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1.
应用多收集器等离子体质谱,采用双分馏系数内部校正法对国际标样Shin-EtsuJN di-1和实验室标样Nd-GIG的143Nd/144Nd比值进行了为期3个月的测量统计,结果分别为0.512121±0.000011(2σ,SD)、0.511531±0.000010(2σ,SD)。采用单分馏系数外部校正法对Nd-GIG标样的测量统计结果为0.511522±0.000008(2σ,SD)。测量结果在分析误差范围内与其推荐值或表面热电离质谱测量值完全一致。对m(Ce)/m(Nd)约为0.10的两份Nd-GIG混合样进行了测量,结果表明,利用多收集器等离子体质谱可直接分析残留铈的样品,其测量结果在误差范围内。 相似文献
2.
多接收器等离子体质谱是近年发展起来的高精度同位素分析手段之一,通过用等离子体质谱测量Nd国际标准材料La Jolla和JMC Nd203以及实际样品GBW04419,研究MC-ICPMS测量Nd的质量分馏特点,解决MC-ICPMS测量的关键所在质量分馏校正.通过修正分馏系数,可以实现理想的分馏校正.结果显示出所得到的分析精度达到热电离质谱的测量水平.具有实际地质样品代表性的实验室内部标准CAGS-Nd-1重现性长期分析结果为:143Nd/144Nd=0.512072±0.000008(2σ,n=140). 相似文献
3.
利用国内首次引进的Nu Plasma型MC-ICPMS,对Nd同位素测试过程的质量歧视效应特征进行了研究.发现该类仪器测试过程的质量歧视效应并不完全符合指数函数,也不符合幂函数.质量歧视引起的同位素分馏随同位素对的平均质量数变化,但不严格遵从线性关系.只是在较小质量范围内呈近似线性关系.据此,用双分馏系数校正法可以获得143Nd/144Nd的校正系数,并用来校正143Nd/144Nd值.用此方法获得的JNdi-1的143Nd/144Nd值为O.512 107±O.OOO 008(2RSD),在测量误差范围内与TIMS测定值完全吻合. 相似文献
4.
钕同位素比值(~(143)Nd/~(144)Nd)是Sm-Nd同位素方法的关键量值,由于被测样品的~(143)Nd/~(144)Nd比值变化范围很小,所以对~(143)Nd/~(144)Nd比值测试的精准度要求很高(精度优于0.005%)。为了获得高精度和高准确度的测试数据,分析过程中所用Nd同位素标准物质起着重要作用。以往的Nd同位素标准物质都是氧化钕,经过近三十年有的已消耗殆尽。本文阐述了钕同位素比值~(143)Nd/~(144)Nd标准溶液的研制,经检验标准溶液的均匀性和稳定性良好,由11家实验室协同定值,采用MC-TIMS和MC-ICP-MS方法测定~(143)Nd/~(144)Nd,确定了Nd同位素标准溶液的特性值~(143)Nd/~(144)Nd=0.512438,不确定度为5×10-6。此标准溶液于2015年5月获得国家标准样品证书(批号为GSB 04-3258—2015),可被用于地质、资源、海洋、环境、考古等多种样品~(143)Nd/~(144)Nd比值测定时的仪器校准和分析过程的质量监控。 相似文献
5.
