激光剥蚀电感耦合等离子体质谱测定岩石样品中稀土元素

以NIST612玻璃标准为外标校正物质, 采用42Ca为内标校正灵敏度漂移、基体效应、剥蚀效率及进样量的变化.将LSX-2 0 0激光剥蚀进样系统与POEMSIII电感耦合等离子体质谱仪联用, 对国际标准物质BCR-2 (玄武岩) 及国内标准物质GSR-11 (花岗岩) 玻璃熔饼进行了稀土元素的测定, 建立了LA -ICP -MS整体分析岩石样品中稀土元素的方法.结果表明, 绝大多数稀土元素准确度优于15 %, 测定精度(RSD) 小于10 %.稀土元素的检出限(LOD) 在21.4×10-9~23 1.6×10-9之间, 样品分析速度为2 0样品/h.在Excel软件下用VBA语言编制宏, 实现了脱机数据处理的自动化, 极大提高了工作效率.      

碳酸盐岩常用主微量元素、同位素分析测试结果差异性探讨: 基于川中下寒武统龙王庙组实例研究*

碳酸盐岩研究中存在多种微量元素、同位素测试方法,为进一步探究各测试手段实际获取地化信息之间是否存在差异?能否进行比对?以川中下寒武统龙王庙组碳酸盐岩样品为例,通过对比研究中常用的主微量元素测试(电子探针[EPMA]、激光剥蚀—等离子质谱[LA-ICP-MS]、溶液法微量[ICP-OES])、氧同位素测定(原位离子探针[in-situ SIMS]、酸溶粉末)结果,揭示讨论各测试结果的差异性,旨在为降低地化信息的多解性提供经验依据。研究发现: (1)各测试手段(EPMA、LA-ICP-MS、ICP-OES)之间的差异性客观存在,但测试结果偏差整体随着所测元素实际浓度的增高而降低。对于主量元素(>10%)各测试结果偏差小于2%;富集元素(>1000 μg/g)各测试结果处于测试误差之内,结果偏差小于6%;微量元素浓度区间(100~1000 μg/g)各测试结果偏差显著增大,并且LA-ICP-MS与ICP-OES结果偏差要小于LA-ICP-MS与EPMA结果偏差,前者偏差幅度由6%增至45%,后者偏差幅度由9.1%增至151%;在低于100 μg/g元素浓度区间,受矿物内非均质性影响LA-ICP-MS与ICP-OES的测试结果可相差几倍。(2)微区原位限定下,EPMA测试结果在邻近检测线区间(100~300 μg/g)与LA-ICP-MS结果偏差逐渐加大,推测此偏差变化是由EPMA结果矫正过程中对低含量元素的矫正补偿机制所造成。(3)in-situ SIMS氧同位素值揭示了矿物微区尺度上的 δ¹⁸O 值差异,但其整体测试结果与传统酸溶法测试的结果存在0.5‰~2.5‰ V-PDB的负偏偏差,推测此偏差可能来自于标样矫正转换误差。(4)实例样品中可见阴极发光特征与Fe、Mn含量无关的现象,故成岩流体判定更需结合岩石学、地化证据探讨。     

