金刚石压腔结合拉曼光谱技术进行氧同位素分馏的实验研究

A Research on the Experiment of Oxygen Isotope Fractionation by Using Diamond Anvil Cell and Raman Spectra

应用水热金刚石压腔结合拉曼光谱技术进行石英和方解石间氧同位素的分馏研究。金刚石压腔装置实现体系的高温高压条件,重氧水为提供18O的中间介质。首先给体系加压至500 MPa左右,然后升温至300℃使石英、方解石发生部分溶解,随后快速降至常温使溶解部分重新结晶,从而使矿物和重氧水之间发生同位素交换。拉曼光谱中,物质特征峰的峰强度比值与相应物质的量的比值呈线性相关,结合同位素分馏系数公式计算得出300℃时石英、方解石之间的氧同位素分馏系数为1.0016。此方法操作简便,实验过程采用原位测量方法,不破坏样品,避免了污染,提高了实验精度。实验数据的准确度证明了金刚石压腔结合拉曼光谱法进行稳定同位素分馏的实验研究是可行的。

In this research oxygen isotope fractionation between quartz and calcite was studied by using Hydrogen Diamond Anvil Cell and Raman spectra.The experimental condition was high temperature and high pressure with DAC,and 18O was provided by using heavy water.The experimental process was as follows： made quartz and calcite dissolved into heavy oxygen water partly under the condition of 300 ℃ and 500 MPa,and then made quartz and calcite recrystallized at room temperature.The whole process made system of quartz and calcite reach oxygen isotope fractionation equilibrium.There was a linear relationship between ratio of Raman peak intensities and ratio of corresponding amount of substances.With the formula of isotope fractionation factor,the oxygen isotope fractionation factors between quartz and calcite is 1.0016 at 300 ℃.The in-situ experimental study of HDAC is convenient.The ratio of heavy isotope to light isotope in one phase could be measured by Raman spectroscopy accurately.So it is feasible to determine the stable isotope fractionation factor by using the technique of Hydrothermal Diamond-Anvil Cell combining with Raman spectroscopy.