SrNd同位素参数广泛应用于岩石物质来源及其成因研究,但绝大多数研究者在应用这些参数时并未说明它们的误差大小,这种做法并不科学。作者首次利用误差传播定律推导出了有关参数的误差估算公式,这些参数包括Sr同位素的初始比值(87Sr/86Sr)t、Nd同位素的初始比值(143Nd/144Nd)t、εSr(t)、εNd(t)、Nd同位素模式年龄等。Rb、Sr含量的高低及其测定误差决定着(87Rb/86Sr)s的误差,Sm、Nd含量的高低及其测定误差决定着 (147Sm/144Nd)s的误差,(87Rb/86Sr)s的大小及其误差、(87Sr/86Sr)s误差、年龄值大小及其误差共同影响着(87Sr/86Sr)t的误差。同样,(147Sm/144Nd)s的大小及其误差、(143Nd/144Nd)s 的误差、年龄值大小及其误差共同影响着(143Nd/144Nd)t的误差。Nd同位素球粒陨石模式年龄TCHUR和单阶段亏损地幔模式年龄TDM的误差影响因素主要包括(147Sm/144Nd)s的大小、(143Nd/144Nd)s 的大小及这两个比值的误差,而Nd同位素两阶段亏损地幔模式年龄TDM2的误差除上述影响因素之外,还包括年龄值大小及其误差。通过对广西姑婆山4个花岗岩样品SrNd同位素参数及其误差的计算,作者对各个影响因素进行了详细分析,认为采用同位素稀释质谱法测试数据和高精度的年龄数据是获得理想示踪参数的保证,Rb、Sr、Sm、Nd含量沿用微量（包括稀土）元素测试结果的做法是不可取的,对高Rb样品更应该谨慎从事。建议研究者在使用SrNd同位素参数时能够估算这些参数的误差,并在文章中有所说明。 相似文献
6.
样品放射性成因Sr-Nd同位素比值受控于源区初始同位素组成、放射性元素母体与子体相对丰度,以及衰变时间等因素。它们具有极强的示踪能力,因而在地质学领域有广泛的应用。传统的Sr-Nd同位素分析使用的是阳离子树脂,提纯Nd元素时往往涉及有机试剂以及调节pH值等操作,其分析效率较低。近年来特效树脂的出现使得分离这些元素变得简单,但是受硫酸根等因素影响,特效树脂使用次数有限。为了提高分析效率,缩短分析时间,本文开发了一种套柱法,该方法结合阳离子树脂和特效树脂,实现了Sr-Nd元素的快速分离,并且能延长特效树脂的使用寿命。实验采用阳离子树脂、Sr特效树脂和LN稀土特效树脂对玄武岩BCR-2标样进行了分析。Sr-Nd回收率均90%,BCR-2玄武岩~(87)Sr/~(86)Sr比值为0.705016±0.000016(n=36,1SD),~(143)Nd/~(144)Nd比值为0.512624±0.000012(n=39,1SD),与前人TIMS法获得的结果吻合(~(87)Sr/~(86)Sr:0.705000～0.705023;~(143)Nd/~(144)Nd:0.512630～0.512650)。最终分离提纯的溶液中~(85)Rb/~(86)Sr值小于0.01,~(147)Sm/~(144)Nd值小于0.001,表明该方法可以高效分离Rb-Sr和Sm-Nd,实现Sr、Nd同位素的准确分析。 相似文献
7.
火山岩及其相关岩右的全岩sm一Nd等时线年龄龄测定表明，安徽省歙县-休宁一带
泛分布的海相火山岩形成于12.86亿年前。这一结果证实皖南地区与江南古陆东南缘其它地段一
样，也存在两个元古代岛弧系，即位于南部江湾一街口二带的晚元古代岛弧系及位于北部歙县一
休宁一带的中元古代岛弧系。Nd同位素特征研究表明，歇县一休宁一带的火山岩的Sm/Nd比值
都大于或接近于0.318(球粒陨石的现代标淮值)，Nd的初始值(143Nd/144Nd)1=0.511187,ε(Nd)(t)=+3.9±0.4,位于亏损地幔演化线附近。因此堆断，歙县一休宁一带海相火山岩可能来自亏损地幔源。 相似文献
8.
