Rheology and Densities of Silicate Melts in the Upper Mantle

这个实验程序将确定在高压下无水和有水自然发生和简单模拟硅酸盐熔体的粘度和密度。该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的实时放射照相来监测实验样品室中标记球体的运动，并确定氧气自扩散的速率。为了从Stokes方程的解中提取熔体粘度和密度的同时测量值，采用不同大小和密度的纯金属和复合标记球进行了落球实验。获得的大范围硅酸盐熔体成分数据将用于扩展熔体粘度和密度的参数化，最高可达12 GPa，并直接应用于模拟早期地球岩浆海凝固过程中的对流和结晶-液体分离，现代扩张脊、弧和板内火山下部分熔融地幔源区的熔体迁移和两相流动，以及深部地幔中富含挥发物的熔体的命运。从拟议的实验项目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、编织纤维绝缘以及其他产品的工业制造的科学和技术理解，这些产品的压力和熔体流变是玻璃纤维挤压和注射成型过程中的关键变量。本研究的实验结果将与社区共享，并将得到的模型广泛分发。本项目将培养研究生和本科生利用同步辐射进行实验岩石学研究的方法，并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.