Collaborative Research: High Pressure Experimental Melt Density

这项研究是一项高度协调的、多个实验室合作的工作，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。这些测量将极大地提高我们预测岩浆将漂浮到地球表面并以熔岩或形成火山的形式喷发的条件的能力。测量还将揭示岩浆密度太高而无法上升到地表的条件和深度，这些岩浆要么被中性浮力困住，要么进一步下沉到我们星球的深处。这些实验数据还将为了解地球在原始形成阶段分化为地壳、地幔和核心的方式提供新的见解。这项合作工作结合了实验技术，这些技术跨越了地球上存在的熔融和岩浆产生的整个压力和温度条件范围。最高压力将在加州理工大学冲击波实验室的动态压缩下进行，最高压力将在加州理工大学冲击波实验室的动态压缩下进行，中等压力将在新墨西哥大学的高压实验室在大型压力机的静态压缩下进行，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熔炉中利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。这个模型应该能够精确地描述上地幔、过渡带、下地幔和D“层中晶体/熔体密度交叉的位置。这一状态方程将用于全地幔岩浆海洋的分异模型，或用于确定现代核幔边界可能发生的硅酸盐熔融的化学和动力学。研究人员预计，这些数据还将为开发包含显式形态和/或非理想混合项的下一代熔体模型提供必要的基础。根据这一建议收集的数据将是未来所有高压熔体性质和火成岩分异研究的宝贵资源。以前从未将如此广泛的技术应用于一组常见的样本；这些互补的数据集将大大增强我们对地球上岩浆物理的了解。

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.