<正>2015年7月,由中国地质科学院地质研究所同位素地质研究实验室研制的"钕同位素比值分析标准样品"获得中华人民共和国国家标准样品证书(编号及批号为GSB 04-3258-2015)。这是国内目前第一个获得国家标准样品证书的143Nd/144Nd比值标准样品,应用前景广泛。钕同位素比值分析标准样品是给定143Nd/144Nd特性量值的标准溶液,可用于地质、资源、海洋、环境、考古等多种样品143Nd/144Nd比值测定的仪器(热电离质谱和多接收等离子体质谱)校准和分析过程的质量监 相似文献
9.
147Sm- 143Nd放射性同位素体系在地球科学研究中得到了广泛的应用,经典的同位素稀释-热表面电离质谱法(ID-TIMS)一直是Sm-Nd同位素高精度测定的基准技术,但具有耗时长、成本高、样品需求量大等缺点,并且难以揭示微观尺度单矿物所蕴含的地球化学信息。近年来兴起的微区原位分析,具有简单、快速、高空间分辨率的特点,可以从微米尺度示踪岩浆和热液的起源及演化过程。本文通过同时测定Sm和Nd同位素质量分馏系数,实现 144Sm对 144Nd干扰的准确校正,获得了人造玻璃、磷灰石、榍石、独居石等几种不同基体标准样品(NIST610、Durango、MAD-2、BLR-1、117531)精确的 143Nd /144Nd比值,与推荐值在误差范围内一致。然而,由于Sm和Nd元素性质的差异,在激光剥蚀和质谱电离过程中会产生明显的元素分馏,导致 147Sm/ 144Nd很难进行精确校正,本文通过在进样系统中引入液态气溶胶,有效克服了基体效... 相似文献
10.
利用多接收器等离子体质谱建立了快速精确测定铼含量及其同位素丰度的方法。溶液中加入铱元素进行铼同位素的质量分馏校正,在常规的溶液雾化进样条件下,采用同位素稀释法可准确测定纳克级的铼含量。铼标样A的自然同位素丰度的测量结果为185Re(37.437±0.008)%、187Re(62.563±0.008)%(2σ,n=5);铼稀释剂的同位素丰度测量结果为185Re(5.576±0.018)%、187Re(94.424±0.018)%(2σ,n=7);与未进行分馏校正的同位素组成的测量结果相比,精度和准确度均有提高。利用同位素稀释法测得铼标样A的浓度为(516.48±0.35)ng/g(2σ,n=5);测量精度和准确度均优于0.10%;利用反同位素稀释法对铼稀释剂B进行了详细的测量,平均测量结果为(62.74±0.26)ng/g(2σ,n=15),在分析误差范围内与其标定值完全一致;与未进行分馏校正的浓度测量结果相比,铼同位素丰度及铼含量的测量准确度均明显提高。 相似文献
11.
牙形石作为划分地层的标准化石，具有确切的地层层位和较高的REE含量，并不容易受成岩作用的影响，因此作为研究古海水演化的指示剂引起人们的广泛关注．利用同位素稀释法对扬子克拉通三峡地区寒武纪一三叠纪海相碳酸盐岩中代表古海水化学组成牙形石的Sm／Nd比值进行测定，Sm／Nd比值在0．108-0．348之间，有较大的变化范围．建立Sm／Nd比值随时间的演化曲线，并结合已有沉积地层学和沉积地球化学的成果进行研究，结果表明，古海水Sm／Nd比值变化与海平面升降、古陆块的隆起有明显对应关系，同时，区域性构造运动，如海底地壳拉张产生的幔源组分和地幔柱活动也会影响古海水的Sm／Nd比值．因此，古海水的Sm／Nd比值对海平面的升降、古大陆的风化作用和区域构造事件有指示意义． 相似文献
12.