碳酸盐岩常用主微量元素、同位素分析测试结果差异性探讨: 基于川中下寒武统龙王庙组实例研究*

碳酸盐岩研究中存在多种微量元素、同位素测试方法,为进一步探究各测试手段实际获取地化信息之间是否存在差异?能否进行比对?以川中下寒武统龙王庙组碳酸盐岩样品为例,通过对比研究中常用的主微量元素测试(电子探针[EPMA]、激光剥蚀—等离子质谱[LA-ICP-MS]、溶液法微量[ICP-OES])、氧同位素测定(原位离子探针[in-situ SIMS]、酸溶粉末)结果,揭示讨论各测试结果的差异性,旨在为降低地化信息的多解性提供经验依据。研究发现: (1)各测试手段(EPMA、LA-ICP-MS、ICP-OES)之间的差异性客观存在,但测试结果偏差整体随着所测元素实际浓度的增高而降低。对于主量元素(>10%)各测试结果偏差小于2%;富集元素(>1000 μg/g)各测试结果处于测试误差之内,结果偏差小于6%;微量元素浓度区间(100~1000 μg/g)各测试结果偏差显著增大,并且LA-ICP-MS与ICP-OES结果偏差要小于LA-ICP-MS与EPMA结果偏差,前者偏差幅度由6%增至45%,后者偏差幅度由9.1%增至151%;在低于100 μg/g元素浓度区间,受矿物内非均质性影响LA-ICP-MS与ICP-OES的测试结果可相差几倍。(2)微区原位限定下,EPMA测试结果在邻近检测线区间(100~300 μg/g)与LA-ICP-MS结果偏差逐渐加大,推测此偏差变化是由EPMA结果矫正过程中对低含量元素的矫正补偿机制所造成。(3)in-situ SIMS氧同位素值揭示了矿物微区尺度上的 δ¹⁸O 值差异,但其整体测试结果与传统酸溶法测试的结果存在0.5‰~2.5‰ V-PDB的负偏偏差,推测此偏差可能来自于标样矫正转换误差。(4)实例样品中可见阴极发光特征与Fe、Mn含量无关的现象,故成岩流体判定更需结合岩石学、地化证据探讨。     

鄂东南铜山口铜(钼)矿床黑云母矿物化学特征及其对岩石成因与成矿的指示

在鄂东南铜山口铜(钼)矿床存在着3种产状的黑云母,分别是赋存于花岗闪长斑岩矿物颗粒间的黑云母、钾长石斑晶内的黑云母以及蚀变带内的黑云母。本文运用电子探针(EMPA)和激光剥蚀-等离子体质谱(LA-ICP-MS)技术,对这3种不同产状的黑云母进行了原位成分分析。结果表明,3种产状的黑云母Ti的含量介于0.38～0.45之间,且Mg/(Mg+Fe)介于0.53～0.72之间,类似于岩浆成因黑云母的成分特征。3种产状的黑云母MgO和FeOT值差别较大,但Al2O3、TiO2、SiO2、Na2O和K2O值差别不明显。作为花岗闪长斑岩质熔体中Rb、Ba、Nb、Ta等不相容元素及Sc、V、Co、Ni、Cr等相容元素的主要载体,黑云母的U、Th、Pb、Sr、Zr、Hf、Y等元素含量显著低于主岩,而且高场强元素Nb、Ta受后期岩浆热液作用的影响较弱。黑云母并不是影响全岩稀土特征的主要矿物相。铜山口花岗闪长斑岩的形成与幔源岩浆作用关系密切,并可能与板块俯冲作用相关。黑云母含Cu量的高低并不是衡量侵入体是否成矿的有效指标,但体系中高的氧逸度(logfO2NiNiO+1),有利于斑岩铜矿的形成。与Cu成矿有关的黑云母具有高镁低铁的特征,与Sn成矿有关的黑云母则具有高铁低镁的特征。     

玄武岩全岩元素含量快速、准确分析新技术:双铱带高温炉与LA-ICP-MS联用法

全岩样品主元素和微量元素的准确测试是地球科学研究的重要手段和依据.传统溶液进样ICP-MS元素测试方法制样和测试所需周期较长(两周以上).相对溶液进样法而言,激光剥蚀系统与ICP-MS联用测试全岩粉末熔融玻璃的方法可以大大地提高测试效率.在前人研究基础上,针对前人熔融制样中Pb、Zn元素的严重丢失问题,研究了Pb、Zn...     

