Pressure measurement and detection of small H 2 O amounts in high‐pressure H 2 O–CO 2 fluid up to 141 MPa using Fermi diad splits and bandwidths of CO 2
Pressure measurement and detection of small H 2 O amounts in high‐pressure H 2 O–CO 2 fluid up to 141 MPa using Fermi diad splits and bandwidths of CO 2
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DOI：
10.1002/jrs.5865
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发表时间：
2020-03
影响因子：
2.5
通讯作者：
Yuuki Hagiwara;J. Torimoto;J. Yamamoto
中科院分区：
文献类型：
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作者：
Yuuki Hagiwara;J. Torimoto;J. Yamamoto
流体包裹体的残余压力与其大小和寄主矿物种类的关系为岩石的深度、物源和p - t路径提供了有价值的信息。虽然基于拉曼的气压测量是确定H2O-CO2流体包裹体内部压力的有效方法，但很少有研究阐明高压H2O-CO2体系中co2的拉曼光谱特征。为了验证拉曼co2气压计在大约22°C和17.3-141.4 MPa的温度和压力条件下的可用性，本研究使用高压光学电池在组成为100、75±2和60±2 mol% co2的二元系统中进行了新的实验。我们的结果表明H2O的存在不影响费米diad分裂（Δ， cm−1）与纯CO2总压之间的关系。这些结果表明，从纯co2得到的Δ-total压力关系也适用于h2o - co2体系，即使在高压下也是如此。但是，与Δ不同的是，当压力大于30 MPa时，h2o - co2体系中费米双极体的峰值位置会比纯co2体系的峰值位置移位到更高的波数，因此峰值位置不太适合于h2o - co2体系的压力尺度。此外，我们证实了co2的带宽作为成分的指示物的可用性，即使在室温下也可以识别非常少量的H2O（至少0.3 mol% H2O）的存在。
Dependence of residual pressures of fluid inclusions on their size and host mineral species provides valuable information related to the depth provenance andP–T–tpath of the rocks. Although Raman‐based barometry is an effective method for ascertaining the internal pressure of H2O–CO2fluid inclusions, few studies have elucidated Raman spectral features of CO2in a system of high‐pressure H2O–CO2. New experiments using a high‐pressure optical cell in this binary system with compositions of 100, 75 ± 2, and 60 ± 2 mol% CO2were conducted for this study to verify the availability of Raman CO2barometers for use in assessing the temperature and pressure conditions of approximately 22°C and 17.3–141.4 MPa. Our results demonstrate that the existence of H2O does not affect the relation between Fermi diad splits (Δ, cm−1) and total pressure of pure CO2. These results suggest that the Δ–total pressure relation obtained from pure CO2is also applicable to H2O–CO2systems, even at high pressure. However, unlike Δ, because the peak positions of the Fermi diad in the system of H2O–CO2shift to a higher wavenumber than those of pure CO2at given pressure higher than 30 MPa, the peak positions are not very suitable for the pressure scale in an H2O–CO2system. Additionally, we confirmed the availability of bandwidths of CO2as an indicator of compositions that can identify the presence of very small amounts of H2O (at least 0.3 mol% H2O), even at room temperature.