Rheology and Densities of Silicate Melts in the Upper Mantle

这个实验计划将确定无水和含水的天然存在的和简单的模拟硅酸盐熔体在高压下的粘度和密度。这项研究将使用经过验证的高压研究方法，利用多砧装置和同步辐射实时射线照相术监测实验样品室中标记球的运动，并确定氧气自扩散的速率。 落球实验是使用各种不同的纯金属和复合标记球的大小和密度，以提取同时测量熔体粘度和密度从解决方案斯托克斯方程。 从各种硅酸盐熔体组成中获得的数据将用于将熔体粘度和密度的参数化扩展到12 GPa，并直接应用于模拟早期地球岩浆海洋凝固过程中的对流和晶体-液体分离，熔体迁移和两相流在现代扩张脊，弧和板内火山下的部分熔融地幔源区，以及地幔深处富含挥发物的熔融物的命运。 从拟议的实验计划中获得的见解将有助于我们对光纤电缆，增强结构复合材料，编织纤维绝缘材料的工业制造的科学和技术理解，以及其他产品，其中压力和熔体流变性是玻璃纤维挤出和注塑成型过程中的关键变量。 这项研究的实验结果将与社区共享，并广泛分发由此产生的模型。 该项目将对研究生和本科生进行利用同步加速器辐射的实验岩石学研究方法的培训，并将促进与国家实验室研究人员的密切联系。

This experimental program will determine the viscosities and densities of anhydrous and hydrous naturally-occurring and simple analog silicate melts at high pressures. The study will use proven methods of high-pressure research that utilize the multianvil device and real-time radiography by synchrotron radiation to monitor motion of marker spheres in the experimental sample chambers and determine the rates of oxygen self-diffusion. Falling sphere experiments are carried out using a variety of pure metal and composite marker spheres that differ in size and density in order to extract simultaneous measurements of melt viscosity and density from solutions to Stokes' equation. The data acquired for a broad range of silicate melt compositions will be used to extend parameterizations of melt viscosity and density up to 12 GPa with direct applications to modeling convection and crystal-liquid segregation during solidification of the early Earth magma ocean, melt migration and two-phase flow in partially molten mantle source regions beneath modern spreading ridges, arcs and intraplate volcanoes, and the fate of volatile-rich melts in the deep mantle. Insights gained from the proposed experimental program will contribute to our scientific and technological understanding of industrial fabrication of fiber optic cable, reinforcing structural composites, woven-fiber insulation, among other products where pressure and melt rheology are the key variables during glass fiber extrusion and injection molding processes. The experimental results from this study will be shared with the community and the resulting models widely distributed. This project will train graduate and undergraduate students in research methods of experimental petrology utilizing synchrotron radiation and will foster closer ties with researchers at the national laboratories.