西藏班戈地区重要矽卡岩型铁（铜）多金属矿床LA-ICP-MS锆石U-Pb测年与花岗岩地球化学特征

选择班戈县雪如、查朗拉2个重要的小型矽卡岩型铁铜矿床为研究对象,在系统的野外地质调查、样品采集和室内岩矿鉴定、分析测试工作的的基础上,开展了2个矿床LA-ICP-MS锆石U-Pb测年与花岗岩地球化学研究。LA-ICP-MS方法测定的锆石U-Pb年龄显示,雪如、查朗拉地区成矿岩体年龄分别为79.72Ma±0.50Ma和76.10Ma±0.40Ma,证明班戈地区存在晚白垩世的岩浆活动。2个岩体的SiO2含量介于70.45%～72.64%之间,K2O（4.62%～5.69%）的含量均高于Na2O（3.05%～3.75%）的含量,CaO的含量偏低（1.32%～2.03%）,富K。A/CNK均小于1.0,A/NK范围为1.03～1.30,为准铝质类型。显示富K特征。在微量元素蛛网图中,富集大离子亲石元素Ra、Th、U、Nd,贫Nb。稀土元素配分模式属于右倾型,∑REE=199.08×10-6～268.41×10-6,LREE/HREE=4.71～7.68,具有中等的负Eu异常。岩体为同碰撞期花岗岩类,具有良好的铁铜铟铋等多金属成矿地质、地球化学条件,显示有良好的找矿前景。     

SIMS测定玻璃固化样品中铀分布的分析方法研究

玻璃固化是一种常用的高放废液固化方法,其优点在于具有较高的抗化学介质侵蚀的能力和很好的辐照稳定性、热稳定性和机械稳定性,其不足之处在于抗水浸出等性能有所下降而使其安全性需要进一步通过抗浸出实验来进行衡量和确认。使用二次离子质谱(SIMS)分析玻璃固化体中的放射性成分(如铀元素)的分布及浸出行为等各项指标,是一种评估玻璃固化体抗浸出性能的分析手段。本文应用SIMS测试模拟玻璃固化体,以碳作为镀膜材料通过真空蒸发镀碳的方法优化样品制备条件,有效地解决了样品导电性差的问题,~(235)U/~(238)U同位素测定结果约为7.9‰±0.395‰,基本符合制作模拟样品时所使用的天然铀的同位素特征(~(235)U/~(238)U参考值约7.3‰)。研究表明,建立的方法实现了铀元素同位素丰度的测量,能直接显示铀的分布情况,该方法可为研究玻璃固化体中放射性元素的浸出行为提供一定的技术支持。     

胶东金翅岭金矿床黄铁矿原位微量元素和硫同位素特征及对矿床成因的指示

位于招远-莱州金成矿带中西部的金翅岭金矿床是胶东地区典型的石英脉型高品位金矿,但其成矿流体来源和矿床成因一直存在争议.在详细的矿相学和黄铁矿显微结构研究基础上,利用LA-ICP-MS技术原位分析与成矿有关黄铁矿的微量元素特征,结合原位硫同位素分析成矿流体来源,为进一步认识矿床成因提供制约.成矿阶段的黄铁矿划分为2种类型（PyI和PyII）,PyI产在石英-黄铁矿阶段,PyII产在石英-多金属硫化物阶段,伴随大量可见金的出现.根据背散射的核-边结构,PyII可细分为含有较多硫化物的核部PyIIa和表面较为干净的边部PyIIb,但二者有明显溶蚀结构.LA-ICP-MS分析结果显示PyI含有一定量的Au（< 0.015×10-6~2.18×10-6,均值0.62×10-6）和As（78.98×10-6~857×10-6,均值542×10-6）,但Pb、Zn等其他元素含量较低.核部PyIIa和PyI微量元素分布特征较为相似,但Au（< 0.015×10-6~0.59×10-6,均值0.11×10-6）和As（0.62×10-6~198×10-6,均值35.81×10-6）的含量相对下降.边部PyIIb较核部PyIIa明显富集Au（< 0.015×10-6~19.71×10-6,均值5.91×10-6）和As（399×10-6~18 153×10-6,均值6 412×10-6）,且Au与As表现出良好的正相关性.PyI和核部PyIIa原位δ34S的分布范围较为一致,集中在3.0‰~4.9‰;而边部PyIIb的原位δ34S值较高（5.2‰~6.6‰）.根据黄铁矿结构、微量元素和硫同位素特征,推断在主成矿期富34S和富Au-As的热液流体加入形成了边部PyIIb且与核部的PyIIa发生了交代作用,同时大量可见金直接从热液中沉淀形成.该研究表明多期次富Au-As成矿流体的注入可能是高品位石英脉矿床形成的主要机制.      