牙形石作为划分地层的标准化石, 具有确切的地层层位和较高的REE含量, 并不容易受成岩作用的影响, 因此作为研究古海水演化的指示剂引起人们的广泛关注.利用同位素稀释法对扬子克拉通三峡地区寒武纪—三叠纪海相碳酸盐岩中代表古海水化学组成牙形石的Sm/Nd比值进行测定, Sm/Nd比值在0.108-0.348之间, 有较大的变化范围.建立Sm/Nd比值随时间的演化曲线, 并结合已有沉积地层学和沉积地球化学的成果进行研究, 结果表明, 古海水Sm/Nd比值变化与海平面升降、古陆块的隆起有明显对应关系, 同时, 区域性构造运动, 如海底地壳拉张产生的幔源组分和地幔柱活动也会影响古海水的Sm/Nd比值.因此, 古海水的Sm/Nd比值对海平面的升降、古大陆的风化作用和区域构造事件有指示意义. 相似文献
13.
利用在南京大学成矿作用研究国家重点实验室建立的新一代高精度高灵敏度的表面热电离质谱仪 (TritonTI) ,可以实现比以往更高精度的Nd同位素测定。 3个国际溶液标样的反复测定结果NdLaJolla :14 3 Nd/ 14 4 Nd为 0 .5 1184 2± 4 ;NdJN di 1:14 3 Nd/ 14 4 Nd为 0 .5 12 10 4± 6 ;NdJMC :14 3 Nd/ 14 4 Nd为 0 .5 115 87± 10。 1个国际岩石标样的测试结果BCR 2 :14 3 Nd/ 14 4 Nd为 0 5 12 6 2 4± 3。上述测试结果与国际上很多实验室的测试结果一致 ,但测试精度优于以往。综合分析表明 ,利用这一最新型号的表面热电离质谱仪 (TritonTI) ,可以实现高精度的Nd同位素组成测试 ,测试精度一般优于 5× 10 -6。 相似文献
14.
湘东北文家市地区仓溪岩群为一套高绿片岩—低角闪岩相的变质岩系,其Sm—Nd全岩等时线年龄：2 090±20 Ma, ∑Nd（T）=5.4 ;2 030±8 Ma, ∑Nd（T）=5.7 代表了原岩形成年龄;1 860±17 Ma, ∑Nd（T）=5.0 代表样品形成年龄。因此,将其形成时代定格为古元古代,属华南陆壳结晶基底的一部份。 相似文献
15.
测定了 7 Ma B.P.以来灵台剖面红粘土和黄土-古土壤序列的酸不溶物 Sr和 Nd同位素组成.样品酸不溶物 87Sr/86Sr变化可明显分为两个阶段.第一个阶段,从 7 Ma B.P.到 2.5 Ma B.P.,为红粘土层,酸不溶物 87Sr/86Sr稳定位于高值,反映了东亚冬季风处于相对平稳的弱势.第二个阶段,从 2.5 Ma B.P.到现在,酸不溶物 87Sr/86Sr呈下降趋势,波动加强,反映了东亚冬季风不断增强,并且冬季风和夏季风交替变化加强. 7 Ma B.P.以来灵台剖面红粘土和上覆的黄土-古土壤的 Nd同位素组成一致,并揭示 7 Ma B.P.以来,北太平洋中部沉积物与黄土高原黄土都来自相同的物源区. 相似文献
16.
