激光剥蚀信号在线平滑和去汞装置:原位微区铅同位素准确分析利器

<正>激光原位微区分析可在微观尺度上完成样品的元素定量分析或同位素组成测定,为研究成岩、成矿物质来源和追踪地壳与地幔演化历史提供了独特的观察视野。但是,激光剥蚀等离子体质谱的一些缺陷阻碍了地质样品的高精度、高空间分辨率分析,比如:剥蚀池的位置效应、低剥蚀速率下信号波动影响、激光剥蚀脉动式信号导致的光谱螺纹效应、高频激光剥蚀造成的元素分馏效应等。为此,一些学者设计了不同规格和样式的激光剥蚀信号平滑装置来克服这些问题。但是,这些信号平滑装置普遍还存在气体吹扫时间过长和降低激光剥蚀信号     

激光剥蚀等离子质谱微区分析在固体地球科学中的应用进展

当前分析化学技术正向着痕量微区方向发展。这使得我们能够用更小更少的样品直接得到更多的地球化学信息。在诸多微区测试技术中,激光剥蚀等离子质谱（LA-ICPMS）技术发展最快。其地质应用较广,激光探针等离子体质谱能够进行固体样品的微区微量元素和同位素的分析,具有灵敏度高、简便、快速的特点,同样具有在同位素定年上的潜力。近年来又研制出激光剥蚀多道接收等离子质谱（LA-MC-ICPMS）仪,使得微区同位素分析开始了新的革命。而多种微区技术综合应用为近几年分析地球化学新的趋势。     

激光剥蚀电感耦合等离子体质谱微区分析 进展评述

激光剥蚀电感耦合(LA-ICP-MS)等离子体以其高空间分辨率、高灵敏度、多元素同时测定并可提供同位素比值信息的检测能力在原位微区分析中已得到广泛应用。现从仪器的发展、基础研究等方面评述了近年来LA-ICP-MS微区分析的进展,重点介绍了与等离子体质谱(ICP-MS)联用的激光器(纳秒和飞秒激光器)的发展、校正方法、分馏效应及其在地球科学微量元素、同位素、包裹体分析中的应用。并简要地阐述了LA-ICP-MS分析技术存在的局限和发展趋势。     

激光剥蚀-电感耦合等离子体质谱线扫描技术的空间分辨率研究

激光剥蚀-电感耦合等离子体质谱(LA-ICP-MS)作为一项实用的技术被广泛应用于原位微区分析。在学者们更为关注的元素空间分布问题上,LA-ICP-MS线扫描较单点剥蚀具有更大的优势。线扫描过程中元素的空间分辨率是影响分析结果准确程度的因素之一。每个脉冲间的信号如果严重叠加会导致较低的空间分辨率。文章通过LA-ICP-MS的单脉冲剥蚀实验,研究了合成硅酸盐玻璃标准样品CGSG中不同元素的信号时间结构,及其对线扫描的空间分辨率的影响。结果表明,当激光束斑40 μm时,应用LA-ICP-MS进行线扫描测量空间分辨率能够满足线扫描技术分析的需求。     

193nm波长脉冲激光剥蚀地质样品的剥蚀速率变化规律

激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)技术广泛用来测量固体样品中的微量元素及同位素比值。然而在缺乏基体匹配校准条件下,发生在激光剥蚀过程中的元素分馏效应使得通常采用外标结合内标的方法很难准确量化待测元素的含量。不同岩石/矿物材料自身密度、表面张力、内部结构、元素成分等物理特性不同,对同一波长激光的吸收系数、反射系数、消光长度不同,导致相同实验条件下的激光对不同岩石/矿物剥蚀速率不同、剥蚀物体积不同、剥蚀后形成气溶胶粒子总数及粒径分布规律不同、在ICP中粒子化程度和效率也不同,最终待测元素分馏效应不同。建立了聚焦脉冲激光剥蚀不同基体材料动态物理模型,理论分析了激光脉冲宽度和能量密度对剥蚀速率影响的物理机制。采用193 nm波长的脉冲激光剥蚀不同地质标样NIST 614、NIST612、NIST610、BHVO-2G、BIR-1G、BCR-2G、橄榄石、石榴石、锆石。激光脉宽15 ns、束斑直径60μm、能量60 m J、频率8 Hz,脉冲数分别为25,50,100,150,200个,线性拟合后直线斜率值分别为0.140 44,0.138 05,0.124 13,0.099 11,0.093 87,0.105 39,0.113 86,0.051 22,0.09 341。实验结果表明,相同参数激光剥蚀不同基体时剥蚀速率(深度/脉冲个数)不同,玻璃标样比其它样品更易剥蚀。5 J/cm2能量条件下,平均剥蚀速率分别为169,159,155,118,104,116,115,62,88 nm/pulse;可见随着激光能量密度增加剥蚀速率缓慢增大,NIST614玻璃和石榴石剥蚀速率分别达到最大和最小。激光剥蚀地质样品剥蚀速率变化规律对理解剥蚀速率对元素分馏效应的影响、约束及校正具有理论意义和实践运用价值。     