Trace Element Analysis of Fused Whole-Rock Glasses by Laser Ablation-ICP-MS and PIXE

The concentrations of fifty trace elements, including relatively volatile elements and transition metal elements, in fused glasses of Geological Survey of Japan rock reference materials GSJ JR-2, JA-1, JA-2, JB-1a, JB-3, JGb-1 and JF-1 were determined by particle (proton) induced X-ray emission (PIXE) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The fused glasses were prepared by rapid fusion and subsequent quenching in welded platinum capsules and were found to be homogeneous for major elements and for trace elements with concentrations of more than 1 μg g^-1 within the observed precision (± 10% mean) on a 70 μm sampling scale. The values obtained by PIXE and LA-ICP-MS for the transition elements (Cr, Mn, Fe, Ni and Cu), the relatively volatile elements (Zn, Ga, Rb and Pb) and the refractory elements (Y, Zr, Nb and Th) with concentrations greater than a few μg g^-1 showed good agreement (within 10 % relative difference). The values for almost all the elements detected at concentrations higher than 1 μg g^-1 as determined by LA-ICP-MS also agreed well with the reference values (mean relative difference < ± 10%), except for B and Cu. The good agreement confirmed the appropriateness of the NIST SRM 600 series glass calibration reference material for LA-ICP-MS analysis of glasses with variable major-element compositions for almost all elements. The concentrations of Cu in all the samples were lower than the reference values, which was attributed to adsorption of the transition metals onto the platinum capsule during preparation.     

青海治多地区晚三叠世石英闪长岩地球化学特征及成岩动力学背景

对羌塘地块东北缘甘孜-理塘缝合带南侧日啊日曲石英闪长岩进行了系统的锆石U-Pb年龄、主量-微量元素及Sr-Nd同位素分析, 以探讨其岩石成因及地球动力学意义.LA-ICP-MS锆石U-Pb定年结果表明, 石英闪长岩侵位年龄为218±1 Ma, 为晚三叠世岩浆活动的产物.岩石SiO₂含量介于53.02%~62.06%之间, 富Al₂O₃(15.84%~17.00%)和CaO(6.71%~8.94%), 贫TiO₂(0.49%~1.01%)和P₂O₅(0.04%~0.12%), 具有较高的MgO(3.31%~5.66%)和Mg#(50~62), 属准铝质钙碱性系列; 岩体稀土元素总量较低(38.05×10-6~61.58×10-6), 轻重稀土分馏不明显, LILE富集, HFSE亏损, 具有含量较高的Cr(33.45×10-6~176.64×10-6)和Ni(13.34×10-6~43.62×10-6).全岩(87Sr/86Sr)_i比值较为一致(0.706 8~0.707 9), ε_Nd(t)变化于-5.5~-1.6.主微量元素及同位素结果表明日啊日曲石英闪长岩具有高镁闪长岩的特征, 与赞岐岩地球化学特征类似, 为俯冲沉积物来源的熔体交代岩石圈地幔形成的尖晶石相金云母二辉橄榄岩低度(10%~15%)部分熔融的产物, 岩浆演化过程中经历了辉石、角闪石等矿物的分离结晶.微量元素构造判别图解表明岩石为俯冲环境下的弧岩浆岩, 结合区内蛇绿岩、研究区南部陆缘弧火山岩和义敦岛弧埃达克岩的发现, 认为古特提斯洋在晚三叠世时期可能仍处于消减状态, 日啊日曲高镁石英闪长岩形成于甘孜-理塘洋南西向俯冲过程中.      