Basement rocks comprising ortho- and paragneisses and schists whose tectono-metamorphic evolution is poorly known, are exposed in the Sierras de Umango, Maz-Espinal and Las Ramaditas, in the northwest of the La Rioja Province, Argentina. These units were included in the Maz, El Taco, El Zaino complexes, as well as the Tambillos Metamorphics that would be part of the northern end of the Cuyania terrane, a microcontinent derived from Laurentia that collided with Western Gondwana during the early Paleozoic, or belong to the active margin of the continent. To recognize rocks belonging to each of these tectonic units and to understand the history and physical conditions of accretion were some of the main goals of the multidisciplinary investigation whose preliminary results are presented here. Geochemical studies, trace and REE elements and Sm-Nd model ages allowed the recognition of several episodes of crustal accretion in these rocks. The oldest one occurred at ca. 2.2 Ga in an arc/back-arc environment along the eastern segment of the Sierra de Maz, and was possibly coeval with development of a early Proterozoic continental crust that acted as source to sediments of Maz Complex. The following episode of crustal accretion that formed rocks in this region was at ca. 1.4 Ga and is registered by tonalites emplaced in an extensional environment cropping out in the western flank of the Sierra del Espinal. In the Sierra de Umango, an arc/back-arc sequence registered an episode of crustal accretion during the Grenvillian Cycle (ca. 1.3 Ga). The last episode of crustal accretion detected in this area (800 Ma) is represented by an old alkaline volcanism in the Sierra de Umango. This episode could be representing the first stage of break-up of the Rodinia supercontinent during the Neoproterozoic. The metamorphic grade reached by these rocks is mostly represented by fabrics with mineral assemblages of intermediate to high pressures and high temperatures, typical of collisional environments. The oldest rock-forming fabrics tectono-metamorphic episode recognized is of middle Proterozoic age (ca. 1.04 to 0.969 Ga, garnet-whole-rock Sm/Nd age) being registered by metapelites from Maz Complex that attained temperatures of 650°C-6.3 kbar. A younger metamorphic event (463 Ma, garnet - whole-rock Sm/Nd age) is verified in metatonalites intrusive in these metapelites. Another metamorphic event at ca. 301 Ma (garnet-WR Sm/Nd age) was recognized in metasediments from El Taco Complex. Peak metamorphic conditions of this event, probably registering the last major tectonic episode that affected rocks of this area was established in 868°C-9.8 kbar. It is impossible to distinguish fabrics belonging to totally different tectonic episodes based on structural or metamorphic data. Therefore, distinction between major tectono-thermal events of totally different ages such as the high-T middle Proterozoic deformation and with N-NWestwards tectonic transport direction registered in the Sierras de Maz-Espinal and Umango from the youngest one (ca. 301 Ma) that attained the highest-P/T conditions, recognized in the Sierra de Las Ramaditas, had to be done on the basis of Sm/Nd ages. Geophysical evidence indicates the presence of extensive WNW-oriented lineaments that separate basements blocks of different magnetic and gravimetric signatures that are thought to represent ancient Grenvillian age suture zones. On the other hand, the northern segment of the Valle Fértil lineament that runs between Sierras de Umango and Maz-Espinal is at present interpreted as marking the eastern boundary of the Cuyania terrane. This is supported by isotopic data as well as the contrasting history of tectono-metamorphic events as determined for both of these segments of the NW Sierras Pampeanas. 相似文献
17.
以硝酸钕、天然矿物电气石和钛酸丁酯为原料,采用凝胶法制备了电气石复合Nd/TiO2和钕掺杂TiO2。用XRD、UV-VIS、ESR对电气石复合Nd/TiO2材料进行了表征;以苯酚为目标降解物,考察了电气石复合Nd/TiO2材料的光催化活性。结果发现TiO2的相变转化区间在600~750℃范围内;电气石掺入对Nd/TiO2材料的光吸收范围基本没有影响,在300~750℃范围煅烧后,随温度升高UV-VIS图谱有逐渐红移现象;电气石的加入使得Nd/TiO2材料在光照及未光照条件下都起到增强.OH强度的作用;在Nd/TiO2材料中掺入0.6%的电气石获得最好的光催化活性,600℃下煅烧光催化效果较优。 相似文献
18.
