Trace element diffusion in rhyolitic melts: comparison between synchrotron radiation X-ray fluorescence microanalysis (μ-SRXRF) and secondary ion mass spectrometry (SIMS)
Trace element diffusion in rhyolitic melts: comparison between synchrotron radiation X-ray fluorescence microanalysis (μ-SRXRF) and secondary ion mass spectrometry (SIMS)
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流纹岩熔体中的微量元素扩散：同步辐射 X 射线荧光微量分析 (μ-SRXRF) 与二次离子质谱 (SIMS) 的比较
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发表时间：
2005
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通讯作者：
M. Wiedenbeck
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作者：
M. Hahn;H. Behrens;Astrid Tegge;J. Koepke;I. Horn;K. Rickers;G. Falkenberg;M. Wiedenbeck
比较了同步辐射X射线荧光显微分析（μ SRXRF）和二次离子质谱（西姆斯）两种微束技术对两种含水流纹质玻璃（1.87wt%H2O和5.00wt%H2O）中微量元素扩散分布的分析。为了验证结果，对一个样品使用了激光烧蚀耦合电感耦合等离子体光发射（LA-ICP-OES）。通过在1200 °C和500 MPa下在内部加热的气体压力容器中进行的扩散偶实验来制备样品。每对的一半掺杂有代表不同地球化学族的24种微量元素：低场强元素（Rb、Sr、Ba）、过渡金属（Cr、Co、Ni、Cu、Zn）、稀土元素（La、Ce、Nd、Sm、Eu、Gd、Er、Yb）+ Y、高场强元素（V、Zr、Nb、Hf、Ta）和主族元素（Ge、Sn）。用μ-SRXRF和西姆斯对两种样品测量了几种分布。原则上，所有元素的浓度可以同时从单个SRXRF光谱中提取。然而，我们的分析系统不能可靠地定量一些微量元素：Ta和Pb（用于探测器准直器材料），Ti，V（低能量K α），Co（K α峰与Fe K β峰重叠）和Cr，Ni，Cu，Zn（与REE的1线重叠）。相比之下，西姆斯分析按顺序测量每个元素。因此，不是所有的元素的大的总组的微量元素可以分析在一个单一的运行。一些需要高质量分辨率的元素（NaSi干扰V，CaO干扰Ni）或产率低的元素（Sn）未进行分析。由μ-SRXRF和西姆斯谱图得到的多重扩散系数对于大多数元素都非常一致。一般来说，微量元素的扩散系数随价态的增加而减小，例如在含1.87wt%H2O的样品D22中，从一价Rb的logD =-10.80到四价Zr的logD =-13.34（Din m2/s）。通过将样品D18中的水含量增加到5.00wt%，对于所研究的所有元素，扩散系数增加约一个数量级。
Two microbeam techniques, synchrotron radiation X-ray fluorescence micro-analysis (μ-SRXRF) and secondary ion mass spectrometry (SIMS) are compared for analyzing diffusion profiles of trace elements in two hydrous rhyolitic glasses (1.87 and 5.00wt% H 2 O). In order to verify the results, laser ablation coupled to inductively coupled plasma optical emission (LA-ICP-OES) has been used on one sample. Samples were produced by diffusion couple experiments performed in an internally heated gas pressure vessel at 1200 °C and 500MPa. One half of each couple was doped with 24 trace elements representing different geochemical groups: low field strength elements (Rb, Sr, Ba), transition metals (Cr, Co, Ni, Cu, Zn), rare earth elements (La, Ce, Nd, Sm, Eu, Gd, Er, Yb) + Y, high field strength elements (V, Zr, Nb, Hf, Ta) and main group elements (Ge, Sn). Several profiles were measured with both μ-SRXRF and SIMS on both samples. In principle, concentrations of all elements can be extracted simultaneously from a single SRXRF spectrum. However, some trace elements could not be reliably quantified with our analytical system: Ta and Pb (used for detector collimator material), Ti, V (low energy of K α ), Co (K α -peak overlapping with Fe K β -peak) and Cr, Ni, Cu, Zn (overlapping with 1-lines of REEs). In contrast, SIMS analyses measure each element sequentially. Hence, not all elements of the large total set of trace elements could be analyzed in a single run. Some elements requiring a high mass resolution (NaSi interfering with V, CaO interfering with Ni) or having low yields (Sn) were not profiled. Multiple diffusivities derived from μ-SRXRF and SIMS profiles are in very good agreement for most elements. In general, the trace element diffusivity decreases with increasing valence state, e.g. in sample D22 containing 1.87wt% H 2 O from log D=-10.80 for the monovalent Rb to log D=-13.34 for the tetravalent Zr (Din m 2 /s). By increasing the water content in sample D18 to 5.00wt%, diffusion coefficients increase approximately by one order of magnitude for all elements studied.