In Situ Multi-Element Analysis of the Mount Pinatubo Quartz-Hosted Melt Inclusions by NIR Femtosecond Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

Microscopic melt inclusions found in magmatic minerals are undoubtedly one of the most important sources of information on the chemical composition of melts. This paper reports on the successful application of near-infrared (NIR) femtosecond laser ablation (LA) - inductively coupled plasma-mass spectrometry to in situ determination of incompatible trace elements (Li, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Ta, Th, U) and ore metals (As, Mo, Pb) in individual melt inclusions hosted in quartz from the Mount Pinatubo dacites, Philippines. The determined elements cover a concentration range of five orders of magnitude. Femtosecond LA-ICP-MS analyses of twenty-eight individual melt inclusions demonstrate the efficiency of the microanalytical technique and suggests a spectacular homogeneity of the entrapped melt, at least with respect to the following incompatible trace elements: Rb, Sr, Nb, Cs, Ba, La, Ce, Pr, Nd, Pb, Th. The analytical precision (1s) for Na, Ca, Rb, Sr, Y, Nb, Ba and LREE ranged from 3 to 20%. Comparison of trace element concentrations in Mt. Pinatubo melt inclusions determined by femtosecond LA-ICP-MS with those of melt inclusions previously analysed by secondary ion mass spectrometry analysis (SIMS) and those of matrix glasses previously determined by nanosecond LA-ICP-MS showed an agreement typically within 30–40%. The homogeneity of trace element concentrations of the Mt. Pinatubo melt inclusions and the matrix glasses is consistent with the melt inclusion origin as homogeneous rhyolitic melt that was trapped in quartz phenocrysts at the final crystallisation stages of the host adakite (dacite) magma.     

三江北段贡觉三叠纪火山岩年代学、地球化学特征及其地质意义

三江北段贡觉三叠纪火山岩是金沙江古特提斯洋向西俯冲消减及随后的弧陆碰撞造山作用的产物,主要由玄武岩、安山质熔结凝灰岩和安山岩等组成,对探讨金沙江古特提斯构造-岩浆演化过程具有重要意义.对贡觉火山岩进行了LA-ICP-MS锆石U-Pb定年和全岩主、微量元素研究.其中代表性样品安山质熔结凝灰岩的LA-ICP-MS锆石U-Pb定年结果显示,锆石23个分析点的206Pb/238U年龄为243~233 Ma,206Pb/238U加权平均年龄为238.3±1.3 Ma（MSWD=1.7,n=23）,代表了岩浆的结晶年龄为中-晚三叠世.地球化学分析表明,火山岩以低钛（0.52%~0.91%）、中镁（3.38%~7.22%）、富钠（3.63%~4.66%）、贫钾（0.09%~4.05%）、富集轻稀土元素（LREE/HREE=4.09~13.27）和大离子亲石元素（Th、U、La、Sm）、亏损高场强元素Nb和Ta（Nb=2.51×10-6~24.5×10-6、Ta=0.22×10-6~1.89×10-6）为特征,La/Nb值（2.13~2.89）较高、Nb/Th值（1.12~1.62）相对较低,具有与岛弧型或晚碰撞造山型火山岩相似的主-微量元素组成特征.贡觉中-晚三叠世火山岩代表了金沙江古特提斯演化过程中晚碰撞造山阶段的岩浆响应,推测是晚碰撞过程中残留的金沙江洋壳物质与岩石圈地幔物质相互作用的结果.      