A detailed Sm/Nd, epsilon Nd and Rb/Sr profile through a 30-cm thick section of Silurian (Llandovery) interbedded turbiditic and hemipelagic mudrocks from the central Wales Basin shows well-marked chemical and isotopic trends. The variations reflect an interplay of depositional mode and diagenetic fractionation. Sm and Nd values are substantially higher and Sm/Nd ratios tend to be lower in the organic-rich hemipelagite layers due to diagenetic concentration in the hemipelagites. There is a corresponding depletion in the turbidite mudstones. Epsilon Nd values range from −0·8 to −7·1 and this is attributed to diagenetic modification of Sm/Nd ratios causing scatter in back-calculated epsilon values. Rubidium–strontium ratios in this succession fall within a narrow range, due to homogenization during diagenesis. By contrast, data from a hemipelagite-dominated (condensed) succession near the northern margin of the Welsh Basin show a lower range of epsilon Nd values and a higher scatter of Rb/Sr values, consistent with less fluid throughput during burial compaction and hence less diagenetic redistribution in these rocks. These patterns demonstrate the sensitivity of mudrock trace element and isotope compositions to both small-scale sedimentary structure and large-scale basin architecture. 相似文献
19.
We examined seven ultramafic xenoliths from 1~3 Ma alkali olivine basalt reefs near the Eurasian continent and one sample of the host alkali basalt to identify the mantle wedge material and to constrain the origin and evolution of mantle beneath SW Japan. Six xenoliths are from Kurose and one xenolith is from Takashima, northern part of the Kyushu islands, SW Japan. The Sr and Nd isotopic ratios vary from 0.70416 to 0.70773 and from 0.51228 to 0.51283, respectively. The Kurose and Takashima xenoliths have higher Sr isotopic ratios and lower Nd isotopic ratios than those of the peridotite xenoliths from the other arc settings such as Simcoe and NE Japan. The Kurose xenoliths have less radiogenic Os isotopic ratios (187Os/188Os = 0.123–0.129) than the primitive upper mantle (PUM) estimate and limited variation compared to the other arc xenoliths. Their Os isotope compositions are rather similar to the ultramafic xenoliths from NE and east China. In addition, the samples of the Kurose and Takashima xenoliths plot along a mixing line between ultramafic xenoliths from SE and NE China and a slab component in Sr–Nd–Os isotopic space. Our results suggest that fragments of continental lithospheric mantle from the China craton may exist beneath Kurose and Takashima after the Sea of Japan expansion when the Japanese islands were rifted away from the Eurasian continent during Miocene. Later magmatism due to subduction of the Philippine Sea Plate beneath the SW Japan arc around 15 Ma ago may have introduced fluids or melts derived from slab component, interpreted to be oceanic sediments rather than altered oceanic crust, that possibly modified the original composition of the lithospheric mantle sampled by the peridotite xenoliths from Kurose and Takashima. 相似文献
20.
A new certified reference material, labelled GSB 04‐3258‐2015, for use as a 143Nd/ 144Nd isotope ratio reference has been prepared by the Institute of Geology, Chinese Academy of Geological Sciences, Beijing. Standardization Administration of the People's Republic of China provided the certification for this reference material. This report presents the reference 143Nd/ 144Nd isotope ratio and supporting production and certification procedures. The reference value was determined by an interlaboratory comparison of results from eleven participating laboratories using MC‐TIMS or MC‐ICP‐MS. The calibration of mass fractionation was conducted by using the exponential law, and the 143Nd/ 144Nd isotope ratios were normalised to the 146Nd/ 144Nd isotope ratio value of 0.7219. Isobaric interference of 144Sm on 144Nd was corrected using an interference‐free 147Sm/ 149Sm isotope ratio value for mass fractionation. GSB 04‐3258‐2015 shows sufficient homogeneity and stability for use as an international isotopic reference material. The certified value was calculated from the unweighted means of the results submitted by the participating laboratories. The 143Nd/ 144Nd isotope ratio value for GSB 04‐3258‐2015 is 0.512438, with a combined expanded uncertainty ( k = 2) of 5 × 10 ?6. Reference material GSB 04‐3258‐2015 is available upon request from the Institute of Geology, Chinese Academy of Geological Sciences, and may be used for accurate interlaboratory calibration of Nd isotope analysis. 相似文献
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