Collaborative Research: Experimental Determination of the Damp Peridolite Solidus

能够控制系统关键组件的新实验方法的开发和应用为突破提供了机会；不仅为开发方法所针对的主题，而且多次为其他系统和学科提供突破。这项研究采用了一种新开发的方法，用于在高温/高压实验中定量控制极少量的H2O，并将其应用于地球上最基本的岩石形成过程之一：地幔岩石(橄榄岩)熔融形成岩浆，其中一些最终到达地球-S表面。由于氢能迅速扩散到橄榄石--地球上最常见的矿物之一--S地幔中，获得这一奖项的研究人员现在能够将预定浓度的水注入直径约300微米的橄榄石球体中。然后，这些橄榄石被用作实验中的湿度计，以确定地幔岩石开始融化的确切时刻(即橄榄岩固相线)的压力依赖关系。了解这一基本反应很重要，因为地球地幔(即橄榄岩)的熔融推动了大洋中脊的扩张，并对从地球S内部到地球表面的质量和热量的转移以及地球？S地壳的厚度有着重要的影响。为了确定二辉橄榄岩在H2O不饱和条件下的固相线，将使用含有特定H2O含量的圣卡洛斯橄榄石球体的合成橄榄岩进行大约1300℃和1到3 Gpa的部分熔融实验。利用球体作为湿度计，用二次离子质谱仪对橄榄石进行分析，以确定橄榄石中的H2O含量何时发生变化，表明熔融的开始。研究目标是确定橄榄岩固相线，以及Na2O和矿物模式对熔融的影响。这些结果将首次提供水不饱和橄榄岩固相线的定量实验测定。这项工作的更广泛影响包括方法的开发和应用，从而为科学建设基础设施。它还提供研究生和本科生水平的学生培训。这种独特的矿物学湿度计还可以应用于材料科学和其他需要特定组成材料的固相线的准确温度和压力的领域。

The development and application of new experimental approaches that can control key components of a system provide opportunities for breakthroughs; not only for the topic for which the method was developed, but many times also for other systems and disciplines. This research takes a novel, newly developed approach for quantitatively controlling very small amounts of H2O in high temperature/pressure experiments and applies it to one of the most fundamental rock forming processes on the planet: the melting of mantle rocks (peridotite) to form magmas, some of which eventually reach Earth?s surface. Because hydrogen diffuses rapidly into olivine, one of the most common minerals in the Earth?s mantle, the researchers receiving this award are now able to infuse predetermined concentrations of H2O into spheres of olivine about 300 microns in diameter. These olivines are then used as hygrometers in experiments that allow the pressure dependence to be determined of the exact instant when melting of mantle rock begins (i.e., the peridotite solidus). Understanding this fundamental reaction is important because the melting of Earth's mantle (i.e., peridotite) drives the spreading apart of the mid-ocean ridges and has a significant impact on the transfer of mass and heat from Earth?s interior to its surface as well as on the thickness of Earth?s crust.To determine the lherzolite solidus at H2O-undersaturated conditions, partial melting experiments around 1300 C and from 1 to 3 GPa will be conducted using synthetic peridotite containing spheres of San Carlos olivine doped with specified H2O contents. Using the spheres as hygrometers, the olivines will be analyzed by secondary ion mass spectrometry to determine when the H2O content of the olivine changes, indicating the initiating of melting. Research goals are to determine the peridotite solidus and the impact of Na2O and mineral mode on melting. Results will provide the first quantitative experimental determination of the H2O-undersaturated peridotite solidus. Broader impacts of the work include method development and application, thus, building infrastructure for science. It also provides student training at the graduate and undergraduate level. The unique mineralogical hygrometer may also have applications for materials science and other areas where the exact temperature and pressure of a solidus for a material of a specific composition is needed.