电子探针多道波谱仪同时测试同一个元素的方法：以石英中Al 和Ti 含量的测试为例

电子探针显微分析是常用的原位分析矿物中各种主量元素含量的技术方法,但是对于微量元素的分析,提高测试精确度和准确度长期以来面临着各种挑战。常用的提高精确度方法有改变加速电压、加大电流和增加计数时间,但是这些方法容易使样品遭到破坏,发生元素迁移从而造成测试结果的不准确,增加计数时间还会降低测试效率。文章提出了一种利用电子探针多道波谱仪同时测试同一个元素的方法来提高待测元素特征X射线的强度值。该方法利用电子探针不同波谱仪同时测试同一个待测元素,通过测试标准样品中待测元素的总净计数和待测样品中待测元素的总净计数,结合标准样品中待测元素的浓度计算待测样品中待测元素的含量。该方法在同等测试条件下可以有效的提高待测元素特征X射线的强度值,从而提高了测试的精确度,降低了测试的检测限。文章以石英中Al和Ti含量的测试为例,验证了多道波谱仪同时测试同一个元素的方法在微量元素测试中的应用。测试Al元素时使用一个TAP晶体和一个TAPL晶体,测试Ti元素时使用三个PETL晶体,结合多点背景测试法准确测试了石英中Al和Ti的含量,在20 kV电压、500 nA束流和20 μm束斑直径的条件下可将Al的检测限降低至2.6×10-6 (3σ),将Ti的检测限降低至2.1×10-6 (3σ),测试获得石英参考标样中Al和Ti的含量分别为163.8×10-6±5.8×10-6 (3σ)和56.5×10-6±2.0×10-6 (3σ),皆在参考值区间(Al：154×10-6±15×10-6;Ti：57×10-6±4×10-6)内,并且具有较好的长期稳定性。     

High Sensitivity Analysis of Trace Element-Poor Geological Reference Glasses by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS)

Fifty-two trace elements in NIST SRM 614, 616 and MPI-DING BM90/21-G glass reference materials as well as in NIST SRM 612, USGS BCR2-G and other MPI-DING reference glasses (KL2-G, GOR132-G, GOR128-G, ATHO-G, Tl-G, StHs6/80-G and ML3B-G) were determined by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Accurate ultra-low trace element abundances in the NIST SRM 614, 616 and BM90/21-G reference glasses down to lower ng g⁻¹ levels were determined with relative standard deviations (RSD) of less than 10%. Limits of detection using He as carrier gas were up to two times lower than with Ar and were 0.004 to 0.12 μg g⁻¹ for elements of lower mass numbers (amu < 85) and 0.002 to 0.06 μg g⁻¹ for elements having amu < 85. The measured concentrations generally agree within 15% with previous studies except for B in NIST SRM 614 and 616, which appears to be heterogeneously distributed, and Co, Zn, Ga and Ag in NIST SRM 616 for which the existing data set is too small to evaluate the discrepancies. New values for As (0.593 μg g⁻¹), Ag (0.361 μg g⁻¹) and Cd (0.566 μg g⁻¹) in NIST SRM 614 and new values for Na (94864 μg g⁻¹) and As (0.276 μg g⁻¹) in NIST SRM 616 are reported.     

Determination of Multiple Trace Element Compositions in Thin (> 30 μm) Layers of NIST SRM 614 and 616 Using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS)

To understand and/or avoid small-scale chemical heterogeneities within geological materials prepared as normal thin sections, in situ multiple trace element determination coupled with the simultaneous microscopic observation of the sample during analysis is preferable. We have examined fifty trace elements in thin (< 30 μm) layers of the NIST SRM 614 and 616 glass reference materials by LA-ICP-MS using different pit diameters and internal standard elements (Ca and Si). Compositional heterogeneities of Tl, Bi, As and Cd were found in NIST SRM 614 and 616 at the spatial resolution of ca. 10 0 μm. Except for these elements, the RSDs of six determinations for most elements were better than 10% in NIST SRM 614 when ablation diameters were < 50 μm. The measured concentrations for most elements in NIST SRM 614 and 616 agree with previous values in the literature at the 95% confidence level with the exception of W and Bi. New LA-ICP-MS data for K, As and Cd are also reported. The results support the view that the latest LA-ICP-MS is a powerful and flexible analytical technique for the determination of multiple ultra-trace element compositions in geological materials prepared as normal thin sections of the type that has been used for polarising optical microscopic observations since the end of the 19th century.     

