Quantitative analysis of trace OH in garnet and pyroxenes
Quantitative analysis of trace OH in garnet and pyroxenes
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发表时间：
2007
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通讯作者：
D. IrrrNcrn;Gnoncr R. RossunN
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作者：
D. IrrrNcrn;Gnoncr R. RossunN
为校正红外光谱定量分析特定矿物中痕量结构OH的方法，我们在真空下加热样品并提取H_2气体后，用测压法测定了幔源镁铝榴石石榴石（56 ± 6 ppm H_2O）、普通辉石（268 ± 8 ppm H_2O）和顽火辉石（217 ± 11 ppm H_2O）纯样品中的H浓度。IR光谱证实了在提取之前这些样品中存在固有的OH，并且表明在提取过程中H的去除在86和100 o/o之间。积分比吸收系数为1.39 + 0. I_4（lo）、7.09 ± 0.32和15.6 ± 0.94 /（ppm）。HrO.cm镁铝榴石，普通辉石，顽火辉石，分别允许精确的光谱测定的OH含量的上地幔石榴石和辉石的浓度水平为百万分之几。准确度取决于矿物成分和OH吸收光谱的特性，估计范围在+ l0和t 500/0之间。
To calibrate infrared (IR) spectroscopy for quantitative analysis of trace structural OH in specific minerals, we have determined concentrations of H in pure separates of mantlederived pyrope garnet (56 + 6 ppm HrO by werght), augite (268 + 8, ppm HrO), and enstatite (217 + I I ppm HrO) by manometry after heating the samples and extracting H, gas under vacuum. IR spectroscopy confirmed the presence of intrinsic OH in these samples prior to extraction and indicated between 86 and l00o/o removal of H during the extraction procedure. The integral specific absorption coefficients of 1.39 + 0. I 4 (lo), 7 .09 + 0.32, and 15.6 + 0.94 /(ppm HrO.cm'?) for pyrope, augite, and enstatite, respectively, allow precise spectroscopic determination of the OH content of upper mantle garnets and pyroxenes to concentration levels of a few parts per million. Uncertainties in accuracy depend on mineral composition and characteristics of the OH absorption spectrum and are estimated to range between + l0 and t 500/0.