Deuterium\Hydrogen Partitioning Between C-O-H species in Silicate Melts and Fluids: An In-Situ Experimental Study at High Pressure and Temperature

水对地球上发生的各种地质过程至关重要。例如，水的循环控制着岩石圈和水圈之间的热量和质量的流动。为了更好地了解地球上的水循环？然而，在其内部，重要的是要限制化学成分的分布，如氢和氘（氢加上中子？?重氢？）这些水溶解在火山玻璃和矿物质中。在这些阶段中的氘和氢丰富的分子的浓度可能会限制所观察到的地幔和海洋H2O水库之间的氢-氘组成的差异，以及俯冲带的地幔-水循环的贡献。水储层之间氢/氘丰度的这些差异意味着地幔中的水循环并不广泛，或者氢和氘在高温下溶解在矿物、熔体和流体中时反应不同。因此，实验结果将揭示地球深处水的命运？在这项研究中，我们将研究在反映下地壳和上地幔条件的压力和温度下，硅酸盐熔体和流体中氘/氢分配和C-O-H挥发分形态之间的关系。我们将在一系列高温高压的水热金刚石对顶砧实验中，通过拉曼和红外光谱原位研究溶解在熔体和共存流体中的甲烷、氢和水的H-D同位素的相对分布。这些实验将通过使用1H/2 H核磁共振和TC/EA-同位素质量比光谱法对淬火熔体进行补充。实验结果将有助于我们约束同位素交换反应的功能元素的形态和熔体之间的分配，结晶相和水溶液。振动光谱用于同位素分子的原位和实时测量的新用途可以扩展到其他应用，包括矿物物理学，地球化学和与能源有关的研究。一名本科生将参加在该项目的第二年和第三年建立的为期10周的实习计划。这项研究也将支持硕士论文的研究生从乔治梅森大学。

Water is essential to a wide range of geological processes occurring on Earth. The cycling of water, for example, governs the flux of heat and mass between the lithosphere and hydrosphere. To better understand the water cycle in the Earth?s interior, however, it is important to constrain the distribution of chemical components such as hydrogen and deuterium (hydrogen with an added neutron ? ?heavy hydrogen?) that constitute the water dissolved in volcanic glasses and minerals. The concentration of deuterium- and hydrogen-rich molecules in these phases likely constrain the observed differences on the hydrogen-deuterium composition between mantle and oceanic H2O reservoir, as well as the subduction zone contributions to the mantle-water cycle. These differences in the abundance of hydrogen/deuterium between water reservoirs implies that cycling of water in the mantle is not extensive or that hydrogen and deuterium react differently at high temperatures when dissolved in minerals, melts and fluids. Experimental results will, thus, shed light on the fate of water that resides deep in the Earth?s interior and promote our current understanding of planetary evolution and formation.In this study, we will investigate the relationship between deuterium/hydrogen partitioning and speciation of C-O-H volatiles in silicate melts and fluids at pressures and temperatures reflecting lower crust and upper mantle conditions. We will study the relative distribution of H-D isotopologues of methane, hydrogen, and water dissolved in melts and coexisting fluids in-situ by Raman and infrared spectroscopy in a series of hydrothermal diamond-anvil cell experiments at high temperature and pressure. These experiments will be complemented by the use of 1H/2H Nuclear Magnetic Resonance and TC/EA-Isotope Mass Ratio Spectrometry on quenched melts. Experimental results will help us constrain isotope exchange reactions as function of elemental speciation and partitioning between melts, crystalline phases and aqueous solutions. The novel use of vibrational spectroscopy for in-situ and real-time measurement of isotope molecules can be expanded to other applications including mineral physics, geochemistry and energy-related research. An undergraduate student will participate during a 10-week internship program established in the second and third year of the project. This research will also support the M.Sc. thesis of a graduate student from the George Mason University.