吉林南部三棵榆树组火山岩的成因:锆石U-Pb年龄和Hf同位素证据

锆石LA-ICP-MS U-Pb测年结果显示,吉林南部地区三棵榆树组粗面岩形成于118 Ma的早白垩世晚期。岩石地球化学研究表明,三棵榆树组粗面岩的SiO2含量为65.11%～65.61%,富碱(K2O=6.29%～7.28%,Na2O=3.71%～4.21%),属于钾玄岩系列,弱过铝质(A/CNK=1.05～1.12),含镁指数Mg#=9～16;稀土元素总量较高(∑REE=317.72×10-6～371.30×10-6),轻重稀土分馏明显(LaN/YbN=19.50～22.80),Eu负异常较弱(δEu=0.75～0.81);微量元素富集Rb、Th、Zr、K,明显亏损Nb、Ta和Sr等,显示典型的大陆地壳特征。锆石的176Hf/177Hf比值介于0.282 206～0.282 309之间,εHf(t)值介于-13.32～-16.97之间,Hf模式年龄(TDM2)介于2.0～2.6 Ga之间,平均为2.2 Ga。上述特征表明,吉林南部地区早白垩世粗面岩主要来源于古元古代地壳物质的部分熔融,形成于伸展构造环境。     

钍—茜素氨羧络合剂极谱络合吸附波的研究

在邻苯二甲酸氢钾和醋酸混合底液(pH5.0)中,钍与茜素氨羧络合剂(ALC)形成电活性络合物，在单扫描极谱仪上于-0.60V(vs.SCE)产生一灵敏的络合吸附波，其二阶导数峰高与钍的浓度在3.0×10-8～3.0×10-6mol/L呈线性关系，检出限为1.5×10-8mol/L。用等摩尔连续变化法测得该络合物的摩尔比为nTh(Ⅳ)∶nALC=1∶1，并探讨了极谱波的性质和电极反应机理。方法用于矿石和粘土中痕量钍的测定，RSD(n=5)<4%,加标回收试验，回收率为101.5%～103.2%。     

Preparation of a Synthetic Titanite Glass Calibration Material for In Situ Microanalysis by Direct Fusion in Graphite Electrodes: A Preliminary Characterisation by EPMA and LA-ICP-MS

This paper describes a technique for the preparation of a titanite (CaTiSiO₅) glass calibration material for use in in situ microanalysis of major, minor, and trace elements in geological materials. The starting composition was a titanite matrix doped with minor and trace elements at ∼ 200 μg g^-1. The elements Sc, Y, REEs, Th and U were added in the form of nitrates in solution, and the elements V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Hf and W were added as solid oxides. The synthetic titanite glass was produced by direct fusion by resistance heating in graphite electrodes at 1600-1700 °C, and quenched in air. Backscattered electron images indicate good homogeneity, with no signs of separate phases or vesicles, and analysis of the major elements Ca, Ti and Si by electron microprobe showed relative standard deviations between 0.5 and 0.7%, based on six independent measurements. Deviations from nominal concentrations for Ca, Si and Ti were measured to -1.2, -3.3 and -0.8%, respectively. The homogeneity of the trace elements in the glass was assessed by LA-ICP-MS analyses, using NIST SRM 610, 612 and 616 as external calibrators, and Ca as the internal standard element. Determinations were made both with a quadrupole mass spectrometer and a sector field instrument, and both raster and spot modes of analysis were used. For the majority of doped elements, precision was better than 10%, and relative deviations from nominal values were, with few exceptions, between 5 and 10%.     

