Towards a Higher Comparability of Geothermometric Data obtained by Raman Spectroscopy of Carbonaceous Material. Part I: Evaluation of Biasing Factors
Towards a Higher Comparability of Geothermometric Data obtained by Raman Spectroscopy of Carbonaceous Material. Part I: Evaluation of Biasing Factors
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DOI：
10.1111/j.1751-908x.2013.12011.x
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发表时间：
2014-03
影响因子：
3.8
通讯作者：
N. K. Lünsdorf;I. Dunkl;B. Schmidt;G. Rantitsch;H. Eynatten
中科院分区：
文献类型：
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作者：
N. K. Lünsdorf;I. Dunkl;B. Schmidt;G. Rantitsch;H. Eynatten
碳质材料的拉曼光谱（RSCM）经常被用来从变质沉积物中所含碳质材料的结构顺序来确定变质峰温度。该方法提供了一种快速、鲁棒且相对便宜的地质温度计。然而，RSCM参数的可比性很低，因为至少有三个主要的偏置因素来源。这些来源是光谱曲线拟合程序、样品本身的特性和实验设计，包括所使用的拉曼系统。为了评估偏差因子对RSCM的影响，进行了一系列实验。实验表明，曲线拟合受到个体操作员偏倚和模型自由度的强烈影响，这意味着需要标准化的曲线拟合程序。由于组件的多样性（光学器件、光检测设备、光栅等），以及它们在拉曼系统中的组合，不同的拉曼仪器通常给出不同的结果。因此，为了从RSCM数据估计可比的变质温度，每个拉曼仪器都需要自己的校准。这就需要覆盖整个温度校准范围的参考材料系列。尽管样品异质性仍会引起一些变化，但参考物质系列结合标准化曲线拟合程序将显著提高不同实验室RSCM数据的整体可比性。
Raman spectroscopy of carbonaceous material (RSCM) is frequently used to determine metamorphic peak temperatures from the structural order of carbonaceous material enclosed in metasediments. This method provides a quick, robust and relatively cheap geothermometer. However, the comparability of the RSCM parameter is low as there are at least three major sources of biasing factors. These sources are the spectral curve‐fitting procedure, the sample characteristics itself and the experimental design including the used Raman system. To assess the impacts of the biasing factors on RSCM, a series of experiments was performed. The experiments showed that curve‐fitting is strongly influenced by individual operator‐bias and the degrees of freedom in the model, implying the need for a standardised curve‐fitting procedure. Due to the diversity of components (optics, light detection device, gratings, etc.) and their combinations within the Raman systems, different Raman instruments generally give differing results. Consequently, to estimate comparable metamorphic temperatures from RSCM data, every Raman instrument needs its own calibration. This demands a reference material series that covers the entire temperature calibration range. Although sample heterogeneity will still induce some variation, a reference material series combined with standardised curve‐fitting procedures will significantly increase the overall comparability of RSCM data from different laboratories.