Collaborative Research: High Pressure Experimental Melt Density

这项研究是一项高度协调的多实验室合作努力，旨在测量地球内部熔化过程中形成的岩浆的密度和可压缩性。这些测量将极大地提高我们预测岩浆上升到地球表面并作为熔岩喷发或形成火山的条件的能力。测量还将揭示岩浆密度太大而无法上升到表面的条件和深度，它们要么被中性浮力捕获，要么进一步沉入我们星球的内部深处。实验数据还将为地球在原始形成阶段分化为地壳、地幔和地核的方式提供新的见解。这项合作努力结合了实验技术，涵盖了地球上存在的熔化和岩浆产生的整个压力和温度条件范围。模拟地幔最深区域的最高压力将在加州理工学院冲击波实验室的动态压缩下进行，中间压力将在新墨西哥州大学高压实验室的大型压力机中进行静态压缩，和近-在密歇根大学的实验室里，将用超声波技术在高温炉中研究地表岩浆的条件岩石学实验室新的数据将导致一个基于热力学的状态方程和多组分硅酸盐熔体模型的发展。该模型应允许精确表征上地幔、过渡带、下地幔和D”层中晶体/熔体密度交叉的位置。这个状态方程将被用于模型的分化的一个全地幔岩浆海洋或在定义化学和动力学可能的硅酸盐熔融在现代核幔边界。研究人员预计，这些数据还将为开发下一代熔体模型提供必要的基础，这些模型包括明确的物种形成和/或非理想的混合条件。根据这一建议收集的数据将是一个宝贵的资源，所有未来的研究熔体性质和火成岩分化在高压下。以前从未将如此广泛的技术应用于一组共同的样本;这些互补的数据集将大大提高我们对地球内岩浆物理学的理解。

This research is a highly coordinated, multi-lab, collaborative effort to measure the density and compressibility of magmas that form during melting in the Earth's interior. The measurements will greatly advance our ability to predict the conditions under which magmas will rise buoyantly to the Earth's surface and erupt as lavas or form volcanoes. The measurements will also reveal the conditions and depths where magmas are too dense to rise to the surface, remaining either trapped by neutral buoyancy, or sinking further into our planet's deep interior. The experimental data will also provide new insight into the way in which the Earth was differentiated into crust, mantle, and core during its primordial formation stage. The collaborative effort combines experimental techniques that span the entire range of pressure and temperature conditions that exist for melting and magma production in the Earth. The highest pressures, simulating the deepest regions of Earth's mantle, will be done under dynamic compression at the Caltech Shockwave Laboratory, the intermediate pressures will be carried out under static compression in large presses at the University of New Mexico's High Pressure Laboratory, and the near-surface magmatic conditions will be studied in high temperature furnaces with ultrasonic techniques at the University of Michigan's Experimental Petrology Laboratory. The new data will lead to the development of an empirically-based equation of state and a model for multicomponent silicate melts. This model should allow precise characterization of the locations of crystal/melt density crossovers in the upper mantle, transition zone, lower mantle, and D" layer. This equation of state will be used in models of differentiation of a whole-mantle magma ocean or in defining the chemistry and dynamics of possible silicate melting at the modern core-mantle boundary. The investigators expect that the data will also provide the essential basis for development of next-generation melt models that encompass explicit speciation and/or non-ideal mixing terms. The data gathered under this proposal will be a precious resource for all future studies of melt properties and igneous differentiation at high pressure. Never before have such a wide range of techniques been applied to a common set of samples; together the complementary data sets will significantly enhance our understanding of magma physics within our planet.