Collaborative Research: High Pressure Experimental Melt Density

这项研究是一项高度协调的、多实验室合作的努力，旨在测量地球内部融化过程中形成的岩浆的密度和可压缩性。这些测量结果将大大提高我们预测岩浆在什么条件下会浮升到地球表面，并以熔岩的形式喷发或形成火山的能力。这些测量还将揭示岩浆密度过大而无法上升到地表的条件和深度，它们要么被中性浮力困住，要么进一步沉入地球的深处。实验数据还将为地球在原始形成阶段划分为地壳、地幔和地核的方式提供新的见解。这项合作结合了实验技术，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大学高压实验室的大型压力机中进行静态压缩，近地表岩浆条件将在密歇根大学实验岩石学实验室的高温炉中使用超声波技术进行研究。新的数据将导致基于经验的状态方程和多组分硅酸盐熔体模型的发展。该模型可以精确地描述上地幔、过渡带、下地幔和D”层中晶体/熔体密度交叉的位置。这个状态方程将用于整个地幔岩浆海洋的分异模型，或用于确定现代核幔边界可能的硅酸盐熔融的化学和动力学。研究人员期望这些数据也将为下一代熔体模型的发展提供必要的基础，这些模型将包含明确的物种形成和/或非理想混合条件。在此建议下收集的数据将成为未来所有高压下熔体性质和火成岩分异研究的宝贵资源。以前从未有过如此广泛的技术被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部岩浆物理的理解。

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.