Rheology and Densities of Silicate Melts in the Upper Mantle

本实验计划将测定高压下无水和有水的自然生成的和简单的模拟硅酸盐熔体的粘度和密度。这项研究将使用经过验证的高压研究方法，利用多砧座设备和同步辐射实时射线照相技术来监测实验样品室中标记球体的运动，并确定氧的自我扩散速度。使用各种大小和密度不同的纯金属和复合标记球进行落球实验，以便从Stokes方程的解中提取熔体粘度和密度的同时测量结果。获得的广泛硅酸盐熔体成分数据将用于将熔体粘度和密度的参数化达12 Gpa，并直接用于模拟早期地球岩浆海洋凝固过程中的对流和晶液分离、现代扩张脊、弧形和板内火山之下部分熔融的地幔源区中的熔体迁移和两相流动，以及深部地幔中富挥发分熔体的命运。从拟议的实验计划中获得的见解将有助于我们对工业制造光缆、增强结构复合材料、编织纤维绝缘等产品的科学和技术理解，在这些产品中，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，由此产生的模型将广泛分布。该项目将利用同步辐射对研究生和本科生进行实验岩石学研究方法的培训，并将与国家实验室的研究人员建立更紧密的联系。

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.