徐淮地区斑井岩体锆石U-Pb测年、岩石成因及其地质意义

斑井岩体位于徐淮推覆体中北部皇藏峪复背斜北段西翼,由于研究重点和关注度不同,对其成因类型及年代学特征研究较少。故此,本次研究将依托于钻孔XZK01中的7个岩石样品,通过大量的主微量元素地球化学分析及锆石U-Pb年代学分析,深入探讨斑井岩体的成因机制、形成年代及其地质意义。LA-ICP-MS锆石U-Pb年代学分析结果揭示斑井岩体的结晶年龄为126.4Ma±2.1Ma,侵位时代为中生代早白垩世,为地球动力学背景转变期间形成的岩体。本次6个样品的主量元素分析结果中w(SiO2)变化范围为56.54%~59.29%,全碱w(Na2O+K2O)变化范围为4.98%~5.68%,为中性岩;里特曼组合指数σ介于1.77~1.98之间,σ<3.3,属于钙碱性岩。其次,该组样品微量元素w(Sr)介于589×10^-6~728×10^-6之间,平均值为659×10^-6;w(Y)介于11.3×10^-6~12.8×10^-6之间,平均值为12.1×10^-6;w(Yb)介于1.13×10^-6~1.4×10^-6之间,平均值为1.23×10^-6;w(Cr)介于100×10^-6~660×10^-6之间,平均为377×10^-6;Mg#值介于47.17~68.14之间,平均值为58.21。该结果指示斑井岩体具富Sr,Sr/Y,贫Y,Yb的特征,指示其源区具有高压的环境,Mg#的变化特征揭示斑井岩体并非来自下地壳镁铁质岩石部分熔融,且w(Cr)的变化特征指示地幔橄榄岩也可能参与其中。此外,LREE/HREE介于6.91~10.98之间,平均值为8.895;LaN/YbN值在7.68~12.95之间,平均值为10.17,为轻稀土较强富集;大离子亲石元素Rb(23.9×10^-6~44.8×10^-6),K(11373×10^-6~14610.6×10^-6),Ba(513×10^-6~694×10^-6),Th(1.5×10^-6~2.5×10^-6),U(0.51×10^-6~0.79×10^-6)相对富集;高场强元素Nb(3.2×10^-6~4.7×10^-6),Ti(3056.7×10^-6~3536.2×10^-6)等表现出明显负异常。     

大别山北缘石炭系碎屑岩地球化学及碎屑锆石年代学分析及其对物源区大地构造属性判别的制约

大别山北缘石炭系作为古生代唯一不变质或轻微变质的沉积地层,记录了其物源信息和古生代的构造演化.针对研究区这一地质特征,本文分析了研究区砂岩的碎屑组分、常量元素、微量元素和稀土元素,以及碎屑锆石的同位素年龄,并据此对物源区的大地构造属性进行了研究.研究区碎屑岩主要以中细粒石英砂岩和长石石英砂岩为主,砂岩的QFL平均值为Q 76.2％,F 15.9％,L7.9％,Q/(F+ L) 4.26;主要元素氧化物平均百分含量SiO263.69％,Al2O3 11.25％,MgO 3.66％,CaO 5.15％,Fe2O3T 6.15％,K2O 1.68％,Na2O 0.68％;部分特征微量元素Th,U,Hf,Sc,Zr,Y平均含量分别为10.78×10-6、2.64×10-6、4.39×10-6、15.67×10-6、166×10-6、25.33×10-6.Rb/Sr,Th/U,La/Y,La/Sc,Th/Sc比值分别为1.49、4.10、14.75、31.92和0.89;稀土元素总量ΣREE平均146.2×10-6(54.11×10-6 ～256.0×10-6),Eu异常0.64,轻稀土略有富集,La/Yb为12.58(3.94～15.42),(La/Yb)N为9.02.锆石年龄测定表明,早石炭世地层中碎屑锆石的年龄主要集中在400 ～500Ma,晚石炭世地层中碎屑锆石年龄主要为900～ 1300Ma,其次为2000～ 2800Ma.上述结果表明大别山北缘石炭系沉积物来源于不同的源区,包括早古生代的大陆岛弧、扬子板块中-新元古代基底以及华北板块古-中元古代基底.