Elasticity of Pyrope-Almandine-Grossular Garnet Solid Solution Series at High Pressure and Temperature using Ultrasonic Interferometry in Conjunction with Synchrotron Radiation.

地球内部最深的钻探被限制在15公里以内。因此，其内部的大部分无法直接取样，其结构和矿物成分只能使用间接证据来推断。努力了解地球的矿物学？的地幔综合了包括地震学、岩石学和地球化学在内的多个不同领域的信息，但是关于地球物理结构的最直接的信息是什么？地震学提供了关于弹性波速度和密度随深度变化的信息。 地震研究提供的模型表明，在地球410至660公里深处地震波迅速增加（速度跳跃或不连续），在不连续之间的区域（称为过渡带）速度梯度异常陡峭。 上地幔矿物的实验岩石学研究表明，它们在过渡带的压力和温度条件下转化为高压形式。 特别是玄武岩和橄榄岩中的主要上地幔矿物之一辉石，在上地幔下部和过渡带的压力和温度条件下转化为石榴石结构。在这项研究计划中，我们建议系统地测量的压力和温度的弹性性能的镁铝榴石（Mg3 Al 2Si 3 O 12？Py）-铁铝榴石（Fe_3Al_2Si_3 O_（12）-Alm）-钙铝榴石（Ca_3Al_2Si_3 O_（12）-Gr）固溶体。我们将使用斯托尼布鲁克高压实验室合成的样品、超声波干涉测量技术，并结合布鲁克海文国家实验室国家同步加速器光源的同步加速器X射线设施进行这些实验研究。

The deepest drilling into the interior of the Earth is limited to less than 15 km. Consequently, the bulk of its interior is inaccessible to direct sampling, and its structure and mineralogical composition can only be inferred using indirect evidence. Efforts to understand the mineralogy of the Earth?s mantle have combined information from several different fields including seismology, petrology and geochemistry, but the most direct information about the physical structure of the Earth?s deep interior comes from seismology which provides information about variation of the elastic wave velocity and density as a function of depth. Seismic studies have provided models that show rapid increases (velocity jumps or discontinuities) in the seismic waves at 410 to 660 km depths in the Earth and unusually steep velocity gradients in the region between the discontinuities, called the transition zone. Experimental petrological studies of minerals of the upper mantle show that they transform to high-pressure forms at the pressure and temperature conditions of the transition zone. In particular pyroxene, one of the dominant upper mantle minerals in basaltic and peridotitic rocks transforms into the garnet structure at pressure and temperature conditions of the lower regions of the upper mantle and transition zone. In this research program, we propose to systematically measure the pressure and temperature dependence of the elastic properties of the pyrope (Mg3Al2Si3O12?Py) - almandine (Fe3Al2Si3O12-Alm)-grossular (Ca3Al2Si3O12-Gr) solid solutions. We will conduct these experimental studies using specimens synthesized in the Stony Brook High Pressure Laboratory, the techniques of ultrasonic interferometry, and in conjunction with the synchrotron X-ray facilities at the National Synchrotron Light Source of the Brookhaven National Laboratory.