌矿石标准样品的条件实验以及实际闪锌矿样品对条件结果的验证显示,当闪锌矿的称样量为0.15 g左右时,仅需将前人对玄武岩等样品Ge同位素处理方法中阴离子树脂洗脱酸(1.4 mol/L硝酸)的用量6 mL调整为10 mL,而阳离子树脂洗脱方法保持不变,此方法即满足闪锌矿样品Ge同位素的化学分离和提纯要求。样品经过本文推荐的阴阳离子交换树脂双柱法处理后,主要干扰元素(Fe、Zn、Se、Ni)及基质元素的剔除率接近100%,Ge的回收率优于99%。而前人对玄武岩等样品的Ge同位素处理方法中,主要干扰元素(Fe、Zn、Se、Ni)及基质元素的剔除效果亦较好,但Ge的回收率仅为97.3%,比本文推荐方法的Ge回收率要差。利用MC-ICP-MS对Ge化学分离和提纯后的富乐铅锌矿床闪锌矿样品的检验结果显示,测试过程中未见同质异位素以及可能的多原子离子影响,样品中Ge同位素符合质量分馏定律,经过调整后的阴阳离子交换树脂双柱法满足闪锌矿样品的Ge同位素测试要求。     

高Rb/Sr岩石样品中Sr同位素多接收等离子体质谱分析校正方法研究

在利用多接收电感耦合等离子体质谱(MC-ICPMS)进行Sr同位素研究中,⁸⁷Rb对于⁸⁷Sr干扰严重。岩石样品经化学分离后,若Rb/Sr≤0.0005,可以采用传统的Rb干扰扣除方法对⁸⁷Sr/⁸⁶Sr测定值进行准确校正;但如果样品经化学分离后仍含有较高的Rb/Sr比,同量异位素的干扰不能完全消除,则无法准确校正⁸⁷Sr/⁸⁶Sr测定值,直接影响测试结果的准确度。本文针对Rb含量较高的地质样品设计两组实验,确定了⁸⁷Sr/⁸⁶Sr同位素比值与Rb/Sr元素含量比值的关系曲线,并在理论分析的基础上,提出包含同位素分馏校正在内的重叠干扰校正方法。通过实际地质样品验证,该校正方法在较高含量Rb元素共存(Rb/Sr<0.2)的Sr纯化液中,能够较为准确地测量⁸⁷Sr/⁸⁶Sr同位素比值,降低了MC-ICPMS分析地质样品中Sr同位素时对化学分离步骤的要求。而对于Rb/Sr>0.2的地质样品,因仪器分馏效应和记忆效应影响,测试精确度大大降低,无论采用何种校正方法均无法得到准确的Sr同位素组成。     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Late Wuchiapingian (Late Dzhulfian,early Late Permian) limestone olistolites within the Tertiary flysch of Glypia Unit (Mount Parnon,central–eastern Peloponnesus,Greece)

Some olistolites reworked in a Tertiary flysch of Mount Parnon (Peloponnesus, Greece) exhibit a Late Permian assemblage, dominated by Paradunbarula (Shindella) shindensis, Hemigordiopsis cf. luquensis and Colaniella aff. minima. This association corresponds to the Late Wuchiapingian (=Late Dzhulfian), a substage whose algae and foraminifera are generally little known. Contemporaneous limestones crop out in the middle part of the Episkopi Formation in Hydra, but they are rather commonly reworked in Mesozoic and Cainozoic sequences. The palaeobiogeographical affinities shared by the foraminiferal markers of Greece, southeastern Pamir, and southern China, are very strong (up to the specific level), and are congruent with the Pangea B reconstructions. To cite this article: E. Skourtsos et al., C. R. Geoscience 334 (2002) 925–931.     

PALEONTOLOGY

正20141596 Liu Yunhuan(School of Earth Sciences and Resources,Chang’an University,Xi’an 710054,China);Shao Tiequan Early Cambrian Quadrapyrgites Fossils of Xixiang Boita in Southern Shaanxi Province(Journal of Earth Sciences and Environment,ISSN1672-6561,CN61-1423/P,35(3),2013,p.39-43,3 illus.,20 refs.)     

GEOCHEMICAL EXPLORATION

正20141719 Chen Zhijun(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China);Chen Jianguo Automated Batch Mapping Solution for Serial Maps:A Case Study of Exploration Geochemistry Maps(Journal of Geology,ISSN1674-3636,CN32-1796/P,37(3),2013,p.456-464,2 illus.,2 tables,10 refs.)     

MICROPALAEONTOLOGY

正20140962 Chen Fenning(Xi’an Institute of Geology and Mineral Resources,Xi’an710054,China);Chen Ruiming Late Miocene-Early Pleistocene Ostracoda Fauna of Gyirong Basin,Southern Tibet(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,87(6),2013,p.872-886,6illus.,56refs.)     

PETROLOGY

正1.IGNEOUS PETROLOGY20142008Cai Jinhui(Wuhan Center,China Geological Survey,Wuhan 430205,China);Liu Wei Zircon U-Pb Geochronology and Mineralization Significance of Granodiorites from Fuzichong Pb-Zn Deposit,Guangxi,South China(Geology and Mineral Resources of South China,ISSN1007-3701,CN42-1417/P,29(4),2013,p.271-281,7illus.,     

ENVIRONMENTAL GEOLOGY

正20141205Cheng Weiming(State Key Laboratory of Resources and Environmental Information System,Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China);Xia Yao Regional Hazard Assessment of Disaster Environment for Debris Flows:Taking Jundu Mountain,Beijing as an     

PROSPECTING EXPLORATION

正20141266Fan Chaoyan(Guangdong Provincial Key Laboratory of Mineral Resources and Geological Processes,Guangzhou 510275,China);Wang Zhenghai On Error Analysis and Correction Method of Measured Strata Section with Wire Projection Method(Journal of