Elastic properties of carbonates at high pressures and temperatures

继续项目的目标仍然是确定高压和高温条件下碳酸盐的弹性波速数据，这些数据可用于评估地幔中碳酸盐组合的可探测性。项目的前三年主要研究方解石型结构的碳酸盐，这种结构从地壳到下地幔中部都很稳定。项目的后三年将重点关注新的高压碳酸盐岩，这些碳酸盐岩稳定在75 GPa和1400 K以上，因此可能位于下地幔的下部。项目将解决的科学问题有：(1)氧逸度对高压碳酸铁稳定性的影响是什么？这些相在地球深处预期的简化条件下是稳定的吗？(2) Mg在高压碳酸铁中的溶解度是多少？(3)在与地球深部有关的压力和温度下，压力、温度和成分对新含铁高压碳酸盐多晶形式的纵波速度和横波速度有什么影响？这些问题的答案将用于量化地球内部深处碳的可探测性。

The objectives of the continuation project remain to determine elastic wave velocity data for carbonates at high pressure and temperature conditions that can be used to assess the detectability of carbonated assemblages in the mantle. The first three years of the project were focused on carbonates with the calcite-type structure that are stable from the crust down to the mid part of the lower mantle. The second three years of the project will be focused on the new high-pressure carbonates that are stable above 75 GPa and 1400 K, hence potentially in the lower part of the lower mantle. The scientific questions that will be addressed by the project are the following: (1) What is the effect of oxygen fugacity on the stability of the high-pressure iron carbonates? Are these phases stable at the reduced conditions expected in the deep Earth? (2) What is the solubility of Mg in the high-pressure iron carbonates? (3) What is the effect of pressure, temperature and composition on the compressional and shear wave velocities of polycrystalline forms of the new iron-containing high-pressure carbonates at pressures and temperatures relevant for the deep Earth? The answers to these questions will be used to quantify the detectability of carbon in the deep Earth's interior.