微束面扫描分析对比

<正>原位微区微束分析技术提供了固体物质的元素及同位素组成的空间分布信息,已在地质、环境、考古和材料科学等领域获得了重要的应用。现有的原位微区微束分析技术包括电子探针,同步辐射,全反射微区分析,激光剥蚀-电感耦合等离子体质谱等。原位微区微束分析技术包括点分析和面扫描两种重要的技术,对于点的分析目前相对比较成熟,而对微束面扫描,目前仍存在一些问题。本文拟就地球科学中常用的三种微束(电子探针EMPA、激光剥蚀-电感耦合等离子体质谱LA ICP-MS和X     

激光剥蚀电感耦合等离子体质谱元素微区分析标准物质研究进展

激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)是目前地球科学分析领域的重要技术手段,元素微区分析标准物质研制是该分析技术发展的重要方向。本文对当前LA-ICP-MS元素微区分析标准物质的种类、元素分布以及应用上的优缺点和标准物质的制备方法进行了评述。现有的有证标准物质数量不多、种类不齐全,部分元素浓度较低,定值不确定度较大,应用上受到较大的局限性;研制标准也不成熟,均匀性检验方面尚未有统一的方法。本文参照岩石粉末标准物质均匀性检验方法提出了两步均匀性检验法,同时指出在标准物质种类方面,铂族元素及Au元素浓度适当、Pb-S等不同硫化物基体标准物质,以及化学成分不同的碳酸岩和磷酸岩基体标准物质是当前的迫切需求;在标准物质研制技术方面,纳米岩石粉末压片技术的研发、原位微区分析标准物质(固体)均匀性检验判别标准研究是亟待解决的问题。     

硫化物矿物中痕量元素的激光剥蚀-电感耦合等离子体质谱微区分析进展

第一行过渡金属元素及痕量贵金属元素高度富集在硫化物矿物中,常形成具有工业意义的矿床,使得硫化物具有重大的经济价值。对天然硫化物矿物中的这些痕量金属元素丰度及其分布的研究,在矿石成因学、经济地质学、环境地球化学等领域具有重要的应用价值。激光剥蚀-电感耦合等离子体质谱(LA-ICP-MS)微区分析技术是一种强大的痕量元素分析工具,非常适合直接分析硫化物矿物中痕量元素的浓度及其空间分布。由于硫化物的激光剥蚀特性与硅酸盐及氧化物不同,分析校准用的标准物质又极度缺乏,严重阻碍了这一技术在硫化物矿物微区分析中的应用。本文评述了硫化物简介、硫化物中痕量金属元素分析的意义、LA-ICP-MS微区分析技术在硫化物矿物痕量元素分析中的优势及近年来的应用进展、硫化物分析中的干扰与校准、包含铂族元素及金的硫化物标准物质的研制进展及合成硫化物标准物质最有应用前景的方法。     

锆石铀-铅定年激光剥蚀-电感耦合等离子体质谱原位微区分析进展

激光剥蚀-电感耦合等离子体质谱(LA-ICP-MS)技术是目前最常用的锆石U-Pb同位素年龄测定方法之一。该方法能够对单颗粒锆石内部年龄差异实现快速、准确的原位微区分析。文章总结了近年来激光剥蚀系统、ICP-MS技术以及LA-ICP-MS锆石U-Pb定年方法、相关应用实例研究的进展和现状。系统评述了激光发生器,剥蚀池,剥蚀参数(激光波长、脉冲宽度、剥蚀气体、孔径大小)以及四极杆和扇形磁场质谱仪对锆石U-Pb年龄数据的精度和准确度的影响。详细介绍了基于锆石年龄标准样品、标准溶液及其他标样的外标定量校准方法,单个U/Pb比值计算方法,普通铅校正方法以及同位素年龄与微量元素同时测定的方法。目前LA-ICP-MS锆石U-Pb定年技术主要应用于碎屑锆石的沉积物源区示踪和岩浆事件的年代学约束研究。     

非破坏性开放式激光剥蚀电感耦合等离子体质谱法原位测定大尺寸陶瓷样品主微量元素组成

激光剥蚀电感耦合等离子体质谱法(LA-ICP-MS)通常采用体积固定的封闭剥蚀池,大尺寸样品要经过切割或破碎,能够放入剥蚀池后才可以再进行LA-ICP-MS分析,因此,这种常规密闭式LA-ICP-MS难以应用于无法破碎的珍稀大尺寸样品分析。为实现大尺寸样品的非破坏性微区原位主微量元素分析,本文基于自行设计的开放式样品采集口,结合气体交换装置,建立了开放式LA-ICP-MS分析方法,以大尺寸陶瓷圆盘样品为例,实现了其未经破碎即可直接在敞开的空气环境中进行微区原位主微量元素含量分析。最佳气流速下的氦气作为屏蔽气,在开放式样品采集口周围形成屏障,将激光剥蚀点与空气隔开,同时激光剥蚀产生的分析物气溶胶被屏蔽气聚拢并携带,在样品采集口负压的作用下进入传输管路,通过气体交换装置,高纯氩气置换掉气溶胶中混入的空气,最后进入等离子体质谱被检测。为验证该方法的准确性,将大尺寸陶瓷样品破碎后对开放式LA-ICP-MS分析点邻近区域进行常规密闭式LA-ICP-MS分析,两种方法所检测的51个元素中大部分元素相对误差小于10%,仅部分元素(如磷铍钪钇镧钐铕镝铪钨等)因含量极低相对误差高于20%,显示开放式LA-ICP-MS法具有较好的分析准确度,适用于对大尺寸样品的非破坏性微区原位主微量元素分析。     

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.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)