比较同位素质谱分析和腔衰荡光谱技术在流体包裹体水同位素分析中的应用。

A comparison of isotope ratio mass spectrometry and cavity ring-down spectroscopy techniques for isotope analysis of fluid inclusion water.

机构信息

Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany.

Ruprecht-Karls University Heidelberg, Institute of Environmental Physics, Heidelberg, Germany.

出版信息

Rapid Commun Mass Spectrom. 2020 Aug 30;34(16):e8837. doi: 10.1002/rcm.8837.

DOI:10.1002/rcm.8837

PMID:32424983

Abstract

RATIONALE

Online oxygen (δ O) and hydrogen (δ H) isotope analysis of fluid inclusion water entrapped in minerals is widely applied in paleo-fluid studies. In the state of the art of fluid inclusion isotope research, however, there is a scarcity of reported inter-technique comparisons to account for possible analytical offsets. Along with improving analytical precisions and sample size limitations, interlaboratory comparisons can lead to a more robust application of fluid inclusion isotope records.

METHODS

Mineral samples-including speleothem, travertine, and vein material-were analyzed on two newly setup systems for fluid inclusion isotope analysis to provide an inter-platform comparison. One setup uses a crusher unit connected online to a continuous-flow pyrolysis furnace and an isotope ratio mass spectrometry (IRMS) instrument. In the other setup, a crusher unit is lined up with a cavity ring-down spectroscopy (CRDS) system, and water samples are analyzed on a continuous standard water background to achieve precisions on water injections better than 0.1‰ for δ O values and 0.4‰ for δ H values for amounts down to 0.2 μL.

RESULTS

Fluid inclusion isotope analyses on the IRMS setup have an average 1σ reproducibility of 0.4‰ and 2.0‰ for δ O and δ H values, respectively. The CRDS setup has a better 1σ reproducibility (0.3‰ for δ O values and 1.1‰ for δ H values) and also a more rapid sample throughput (<30 min per sample). Fluid inclusion isotope analyses are reproducible at these uncertainties for water amounts down to 0.1 μL on both setups. Fluid inclusion isotope data show no systematic offsets between the setups.

CONCLUSIONS

The close match in fluid inclusion isotope results between the two setups demonstrates the high accuracy of the presented continuous-flow techniques for fluid inclusion isotope analysis. Ideally, experiments such as the one presented in this study will lead to further interlaboratory comparison efforts and the selection of suitable reference materials for fluid inclusion isotopes studies.

摘要

原理

矿物中包裹的流体包裹体水的氧（δ O）和氢（δ H）同位素的在线分析在古流体研究中得到了广泛应用。然而，在流体包裹体同位素研究的最新技术中，缺乏报道的技术间比较来解释可能的分析偏移。除了提高分析精度和样品尺寸限制外，实验室间的比较可以更有效地应用流体包裹体同位素记录。

方法

对包括石笋、钙华和脉材在内的矿物样品进行了两种新建立的流体包裹体同位素分析系统的分析，以提供平台间的比较。一个装置使用与连续流动热解炉和同位素质谱仪（IRMS）仪器在线连接的破碎机单元。在另一个装置中，破碎机单元与腔衰荡光谱（CRDS）系统并列，水样品在连续的标准水背景下进行分析，对于注入量低至 0.2 μL 的水，δ O 值的精度优于 0.1‰，δ H 值的精度优于 0.4‰。

结果

IRMS 装置上的流体包裹体同位素分析的平均 1σ 重现性分别为 0.4‰和 2.0‰。CRDS 装置的 1σ 重现性更好（δ O 值为 0.3‰，δ H 值为 1.1‰），且样品通量更快（<30 分钟/个样品）。在这两种装置上，对于低至 0.1 μL 的水，流体包裹体同位素分析在这些不确定度下具有可重复性。流体包裹体同位素数据显示两个装置之间没有系统的偏移。